Article
To read the full-text of this research, you can request a copy directly from the authors.

Abstract

• The Mw 7.8 earthquake that struck the north‐east coast of the South Island of New Zealand in November 2016 caused extensive upheaval, of up to 6 m, over 110 km of coastline. Intertidal habitats were greatly affected with extensive die‐off of algal communities, high mortalities of benthic invertebrates, and greatly reduced ecosystem functioning, such as primary productivity. Only isolated pockets of key species remained in these areas, many of which were within protected areas around Kaikōura. • The loss of key species of algae and invertebrates fragmented marine populations and compromised connectivity and recovery processes because of the large dispersal distances needed to replenish populations. Severe sedimentation from terrestrial slips and erosion of newly exposed sedimentary rock compromised settlement and recruitment processes of marine species at many sites, even if distant propagules should arrive. • The combination of habitat disruption, loss of species and their functioning, and impacts on commercial fisheries, especially of abalone (Haliotis iris), requires multiple perspectives on recovery dynamics. • This paper describes these effects and discusses implications for the recovery of coastal ecosystems that include the essential involvement of mana whenua (indigenous Māori people), fishers, and the wider community, which suffered concomitant economic, recreational, and cultural impacts. These community perspectives will underpin the protection of surviving remnants of intertidal marine populations, the potential use of restoration techniques, and ultimately a successful socio‐ecological recovery.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the authors.

... It also occurs primarily on the most wave-exposed rocky reef habitats. Not only has this species been greatly reduced by marine heat waves that caused additional localised ex-tinctions [1], but large-scale coastal uplift from a 7.8 magnitude earthquake [13][14][15] severely affected populations, causing complete loss across uplifted rocky reef habitats [16]. These impacts occurred over 130 km of a sparsely inhabited, very heterogenous coastline featuring platforms, rocky outcrops and boulder fields that made in-situ sampling difficult or impossible in many places. ...
... Perhaps first and foremost is the very highly localised and patchy diversity evident in nearshore marine systems [24]. In the focal area, over 200 species have been recorded, and there is an average of around 20 species per square meter in the lower intertidal zone [16]. The varying sizes of individuals of each species, ranging from sub-cm to m, and the layering of their canopies [25] render them difficult or impossible to see in their entirety from above. ...
... This paper outlines the utility, limitations and caveats to the use of drones in monitoring vulnerable marine rocky reef habitats and proposes a consistent standardised approach to the capture of imagery and validation samples to ensure that such imagery meets the requirements of agencies tasked with management and conservation of vulnerable or threatened species. We use two examples to illustrate the utility of drones for conservation management: (1) The 2016 Kaikōura earthquake, which shifted relative sea levels, caused mass mortality of key habitat-forming macroalgae (especially of the southern bull kelp species), and shifted assemblages to ephemeral red and green algae [16,32]; and (2) highly wave-exposed rocky reef platforms located on the West Coast of New Zealand. ...
Article
Full-text available
Coastal marine ecosystems are under stress, yet actionable information about the cumulative effects of human impacts has eluded ecologists. Habitat-forming seaweeds in temperate regions provide myriad irreplaceable ecosystem services, but they are increasingly at risk of local and regional extinction from extreme climatic events and the cumulative impacts of land-use change and extractive activities. Informing appropriate management strategies to reduce the impacts of stressors requires comprehensive knowledge of species diversity, abundance and distributions. Remote sensing undoubtedly provides answers, but collecting imagery at appropriate resolution and spatial extent, and then accurately and precisely validating these datasets is not straightforward. Comprehensive and long-running monitoring of rocky reefs exist globally but are often limited to a small subset of reef platforms readily accessible to in-situ studies. Key vulnerable habitat-forming seaweeds are often not well-assessed by traditional in-situ methods, nor are they well-captured by passive remote sensing by satellites. Here we describe the utility of drone-based methods for monitoring and detecting key rocky intertidal habitat types, the limitations and caveats of these methods , and suggest a standardised workflow for achieving consistent results that will fulfill the needs of managers for conservation efforts.
... Recently, the habitat-cascade concept has highlighted that primary habitatforming organisms also promote sequential habitat formation that can increase biodiversity through the provision of more or novel niche space and supplies of food (Thomsen et al., 2018;Gribben et al., 2019). Such primary habitat-forming organisms have been decimated in many parts of the world by anthropogenic activities (Halpern et al., 2008) and, occasionally, natural mega-disturbances including earthquakes and volcanic activity (Bodin and Klinger, 1986;Castilla, 1988;Castilla and Oliva, 1990;Castilla et al., 2010;Williams et al., 2010;Schiel et al., 2019). However, the implications of the combined loss of both primary and sequential habitat formers following severe disturbances are poorly understood because most studies have only focused on losses of primary habitat formers (Halpern et al., 2008). ...
... Building a framework to predict impacts on shallow coastal systems from mega-disturbances is further complicated because underpinning processes operate over very different spatio-temporal scales. For example, following instantaneous uplifts, smaller scale processes like herbivory, competition, light availability and desiccation stress are dramatically altered in concert with larger scale processes like limited propagule pressure and disrupted population connectivity, (Castilla and Oliva, 1990;Waters et al., 2013;Schiel et al., 2019), making it challenging to predict survival and recovery trajectories. Nevertheless, case studies that document ecological impacts from mega-disturbances will increase our collective knowledge about what types of organisms are particularly sensitive (or resilient) and whether micro-habitats can modify effects. ...
... As a result, this region will likely support fewer and smaller populations of Hormosira, Notheia and C. torulosa in the future. Another issue facing the Kaikōura coastline is accelerated erosion of newly uplifted rock, and the subsequent enhanced sediment deposition in the intertidal zone (Schiel et al., 2018;Schiel et al., 2019), resulting in either bare (and continually eroding) rock or gravel substrates at possible colonisation sites. Elsewhere along the uplifted coast, small green ephemeral seaweeds (Ulva spp.) have become abundant in lower to mid zones (Schiel et al., 2018;Schiel et al., 2019) and these seaweeds may compete for space with recolonizing primary habitat formers, at least in the short term (Sousa, 1979). ...
Article
Large scale disturbances associated with anthropogenic activities or natural disasters can destroy primary habitat-forming species like corals, seagrasses and seaweeds. However, little research has documented if and on how large-scale disturbances affect secondary habitat formers, such as epiphytes and small animals that depend on biogenic habitats. Here we quantified changes in the abundance of both primary and secondary habitat-forming seaweeds as well as seaweed-associated invertebrates before and after a 7.8 Mw earthquake that uplifted four intertidal reef platforms by 0.5-0.8 m on the Kaikōura coastline in New Zealand. We found that the dominant primary (Hormosira banksii and three Cystophora species) and secondary (obligate and facultative epiphytes) habitat-forming seaweeds were all decimated and that mobile seaweed-associated animals were significantly less abundant (per gram of seaweed biomass) after the earthquake. Importantly, epiphytes became functionally extinct after the earthquake, as less than 0.1% of the populations survived, whereas primary habitat formers survived in suitable microhabitats, like water covered tide-pools and tidal channels. Based on these results we also discuss possible cascading ecosystem effects and future scenarios for natural recovery vs. active restoration that could speed up the recovery of habitat-forming species on degraded reefs.
... Recently, the habitat cascade concept has highlighted that primary habitat-forming organisms also promote sequential habitat formation that can increase biodiversity through the provision of more or novel niche space and supplies of food Gribben et al., 2019). Such primary habitat-forming organisms have been decimated in many parts of the world by anthropogenic activities (Halpern et al., 2008) and, occasionally, natural mega-disturbances including earthquakes and volcanic activity (Bodin and Klinger, 1986;Castilla, 1988;Castilla and Oliva, 1990;Castilla et al., 2010;Williams et al., 2010;Schiel et al., 2019). However, the implications of the combined loss of both primary and sequential habitat formers following severe disturbances are poorly understood because most studies have only focused on losses of primary habitat formers (Halpern et al., 2008). ...
... Building a framework to predict impacts on shallow coastal systems from mega-disturbances is further complicated because underpinning processes operate over very different spatio-temporal scales. For example, following instantaneous uplifts, smaller scale processes like herbivory, competition, light availability and desiccation stress are dramatically altered in concert with larger scale processes like limited propagule pressure and disrupted population connectivity, (Castilla and Oliva, 1990;Waters et al., 2013;Schiel et al., 2019), making it challenging to predict survival and recovery trajectories. Nevertheless, case studies that document ecological impacts from mega-disturbances will increase our collective knowledge about what types of organisms are particularly sensitive (or resilient) and whether micro-habitats can modify effects. ...
... As a result, this region will likely support fewer and smaller populations of Hormosira, Notheia and C. torulosa in the future. Another issue facing the Kaikōura coastline is accelerated erosion of newly uplifted rock, and the subsequent enhanced sediment deposition in the intertidal zone (Schiel et al., , 2019, resulting in either bare (and continually eroding) rock or gravel substrates at possible colonisation sites. Elsewhere along the uplifted coast, small green ephemeral seaweeds (Ulva spp.) have become abundant in lower to mid zones (Schiel et al., , 2019 and these seaweeds may compete for space with recolonizing primary habitat formers, at least in the short term (Sousa, 1979). ...
... This is a high-energy coastline with near-constant oceanic swells, generally turbid inshore waters, and rocky reefs and boulder fields interspersed with sand and gravel. The immediate effect of the earthquake on nearshore marine species was high mortality of algal beds and their resident species (Schiel et al. 2019). There were 3 potentially negative effects on pāua populations. ...
... There were 3 potentially negative effects on pāua populations. The most evident was in higher uplift areas, where entire reef complexes were permanently lifted above the high water mark, causing mortality of adult pāua, as tens of thousands were stranded at many sites (Schiel et al. 2019). The second potential impact was failure of post-earthquake recruitment because of reduced adult populations or sublethal effects on surviving pāua. ...
... Unfortunately, very little quantitative data exist in the study area for pre-earthquake pāua populations, habitat structure and distribution of juvenile habitat. However, at one site with 0.2 m of uplift for which pre-and post-earthquake data were available, an estimated 45% of juvenile habitat was lost by being pushed upwards into a harsher tidal zone (Schiel et al. 2019) and, across the region, around 21% of commercially fished reefs were destroyed through uplift or burial by sediment (P. Neubauer unpubl.). ...
Article
The 2016 Mw7.8 Kaikōura earthquake lifted 140km of coastline on New Zealand’s South Island by up to 6.4m. This caused extensive mortality and destruction of habitat critical for early life stages of blackfoot abalone, Haliotis iris (called pāua), a species of cultural and commercial importance. The fishery for pāua was closed, at considerable financial loss to local communities. This study determined the extent to which habitats and populations of pāua survived along the coastline. With aerial imaging, the coast was categorised into broad habitats at a 10m scale. This was used to select areas for in situ assessments of pāua populations and specific habitat features at 26 sites over 1.5 years. We quantified key habitat features to identify correlates and potential drivers of pāua abundance and distribution. We found that despite extensive habitat degradation from uplift, erosion and sedimentation, abundant pāua in size classes <30mm shell length indicated successful settlement and juvenile recruitment had occurred soon after the earthquake. Pāua up to 170mm shell length had also survived in shallow habitats. A generalized linear mixed model showed that pāua were negatively influenced by the degree of uplift, and positively associated with the cover of unconsolidated layered rocks. Juvenile pāua (<85mm) abundance was greatest at sites with <2.5m of uplift. There was further recruitment 1.5 years post-earthquake and evidence of good growth of the previous year’s cohort. Despite major disruption to this coastline, there appears to be very good potential for recovery of pāua and the fishery.
... With a shallow hypocentre of 15 km and many complex inshore and offshore faults, slips, vertical displacements, coastal uplifts of up to 6.5 m, and >2,000 aftershocks in only 3 days, four of which had magnitude >6 M w , these earthquakes directly affected c. 130 km coastline Hamling et al., 2017;Xu et al., 2018). Over the next few months, we observed extensive loss of habitat-forming seaweeds and slow-moving benthic invertebrates, with associated losses of primary productivity, biogenic habitat and altered food webs Schiel et al., 2019;Thomsen et al., 2020). A year later, over the austral summer of 2017/18, New Zealand experienced the strongest marine heatwave on record (Salinger et al., 2019(Salinger et al., , 2020. ...
... A year later, over the austral summer of 2017/18, New Zealand experienced the strongest marine heatwave on record (Salinger et al., 2019(Salinger et al., , 2020. This large-scale extreme marine event, coincided with high air temperatures, low tides and calm sea conditions (Salinger et al., 2020;, and had widespread effects such as high glacial melting, losses of habitat-forming seaweeds, and movement of fish into warm waters (Salinger et al., 2020;Schiel et al., 2019;Tait et al., 2021;. Following Hobday et al. (2018), this large-scale temperature anomaly was named the "Tasman Sea 2017/18 marine heatwave" Salinger et al., 2019). ...
... The mid band was a bright "green" because it was dominated by the ephemeral green algae Ulva spp. (Figure 1b,g) Schiel et al., 2019). ...
Article
Full-text available
Aim Ecologists traditionally study how contemporary local processes, such as biological interactions and physical stressors, affect the distribution and abundance of organisms. By comparison, biogeographers study the distribution of the same organisms, but focus on historic, larger-scale processes that can cause mass mortalities, such as earthquakes. Here we document cascading effects of rare biogeographical (seismic) and more common ecological (temperature-related) processes on the distribution and abundances of coastal foundation species. Location Intertidal wave-exposed rocky reefs around Kaikōura, New Zealand, dominated by large, long-lived, and iconic southern bull kelps (Durvillaea antarctica and Durvillaea willana). Methods In November 2016, a 7.8 Mw earthquake uplifted the coastline around Kaikōura by up to 2 m, and a year later the region experienced the hottest summer on record. Extensive sampling of intertidal communities over 15 km coastline were done shortly after the earthquake and heatwaves and 4 years after the earthquake. Results Durvillaea lost 75% of its canopy to uplift and the heatwaves reduced canopies that had survived the uplift by an additional 35%. The survey done 4 years after the earthquake showed that Durvillaea had not recovered and that the intertidal zone in many places now was dominated by small turfs and foliose seaweed. Main conclusions Cascading impacts from seismic uplift and heatwaves have destroyed populations of Durvillaea around Kaikōura. Surviving smaller and sparser Durvillaea patches will likely compromise capacity for self-replacement and lower resilience to future stressors. These results are discussed in a global biogeographical-ecological context of seismic activity and extreme heatwaves and highlight that these events, which are not particularly rare in a geological context, may have common long-lasting ecological legacies.
... Southern bull kelps are classic primary foundation species because their large, heavy fronds control community structures through whiplash and shading, and their complex perennial holdfast provides biogenic habitats to highly diverse invertebrate communities [68,70,[75][76][77][78]. However, although the ecology of southern bull kelps as a primary foundation species has been studied in detail (see [79] and references therein), and diebacks following seismic uplifts, marine heatwaves and storms have been described [52,[80][81][82], it is unknown whether any alternative foundation species replace lost Durvillaea spp. ...
... The future of some New Zealand Durvillaea spp. populations is presently in doubt due to heatwave-induced die-backs and dramatic changes in shore height following seismic uplift in central New Zealand [52,80]. Durvillaea spp. ...
Article
Full-text available
Southern bull kelps (Durvillaea spp., Fucales) are ‘primary’ foundation species that control community structures and ecosystem functions on temperate wave-exposed rocky reefs. However, these large foundation species are threatened by disturbances and stressors, including invasive species, sedimentation and heatwaves. It is unknown whether ‘alternative’ foundation species can replace lost southern bull kelps and its associated communities and networks. We compared community structure (by quantifying abundances of different species) and attachment-interaction networks (by quantifying which species were attached to other species) among plots dominated by Durvillaea spp. and plots where Durvillaea spp. were lost either through long-term repeated experimental removals or by recent stress from a marine heatwave. Long-term experimental removal plots were dominated by ‘alternative’ foundation species, the canopy-forming Cystophora spp. (Fucales), whereas the recent heatwave stressed plots were dominated by the invasive kelp Undaria pinnatifida (Laminariales). A network analysis of attachment interactions showed that communities differed among plots dominated by either Durvillaea spp., Cystophora spp. or U. pinnatifida, with different relationships between the primary, or alternative, foundation species and attached epiphytic ‘secondary’ foundation species. For example, native Cystophora spp. were more important as hosts for secondary foundation species compared to Durvillaea spp. and U. pinnatifida. Instead, Durvillaea spp. facilitated encrusting algae, which in turn provided habitat for gastropods. We conclude that (a) repeated disturbances and strong stressors can reveal ecological differences between primary and alternative foundation species, (b) analyses of abundances and attachment-networks are supplementary methods to identify linkages between primary, alternative and secondary foundation species, and (c) interspersed habitats dominated by different types of foundation species increase system-level biodiversity by supporting different species-abundance patterns and species-attachment networks.
... Fine sediment has been carried to the sea, and has smothered and suffocated tidal to intertidal shallow-marine ecosystems (Schiel et al., 2019). Coupled high sedimentation and coastal uplift has caused the biogeomorphology of the region to change dramatically following the earthquake (Schiel et al., 2019). ...
... Fine sediment has been carried to the sea, and has smothered and suffocated tidal to intertidal shallow-marine ecosystems (Schiel et al., 2019). Coupled high sedimentation and coastal uplift has caused the biogeomorphology of the region to change dramatically following the earthquake (Schiel et al., 2019). The ongoing stability of marine species has the potential to indicate sedimentation rates and the effect that the geomorphology of the area has on marine populations. ...
Preprint
Full-text available
Abstract. Mixed-method bicultural research in Aotearoa New Zealand, including the weaving of Indigenous and other knowledges, is experiencing a resurgence within many academic disciplines. However, mātauranga Māori – the knowledge, culture, value and worldview of the Indigenous peoples of Aotearoa New Zealand – and Te Ao Māori, the Māori world, is poorly represented within geomorphological investigations. Here, we review existing efforts to include Indigenous knowledge in geologic and geomorphic studies from the international research community and provide an overview of the current state of mātauranga Māori within research endeavours in Aotearoa New Zealand. We review three theoretical frameworks for including mātauranga Māori in research projects and three models for including Māori values within research. We identify direct benefits to geomorphology and discuss how these frameworks and models can be adapted for use with Indigenous knowledge systems outside of Aotearoa New Zealand. The aim of this review is to encourage geomorphologists around the world to engage with local Indigenous peoples to develop new approaches to geomorphic research. In Aotearoa New Zealand, we hope to inspire geomorphologists to embark on research journeys that engender genuine partnership with Māori and that promote toitū te mātauranga, the enduring protection, promotion and respect of mātauranga Māori.
... Our demographic modelling supports the geologically derived hypothesis [26] that the Akatore Fault rupture event around 800 years ago caused widespread extirpation of intertidal kelps from the area (electronic supplementary material, table S8), consistent with direct observations of recent uplift events elsewhere [23,36]. Durvillaea kelps are habitat-forming species, hosting diverse epibiotic taxa, and thus their re-establishment can play an important role in post-disturbance recovery of southern rocky intertidal ecosystems [36]. ...
... Our demographic modelling supports the geologically derived hypothesis [26] that the Akatore Fault rupture event around 800 years ago caused widespread extirpation of intertidal kelps from the area (electronic supplementary material, table S8), consistent with direct observations of recent uplift events elsewhere [23,36]. Durvillaea kelps are habitat-forming species, hosting diverse epibiotic taxa, and thus their re-establishment can play an important role in post-disturbance recovery of southern rocky intertidal ecosystems [36]. Demographic modelling suggests that D. poha started to colonize the uplifted habitats earlier than D. antarctica, but took longer to expand its range than D. antarctica ( figure 3; electronic supplementary material, table S8). ...
Article
Full-text available
Theory suggests that catastrophic earth-history events can drive rapid biological evolution, but empirical evidence for such processes is scarce. Destructive geological events such as earthquakes can represent large-scale natural experiments for inferring such evolutionary processes. We capitalized on a major prehistoric (800 yr BP) geological uplift event affecting a southern New Zealand coastline to test for the lasting genomic impacts of disturbance. Genome-wide analyses of three co-distributed keystone kelp taxa revealed that post-earthquake recolonization drove the evolution of novel, large-scale intertidal spatial genetic ‘sectors’ which are tightly linked to geological fault boundaries. Demographic simulations confirmed that, following widespread extirpation, parallel expansions into newly vacant habitats rapidly restructured genome-wide diversity. Interspecific differences in recolonization mode and tempo reflect differing ecological constraints relating to habitat choice and dispersal capacity among taxa. This study highlights the rapid and enduring evolutionary effects of catastrophic ecosystem disturbance and reveals the key role of range expansion in reshaping spatial genetic patterns.
... The earthquake caused over 20 000 landslides that delivered mass amounts of sediment to river catchments (Massey et al., 2018). Fine sediment has been carried to the sea and has smothered and suffocated tidal to intertidal shallow-marine ecosystems (Schiel et al., 2019). High sedimentation coupled with coastal uplift has caused the biogeomorphology of the region to change dramatically following the earthquake (Schiel et al., 2019). ...
... Fine sediment has been carried to the sea and has smothered and suffocated tidal to intertidal shallow-marine ecosystems (Schiel et al., 2019). High sedimentation coupled with coastal uplift has caused the biogeomorphology of the region to change dramatically following the earthquake (Schiel et al., 2019). The ongoing stability of marine species has the potential to indicate sedimentation rates and the effect that the geomorphology of the area has on marine populations. ...
Article
Full-text available
Mixed-method bicultural research in Aotearoa New Zealand, including the weaving of Indigenous and other knowledge, is emerging within many academic disciplines. However, mātauranga Māori (the knowledge, culture, values, and world view of the Indigenous peoples of Aotearoa New Zealand) and Te Ao Māori (the Māori world) is poorly represented within geomorphological investigations. Here, we review international efforts to include Indigenous knowledge in geologic and geomorphic studies and provide an overview of the current state of mātauranga Māori within research endeavours in Aotearoa New Zealand. We review three theoretical frameworks (i.e. methodologies) for including mātauranga Māori in research projects and three models (i.e. methods) for including Māori values within research. We identify direct benefits to geomorphology and discuss how these frameworks and models can be adapted for use with Indigenous knowledge systems outside of Aotearoa New Zealand. The aim of this review is to encourage geomorphologists around the world to engage with local Indigenous peoples to develop new approaches to geomorphic research. In Aotearoa New Zealand, we hope to inspire geomorphologists to embark on research journeys in genuine partnership with Māori that promote toitū te mātauranga – the enduring protection, promotion and respect of mātauranga Māori.
... The onshore portion of the Akatore fault has, in the past millennium, uplifted ~30 km of the coast by 2-3 m above the high-tide zone (Litchfield & Norris, 2000). Recent ecological studies of tectonically active shores elsewhere have shown that uplift events approaching this magnitude are sufficient to extirpate habitat-forming macroalgae and their associated epibiota, thus creating empty intertidal habitats for recolonization Jaramillo et al., 2012;Schiel et al., 2019;Thomsen et al., 2020Thomsen et al., , 2021. In the case of the Akatore fault, radiocarbon dating has constrained the most recent rupture event to 800-1000 years BP (Craw et al., 2021;Litchfield & Norris, 2000). ...
... Phylogeographic model selection using the narrow time prior showed higher power in distinguishing between different recolonization routes (Table S5). (Castilla, 1988;Clark et al., 2017;Ortega et al., 2014;Schiel et al., 2019). As a case in point, New Zealand's 2016 Kaikoura earthquake ( Figure 1a,c) led to major changes in the configuration of rocky reefs, and dramatic reductions in populations of numerous intertidal habitat-forming seaweeds and associated invertebrates (Thomsen et al., 2020. ...
Preprint
Full-text available
The elimination of lower trophic levels following severe habitat disturbance can trigger new community assembly processes. However, little is known about how past habitat disturbances have affected codependent evolution of trophically-linked and closely interacting taxa. Using genome-wide analysis of a macroalgal community affected by ancient catastrophic coastal uplift, we track the ecological dynamics of past co-dispersal and co-diversification among obligate interacting taxa. Our study reveals rapid and concerted reassembly of an intertidal community following disturbance. Specifically, hierarchical co-demographic analyses of multispecies genomic data support synchronous expansions of four strictly intertidal species in the wake of tectonic disturbance. These data show that tight algal-epifaunal links underpin parallel demographic responses across distinct trophic levels. These results highlight that high-resolution comparative genomic data can elucidate the strength of obligate ecological interactions, and the evolutionary dynamics of past co-dispersal and co-diversification in post-disturbance communities.
... The associated fault ruptures were among the most complex ever recorded [27][28][29] and manifested as a highly variable pattern of ground-level displacement but mostly in the direction of uplift [30]. These physical impacts led to widespread reassembly of ecological communities on rocky shorelines [31][32][33]. Associated social and economic effects included new landscape configurations altering access to the coast, and the closure of commercial fisheries and recreational harvesting of seaweeds and shellfish [34,35]. ...
... Once populations of large algae are removed, recovery can be slow where reproductive adults become widely separated due to connectivity effects between suitable habitat for re-colonisation and the remaining recruitment sources [32]. A wide range of processes are likely hindering recovery in the post-earthquake landscape, including the now widely dispersed adult populations, the relatively short distance of propagule dispersal (usually only tens of meters), and limited ability of drifting detached reproductive algae to reach sites [37]. ...
Article
Full-text available
Widespread mortality of intertidal biota was observed following the 7.8 Mw Kaikoura earthquake in November 2016. To understand drivers of change and recovery in nearshore ecosystems, we quantified the variation in relative sea-level changes caused by tectonic uplift and evaluated their relationships with ecological impacts with a view to establishing the minimum threshold and overall extent of the major effects on rocky shores. Vertical displacement of contiguous 50 m shoreline sections was assessed using comparable LiDAR data to address initial and potential ongoing change across a 100 km study area. Co-seismic uplift accounted for the majority of relative sea-level change at most locations. Only small changes were detected beyond the initial earthquake event, but they included the weathering of reef platforms and accumulation of mobile gravels that continue to shape the coast. Intertidal vegetation losses were evident in equivalent intertidal zones at all uplifted sites despite considerable variation in the vertical displacement they experienced. Nine of ten uplifted sites suffered severe (>80%) loss in habitat-forming algae and included the lowest uplift values (0.6 m). These results show a functional threshold of c.1/4 of the tidal range above which major impacts were sustained. Evidently, compensatory recovery has not occurred—but more notably, previously subtidal algae that were uplifted into the low intertidal zone where they ought to persist (but did not) suggests additional post-disturbance adversities that have contributed to the overall effect. Continuing research will investigate differences in recovery trajectories across the affected area to identify factors and processes that will lead to the regeneration of ecosystems and resources.
... Pacific Conservation Biology C study period, but they have been recorded in the past. All of the study sites, with the exception of Oaro, were affected by tectonic uplift of between 0.6 and 0.9 m during the 2016 Kaikōura earthquake (Clark et al. 2017;Schiel et al. 2019), which has generally increased the elevation of these lagoons and lower river reaches in relation to sea level. In the case of Lyell Creek and Middle Creek high spring tides would occasionally inundate the lower reaches pre-earthquake, but this no longer occurs since the uplift event (P. ...
Article
Full-text available
Galaxias maculatus is a declining amphidromous fish that supports New Zealand’s culturally-important whitebait fisheries targeting the migratory juvenile stage. Spawning ground protection and rehabilitation is required to reverse historical degradation and improve fisheries prospects alongside conservation goals. Although spawning habitat has been characterised in tidal rivers, there has been no previous study of spawning in non-tidal rivermouths that are open to the sea. We assessed seven non-tidal rivers over four months using census surveys to quantify spawning activity, identify environmental cues, and characterise fundamental aspects of the biogeography of spawning grounds. Results include the identification of compact spawning reaches near the rivermouths. Spawning events were triggered by periods of elevated water levels that were often of very short duration suggesting that potential lunar cues were less important, and that rapid fish movements had likely occurred within the catchment prior to spawning events. Spawning grounds exhibited consistent vertical structuring above typical low-flow levels, with associated horizontal translation away from the river channel leading to increased exposure to anthropogenic stressors and associated management implications for protecting the areas concerned. These consistent patterns provide a sound basis for advancing protective management at non-tidal rivermouths. Attention to flood management, vegetation control, and bankside recreational activities is needed and may be assisted by elucidating the biogeography of spawning grounds. The identification of rapid responses to environmental cues deserves further research to assess floodplain connectivity aspects that enable fish movements in emphemeral flowpaths, and as a confounding factor in commonly-used fish survey techniques.
... The project has documented a wide range of biological and physical impacts in the coastal environment over the past four years. These include the widespread mortality of habitat-forming species that support characteristic ecosystems and natural resources on the coast (Alestra et al. 2021;Schiel et al. 2019;Tait et al. 2021). Due to the popularity of the coast for recreational use, interactions between people and the recovering environment are an important influence on recovery processes. ...
Technical Report
Full-text available
This report contributes to a collaborative project between the Marlborough District Council (MDC) and University of Canterbury (UC) which aims to help protect and promote the recovery of native dune systems on the Marlborough coast. It is centred around the mapping of dune vegetation and identification of dune protection zones for old-growth seed sources of the native sand-binders spinifex (Spinifex sericeus) and pīngao (Ficinia spiralis). Both are key habitat-formers associated with nationally threatened dune ecosystems, and pīngao is an important weaving resource and Ngāi Tahu taonga species. The primary goal is to protect existing seed sources that are vital for natural regeneration following major disturbances such as the earthquake event. Several additional protection zones are also identified for areas where new dunes are successfully regenerating, including areas being actively restored in the Beach Aid project that is assisting new native dunes to become established where there is available space.
... Of particular importance economically was the great mortality of NZ black-foot abalone, Haliotis iris (Gerrity et al., 2020). Tens of thousands of individuals were propelled upwards beyond the tidal influence where they suffered severe heat stress and died (picture in Schiel et al., 2019). Their recruitment habitats among small rocks in the lowest intertidal and upper subtidal zone were also uplifted along much of the coast, causing concerns about future recruitment rates. ...
Article
Full-text available
Understanding the resilience and recovery processes of coastal marine ecosystems is of increasing importance in the face of increasing disturbances and stressors. Large-scale, catastrophic events can re-set the structure and functioning of ecosystems, and potentially lead to different stable states. Such an event occurred in south-eastern New Zealand when a Mw 7.8 earthquake lifted the coastline by up to 6 m. This caused widespread mortality of intertidal algal and invertebrate communities over 130 km of coast. This study involved structured and detailed sampling of three intertidal zones at 16 sites nested into four degree of uplift (none, 0.4–1, 1.5–2.5, and 4.5–6 m). Recovery of large brown algal assemblages, the canopy species of which were almost entirely fucoids, were devastated by the uplift, and recovery after 4 years was generally poor except at sites with < 1 m of uplift. The physical infrastructural changes to reefs were severe, with intertidal emersion temperatures frequently above 35°C and up to 50°C, which was lethal to remnant populations and recruiting algae. Erosion of the reefs composed of soft sedimentary rocks was severe. Shifting sand and gravel covered some lower reef areas during storms, and the nearshore light environment was frequently below compensation points for algal production, especially for the largest fucoid Durvillaea antarctica/poha. Low uplift sites recovered much of their pre-earthquake assemblages, but only in the low tidal zone. The mid and high tidal zones of all uplifted sites remained depauperate. Fucoids recruited well in the low zone of low uplift sites but then were affected by a severe heat wave a year after the earthquake that reduced their cover. This was followed by a great increase in fleshy red algae, which then precluded recruitment of large brown algae. The interactions of species’ life histories and the altered physical and ecological infrastructure on which they rely are instructive for attempts to lessen manageable stressors in coastal environments and help future-proof against the effects of compounded impacts.
... All studies reviewed found a strong negative relationship between benthic sediment accumulation and kelp survival with near total extirpation of floating and nonfloating kelp species after the introduction of large volumes of sediment from mine tailings ; landslides (Schiel et al., 2019); discharged sewage effluent (Stull, 1996); and in the Salish Sea, dam removal (Rubin et al., 2017) ( Figure 5). ...
Article
Full-text available
Kelp forests are in decline across much of their range due to place-specific combinations of local and global stressors. Declines in kelp abundance can lead to cascading losses of biodiversity and productivity with far-reaching ecological and socioeconomic consequences. The Salish Sea is a hotspot of kelp diversity where many species of kelp provide critical habitat and food for commercially, ecologically, and culturally important fish and invertebrate species. However, like other regions, kelp forests in much of the Salish Sea are in rapid decline. Data gaps and limited long-term monitoring have hampered attempts to identify and manage for specific drivers of decline, despite the documented urgency to protect these important habitats. To address these knowledge gaps, we gathered a focus group of experts on kelp in the Salish Sea to identify perceived direct and indirect stressors facing kelp forests. We then conducted a comprehensive literature review of peer-reviewed studies from the Salish Sea and temperate coastal ecosystems worldwide to assess the level of support for the pathways identified by the experts, and we identified knowledge gaps to prioritize future research. Our results revealed major research gaps within the Salish Sea and highlighted the potential to use expert knowledge for making informed decisions in the region. We found high support for the pathways in the global literature, with variable consensus on the relationship between stressors and responses across studies, confirming the influence of local ecological, oceanographic, and anthropogenic contexts and threshold effects on stressor–response relationships. Finally, we prioritized areas for future research in the Salish Sea. This study demonstrates the value expert opinion has to inform management decisions. These methods are readily adaptable to other ecosystem management contexts, and the results of this case study can be immediately applied to kelp management.
... This concern is particularly pertinent to New Zealand as it lies on the Ring of Fire and the Indo-Pacific plate subduction zone, and is therefore prone to volcanic and tectonic disruption. As shown by Schiel et al. (2019) (Whittaker & Fernandez-Palacios, 2007), although little work appears to have been conducted on freshwater-marine ecosystem linkages under a changing climate. ...
Article
Island nations such as New Zealand provide valuable insights into conservation challenges posed by strongly connected and recently developed or exploited freshwater and marine ecosystems. The narrow land mass, high rainfall, and steep terrain of New Zealand, like many other island nations, mean that land‐based stressors are rapidly transferred to freshwater habitats and propagated downstream to coastal environments via short, fast‐flowing river systems. Freshwater and marine environments are linked through faunal life histories; for example, diadromous fishes, many of which are considered threatened or at risk of extinction, and require cross‐ecosystem conservation to ensure survival of critical life stages and persistence of source populations. Recent invasions of marine and freshwater environments by non‐indigenous species reveal rapid impacts on a naïve biota and highlight conservation conundrums caused by management aimed at enhancing native biodiversity by improving habitat connectivity. Understanding and managing interconnected freshwater and marine ecosystems is a key concept for local indigenous communities, and highlights socio‐cultural connectivity and sustainable local harvesting of traditional resources as key elements of contemporary marine and freshwater conservation planning in New Zealand.
... Earthquake uplift can therefore cause mortality in D. antarctica if it is sufficient to move individuals above the high tide mark. For example, shores uplifted by several metres during the 2010 Chilean and 2016 Kaikōura earthquakes resulted in large-scale die-offs of intertidal Durvillaea (Castilla et al., 2010;Clark et al., 2017;Peters et al., 2020;Schiel et al., 2019;Tait et al., 2021;Thomsen et al., 2021 (Fraser, Davies, et al., 2018). ...
Article
Full-text available
Large‐scale disturbance events have the potential to drastically reshape biodiversity patterns. Notably, newly vacant habitat space cleared by disturbance can be colonised by multiple lineages, which can lead to the evolution of distinct spatial ‘sectors’ of genetic diversity within a species. We test for disturbance‐driven sectoring of genetic diversity in intertidal southern bull kelp, Durvillaea antarctica (Chamisso) Hariot following the high‐magnitude 1855 Wairarapa earthquake in New Zealand. Specifically, we use genotyping‐by‐sequencing (GBS) to analyse fine‐scale population structure across the uplift zone and apply machine learning to assess the fit of alternative recolonisaton models. Our analysis reveals that specimens from the uplift zone carry distinctive genomic signatures potentially linked to post‐earthquake recolonisation processes. Specifically, our analysis identifies two parapatric spatial‐genomic sectors of D. antarctica at Turakirae Head, which experienced the most dramatic uplift. Based on phylogeographic modelling, we infer that bull kelp in the Wellington region was likely a source for recolonisation of the heavily uplifted Turakirae Head coastline, via two parallel, eastward recolonisation events. By identifying multiple parapatric genotypic sectors within a recently recolonised coastal region, the current study provides support for the hypothesis that competing lineage expansions can generate striking spatial structuring of genetic diversity, even in highly dispersive taxa.
Technical Report
Full-text available
The 7.8 magnitude Kaikōura earthquake in November 2016 caused extensive uplift along approximately 130 km of the north-eastern coastline of the South Island of New Zealand. This resulted in widespread mortality of marine organisms and alteration to the community structure and, in many places, the integrity of intertidal and subtidal rocky reefs. The disturbance adversely affected important taonga and habitat-forming species, such as pāua (Haliotis iris) and bull kelp (Durvillaea spp.), prompting an emergency ban on harvesting shellfish and seaweeds that is still in place. This report describes the results of nearshore reef surveys done at long-term monitoring sites between 2.5 and 3.5 years after the earthquake to assess the community structure and trajectories of recovery of rocky reef communities. A major goal of this work is to provide detailed information for underpinning informed decisions about re-opening fishery closures. The sites were first surveyed in 2017 as part of the Ministry for Primary Industries (MPI) Kaikōura Earthquake Marine Recovery Package. The new results included in this report relate to the fifth and fourth rounds of intertidal and subtidal surveys, respectively. These include (i) intertidal surveys done in November 2019 at 16 sites along the coastline between Oaro and Cape Campbell, encompassing uplift levels between approximately 0 and 6 metres; and (ii) subtidal surveys at 6 sites (2 around the Kaikōura Peninsula and 4 north of Kaikōura, in the Okiwi Bay/Waipapa Bay area) in mid-2019 and mid-2020, encompassing uplift levels between approximately 0.7 and 6 metres.
Article
After New Zealand's 7.8 Mw Kaikōura earthquake in late 2016 an unexpected anthropogenic effect involved increased motorised vehicle access to beaches. We show how these effects were generated by landscape reconfiguration associated with coastal uplift and widening of high-tide beaches, and present analyses of the distribution of natural environment values in relation to vehicle movements and impacts. Access changes led to extensive vehicle tracking in remote areas that had previously been protected by natural barriers. New dunes formed seaward of old dunes and have statutory protection as threatened ecosystems, yet are affected by vehicle traffic. Nesting grounds of nationally vulnerable banded dotterel (Charadrius bicinctus bicinctus) co-occur with vehicle tracking. An artificial nest experiment showed that vehicle strikes pose risks to nesting success, with 91% and 83% of nests destroyed in high and moderate-traffic areas, respectively, despite an increase in suitable habitat. Despite gains for recreational vehicle users there are serious trade-offs with environmental values subject to legal protection and associated responsibilities for management authorities. In theory, a combination of low-impact vehicle access and environmental protection could generate win-win outcomes from the landscape changes, but is difficult to achieve in practice. Detailed information on sensitive areas would be required to inform designated vehicle routes as a potential solution, and such sensitivities are widespread. Alternatively, vehicle access areas that accommodate longstanding activities such as boat launching could be formally established using identified boundaries to control impacts further afield. Difficulties for the enforcement of regulatory measures in remote areas also suggest a need for motivational strategies that incentivise low-impact behaviours. We discuss options for user groups to voluntarily reduce their impacts, the importance of interactions at the recreation-conservation nexus, and need for timely impact assessments across the social-ecological spectrum after physical environment changes -- all highly transferable principles for other natural hazard and disaster recovery settings worldwide.
Preprint
Full-text available
Galaxias maculatus is a declining amphidromous fish that supports culturally-important whitebait fisheries in New Zealand and elsewhere in the Pacific. As a largely annual species, the seasonal productivity of spawning grounds has a strong influence on the availability of recruits. Spawning ground protection is urgently required to reverse historical degradation and improve prospects for the maintenance of sustainable fisheries. Although spawning habitat has been well characterised in tidal rivers where it is structured by water level changes on spring high tides, there has been no previous study of spawning in non-tidal rivermouths. We assessed seven non-tidal rivers over four months using a census survey approach to quantify spawning activity, identify environmental cues, and characterise fundamental aspects of the biogeography of spawning grounds. We report conclusive results that include a) identification of compact spawning reaches near the rivermouths, b) triggering of spawning events by periods of elevated water levels that were often of very short duration, suggesting that potential lunar cues were less important and that rapid fish movements had likely occurred within the catchment prior to spawning events, and c) consistent vertical structuring of spawning grounds above typical low-flow levels with associated horizontal translation away from the river channel, leading to increased exposure to anthropogenic stressors and associated management implications for protecting the areas concerned. These consistent patterns provide a sound basis for advancing the management of non-tidal rivermouths. Attention to flood management, vegetation control, and bankside recreational activities is required and may be assisted by quantifying spawning ground biogeography. The identification of rapid responses to environmental cues deserves further research to assess implications for floodplain connectivity management to support fish movements in emphemeral flowpaths, and as a potential source of bias in commonly-used fish survey methodologies.
Technical Report
Full-text available
This report responds to a request from Marlborough District Council (MDC) for information on the coastal environment, with a particular focus on supporting the development of a bylaw to address changes in recreational use patterns that have occurred since the Kaikōura earthquake. We present a selection of information from our earthquake recovery research that has a focus on understanding the impacts and ongoing processes of change. Major impacts of the natural disaster are associated with vertical uplift of the coastal environment, although ongoing erosion and deposition processes are also important. In addition, interactions with human activities are important because they can exert strong influences on the reassembly of ecosystems which is a critical aspect of outcomes over the longer-term. Earthquake uplift caused widespread mortality of many coastal habitats and species (e.g., algal assemblages) that are adapted to a relatively specific set of conditions, often associated with characteristic locations in relation to the tidal range. In uplifted areas the intertidal zone has moved seaward leading to a physical widening of many beaches. This has provided greater opportunity for off-road vehicle access to the coast and has become particularly noticeable at headlands and other natural barriers that were previously impassable at high tide. Off-road vehicles pose threats to sensitive vegetation and wildlife unless appropriately managed. Achieving this is assisted by an understanding of the specific impacts of vehicle use, which in turn requires information on the location of sensitive areas. To ensure the best outcomes for earthquake recovery there is an urgent need to assess and respond to the new spatial patterns, and to make plans to avoid conflicts where possible. In our RECOVER (Reef Ecology and Coastal Values, Earthquake Recovery) project funded by the Ministry of Business, Innovation and Employment (MBIE) and supported by the Ministry for Primary Industries (MPI) we are collecting information on important conservation values and activities. Although research is continuing, this report provides findings that include mapping of indigenous dune system remnants, recruitment of the indigenous sand-binders spinifex (Spinifex sericeus) and pīngao (Ficinia spiralis) on uplifted beaches, distribution of red katipō (Latrodectus katipo) within earthquake-affected dune systems, distribution of banded dotterel / pohowera (Charadrius bicinctus bicinctus) nesting pairs to determine important areas, and spatial overlaps with vehicle tracking measurements along the coast. Available under an Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) license
Article
Full-text available
Rocky shore ecology has been studied for a long time, starting with qualitative descriptions and becoming more quantitative and experimental over time. Some of the earliest manipulative experimental ecological studies were undertaken on rocky shores. Many, over time, have made considerable contributions to ecological theory, especially highlighting the importance of biological interactions at the community level. The suitability of rocky shores as convenient test systems for ecological experimentation is outlined. Here we consider contributions from rocky shores to the emerging concepts of supply-side ecology, the roles of competition, predation and grazing, disturbance and succession and positive interactions in structuring communities along environmental gradients. We then address alternative stable states, relationships between biodiversity and ecosystem functioning, and bottom-up and top-down control of ecosystems. We briefly consider the feedback and synergies between ecological concepts and experimental work on rocky shores, whilst still emphasizing the traditional values of marine natural history upheld in JMBA since its first publication. The importance of rigorous experimental designs championed by Underwood and co-workers is emphasized. Recent progress taking advantage of new technologies and emerging approaches is considered. We illustrate how experimental studies have shown the importance of biological interactions in modulating species and assemblage-level responses to climate change and informed conservation and management of coastal ecosystems.
Article
Marine communities are dynamic and spatially heterogeneous. Earthquakes and tsunamis modulate the structure of marine communities at short and long-term scales. The objective of this review was to evaluate how such disturbances impact the morphodynamics of coastal areas and the dynamics and structure of marine benthic communities from soft and hard bottoms from intertidal, subtidal and deep-sea habitats. The results reveal that earthquakes and tsunamis caused mortality of algae and bivalves by dissection after coastal uplift. Changes on the vertical distribution of nematodes and coral fragmentation were also recorded. Recovery of the marine communities to pre-disturbance state occurred by migration and recolonization of impacted habitats. The meiofaunal organisms recovered quickly, while some communities recovered after three years. Information predisturbance is often lacking or covers a short temporal extent. It is important to establish long-term monitoring programs in areas where the likelihood of impact of disturbance of such magnitude is high to understand how marine communities are shaped at geological scales.
Article
Major ecological disturbance events can provide opportunities to assess multispecies responses to upheaval. In particular, catastrophic disturbances that regionally extirpate habitat-forming species can potentially influence the genetic diversity of large numbers of co-distributed taxa. However, due to the rarity of such disturbance events over ecological timeframes, the genetic dynamics of multispecies recolonization processes have remained little understood. Here we use single nucleotide polymorphism (SNP) data from multiple coastal species to track the dynamics of co-colonization events in response to ancient earthquake disturbance in southern New Zealand. Specifically, we use a comparative phylogeographic approach to understand the extent to which epifauna (with varying ecological associations with their macroalgal hosts) share comparable spatial and temporal recolonization patterns. Our study reveals concordant disturbance-related phylogeographic breaks in two intertidal macroalgal species along with two associated epibiotic species (a chiton and an isopod). By contrast, two co-distributed species, one of which is an epibiotic amphipod and the other a subtidal macroalga, show few if any genetic effects of palaeoseismic coastal uplift. Phylogeographic model selection reveals similar post-uplift recolonization routes for the epibiotic chiton and isopod and their macroalgal hosts. Additionally, co-demographic analyses support synchronous population expansions of these four phylogeographically similar taxa. Our findings indicate that coastal paleoseismic activity has driven concordant impacts on multiple codistributed species, with concerted recolonization events likely facilitated by macroalgal rafting. These results highlight that high-resolution comparative genomic data can help reconstruct concerted multispecies responses to recent ecological disturbance.
Article
Full-text available
Catastrophic events can have profound effects on the demography of a population and consequently, on genetic diversity. The dynamics of post‐catastrophic recovery as well as the role of sexual versus asexual reproduction in buffering the effects of massive perturbations remain poorly understood, in part because the opportunity to document genetic diversity before and after such events is rare. Six natural (purely sexual) and seven cultivated (mainly clonal due to farming practices) populations of the red alga Agarophyton chilense were surveyed along the Chilean coast before, in the days after and two years after the 8.8 magnitude earthquake in 2010. The genetic diversity of sexual populations appeared sensitive to this massive perturbation, notably through the loss of rare alleles immediately after the earthquake. By 2012, the levels of diversity returned to those observed before the catastrophe, probably due to migration. In contrast, enhanced rates of clonality in cultivated populations conferred a surprising ability to buffer the instantaneous loss of diversity. After the earthquake, farmers increased the already high rate of clonality to maintain the few surviving beds, but most of them collapsed rapidly. Contrasting fates between sexual and clonal populations suggest that betting on strict clonality to sustain production is risky, probably because this extreme strategy hampered adaptation to the brutal environmental perturbation induced by the catastrophe.
Article
Full-text available
The 13 November 2016 Kaikoura, New Zealand, M w 7.8 earthquake ruptured multiple crustal faults in the transpressional Marlborough and North Canterbury tectonic domains of northeastern South Island. The Hikurangi trench and underthrust Pacific slab terminate in the region south of Kaikoura, as the subdution zone transitions to the Alpine fault strike-slip regime. It is difficult to establish whether any coseismic slip occurred on the megathrust from on-land observations. The rupture generated a tsunami well recorded at tide gauges along the eastern coasts and in Chatham Islands, including a ~4 m crest-to-trough signal at Kaikoura where coastal uplift was about 1 m, and at multiple gauges in Wellington Harbor. Iterative modeling of teleseismic body waves and the regional water-level recordings establishes that two regions of seafloor motion produced the tsunami, including an M w ~7.6 rupture on the megathrust below Kaikoura and comparable size transpressional crustal faulting extending offshore near Cook Strait.
Article
Full-text available
To assess the course and status of recovery of rocky intertidal zonation after massive subsidence caused by the 2011 Great East Japan Earthquake, from 2011 to 2013 we censused the vertical distribution of 10 dominant macrobenthic species (six sessile and four mobile species) in the mid-shore zone of 23 sites along the Sanriku coastline, 150–160 km north-northwest of the earthquake epicentre, and compared the vertical distributions of each species with their vertical distributions in the pre-earthquake period. The dynamics of rocky intertidal zonation varied substantially among species. Among sessile species, one barnacle dramatically increased in abundance and expanded its vertical range in 2011, but then decreased and completely disappeared from all plots by 2013. Zonations of other sessile species shifted downward following the subsidence in 2011. With some species, there was no clear change in abundance immediately after the earthquake, but they then began to increase and move upward after a few years; with other species, abundance continuously decreased. There was no clear change in the vertical distribution of any of the mobile species immediately after the earthquake. Abundance of two mobile species was unchanged, but abundance of the others decreased from 2012 and had not recovered as of 2013.
Article
Full-text available
As climatic changes and human uses intensify, resource managers and other decision makers are taking actions to either avoid or respond to ecosystem tipping points, or dramatic shifts in structure and function that are often costly and hard to reverse. Evidence indicates that explicitly addressing tipping points leads to improved management outcomes. Drawing on theory and examples from marine systems, we distill a set of seven principles to guide effective management in ecosystems with tipping points, derived from the best available science. These principles are based on observations that tipping points (1) are possible everywhere, (2) are associated with intense and/or multifaceted human use, (3) may be preceded by changes in early-warning indicators, (4) may redistribute benefits among stakeholders, (5) affect the relative costs of action and inaction, (6) suggest biologically informed management targets, and (7) often require an adaptive response to monitoring. We suggest that early action to preserve system resilience is likely more practical, affordable, and effective than late action to halt or reverse a tipping point. We articulate a conceptual approach to management focused on linking management targets to thresholds, tracking early-warning signals of ecosystem instability, and stepping up investment in monitoring and mitigation as the likelihood of dramatic ecosystem change increases. This approach can simplify and economize management by allowing decision makers to capitalize on the increasing value of precise information about threshold relationships when a system is closer to tipping or by ensuring that restoration effort is sufficient to tip a system into the desired regime.
Article
Full-text available
A magnitude 7.1 earthquake struck the Canterbury Region of New Zealand at 4:35 am on 4 September 2010. It was centred 11 km beneath the rural town of Darfield, on the Greendale Fault, which was previously unidentified. Christchurch City lies 40 km east of Darfield, and was home to a population of approximately 370,000 at the time of the earthquake. There was extensive damage as a result of the MM9 shaking, particularly to buildings and infrastructure, but fortunately there were no deaths. The residents began the recovery process, plagued by frequent aftershocks. Then, more than five months after the mainshock, on 22 February 2011, a M6.3 aftershock occurred 5 km south-east of Christchurch at a depth of only 5 km. This earthquake struck at lunchtime on a working day, causing catastrophic damage to the city, and resulting in 185 deaths. Most of these casualties occurred as a result of the collapse of two large office buildings, with further deaths resulting from falling bricks and masonry, and rockfalls in city suburbs. The M7.1 earthquake and associated aftershocks have caused extensive impacts on the local built, economic, social, and natural environments. The on-going aftershocks have also caused a disrupted environment in which to recover. This paper will outline the nature of the Canterbury earthquakes and provide an introduction to the ongoing effects the earthquakes have had on these local environments to help frame the growing body of research coming out of the Canterbury earthquakes.
Article
Full-text available
The devastating earthquake (moment magnitude: 8.8 MW) that struck Chile on 27 February 2010 and the following tsunami waves produced widespread damage, coastal coseismic uplifts, and large-scale mortality of rocky intertidal and shallow subtidal organisms. The effects were particularly remarkable around the Gulf of Arauco, Santa Mar a Island and the Bay of Concepcion (similar to 36 to 38 degrees S). Measurements of rocky intertidal and shallow subtidal belt-forming (biomarker) species conducted a few weeks after the earthquake indicated coastal uplifts ranging from similar to 0.2 to 3.1 m, which are similar to uplifts estimated by FitzRoy (1839; Voyages of the Adventure and Beagle, Vol. II) and Darwin (1839; Voyages of the Adventure and Beagle, Vol. III) after the 1835 Chilean earthquake. In major uplifted sites, there was massive mortality of the main intertidal and shallow subtidal belt-forming species, such as lithothamnioid melobesioid coralline algae, brown kelps and mussels, and dramatic changes in the marine rocky intertidal ecosystem. We suggest that in the southeastern Pacific, drastic and rapid coastal deformations seriously impinge on rocky shore populations, communities and ecosystems and may have significance for management and conservation practices, as for example in connection with alterations of parental stocks and recruitment rates.
Article
Full-text available
Phototrophs underpin most ecosystem processes, but to do this they need sufficient light. This critical resource, however, is compromised along many marine shores by increased loads of sediments and nutrients from degraded inland habitats. Increased attenuation of total irradiance within coastal water columns due to turbidity is known to reduce species' depth limits and affect the taxonomic structure and architecture of algal-dominated assemblages, but virtually no attention has been paid to the potential for changes in spectral quality of light energy to impact production dynamics. Pioneering studies over 70 years ago showed how different pigmentation of red, green and brown algae affected absorption spectra, action spectra, and photosynthetic efficiency across the PAR (photosynthetically active radiation) spectrum. Little of this, however, has found its way into ecological syntheses of the impacts of optically active contaminants on coastal macroalgal communities. Here we test the ability of macroalgal assemblages composed of multiple functional groups (including representatives from the chlorophyta, rhodophyta and phaeophyta) to use the total light resource, including different light wavelengths and examine the effects of suspended sediments on the penetration and spectral quality of light in coastal waters. We show that assemblages composed of multiple functional groups are better able to use light throughout the PAR spectrum. Macroalgal assemblages with four sub-canopy species were between 50-75% more productive than assemblages with only one or two sub-canopy species. Furthermore, attenuation of the PAR spectrum showed both a loss of quanta and a shift in spectral distribution with depth across coastal waters of different clarity, with consequences to productivity dynamics of diverse layered assemblages. The processes of light complementarity may help provide a mechanistic understanding of how altered turbidity affects macroalgal assemblages in coastal waters, which are increasingly threatened by diminishing light quantity and altered spectral distributions through sedimentation and eutrophication.
Article
Full-text available
Regime shifts have been observed in marine ecosystems around the globe. These phenomena can result in dramatic changes in the provision of ecosystem services to coastal communities. Accounting for regime shifts in management clearly requires integrative, ecosystem-based management (EBM) approaches. EBM has emerged as an accepted paradigm for ocean management worldwide, yet, despite the rapid and intense development of EBM theory, implementation has languished, and many implemented or proposed EBM schemes largely ignore the special characteristics of regime shifts. Here, we first explore key aspects of regime shifts that are of critical importance to EBM, and then suggest how regime shifts can be better incorporated into EBMusing the concept of integrated ecosystem assessment (IEA). An IEA uses approaches that determine the likelihood that ecological or socio-economic properties of systems will move beyond or return to acceptable bounds as defined by resource managers and policy makers. We suggest an approach for implementing IEAs for cases of regime shifts where the objectives are either avoiding an undesired state or returning to a desired condition. We discuss the suitability and short-comings of methods summarizing the status of ecosystem components, screening and prioritizing potential risks, and evaluating alternative management strategies. IEAs are evolving as an EBM approach that can address regime shifts; however, advances in statistical, analytical and simulation modelling are needed before IEAs can robustly inform tactical management in systems characterized by regime shifts.
Article
Full-text available
Changes in populations of the abalone Haliotis discus hannai and sea urchin Strongylocentrotus nudus following the tsunami and other events associated with the Great East Japan Earthquake which occurred on March 11, 2011, are compared between two sites, Tomarihama on the Oshika Peninsula and Nagane in Otsuchi Bay on the Sanriku Coast in northeastern Japan. As Tomarihama faces directly onto the Pacific Ocean, effects of the tsunami are likely to be heavier than at Nagane located near the mouth of Otsuchi Bay. At Tomarihama, both adult and juvenile abalone were apparently affected by the tsunami disturbance, while at Nagane in Otsuchi Bay, juvenile abalone <4 cm SL appeared to be more seriously affected by the tsunami than adults. Sea urchin densities decreased considerably at both Tomarihama and Nagane, indicating that sea urchins were more severely impacted by the event compared with abalone. The sea urchin density remained low for two years after the event at Tomarihama, but recovered to almost the same level as before the tsunami within six months from the event at Nagane. The results of the present study suggest that benthic organisms which attach weakly to bottom substrates were more seriously impacted than strongly attached organisms. Organisms inhabiting exposed areas suffer more effects than those inhabiting perennial kelp forests, where the current velocity of the tsunami may be attenuated by the presence of the algal canopy. Although the damaged populations have started recovering and/or adapting to the new environment, the speed and process of change differ between the organisms and areas.
Article
Full-text available
Following widespread deterioration of coastal ecosystems since the 1960s, current environmental policies demand ecosystem recovery and restoration. However, vague definitions of recovery and untested recovery paradigms complicate efficient stewardship of coastal ecosystems. We critically examine definitions of recovery and identify and test the implicit paradigms against well-documented cases studies based on a literature review. The study highlights a need for more careful specification of recovery targets and metrics for assessing recovery in individual ecosystems. Six recovery paradigms were identified and examination of them established that partial (as opposed to full) recovery prevails, that degradation and recovery typically follow different pathways as buffers act to maintain the degraded state, and that recovery trajectories depend on the nature of the pressure as well as the connectivity of ecosystems and can differ between ecosystem components and among ecosystems. A conceptual model illustrates the findings and also indicates how restoration efforts may accelerate the recovery process.
Article
Full-text available
The risk of flood disasters is increasing for many coastal societies owing to global and regional changes in climate conditions, sea-level rise, land subsidence and sediment supply. At the same time, in many locations, conventional coastal engineering solutions such as sea walls are increasingly challenged by these changes and their maintenance may become unsustainable. We argue that flood protection by ecosystem creation and restoration can provide a more sustainable, cost-effective and ecologically sound alternative to conventional coastal engineering and that, in suitable locations, it should be implemented globally and on a large scale.
Article
Full-text available
On February 27, 2010 at 03:34:08 AM an Mw8.8 earthquake, with epicenter located off Cobquecura (73.24°W; 36.29°S), severely hit Central Chile. The tsunami waves that followed this event affected the coastal regions between the cities of Valparaíso and Valdivia, with minor effects as far as Coquimbo. The earthquake occurred along the subduction of the Nazca oceanic plate beneath the South American plate. Coseismic coastal uplift was estimated through observations of bleached lithothamnioids crustose coralline algae, which were exposed after the mainshock between 34.13°S and 38.34°S, suggesting the latitudinal distribution of the earthquake rupture. The measured coastal uplift values varied between 240±20 cm at sites closer to the trench along the western coast of the Arauco peninsula and 15±10 cm at sites located farther east. A maximum value of 260±50 cm was observed at the western coast of Santa María Island, which is similar to the reported uplift associated with the 1835 earthquake at Concepción. Land subsidence values on the order of 0.5 m to 1 m evidenced a change in polarity and position of the coseismic hinge at 110-120 km from the trench. In four sites along the coast we observed a close match between coastal uplift values deduced from bleached lithothamnioids algae and GPS measurements. According to field observations tsunami heights reached ca. 14 m in the coastal area of the Maule Region immediately north of the epicenter, and diminished progressively northwards to 4-2 m near Valparaíso. Along the coast of Cobquecura, tsunami height values were inferior to 2-4 m. More variable tsunami heights of 6-8 m were measured at Dichato-Talcahuano and Tirúa-Puerto Saavedra, in the Biobío and Arauco regions, respectively, to the south of the epicenter. According to eyewitnesses, the tsunami reached the coast between 12 to 20 and 30 to 45 minutes in areas located closer and faraway from the earthquake rupture zone, respectively. Destructive tsunami waves arrived also between 2.5 and 4.5 hours after the mainshock, especially along the coast of the Biobío and Arauco regions. The tsunami effects were highly variable along the coast, as a result of geomorphological and bathymetric local conditions, besides potential complexities induced by the main shock.
Article
Full-text available
Deep seismic reflection profiles west of Denmark across the suture between Baltica and Eastern Avalonia reveal weak, southward-dipping reflectors within the crystalline basement. These reflectors are interpreted as thrusts resulting from emplacement of Eastern Avalonia onto the southern edge of Baltica. North of these reflectors are the remains of a dissected Silurian foredeep. The presence of this foredeep and the 440 Ma age of metamorphism in rocks recovered from boreholes into Eastern Avalonian rocks suggest that closure of the Tornquist sea occurred in the Late Ordovician, which is consistent with paleobiogeographic data and paleomagnetic apparent polar wander paths for Eastern Avalonia and Baltica. The similarity between these reflection data and the BABEL AC profile permits correlation of reflectors beneath Denmark into the southern North Sea.
Article
Full-text available
This paper describes studies on the settlement of the abalone Haliotis australis Gmelin. Ten‐day‐old H. australis larvae had a slower rate of settlement than 5‐day‐old larvae. A high proportion of veliger larvae had the ability to prolong the searching phase of settlement and delay metamorphosis, even over prepared settlement surfaces but radula development continued at a similar rate in both settled and swimming larvae. In any one batch of larvae settlement was slow and asynchronous and post‐settlement survival was low. Light was shown to influence the swimming behaviour of larvae in settlement tanks, with more larvae swimming in the dark than in the light. The implications of these behaviours are discussed in relation to larval and post‐larval energetics and feeding.
Article
Full-text available
Larvae of Haliotis iris were reared in the laboratory and, at 13 days post-fertilization, the veligers were released into a semi-enclosed gully on an exposed rocky shore. Settlement occurred on Lithothamnium surfaces and the post-larvae were monitored through to metamorphosis and the early juvenile stage at 2–3 mm. Densities of juveniles in the experimental site ranged from 12 to 68/m2 whilst control sites had a maximum of 8/m2. The use of larvae for the enhancement of natural populations of abalones is discussed.
Article
Full-text available
Tag‐recapture studies revealed differences in the growth rate of Haliotis iris between headlands and bays separated by as little as 200 m. Individuals off headlands had a significantly higher incremental growth and reached a higher maximum size than those in bays. These results were consistent with observations of the size composition of H. iris which showed that few individuals of harvestable size (> 125 mm shell length) were found in bays. Differences in the growth rate of H. iris may account for the apparent differences in the size at onset of maturity: individuals off headlands, and from a fast‐growing population off Wellington, reached reproductive maturity at a smaller size compared with those in bays. Yield‐per‐recruit modelling showed greater yields from headlands than bays, but egg‐per‐recruit modelling revealed more egg production was conserved in bays than off headlands. Yields could be increased from bays by decreasing the minimum size to 110 mm. Egg‐ and yield‐per‐recruit models were sensitive to the natural mortality rate (M = 0.03, 0.05 and 0.10 compared). The results show that parameters important in the management of commercial fisheries for abalone can vary over small distances: such variation should be incorporated in management strategies for abalone fisheries.
Article
Full-text available
Following the Great East Japan Earthquake in 2011, a large tsunami developed and struck the Pacific coast of eastern Japan. To assess the immediate impacts of the tsunami on coastal communities, changes in taxon composition and richness of macrobenthic animals before and after the tsunami were examined at nine intertidal flats in Sendai Bay and the Sanriku Ria coast. The results showed that 30-80% of taxa indigenously inhabiting intertidal flats disappeared after the tsunami. Among animal types, endobenthic and sessile epibenthic animals were more vulnerable to the tsunami than mobile epibenthic animals like shore crabs and snails. For all the intertidal flats examined, animals that were originally dwellers in lower tidal zones and not recorded before the tsunami were also found right after the tsunami, indicating that the tsunami not only took away many benthic taxa from the intertidal flats but also brought in some taxa from elsewhere. However, overall changes in taxon community composition were greater for intertidal flats that experienced larger inundation heights. These results showed that the ecological impacts of the tsunami were proportional to the physical impacts as gauged by wave height and that mobile epibenthic animals were less vulnerable to the tsunami.
Article
Full-text available
Severe storm events are important agents of disturbance that can transport large quantities of algal detritus from highly productive kelp beds (or forests) in shallow water to deeper, more food-limited areas. We measured canopy cover in shallow kelp beds (5 to 15 m depth) and the cover of detrital kelp in sedimentary habitats directly offshore of these beds (20 to 45 m) before and after Hurricane Earl, which struck the Atlantic coast of Nova Scotia in September 2010. The storm resulted in large losses of kelp canopy cover (from 71.0 to 38.7%, averaged across sites) and significantly increased the cover of detrital kelp deposits below the kelp beds (from 1.5 to 3.4%). Detrital deposits were more commonly found in a semi-protected bay than off an exposed headland and persisted in the bay for at least 6 wk. Sea urchins Strongylocentrotus droebachiensis were associated with detrital kelp deposits in offshore habitats. At sites with the greatest amount of detrital kelp, we estimated that sea urchins could consume this material within 2 mo, indicating that storm-generated detrital pulses may be an important form of trophic connectivity between adjacent ecosystems off this coast.
Article
Full-text available
There is concern about historical and continuing loss of canopy-forming algae across the world's temperate coastline. In South Australia, the sparse cover of canopy-forming algae on the Adelaide metropolitan coast has been of public concern with continuous years of anecdotal evidence culminating in 2 competing views. One view considers that current patterns existed before the onset of urbanisation, whereas the alternate view is that they developed after urbanisation. We tested hypothe- ses to distinguish between these 2 models, each centred on the reconstruction of historical covers of canopies on the metropolitan coast. Historically, the metropolitan sites were indistinguishable from con- temporary populations of reference sites across 70 km (i.e. Gulf St. Vincent), and could also represent a random subset of exposed coastal sites across 2100 km of the greater biogeographic province. Thus there was nothing 'special' about the metropolitan sites historically, but today they stand out because they have sparser covers of canopies compared to equivalent locations and times in the gulf and the greater province. This is evidence of wholesale loss of canopy-forming algae (up to 70%) on parts of the Adelaide metropolitan coast since major urbanisation. These findings not only set a research agenda based on the magnitude of loss, but they also bring into question the logic that smaller metropolitan populations of humans create impacts that are trivial relative to that of larger metropolitan centres. Instead, we highlight a need to recognise the ecological context that makes some coastal systems more vulnerable or resistant to increasing human-domination of the world's coastlines. We discuss challenges to this kind of research that receive little ecological discussion, particularly better leadership and administration, recognising that the systems we study out-live the life spans of individual research groups and operate on spatial scales that exceed the capacity of single research providers.
Article
Coseismic coastal deformation is often used to understand slip on offshore faults in large earthquakes but in the 2016 Kaikōura earthquake multiple faults ruptured across and sub-parallel to the coastline. Along ∼110 km of coastline, a rich dataset of coastal deformation comprising airborne lidar differencing, field surveying and satellite geodesy reveals highly variable vertical displacements, ranging from −2.5 to 6.5 m. These inform a refined slip model for the Kaikōura earthquake which incorporates changes to the slip on offshore faults and inclusion of an offshore reverse crustal fault that accounts for broad, low-amplitude uplift centered on Kaikōura Peninsula. The exceptional detail afforded by differential lidar and the high variability in coastal deformation combine to form the highest-resolution and most complex record of coseismic coastal deformation yet documented. This should prompt reassessment of coastal paleoseismic records that may not have considered multi-fault ruptures and high complexity deformation fields.
Article
The 2016 Mw 7.8 Kaikōura earthquake continued a notable decade of damaging earthquake impacts in New Zealand. The effects were wide ranging across the upper South Island, and included two fatalities, tsunami, tens of thousands of landslides, the collapse of one residential building, and damage to numerous structures and infrastructure. We present a preliminary overview focused on the seismological aspects of this earthquake and the corresponding seismological response effort. The earthquake rupture was extremely complex, involving at least 13 separate faults extending over ∼150 km, from the epicenter in north Canterbury to near the Cook Strait. We use backprojection and slip inversion methods to derive preliminary insights into the rupture evolution, identifying south-to-north rupture, including at least three distinct southwest-to-northeast propagating phases. The last phase is associated with a strong second pulse of energy release in the northern half of the rupture zone ∼70 s after rupture initiation, which we associate with the Kekerengu-Needles faults where some of the largest surface displacements (dextral) were observed. The mechanism of the mainshock was oblique thrust and relocated aftershocks show a range of thrust and strike-slip mechanisms across three dominant spatial clusters. GeoNet datasets collected during the Kaikōura earthquake will be crucial in further unraveling details of the complex earthquake rupture and its implications for seismic hazard. Ground motions during the earthquake exceeded 1g at both ends of the rupture. Spectral accelerations exceeded 500-year return period design level spectra in numerous towns in the upper South Island, as well as in parts of the capital city of Wellington at critical periods of 1-2 s, influenced by site/basin and directivity effects. Another important part of the response effort has been the provision of earthquake forecasts, as well as consideration of the implications of slow slip on the Hikurangi subduction interface triggered as a result of the Kaikōura earthquake.
Article
On 14th November 2016, the northeastern South Island of New Zealand was struck by a major Mw 7.8 earthquake. Field observations, in conjunction with InSAR, GPS, and seismology reveal this to be one of the most complex earthquakes ever recorded. The rupture propagated northward for more than 170 km along both mapped and unmapped faults, before continuing offshore at its northeastern extent. Geodetic and field observations reveal surface ruptures along at least 12 major faults, including possible slip along the southern Hikurangi subduction interface, extensive uplift along much of the coastline and widespread anelastic deformation including the ~8 m uplift of a fault-bounded block. This complex earthquake defies many conventional assumptions about the degree to which earthquake ruptures are controlled by fault segmentation, and should motivate re-thinking of these issues in seismic hazard models.
Article
Marine ecosystems are subject to anthropogenic change at global, regional and local scales. Global drivers interact with regional- and local-scale impacts of both a chronic and acute nature. Natural fluctuations and those driven by climate change need to be understood to diagnose local- and regional-scale impacts, and to inform assessments of recovery. Three case studies are used to illustrate the need for long-term studies: (i) separation of the influence of fishing pressure from climate change on bottom fish in the English Channel; (ii) recovery of rocky shore assemblages from the Torrey Canyon oil spill in the southwest of England; (iii) interaction of climate change and chronic Tributyltin pollution affecting recovery of rocky shore populations following the Torrey Canyon oil spill. We emphasize that “baselines” or “reference states” are better viewed as envelopes that are dependent on the time window of observation. Recommendations are made for adaptive management in a rapidly changing world.
Article
The =7.8 Kaikoura (New Zealand) earthquake involved a remarkably complex rupture propagating in an intricate network of faults at the transition between the Alpine fault in the South Island and the Kermadec-Tonga subduction zone. We investigate the main features of this complicated rupture process using long-period seismological observations. Apparent Rayleigh-wave moment-rate functions reveal a clear northeastward directivity with an unusually weak rupture initiation during 60 s followed by a major 20 s burst of moment rate. To further explore the rupture process, we perform a Bayesian exploration of multiple point-source parameters in a 3-D Earth model. The results show that the rupture initiated as a small strike-slip rupture and propagated to the northeast, triggering large slip on both strike-slip and thrust faults. The Kaikoura earthquake is thus a rare instance in which slip on intraplate faults trigger extensive interplate thrust faulting. This clearly outlines the importance of accounting for secondary faults when assessing seismic and tsunami hazard in subduction zones.
Article
Processes responsible for transporting detached macroalgae through the nearshore environment and offshore to where long distance dispersal (LDD) can occur have rarely been examined. Here, we test the influence of nearshore winds, tidal currents and position of release (low, mid or high tidal zone) on the dispersal of drifting fucoid algae were tested. “Drift sets” (tagged Hormosira banksii, Durvillaea antarctica, Cystophora torulosa and GPS drifters) were tracked over single tidal cycles. Wind direction had the greatest effect on movement of drift sets, but interacted with tidal direction. Overall, offshore winds and outgoing tides were most favourable for LDD, but their effect differed between species. Approximately 90% of H. banksii, D. antarctica and GPS-tracked drifters were beach-cast after one tidal cycle during onshore winds, while 19% were beach-cast during offshore winds. In contrast, 50–75% of C. torulosa were beach-cast after one tide, regardless of wind direction. Displacement of drifters was affected by tidal zone of release, but interacted with wind and tidal direction. Drifting velocities varied between drifter types, with surface drifters travelling further and faster than the benthic-drifting species. Analysis of 20 years of wind data found seasonal differences in the percentage of hourly winds, with greater periods of south-westerly and north-westerly winds, and fewer onshore north-easterly winds, during autumn and winter periods. Conditions for successful offshore dispersal from the major algal dominated peninsulas of southern New Zealand are, therefore, more likely to occur if detachment of algae occurs during outgoing tides in autumn and winter.
Article
Predictions of the effects of climate change in the coastal zone require an understanding of the relationships between environmental and biotic variables. These are often highly complex and uncertain because of the many ways marine biota interact with each other under different environmental conditions. We use data collected over the past several decades to de termine changes in the key environmental variables and area-specific changes in the dominant habitat-forming macroalgae. Sea surface temperature (SST) data and wave heights from ERA-Interim reanalysis were analysed for 3 areas of the east coast of New Zealand's South Island to detect trends over the past 30 yr. We then used detailed benthic survey data acquired quarterly or half-yearly in 2 tidal zones at the same coastal areas from 1994 onwards. There were significant increases in the mean SST at 2 of the 3 areas, with average increases of 0.16°C per decade over 3 decades. Maximum SST did not increase, but the minimum seawater temperatures did, by up to 0.34°C per decade. Mean significant wave height also increased over this period by 0.06 m per decade, and maximum wave height by up to 0.3 m per decade at 2 of the 3 areas. Boosted regression tree analysis was used to determine any consistent patterns between physical variables and benthic algal cover. Generally, air temperature and the Southern Oscillation Index (SOI) were the most influential variables on cover of fucoid macroalgae. SST and wave height were also important but less influential. Fucoid cover increased with maximum air temperature beyond ca. 22 to 24°C, and cover decreased during La Niña periods at the most northern site, but increased during La Niña periods at the most southern site. The relative contributions of SST and wave height variables to the models were area- and tidal zone-specific. Overall, this study showed highly variable effects of a changing climate on an ecologically important habitat-former, highlighting the problems of dealing with ecological and climate variables that operate at differing spatial and temporal scales. We discuss this with respect to community structure and dynamics.
Article
The coastal zone worldwide is not well served by management policies that fail to deal effectively with land-sourced contaminants from streams, rivers and urban runoff. We discuss this using examples from New Zealand, where there is a wide recognition of such problems but little effective policy that specifically accounts for the interconnectedness of the land-to-freshwater-to-sea domain. Increasing land-use intensification, mostly in arable pasture, has greatly increased the nutrient load to the coast and has contributed to the already high sediment loading of coastal waters. We argue that renewed effort is needed for a more holistic approach to management, encapsulated in the New Zealand Maori concept of ki uta ki tai - an appreciation of mountains-to-sea connections. Limit-setting, especially of nitrogen from terrestrial sources, seems to a main way forward for reducing loads and halting cumulative effects. However, this must account for current impacts and also the 'load to come' because of time lags associated with accumulated groundwater nutrients and cumulative impacts in receiving waters. Despite many approaches being tried, there are increasing impacts of catchment activities on coasts worldwide. The need is therefore great for new approaches, renewed effort, and for a very long-term perspective to ensure effective and enduring solutions.
Article
Frameworks play an important role in analyzing social-ecological systems (SESs) because they provide shared concepts and variables that enable comparison between and accumulation of knowledge across multiple cases. One prominent SES framework focusing on local resource use has been developed by Elinor Ostrom and her colleagues. This framework is an extensive multi-tier collection of concepts and variables that have demonstrated relevance for explaining outcomes in a large number of case studies in the context of fishery, water, and forestry common-pool resources. The further development of this framework has raised a number of issues related to the formal relationships between the large number of concepts and variables involved. In particular, issues related to criteria for ordering the concepts into tiers, adding new concepts, defining outcomes metrics, and representing dynamics in the framework have been identified. We address these issues by applying methods from research fields that study formal relationships between concepts such as domain-specific languages, knowledge representation, and software engineering. We find that SES frameworks could include the following seven formal components: variables, concepts, attribution relationships, subsumption relationships, process relationships, aggregation relationships, and evaluation metrics. Applying these components to the Ostrom framework and a case study of recreational fishery, we find that they provide clear criteria for structuring concepts into tiers, defining outcome metrics, and representing dynamics. The components identified are generic, and the insights gained from this exercise may also be beneficial for the development of other SES frameworks.
Article
As human pressure in coastal areas increases, it is important to understand how key functional components of nearshore ecosystems respond to combinations of global climate changes and local non-climatic stressors. Stressors originating at local scales such as elevated nutrient concentrations and sediment loads are known to contribute to the regression of large habitat-forming macroalgae in temperate rocky reefs. How the persistence of algal beds will be affected by combinations of altered nutrient and sediment regimes and increased temperatures under future global change scenarios is still unclear. We used a series of laboratory experiments to test short- (48 h) and long-term (eight weeks) effects of different combinations of nutrient, sediment and temperature on the early life stages of the habitat-forming fucoids Hormosira banksii, Cystophora torulosa, and Durvillaea antarctica. A light coating of sediment affected the post-settlement survival of H. banksii and C. torulosa germlings within 48 h and reduced growth and survival of all species over eight weeks. Temperatures 3 °C higher than ambient levels during the reproductive season of each species caused increased mortality of the germlings of the three fucoids after eight weeks, but these effects were only evident in the absence of sediment. The cold adapted D. antarctica was particularly susceptible to temperature increase, with reduced germling survival in warmer waters after 48 h. In the absence of sediment, nutrient enrichment stimulated the growth of H. banksii and C. torulosa, but caused a decline in the survival and growth of D. antarctica. This was probably due to the poor adaptation of D. antarctica to laboratory conditions. This study contributes to a better understanding of the impacts of altered physical conditions on important habitat-forming species. Our results highlight mechanisms that may well apply in natural contexts, and they reinforce the need for appropriate management of local stressors in order to mitigate the impacts of altered climate conditions.
Article
A three-year experimental study was performed to evaluate the interactive effects of topographic complexity and sedimentation in determining the structure of rocky macroalgal assemblages. The following hypotheses were tested: i) the structure of macroalgal assemblages varies according to the complexity of the substratum; ii) high sediment deposition reduces variations in the structure of assemblages among substrata characterized by different complexity. At natural levels of sediment deposition, greater substratum complexity enhanced species richness and favored the development of assemblages dominated by architecturally complex species, such as large corticated Rhodophyta. Under high sediment deposition, turfs became the main component of macroalgal assemblages, although different filamentous forms responded differently to substratum complexity. In addition, high sediment deposition increased the abundance of the invasive Chlorophyta, Caulerpa cylindracea, on low complexity substrata, but decreased it on high complexity substrata. These results show that an increase in sediment deposition can dampen variations between assemblages associated to substrata characterized by different complexity, with consequent reduction of both alpha (i.e., species loss) and beta diversity (i.e., decreased small-scale variation in community structure).
Article
Experimentally investigated the consequences of variable spore settlement and early (prerecruit) competition on the recruitment patterns of the sympatric sublittoral Macrocystis pyrifera and Pterygophora californica. For both kelps, a minimum density of at least 1 spore/mm2 was needed for successful recruitment. This minimum density was probably determined in part by the maximum distance that could separate male and female gametophytes while still allowing fertilization to occur. Although greater spore density often resulted in higher numbers of sporophyte recruits, strong density-dependent mortality still occurred whenever there was recruitment. "Safe sites' for the recruitment of kelp were highly variable in time; recruitment of both kelps was negatively correlated with the natural recruitment of ephemeral species of filamentous brown algae. Differences in post-settlement mortality between Macrocystis and Pterygophora often caused patterns of sporophyte recruitment to vary from those of initial spore settlement. Pterygophora spore settlement generally inhibited the recruitment of Macrocystis at both high (750-1500 spores/mm2) and low (10-20 spores/mm2) densities. Macrocystis settlement had no effect on Pterygophora recruitment. -from Author
Article
The viability of enhancing populations of abalone Haliotis iris by placing hatchery-raised juveniles into natural habitats was evaluated at the Chatham Islands, New Zealand. Eighty thousand abalone, from 3 to 30 mm (shell length) in size, were seeded into 8 sites during 1990 and 1991 and sampled for survival and growth at times ranging from 5 to 23 mo. Annual mortality rates were 27.6 to 98.8 ' X and instantaneous mortality ranged from 0.323 to 4.440. Mortality was greatest in sites affected by sand movement, which partially buried juvenile habitat. Desirable characteristics of sites for en-hancement were identified so that the risk of mortality due to habitat shifts can be greatly reduced in the future. Average annual growth increments ranged from 13.5 to 23.8 mm, but the lower value may be conservative because of the varying growth periods that seed were in place at the different sites. Preliminary economic analyses showed that, based on the current price of abalone, 3 individual sites should produce positive financial returns on the future harvest of abalone at the minimum legal size of 125 mm. Although 5 sites will have negative financial returns, the overall return of the 8 sites should exceed the original investment.
Article
As a result of anthropogenic habitat degradation worldwide, coastal ecosystems are increasingly dominated by low-lying, turf-forming species, which proliferate at the expense of complex biogenic habitats such as kelp and fucoid canopies. This results in dramatic alterations to the structure of the associated communities and large reductions in primary productivity. The persistence of turf-dominated systems has been attributed to the impacts of the turfs on the recovery of algal canopies and also to the different susceptibility of canopy- and turf-forming algae to altered physical conditions, in particular increased sedimentation. Here we tested the impacts of turfing geniculate coralline algae and sediment on fucoid recovery dynamics and their influence on assemblage net primary productivity (NPP). The recruitment of the habitat-forming fucoid Hormosira banksii on bare substrata was significantly higher than in treatments in which sediments, coralline turfs or turf mimics covered the substratum, indicating that sediment deposition and space pre-emption by algal turfs can synergistically affect the development of fucoid beds. NPP of coralline turfs was much lower than that of fucoid-coralline assemblages, which included a H. banksii canopy, and was reduced further by sediment accumulation. When devoid of sediment, however, coralline algae contributed to enhance fucoid-coralline assemblage NPP, because of synergistic interactions among the components of the multi-layered assemblage in optimizing light use. Our findings amplify extensive research addressing the global loss of macroalgal canopies and highlight key processes involving sediment accumulation in the benthic environment and effects on the replenishment and productivity of fucoid stands.
Article
Fragmentation and loss of extensive populations of habitat-forming macroalgae have occurred worldwide as a result of human-driven coastal habitat degradation. Contributing to such declines may be the influence of opportunistic algae, which quickly respond to stresses such as nutrient loading and warmer sea temperatures. The early life stages of fucoids are particularly likely to be affected by the combined impacts of altered physical conditions and increased competition with stress-tolerant species. In this study, we examined the interactions between the early life stages of the intertidal fucoid Hormosira banksii and fast-growing, opportunistic green algae Ulva spp. Through a series of laboratory experiments, we tested (1) the impact of Ulva spp. on the settlement of H. banksii zygotes; (2) the impact of Ulva spp. on the rates of post-settlement survival and growth of H. banksii germlings under ambient and increased levels of temperature and nutrient concentration; (3) the interactions between the 2 taxa under grazing pressure of the abundant intertidal trochid Lunella smaragdus. Ulva spp. impaired the settlement of H. banksii zygotes, through both physical and chemical mechanisms, and the growth of the germlings; but Ulva spp. was also preferentially consumed by the grazers, thereby indirectly facilitating H. banksii. In addition, Ulva spp. responded positively to increased temperature and nutrients, while we found an indication that post-settlement survival of H. banksii may decline with warmer waters. These findings augment extensive field-based research addressing the loss of algal beds and shed light on biotic and physical mechanisms affecting the most critical phases of the life cycle of a key habitatforming species.
Article
(1) Naturally-occurring monospecific stands of two subtidal fucoid species, an annual, Sargassum sinclairii and a perennial, Carpophyllum maschalocarpum, were monitored from recruitment, at high and low densities, in northern New Zealand. (2) Individuals of both species grew faster and attained a larger size in the high-density stands. (3) Survivorship rates fluctuated throughout the year for low- and high-density Sargassum sinclairii, but a higher proportion of low-density plants survived at the end of the year. Carpophyllum maschalocarpum plants showed higher survivorship at low density, but all plants in these stands which remained at the end of the study were stunted. (4) Size-frequency distributions through time tended to be positively skewed for both low- and high-density stands of Sargassum sinclairii. For both species, however, there was little indication that most plants at high density were being trapped under the canopy of a few large individuals. (5) Ninety-two per cent of the S. sinclairii plants became reproductive in high-density stands, compared with 46% at low density. Forty per cent of the Carpophyllum maschalocarpum plants became fertile after the second year of growth at high-density, while none of the low-density plants became reproductive. (6) The bearing of receptacles is clearly related to plant size, and most plants of both species at low density did not attain a large enough size to reproduce. For both species, the proportion of plant weight invested in receptacles increased with plant size. In addition, the greatest recruitment for Sargassum sinclairii occurred near dense adult stands. (7) High density aggregations may be important for the establishment and maintenance of populations of large brown algae. There may be important differences between terrestrial and marine systems with respect to some density effects.
Article
Omnivores play an important role in the routing and distribution of organic matter across food webs. We demonstrate a novel approach to quantifying the coincidence of landscape-scale nutritional gradients with niche breadth in terms of variability in trophic level and use of basal organic matter sources. We provide an example of the links between individual variability in resource use and habitat of a broad-spectrum omnivore, the red rock lobster Jasus edwardsii. Information on the co-occurrence of J. edwardsii with kelp bed habitats Ecklonia radiata and with their preferred prey Mytilus edulis galloprovinciallis were collected at 60 sites across Fiordland, southwest New Zealand. Analysis of distance-based linear models (DISTLM) indicated that the presence of mussels was the best predictor of lobster occurrence in the model set. At a subset of sites, we collected lobster muscle for stable isotope analysis and measured 3 demographic parameters from the lobsters: relative abundance, sex and carapace lengths. We characterised habitats with surveys of common kelp and mussels. Using stable isotope signatures (delta C-13 and delta N-15), we calculated individual-based estimates of trophic level and the mixture of organic matter sources, i.e. phytoplankton and macroalgae. Using DISTLM, lobster and mussel densities best explained variability in lobster diet. Variability in resource use was distinct inside and outside of kelp bed habitat. In kelp beds, lobsters fed at a higher average trophic level, with low variability among individuals in trophic level and use of organic matter sources. Outside kelp beds, individual variability indicated broad trophic diversification. These patterns indicate a strong influence of the nutritional landscape at the scale of the metapopulation, which has important implications for understanding dietary influences on population structure.
Article
On February 27, 2010, the world’s sixth strongest earthquake on record (8.8 M w) and tsunami hit central Chile. We assess the response of the epibenthic macrofaunal community following this event in Coliumo Bay, one of the areas most affected by this mega-perturbation. The indicators of aggregate and compositional variability show that 3 years after this event, the community appears to have undergone the following dynamics: (1) At an inter-annual timescale, the community (both in density and biomass) shifted through different structures with apparent directionality; (2) Oceanographic and biological seasonality had a strong cyclical influence on the inter-annual community response; (3) There was spatial homogenization of the community over time (i.e., recovery of diversity), probably promoted by the ecological functionality of scavenger species (i.e., crab Cancer coronatus and snail Nassarius spp.) and by the proportional increase in non-dominant species; (4) Bathymetry and bottom dissolved oxygen also played significant roles in the spatial structure of this community; (5) Three years after the perturbation, total density and total community biomass were still considerably below those described under unperturbed conditions, mainly associated with the decrease in density and biomass of dominant species. Therefore, in spite of this apparent community compositional recovery, the aggregate variability currently remains below the levels reported prior to the effect of the mega-earthquake and tsunami. These results provide evidence that supports both the Cross-Scale Resilience Hypothesis and the Response Diversity Hypothesis.
Article
Coseismic coastal uplift has been quantified using sessile intertidal organisms after several great earthquakes following FitzRoy's pioneer measurements in 1835. A dense survey of such markers may complement space geodetic data to obtain an accurate distribution of fault slip and earthquake segmentation. However, uplift estimates based on diverse intertidal organisms tend to differ, because of few methodological and comparative studies. Here, we calibrate and estimate coastal uplift in the southern segment of the 2010 Maule, Chile earthquake (Mw = 8.8) using >1100 post-earthquake elevation measurements of the sessile mussel Perumytilus purpuratus. This mussel is the predominant competitor for rocky shores all along the Pacific coast of South America, where it forms fringes or belts distinctively in the middle intertidal zone. These belts are centered at mean sea level and their width should equal one third of the tidal range. We measured belt widths close to this value at 40% of the sites, but overall widths are highly variable due to the unevenness in belt tops; belt bases, in turn, are rather regular. Belt top unevenness apparently results from locally-enhanced wave splash, whereas belt base evenness is controlled by predation. According to our measurements made beyond the earthquake rupture, the belt base is at the bottom of the middle intertidal zone, and thus we propose to estimate coastal uplift using the belt base mean elevation plus one sixth of the tidal range to reach mean sea level. Within errors our estimates agree with GPS displacements but differ from other methods. Comparisons of joint inversions for megathrust slip suggest combining space geodetic data with estimates from intertidal organisms may locally increase the detail of slip distributions.
Article
The ability of propagules (fertilized eggs) of five species of fucoid algae ( Hormosira banksii, Durvillaea antarctica, Cystophora torulosa from New Zealand, and Fucus gardneri and Pelvetiopsis limitata from Oregon, U.S.A.) to settle and attach was tested in a turbulent, stirred tank. The time taken to reach a steady state of settlement numbers varied between species and turbulence intensities. Normalized steady-state (NSS) settlement numbers showed differences among species. A settlement model, based on principles invoked in the analysis of motion of bed sediments in rivers, was developed. The model indicates that the NSS settlement number depends on two parameters, a propagule Reynolds number and an entrainment function that represents the relative importance of the shear stress experienced by settled propagules and their submerged weight. The inability of this model to collapse the data for all species suggests that the stickiness of the propagules, due to their mucus coatings, plays a significant role in the settlement process. P. limitata (largest propagules) exhibited the least effective attachment to the substratum, whereas F. gardneri (second largest) and D. antarctica (smallest propagules) were the most effective at withstanding hydrodynamic forces that detach propagules. We also model the boundary layer above a flat-bed, driven by linear water-waves, using a skin-friction drag coefficient and show that this study represents the lower end of the shear velocity u* range. However, these experiments capture the main region of variability in long-term propagule attachment, and indicate that most of these fucoid species will have successful settlement only during calm conditions.
Article
The April 25,1992, Cape Mendocino earthquake (Ms 7.1) uplifted ˜24 km of the northern California coast at the southern end of the Cascadia subduction zone, uplift which resulted in coastal emergence that caused extensive mortality of intertidal organisms between Cape Men docino and Punta Gorda. We estimated the amount of uplift by measuring the vertical extent of mortality of 14 sessile intertidal species on rocky sections of shore. The uplift profile along the coast is generally parallel to the strike of the earthquake focal mechanism and forms a broad, flat-topped arch ˜24 km long with a gentle south limb and a steeper north limb. The maximum uplift of 1.4 ±0.2 m is near the center of the profile. The profile is a manifestation of the more widespread domal upwarp produced by slip on an east-dipping buried thrust fault along or near the Cascadia megathrust. Small, new emergent terraces have formed where wave-cut intertidal platforms have been elevated. The new terraces resemble raised late Holocene benches that probably record paleoearthquakes similar to the 1992 event. However, several of the late Holocene terraces are broader and more continuous. These terraces, which extend several tens of kilometres north and south of the 1992 uplift, suggest that some paleoearthquakes were much larger than magnitude 7.
Article
Sediments are likely to influence the distribution of limpets and dominant sessile species on intertidal rocky shores by smothering and interfering with feeding activity. This hypothesis was tested by field observations and laboratory experiments in which the effects of different amounts and grain sizes of sediments on the grazing and survival of the limpet Patella vulgata L. were measured. On rocky shores close to Plymouth (south-west UK), natural patchiness of sediment deposits was related to the distribution of P. vulgata and macroalgae. Sediments severely impaired P. vulgata. Even a similar to 1 mm thick layer of sediment (equivalent to 50 mg cm(-2)) decreased grazing activity by 35 %, with total inhibition and mortality at loads of 200 mg cm(-2) of fine sediments. Coarse sediments had less severe effects than fine sediments.
Article
Knowledge of the long-term rates of erosion of shore platforms are needed to assist modeling platform development, understand rates and modes of development and decipher issues of inheritance from former sea level. Few studies report rates from more than 2 years of monitoring. We report decadal scale erosion rates using both a micro-erosion meter and a traversing micro-erosion meter with measurements from 30 years and 10 years, respectively. Gross mean surface lowering rates measured over 10 years with a traversing micro-erosion meter were 0.901 (S.E.=0.116) mm/yr compared with 1.130 (S.E.=0.217) mm/yr over two years. Over thirty years (1973–2003) 12 micro-erosion meter sites provide a mean surface lowering rate of 1.09 (S.E.=0.126) mm/yr compared to 1.43 (S.E. 0.128) mm/yr calculated over twenty years (1973–1993) from 15 bolt sites and 1.53 (S.D.=1.45) mm/yr from 31 bolt sites. Rates calculated over longer time periods are reduced compared to short-term rates as a result of faster eroding bolt sites being removed from the data set. Comparison of means between short and long time periods for existing bolts show no significant difference. That is, short-term measurements over two years are representative of decadal scale erosion rates. In fact decadal scale rates may under represent rates of platform development because of the loss of faster eroding bolt sites. The loss of such bolts means that obtaining long-term erosion rates is problematic. Future modeling of shore platform development can use MEM rates with more certainty, but we recommend using higher rates from shorter term studies, unless longer records are complete.
Article
Disturbances over a range of intensities are common in intertidal communities, often causing partial removal of dominant species. However, most studies testing effects of disturbance on community structure use treatments where the dominant species is either present or absent, and usually record responses of only a few community components. Here, we test responses of the entire local community of benthic algae and invertebrates across a gradient of distur- bance to a habitat dominant in southern New Zealand, the fucoid alga Hormosira banksii. Replicate 0.25 m 2 plots of 100% cover of H. banksii were manipulated and maintained at 0, 25, 50 and 75% cover at 2 sites for 13 mo. Throughout the experiment, communities in the complete removal and control plots were the most different from each other, but intermediate plots had varied responses and were usually not significantly different from each other. Generally, as cover of H. banksii decreased, community variability increased through time. Taxa richness declined with reduced H. banksii cover, with up to 77% of its variation explained by variation in canopy cover. Other fucoid algae declined across the gradient, with complete canopy removals having 92% less fucoid cover than control plots. Complete canopy removal had positive effects on ephemeral algae, especially at one site which exhibited large seasonal blooms. Bare space was greatest where canopies were completely removed and understory algae died. Diversity was greatest in plots with complete canopies rather than at intermedi- ate levels, and there was no replacement of the domi- nant H. banksii by other species. There was no consis- tent effect on taxa across the gradient; some species responded linearly while others responded at thresh- old levels of canopy cover. This study shows the impor- tance of disturbance gradients interacting with key species, which may have considerable bearing on reef community structure.
Article
Life on Earth has repeatedly displayed abrupt and massive changes in the past, and there is no reason to expect that comparable planetary-scale regime shifts will not continue in the future. Different lines of evidence indicate that regime shifts occur when the climate or biosphere transgresses a tipping point. Whether human activities will trigger such a global event in the near future is uncertain, due to critical knowledge gaps. In particular, we lack understanding of how regime shifts propagate across scales, and whether local or regional tipping points can lead to global transitions. The ongoing disruption of ecosystems and climate, combined with unprecedented breakdown of isolation by human migration and trade, highlights the need to operate within safe planetary boundaries.
Article
This paper reports the occurrence of swelling of coastal bedrock measured with a traversing micro-erosion meter (TMEM) on inter-tidal mudstone and limestone shore platforms. While numerous micro-erosion meter (MEM) studies have been made, only a small number have reported surface swelling. During this study, 24,055 measurements were made with a TMEM, of those 4047 indicated swelling or 17% of the total number of measurements. Vertical swelling of up to 8.9 mm was measured and values of 3 and 4 mm were common. Swelling displayed a complex pattern with minor swelling being superimposed on longer period episodes. Duration of swelling events in excess of 697 days were recorded, while other events were commonly in the order of 3 to 4 months. There is a distinct seasonal variation with greater and more frequent swelling occurring during summer months compared with winter. Explanation for swelling includes the growth of salt crystals in rock lattices and expansion from wetting and drying. Warm summer temperatures provide the best conditions for both processes. Swelling appears to be an important precursor to erosion of material from shore platform surfaces. The conclusion drawn is that subaerial weathering makes an important contribution to the lowering of the shore platforms on the Kaikoura Peninsula.