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.
Coastal News (74): 6-8. Available online https://www.coastalsociety.org.nz/assets/Publications/Coastal-News/CN-74-2021-3.pdf
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.
The November 2016 Kaikōura earthquake reshaped the coastal landscape causing significant impacts on the coastline and marine ecosystems. This article provides an overview of the coastal recovery process three and half years later based on results from an intensive monitoring programme across 130 km of coast.
We investigated the response of a tidal lagoon system to a unique situation of relative sea-level change induced by powerful earthquakes (up to Mw 7.1) on the east coast of New Zealand in 2010–2011. Spatiotemporal impacts were quantified using airborne light detection and ranging (LiDAR) datasets complemented by hydrodynamic modelling and evaluation of anthropogenic influences. Ground-level changes included examples of uplift and extensive subsidence (ca. 0.5 m) associated with intertidal area reductions, particularly in supratidal zones. ‘Coastal squeeze’ effects occurred where incompatible infrastructure prevented upland ecosystem movement with relative sea-level rise. Despite large-scale managed retreat, legacy effects of land-filling have reduced the reversibility of human modifications, impairing system resiliency through poor land-use design. Elsewhere, available space in the intertidal range shows that natural environment movement could be readily assisted by simple engineering techniques though is challenged by competing land-use demands. Quantification of gains and losses showed that lagoon expansion into previously defended areas is indeed required to sustain critical habitats, highlighting the importance of a whole-system view. Identifiable coastal planning principles include the need to assess trade-offs between natural and built environments in the design of hazard management plans, requiring greater attention to the natural movement of ecosystems and areas involved. Treating these observations as a scenario illustrates the mechanisms by which coastal squeeze effects may develop under global sea-level rise, but our purpose is to help avoid them by identifying appropriate human responses. We highlight the need for an improved focus on whole-system resilience, and the importance of disaster recovery processes for adaptation to climate change.
Vegetated coastal ecosystems (VCEs) are in global decline and sensitive to climate change; yet may also assist its mitigation through high rates of ‘blue’ carbon sequestration and storage. Alterations of relative sea-level (RSL) are pervasive drivers of change that reflect the interaction between tidal inundation regimes and ground surface elevation. Although many studies have investigated sediment accretion within VCEs, relatively few have addressed spatiotemporal patterns of resilience in response to RSL change. In this study, we used high resolution elevation models and field surveys to identify RSL changes and socio-ecological responses in a tidal lagoon system following earthquakes in New Zealand. We expected that vegetation changes would result from RSL effects caused by surface-elevation changes in intertidal zones. Elevation measurements showed a sequence of vertical displacements resulting from major earthquakes in 2011 and 2012, and additional surface-elevation loss since. VCE losses were recorded over an 8 year period post-2011 in response to high rates of RSL rise (up to 41 mm yr⁻¹). Anthropogenic factors influenced the pattern of losses and illustrate opportunities for managing risks to other VCEs facing RSL rise. Four key principles for building VCE resilience were identified: i) anthropogenic encroachment results in resilience loss due to the need for landward migration when changes exceed the tolerance thresholds of VCEs at their lower elevational limits; ii) connectivity losses exacerbate encroachment effects, and conversely, are a practical focus for management; iii) landscape-scale risk exposure is disproportionately influenced by the largest wetland remnants illustrating the importance of site-specific vulnerabilities and their assessment; and iv) establishing new protected areas to accommodate the movement of VCEs is needed, and requires a combination of land tenure rearrangements and connectivity conservation. Embracing these concepts offers promise for improving whole-system resilience to help address the challenge of global climate change.
• Galaxias maculatus is a riparian spawning fish that supports an important recreational fishery in New Zealand, with spawning habitat requirements strongly structured by salinity gradients at river mouths. This study reports changes to the spawning habitat following a series of large earthquakes that resulted in the widespread deformation of ground surfaces in the vicinity of waterways. • Assessments of habitat recovery focused on two river systems, the Avon and Heathcote, with pre‐disturbance data available over a 20‐year period. Recovery dynamics were assessed by field survey and mapping of spawning habitat prior to and on seven occasions after the disturbance event. Riparian land‐use and management patterns were mapped and analysed using overlay methods in a geographical information system (GIS). • Habitat migration of up to 2 km occurred in comparison with all previous records, and several anthropogenic land uses have become threats because of changed patterns of co‐occurrence. Incompatible activities now affect more than half of the spawning habitat in both rivers, particularly in areas managed for flood control purposes and recreational use. • The results are an example of landscape‐scale responses to salinity and water‐level changes driven by tectonic dynamics. These dynamics are not the source of the stress per se; rather, they have increased the exposure of the species to pre‐existing stressors. • The case illustrates important principles for managing subtle, yet widespread, change. Adaptive conservation methods and investments in information are priorities for avoiding management failure following environmental change.
This report is the third and final report in the Ecological Regeneration Options (ERO) project series. Its purpose is to assist in developing integrated assessment methodologies for evaluating ecological regeneration options in the Avon-Ōtākaro Red Zone (AORZ). This is an important topic to ensure that their potential benefits are recognised alongside those of alternative land uses. This report complements the previous two reports in the ERO series. These provide information on floodplain restoration principles (Orchard, 2017) and an assessment of restoration opportunities in the AORZ using a local knowledge approach (Orchard et al., 2017). The focus of this report is on facilitating robust assessments of the ecological regeneration options presented by the AORZ. A specific objective was to develop an integrated assessment framework to support comparison of those options against each other and against alternative land uses. First, the topics of river corridor evaluation and integrated assessment are briefly introduced and examples of integrated assessment in relevant planning contexts identified. A framework for the integrated assessment of ecological regeneration options is then presented.
Guidelines for sustainability and ecosystem-based climate change adaptation in the coastal zone Coastal zones worldwide are highly vulnerable to the impacts of climate change, and communities who depend on these areas and the ecosystems services and assets that occur there are highly exposed to loss and damage. Whereas some of these impacts can be addressed through natural solutions, others might be irreversible. Addressing climate change adaptation and disaster-risk reduction in an integrated manner, is therefore particularly relevant in these areas, in particular to reduce long-term vulnerability. During this session, case studies on climate change adaptation action from different areas of the world will be examined, and lessons learned for both management and policy will be derived as the basis for new recommendations. Key Speakers Liette Vasseur, Brock University, Canada; Shane Orchard, WCPA and CEM; Milika Sobey, IUCN; Robert Mather, Southeast Asia Group, IUCN; Mark Ford, U.S. National Park Service; Robert Young, Western Carolina University
The purpose of this assessment is to compare records of known inanga spawning sites in the waterways of Ōtautahi Christchurch from before and after the Canterbury earthquakes, with particular emphasis on information used in the design of planning methods for spawning site protection. Environment Canterbury (ECan) has recently notified a list of known inanga spawning sites in Schedule 17 of the Plan Change 4 (ECan, 2015a) to the Canterbury Land and Water Regional Plan (ECan, 2015b). Ecan has also prepared maps of ‘potential’ inanga spawning sites for planning purposes (ECan, 2015b). Christchurch City Council (CCC) has developed maps of inanga spawning sites for consenting purposes, as extra mitigation is required by the Council when working in spawning areas (Margetts, 2016). ). These maps consist of reaches of waterways that include locations at which eggs have been observed, as well as areas of suitable habitat immediately upstream and downstream of these eggs. The mapping process consisted of a desktop assessment of egg survey records, with the last update encompassing surveys from 2004-2011. Suitable habitat was assessed on a site-specific manner, based on a number of factors, including access for adult fish, aspect, soil conditions, bank slope and vegetation (B. Margetts, pers. comm.). The suitable habitat areas were included in the inanga spawning sites defined by CCC to address the difficulties in finding eggs in the field and the high potential for similar areas of suitable habitat immediately adjacent to observed eggs to also have had eggs in the past, or in the future. These sites informed, inter alia, the identification of Sites of Ecological Significance in the Proposed Christchurch Replacement District Plan (CCC, 2015). Inanga spawning in the waterways of Ōtautahi Christchurch has been well documented since the late 1980s (Taylor et al., 1992). Following the Canterbury earthquakes, a change in the distribution of spawning sites has been identified based on extensive surveys conducted in 2015. The methodology used in these surveys is described in Orchard & Hickford (2016) together with detailed results. This information is particularly relevant to planning methods which seek to protect inanga spawning sites. It is therefore timely to consider the means by which spawning sites are defined in plans, and whether any changes are needed to include the new information.