Article

A global analysis of complexity-biodiversity relationships on marine artificial structures

October 2020
Global Ecology and Biogeography

DOI:10.1111/geb.13202

Authors:

Elisabeth M. A. Strain

University of Tasmania

Peter Steinberg

UNSW Sydney

Maria Vozzo

The Commonwealth Scientific and Industrial Research Organisation

Emma L Johnston

UNSW Sydney

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Abstract Aim: Topographic complexity is widely accepted as a key driver of biodiversity, but at the patch-scale, complexity–biodiversity relationships may vary spatially and temporally according to the environmental stressors complexity mitigates, and the species richness and identity of potential colonists. Using a manipulative experiment, we assessed spatial variation in patch-scale effects of complexity on intertidal biodiversity. Location: 27 sites within 14 estuaries/bays distributed globally. Time period: 2015–2017. Major taxa studied: Functional groups of algae, sessile and mobile invertebrates. Methods: Concrete tiles of differing complexity (flat; 2.5-cm or 5-cm complex) were affixed at low–high intertidal elevation on coastal defence structures, and the richness and abundance of the colonizing taxa were quantified after 12 months. Results: The patch-scale effects of complexity varied spatially and among functional groups. Complexity had neutral to positive effects on total, invertebrate and algal taxa richness, and invertebrate abundances. However, effects on the abundance of algae ranged from positive to negative, depending on location and functional group. The tidal elevation at which tiles were placed accounted for some variation. The total and invertebrate richness were greater at low or mid than at high intertidal elevations. Latitude was also an important source of spatial variation, with the effects of complexity on total richness and mobile mollusc abundance greatest at lower latitudes, whilst the cover of sessile invertebrates and sessile molluscs responded most strongly to complexity at higher latitudes. Conclusions: After 12 months, patch-scale relationships between biodiversity and habitat complexity were not universally positive. Instead, the relationship varied among functional groups and according to local abiotic and biotic conditions. This result challenges the assumption that effects of complexity on biodiversity are universally positive. The variable effect of complexity has ramifications for community and applied ecology, including eco-engineering and restoration that seek to bolster biodiversity through the addition of complexity.

Understanding the role of microhabitats in intertidal rock pools to guide future eco-engineering designs

Article

Full-text available

Mar 2023
MAR BIOL

Intertidal rock pools support diverse assemblages. While there is much research on the importance of rock pools in supporting mobile diversity on rocky shores, there is limited knowledge regarding the role of physical features (microhabitats) within these habitats. Understanding the features of pools that support diversity is crucial to conserve and potentially mimic these important intertidal habitats in restoration projects. Here, we classified and quantified the types of physical features, hereafter “microhabitats” (overhangs and pits), within rock pools at different locations in and around a highly urbanised estuary, Sydney Harbour, Australia. The use of different microhabitats within rock pools by mobile macro-invertebrates was also examined in one location. We surveyed natural rock pools in summer (2 times) and winter (2 times) at seven sites: two sites from each of the inner and outer zones of Sydney Harbour, and three sites along the open coast of Sydney. We found that the type and size of microhabitats within pools decreased from the coastal towards inner harbour sites. Along the open coast, the richness of mobile taxa increased in rock pools with overhangs or pits. Only rock pools with overhangs had increased mobile abundances, likely driven by the gastropod Nerita melanotragus. Several species occurred in greater frequency in pools with overhangs. There was no effect of pits on abundances. This survey suggests that some microhabitats may play an important role in the diversity and abundance of mobile macro-invertebrates in rock pools. A detailed understanding of the local and regional scales of microhabitats should be used to inform eco-engineering of intertidal foreshores.

Effect of habitat topography on the structure and diversity of benthic communities across five marinas from the southwestern Atlantic Ocean

Article

Sep 2022

Marine urbanization promotes the addition of hard substrata that barely resembles natural substrate nearby. We manipulated habitat topography in five marinas across one of the most populated regions from the Southwestern Atlantic Ocean to describe the effect of habitat complexity on the diversity of benthic communities across sites with distinct conditions and biotas. The highest biomass was found in the two marinas under high pollution and freshwater disturbances, regardless of habitat complexity. Habitat topography did not affect species richness but determined the structure of sessile communities in all marinas. The structure of mobile communities was affected only in the most diverse site, increasing the abundance of isopods. In general, fragile ascidians, hydrozoans, and non‐calcified polychaetes dominated complex habitats, while structurally defended animals such as barnacles, serpulids, and encrusting bryozoans dominated simple habitats, suggesting that dominant species are selected by habitat complexity based on their morphological traits. However, the final community structure was also determined by differences across marinas, suggesting that the effect of increasing habitat topography is mostly site‐specific. Therefore, strategies to minimize the disparity between natural and artificial habitats must consider historic local community and a multiple stressors scenario.

Complexity–biodiversity relationships on marine urban structures: reintroducing habitat heterogeneity through eco-engineering

Article

Full-text available

Jun 2022

Urbanization is leading to biodiversity loss through habitat homogenization. The smooth, featureless surfaces of many marine urban structures support ecological communities, often of lower biodiversity, distinct from the complex natural habitats they replace. Eco-engineering (design for ecological co-benefits) seeks to enhance biodiversity and ecological functions on urban structures. We assessed the benefits to biodiversity of retrofitting four types of complex habitat panels to an intertidal seawall at patch (versus flat control panels) and site (versus unmodified control seawalls and reference rocky shores) scales. Two years after installation, patch-scale effects of complex panels on biodiversity ranged from neutral to positive, depending on the protective features they provided, though all but one design (honeycomb) supported unique species. Water-retaining features (rockpools) and crevices, which provided moisture retention and cooling, increased biodiversity and supported algae and invertebrates otherwise absent. At the site scale, biodiversity benefits ranged from neutral at the high- and mid-intertidal to positive at the low-intertidal elevation. The results highlight the importance of matching eco-engineering interventions to the niche of target species, and environmental conditions. While species richness was greatest on rockpool and crevice panels, the unique species supported by other panel designs highlights that to maximize biodiversity, habitat heterogeneity is essential. This article is part of the theme issue ‘Ecological complexity and the biosphere: the next 30 years’.

How and to What Degree Does Physical Structure Differ Between Natural and Artificial Habitats? A Multi-Scale Assessment in Marine Intertidal Systems

Article

Full-text available

Nov 2021

Marine infrastructures are increasing, generating a variety of impacts and introducing artificial habitats which have low ecological value and support assemblages that differ significantly from those on natural rocky coasts. While in the past there was little ecological consideration as to how artificial structures were built, now the trend is to look for “greener” designs inspired by or mimicking nature. These greening efforts have had a strong focus on enhancing physical habitat structure to support more diverse assemblages, driven by the untested assumption that artificial habitats lack the physical structure proper to natural habitats. We tested this assumption by comparing five descriptors of physical structure (inclination; exposure; roughness; abundance, and diversity of surface morphological microelements) across a combination of natural and artificial habitats of regular and irregular morphologies (seawalls = artificial regular; cliffs = natural regular; breakwaters = artificial, irregular; and boulder fields = natural irregular) in the North Adriatic Sea. Most structural descriptors were similar between artificial and natural habitats. Only inclination was consistently steeper in the artificial than in the natural habitats. Other minor differences in roughness or in the abundance of some surface microelements were related to the general morphology (regular or irregular) of the habitat rather than to its artificial or natural identity. The outcomes challenge the widespread assumption that artificial habitats lack the physical structure proper to natural habitats and stimulate renewed consideration about other structural and non-structural elements that could enhance the performance and sustainability of artificial marine structures, such as construction material, environmental setting or maintenance. They also encourage a wider reflection about what makes an artificial building surface “greener”: structural complexity is an important ecological parameter, and its deliberate increase will lead to responses in the biota, however, this may not necessarily match “more natural” conditions.

Spatially Variable Effects of Artificially-Created Physical Complexity on Subtidal Benthos

Article

Full-text available

Aug 2021

In response to the environmental damage caused by urbanization, Nature-based Solutions (NbS) are being implemented to enhance biodiversity and ecosystem processes with mutual benefits for society and nature. Although the field of NbS is flourishing, experiments in different geographic locations and environmental contexts have produced variable results, with knowledge particularly lacking for the subtidal zone. This study tested the effects of physical complexity on colonizing communities in subtidal habitats in two urban locations: (1) Plymouth, United Kingdom (northeast Atlantic) and (2) Tel Aviv, Israel (eastern Mediterranean) for 15- and 12-months, respectively. At each location, physical complexity was manipulated using experimental tiles that were either flat or had 2.5 or 5.0 cm ridges. In Plymouth, biological complexity was also manipulated through seeding tiles with habitat-forming mussels. The effects of the manipulations on taxon and functional richness, and community composition were assessed at both locations, and in Plymouth the survival and size of seeded mussels and abundance and size of recruited mussels were also assessed. Effects of physical complexity differed between locations. Physical complexity did not influence richness or community composition in Plymouth, while in Tel Aviv, there were effects of complexity on community composition. In Plymouth, effects of biological complexity were found with mussel seeding reducing taxon richness, supporting larger recruited mussels, and influencing community composition. Our results suggest that outcomes of NbS experiments are context-dependent and highlight the risk of extrapolating the findings outside of the context in which they were tested.

Metrics matter: Multiple diversity metrics at different spatial scales are needed to understand species diversity in urban environments

Article

Jun 2023
SCI TOTAL ENVIRON

Worldwide, natural habitats are being replaced by artificial structures due to urbanisation. Planning of such modifications should strive for environmental net gain that benefits biodiversity and ecosystems. Alpha (α) and gamma (γ) diversity are often used to assess 'impact' but are insensitive metrics. We test several diversity measures across two spatial scales to compare species diversity in natural and artificial habitats. We show γ-diversity indicates equivalency in biodiversity between natural and artificial habitats, but natural habitats support greater taxon (α) and functional richness. Within-site β-diversity was also greater in natural habitats, but among-site β-diversity was greater in artificial habitats, contradicting the commonly held view that urban ecosystems are more biologically homogenous than natural ecosystems. This study suggests artificial habitats may in fact provide novel habitat for biodiversity, challenges the applicability of the urban homogenisation concept and highlights a significant limitation of using just α-diversity (i.e., multiple metrics are needed and recommended) for assessing environmental net gain and attaining biodiversity conservation goals.

Nature-based and bioinspired solutions for coastal protection: an overview among key ecosystems and a promising pathway for new functional and sustainable designs

Article

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May 2023

Coastal erosion is occurring at a faster rate than in the past. The adverse impacts are not negligible at environmental, economic, and socio-cultural levels. Hence, coastal protection is currently seen as an emerging need to counteract erosion impacts and their many negative effects on worldwide ecosystems. In this regard, natural systems and their organisms represent a complex system of solutions that can efficiently create and/or inspire the development of natural, sustainable, and cutting-edge coastal barriers. Coastal ecosystems, such as coral reefs, oyster reefs, mangroves, saltmarshes, seagrasses, and polychaete reefs, act as a natural barrier for destructive waves and wind forces. Moreover, living organisms have evolved unique strategies to withstand their environmental hydrodynamic loadings. This review intends to provide an overview regarding natural systems and related nature-based and bioinspired strategies in the specific field of coastal protection, describing the state of the art, methods, processes, and tools, as well as delineating a promising pathway for new functional and sustainable designs.

Physical and biogenic complexity mediates ecosystem functions in urban sessile marine communities

Article

Dec 2022

The influence of habitat complexity on biodiversity is a central theme in ecology, with many studies reporting positive relationships. Reconciliation approaches in urbanised areas, such as eco‐engineering, have increasingly focused on ‘re‐building’ the complexity of degraded and/or homogenised habitats to support biodiversity. Yet, the effects of increasing complexity and biodiversity on ecological functions are rarely measured. We assessed how increasing the physical and/or biogenic complexity of habitats affects the net primary productivity (NPP) and gross primary productivity (GPP), community respiration and nutrient cycling (specifically dissolved inorganic phosphorus and nitrogen) of intertidal sessile marine communities at three sites. We manipulated physical complexity using two types of settlement tiles: ‘complex’, with crevices and ridges, and ‘flat’. We increased biogenic complexity on half the replicates of each tile type by seeding with oysters. Increased physical and biogenic complexity resulted in greater sessile species richness at all sites. Although many variables assessed varied with sites and time of measurements, overall, GPP and NPP were greater on flat tiles than on complex ones. These patterns were not explained by differences in the total surface area of tiles. Daily flux rates of dissolved inorganic phosphorus had a significant positive relationship with biogenic complexity. There were no effects of biogenic or physical complexity on the net fluxes of dissolved inorganic nitrogen. Effects of habitat complexity on the productivity and nutrient cycling of marine sessile communities were largely unrelated to diversity measures, such as richness or abundance of key taxa and functional groups. Synthesis and applications . Eco‐engineering practices that manipulate habitat complexity might benefit from explicit functional targets that also consider associated ecosystem services, as we found that under some conditions there is a trade‐off between biodiversity and functional targets. Our results suggest that increasing habitat complexity has a positive effect on sessile species richness, but not necessarily on productivity (GPP and NPP). The species pool available as well as light availability is likely to mediate effects of complexity on assemblages, so local environment needs to be a key consideration when designing interventions.

Heterogeneity within and among co-occurring foundation species increases biodiversity

Article

Full-text available

Jan 2022

Habitat heterogeneity is considered a primary causal driver underpinning patterns of diversity, yet the universal role of heterogeneity in structuring biodiversity is unclear due to a lack of coordinated experiments testing its effects across geographic scales and habitat types. Furthermore, key species interactions that can enhance heterogeneity, such as facilitation cascades of foundation species, have been largely overlooked in general biodiversity models. Here, we performed 22 geographically distributed experiments in different ecosystems and biogeographical regions to assess the extent to which variation in biodiversity is explained by three axes of habitat heterogeneity: the amount of habitat, its morphological complexity, and capacity to provide ecological resources (e.g. food) within and between co-occurring foundation species. We show that positive and additive effects across the three axes of heterogeneity are common, providing a compelling mechanistic insight into the universal importance of habitat heterogeneity in promoting biodiversity via cascades of facilitative interactions. Because many aspects of habitat heterogeneity can be controlled through restoration and management interventions, our findings are directly relevant to biodiversity conservation.

Habitat Complexity Affects the Structure but Not the Diversity of Sessile Communities on Tropical Coastal Infrastructure

Article

Full-text available

Oct 2021

Increasing human population, urbanisation, and climate change have resulted in the proliferation of hard coastal infrastructure such as seawalls and breakwaters. There is increasing impetus to create multifunctional coastal defence structures with the primary function of protecting people and property in addition to providing habitat for marine organisms through eco-engineering - a nature-based solutions approach. In this study, the independent and synergistic effects of physical complexity and seeding with native oysters in promoting diversity and abundances of sessile organisms were assessed at two locations on Penang Island, Malaysia. Concrete tiles with varying physical and biological complexity (flat, 2.5 cm ridges and crevices, and 5 cm ridges and crevices that were seeded or unseeded with oysters) were deployed and monitored over 12 months. The survival of the seeded oysters was not correlated with physical complexity. The addition of physical and biological complexity interacted to promote distinct community assemblages, but did not consistently increase the richness, diversity, or abundances of sessile organisms through time. These results indicate that complexity, whether physical or biological, is only one of many influences on biodiversity on coastal infrastructure. Eco-engineering interventions that have been reported to be effective in other regions may not work as effectively in others due to the highly dynamic conditions in coastal environment. Thus, it is important that other factors such as the local species pools, environmental setting (e.g., wave action), biological factors (e.g., predators), and anthropogenic stressors (e.g., pollution) should also be considered when designing habitat enhancements. Such factors acting individually or synergistically could potentially affect the outcomes of any planned eco-engineering interventions.

Decommissioning Research Needs for Offshore Oil and Gas Infrastructure in Australia

Article

Full-text available

Jul 2021

When offshore oil and gas infrastructure is no longer needed, it is either removed, partially removed, left in place, or left in place but repurposed. These processes are collectively referred to as decommissioning. Australian legislation requires oil and gas companies to develop acceptable plans for the safe removal of all offshore infrastructure at the end of a project’s life. Over the next 50 years, the liability for this decommissioning in Australia is expected to exceed US$45 billion. Unlike countries such as Norway, the United Kingdom and the Netherlands, Australian decommissioning activities are in their infancy, with only three cases (to date) in Commonwealth waters where infrastructure has been left in place or partially removed as part of decommissioning. Differences between the Australian marine environment and that of other regions around the world where decommissioning-related research is better progressed include very low sedimentation rates, both tropical and temperate habitats, different species composition, low primary production, and frequent tropical cyclones, as well as unique sociodemographic and cultural characteristics. Accordingly, the outcomes of the decision support tools used in other regions to identify preferred decommissioning options may not be equally applicable in Australia. Here we describe research to support risk and impact assessment for offshore decommissioning in Australia, where full removal of infrastructure is the “base case” regulatory default, but other options including partial removal and/or repurposing might provide similar or better outcomes when environmental, social, economic and seafood safety aspects are considered. Based on our review we propose an integrated framework for research needs to meet legislative requirements for decommissioning and identify research gaps that need to be addressed to inform decision-making for decommissioning in the Australian context.

Oceanic Environmental Impact in Seaports

Article

Full-text available

Nov 2023

Seaports are gateways that connect a nation to the world economy. With trade by sea increasing due to globalization, the need for the improvement and development of seaports cannot be overlooked. While the development of ports is considered essential for the economic growth and prosperity of a nation, they also result in environmental deterioration that can hurt the future of humanity. The factors that cause such deterioration are many and have been discussed and studied in some detail over the years. Of these, however, studies associated with the environmental impacts of seaports emanating from the oceanfront are limited. It is with this understanding that the current work discusses the physical and biological impacts that occur due to the oceanic environment in seaports, the existing policy provisions, and the possible ways ahead to reduce environmental deterioration and allow their sustainable operation, by means of reviewing published works.

Unveiling the transition from niche to dispersal assembly in ecology

Article

Full-text available

Jun 2023
NATURE

A central goal in ecology is to understand what maintains species diversity in local communities. Classic ecological theory1,2 posits that niches dictate the maximum number of species that can coexist in a community and that the richness of observed species will be below this maximum only where immigration is very low. A new alternative theory3,4 is that niches, instead, dictate the minimum number of coexisting species and that the richness of observed species will usually be well above this because of ongoing immigration. We conducted an experimental test to discriminate between these two unified theories using a manipulative field experiment with tropical intertidal communities. We found, consistent with the new theory, that the relationship of species richness to immigration rate stabilized at a low value at low immigration rates and did not saturate at high immigration rates. Our results suggest that tropical intertidal communities have low niche diversity and are typically in a dispersal-assembled regime where immigration is high enough to overfill the niches. Observational data from other studies3,5 suggest that these conclusions may generalize to other ecological systems. Our new experimental approach can be adapted for other systems and be used as a ‘niche detector’ and a tool for assessing when communities are niche versus dispersal assembled.

Review of the Effects of Enclosure Complexity and Design on the Behaviour and Physiology of Zoo Animals

Article

Full-text available

Apr 2023

The complexity of the habitat refers to its physical geometry, which includes abiotic and biotic elements. Habitat complexity is important because it allows more species to coexist and, consequently, more interactions to be established among them. The complexity of the habitat links the physical structure of the enclosure to the biological interactions, which occur within its limits. Enclosure complexity should vary temporally, to be able to influence the animals in different ways, depending on the period of the day and season and throughout the year. In the present paper, we discuss how habitat complexity is important, and how it can positively influence the physical and mental states of zoo animals. We show how habitat complexity can ultimately affect educational projects. Finally, we discuss how we can add complexity to enclosures and, thus, make the lives of animals more interesting and functional.

Weak effects of age but important role of microhabitats in community differences between breakwaters and natural rocky shores across a latitudinal gradient

Article

Full-text available

Aug 2022
GLOBAL ECOL BIOGEOGR

Aim Coastal infrastructures are increasing at different latitudes, and their deployment often results in a complete replacement of natural habitats. Although infrastructure provides novel habitats, ecological engineering can increase their similarity to natural rocky habitats. One hurdle for effective design of greener infrastructure is the scarce information on the processes that underpin differences in the structure of communities between built and natural habitats. Using long‐term data of intertidal community structure, we tested whether the magnitude of between‐habitat differences changes with breakwater age and across latitudes, and we examined the role of topographic microhabitats (i.e., rock pools) in driving these differences. Location Nine locations distributed from 18 to 41°S. Time period 2016–2020. Methods We sampled the mid‐intertidal community structure on breakwaters of different age and on natural rocky habitats (platforms and boulder fields) and assessed the availability of microhabitats, such as crevices and rock pools, along a coastline spanning 23° of latitude. Using generalized additive models (GAMs), we assessed the effect of the different factors on species diversity and functional group abundances. Results Age since construction was a poor predictor of differences between breakwaters and natural habitats. Communities on older breakwaters bore a poor resemblance to the species composition or functional group abundances found in natural habitats. The magnitude of differences between breakwaters and natural habitats varied with latitude, with season and with the type of natural habitat attributable to differences in microhabitats, especially in rock pool availability. Conclusions Our results indicate that replacement of rocky habitats with breakwaters will cause permanent alterations to coastal ecosystems. Our findings suggest that the availability of microhabitats able to shelter species from stressful environmental conditions is more important at lower and intermediate latitudes; hence, they should be incorporated primarily into infrastructures in tropical or subtropical areas. These strategies could help to compensate for the impacts on rocky ecosystems associated with increases in coastal urbanization.

Bacterial biofilm colonization and succession in tropical marine waters are similar across different types of stone materials used in seawall construction

Article

Full-text available

Jul 2022

Seawalls are important in protecting coastlines from currents, erosion, sea-level rise, and flooding. They are, however, associated with reduced biodiversity, due to their steep orientation, lack of microhabitats, and the materials used in their construction. Hence, there is considerable interest in modifying seawalls to enhance the settlement and diversity of marine organisms, as microbial biofilms play a critical role facilitating algal and invertebrate colonization. We assessed how different stone materials, ranging from aluminosilicates to limestone and concrete, affect biofilm formation. Metagenomic assessment of marine microbial communities indicated no significant impact of material on microbial diversity, irrespective of the diverse surface chemistry and topography. Based on KEGG pathway analysis, surface properties appeared to influence the community composition and function during the initial stages of biofilm development, but this effect disappeared by Day 31. We conclude that marine biofilms converged over time to a generic marine biofilm, rather than the underlying stone substrata type playing a significant role in driving community composition.

A Regional View of the Response to Climate Change: A Meta-Analysis of European Benthic Organisms’ Responses

Article

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Jun 2022

Climate change is impacting organisms in every region of the world ocean by acting though on individuals in response to their local environments. Given projected future risks derived from these changes, it is becoming increasingly important to understand regional signals of how organisms respond to facilitate their governance and protection. Benthic organisms structure ecological compositions and ecosystem dynamics, therefore not only providing insights into their own response to climate change but also how ecosystems might respond to future conditions. European seas are transitional areas including boreal, warm-temperate, and subarctic waters with organisms frequently at limits of their distributions. Here, we use a meta-analytical approach to assess how calcification, growth, metabolism, photosynthesis, reproduction, and survival in European benthic organisms respond to ocean acidification and warming. Using meta-regression, we examine how study design factors influence effect-size outcomes. Longer experimental periods generally amplified the effects of climate change on taxonomic groupings and related physiological traits and against expectation do not result in acclimation. In agreement with global studies, we find that impacts vary considerably on different taxonomic groupings and their physiological traits. We found calcifying organisms are an at-risk taxon in European waters, with climate stressors decreasing growth rates, reproduction, and survival rates. Fleshy algal species demonstrate resilience to climate stressors, suggesting future European benthic ecosystems will undergo restructuring based on current climate emission pathways.

Multi-decadal Responses of Coastal Ecosystems to Climate Change, Pollution and Non-indigenous Species in the Western and Mid-English Channel

Chapter

Apr 2022

Estuarine and coastal waters are acknowledged centres for anthropogenic impacts. Superimposed on the complex natural interactions between land, rivers and sea are the myriad consequences of human activity – a spectrum ranging from locally polluting effluents to some of the severest consequences of global climate change. For practitioners, academics and students in the field of coastal science and policy, this book examines and exemplifies current and future challenges: from upper estuaries to open coasts and adjacent seas; from tropical to temperate latitudes; from Europe to Australia. This authoritative volume marks the 50th anniversary of the Estuarine and Coastal Sciences Association, and contains a prologue by founding member Professor Richard Barnes and a short history of the Association. Individual chapters then address coastal erosion and deposition; open shores to estuaries and deltas; marine plastics; coastal squeeze and habitat loss; tidal freshwaters – saline incursion and estuarine squeeze; restoration management using remote data collection; carbon storage; species distribution and non-natives; shorebirds; modelling environmental change; physical processes such as sediments and modelling; sea level rise and estuarine tidal dynamics; estuaries as fish nurseries; policy versus reality in coastal conservation; developments in estuarine, coastal and marine management.

Conceptualisation of multiple impacts interacting in the marine environment using marine infrastructure as an example

Article

Mar 2022
SCI TOTAL ENVIRON

The human population is increasingly reliant on the marine environment for food, trade, tourism, transport, communication and other vital ecosystem services. These services require extensive marine infrastructure, all of which have direct or indirect ecological impacts on marine environments. The rise in global marine infrastructure has led to light, noise and chemical pollution, as well as facilitation of biological invasions. As a result, marine systems and associated species are under increased pressure from habitat loss and degradation, formation of ecological traps and increased mortality, all of which can lead to reduced resilience and consequently increased invasive species establishment. Whereas the cumulative bearings of collective human impacts on marine populations have previously been demonstrated, the multiple impacts associated with marine infrastructure have not been well explored. Here, building on ecological literature, we explore the impacts that are associated with marine infrastructure, conceptualising the notion of correlative, interactive and cumulative effects of anthropogenic activities on the marine environment. By reviewing the range of mitigation approaches that are currently available, we consider the role that eco-engineering, marine spatial planning and agent-based modelling plays in complementing the design and placement of marine structures to incorporate the existing connectivity pathways, ecological principles and complexity of the environment. Because the effect of human-induced, rapid environmental change is predicted to increase in response to the growth of the human population, this study demonstrates that the development and implementation of legislative framework, innovative technologies and nature-informed solutions are vital, preventative measures to mitigate the multiple impacts associated with marine infrastructure.

Frontiers in Ecol Environ - 2022 - Watchorn - Artificial habitat structures for animal conservation design and

Article

Full-text available

Feb 2022

Barbara A Wilson

Epibionts in artificial collectors

Article

Full-text available

Nov 2021

ABSTRACT Artificial collectors are tools that explain the settlement dynamics of marine invertebrates. What is known about these in the Caribbean is very limited. In order to identify and quantify the diversity of epibionts in relation to depth, between December, 2015 and August, 2016, cylindrical collectors were suspended on a long line at varying depths. At each experimental depth, bimonthly temperature, chlorophyll a, and total seston records were obtained. 7,078 individuals belonging to five phyla were counted: Chordata, Echinodermata, Arthropoda, and Mollusca. The mollusks, mainly bivalves, were the most abundant, represented by: Pinctada imbricata, Pteria colymbus, and Crassotrea rhizophorae. The recruitment of organisms showed significant changes over time, with different fixation patterns. Abundance, wealth, and diversity, in each of the experimental depths were modulated by the temperature and phytoplankton biomass and the seston. The collectors, regardless of depth and time, acted as artificial habitats, reflecting the variety of benthic organisms, mainly mollusks, that naturally share the different environments that surround the southern coast of the Gulf of Cariaco, which could be a dynamic observed in the southeast Caribbean. The Gulf of Cariaco is an important ecosystem service due to the larval supply it provides to the environment, related to the fertility of its waters. Keywords: Culture, depth, mollusks, environmental factors

Artificial habitat structures for animal conservation: design and implementation, risks and opportunities

Article

Full-text available

Feb 2022
FRONT ECOL ENVIRON

Habitat destruction and degradation, and their interaction with other threats, are driving animal declines worldwide. One approach increasingly proposed for mitigating these threats is to create artificial habitat structures as substitutes for destroyed natural structures. Here, we provide the first general definition of artificial habitat structures and synthesize important considerations for effective use. We show that they are a versatile conservation tool that have been trialed in a variety of contexts globally, to varying degrees of success. Their design must be well-informed by the drivers of natural habitat selection and their use should be part of an experimental framework to enable evaluation and refinement. We highlight possible ecological risks associated with their use and urge that artificial habitat structures are not used as inappropriate biodiversity offsets or for greenwashing. Looking forward, cross-disciplinary collaborations will help design sophisticated and effective structures to assist animal conservation in this era of rapid global change.

Mediterranean rocky reefs in the Anthropocene Mediterranean rocky reefs in the Anthropocene: present status and future concerns

Book

Jan 2021

Mediterranean rocky reefs in the Anthropocene: Present status and future concerns

Article

Full-text available

Sep 2021
ADV MAR BIOL

Global change is striking harder and faster in the Mediterranean Sea than elsewhere, where high levels of human pressure and proneness to climate change interact in modifying the structure and disrupting regulative mechanisms of marine ecosystems. Rocky reefs are particularly exposed to such environmental changes with ongoing trends of degradation being impressive. Due to the variety of habitat types and associated marine biodiversity, rocky reefs are critical for the functioning of marine ecosystems, and their decline could profoundly affect the provision of essential goods and services which human populations in coastal areas rely upon. Here, we provide an up-to-date overview of the status of rocky reefs, trends in human-driven changes undermining their integrity, and current and upcoming management and conservation strategies, attempting a projection on what could be the future of this essential component of Mediterranean marine ecosystems.

A centuries-old manmade reef in the Caribbean does not substitute natural reefs in terms of species assemblages and interspecific competition

Article

Full-text available

Jun 2021
MAR POLLUT BULL

A R T I C L E I N F O Keywords: 18th century Artificial reef Crustose coralline algae Turf algae Palythoa caribaeorum Millepora spp. A B S T R A C T With increasing maritime activities in the proximity of coral reefs, a growing number of manmade structures are becoming available for coral colonisation. Yet, little is known about the sessile community composition of such artificial reefs in comparison with that of natural coral reefs. Here, we compared the diversity of corals and their competitors for substrate space between a centuries-old manmade structure and the nearest natural reef at St. Eustatius, eastern Caribbean. The artificial reef had a significantly lower species richness and fewer competitive interactions than the natural reef. The artificial reef was dominated by a cover of crustose coralline algae and zoantharians, instead of turf algae and fire corals on the natural reef. Significant differences in species composition were also found between exposed and sheltered sites on both reefs. Our study indicates that even a centuries-old manmade reef cannot serve as a surrogate for natural reefs.

The impact of habitat complexity on the structure of marine sessile communities and larvae supply

Article

Nov 2023
MAR ENVIRON RES

Material type and origin influences the abundances of key taxa on artificial structures

Article

Oct 2023
COAST ENG

Habitat structure shapes temperate reef assemblages across regional environmental gradients

Article

Oct 2023
SCI TOTAL ENVIRON

Intertidal artificial habitats are proliferating, but are generally simpler in structure and host lower biodiversity than natural rocky reefs. Eco-engineering aims to enhance the biodiversity of coastal infrastructure, often through physical structural modifications that mimic topographic properties of natural shores. Relationships between biotic assemblages and structural properties of natural and artificial reefs have been extensively studied at sampling scales of up to 1 m2. But evidence that quantified local structural variation has an appreciable influence on biotic assemblages, at a shore-wide scale across regional environmental gradients, is lacking. Here we addressed this knowledge gap with an observational study at 32 natural and artificial intertidal reef sites in Wales, UK. We used multivariate community analysis and permutation tests to examine associations between local physical structure, regional environmental variables and sessile biotic assemblages. A potential influence of local habitat structure on assemblage composition was evident across regional-scale environmental gradients. Compared to natural sites, artificial reefs had lower taxonomic richness, distinct and more variable assemblage composition, and different physical structure. After removing the effect of habitat (natural or artificial), canonical correspondence analysis showed that environmental variables (wave exposure, sea surface temperature and salinity variation), along with two metrics of physical structure (standard deviation in log-transformed detrended roughness and skewness of surface verticality, both at 0.5 m scale), explained 40 % of the variation in assemblage composition among sites. The two structural metrics independently explained 14.5 % of the variation. Associations identified between individual taxa and environmental variables indicated that sites with a higher proportion of horizontal surfaces hosted more canopy macroalgae, which in turn support other algae and invertebrates. Our findings provide evidence to inform scaling-up of structural eco-engineering interventions from experimental contexts to enhance the biodiversity of coastal infrastructure across regional extents.

The distribution of metal and petroleum-derived contaminants within sediments around oil and gas infrastructure in the Gippsland Basin, Australia

Article

Jul 2023

As oil and gas infrastructure comes to the end of its working life, a decommissioning decision must be made: should the infrastructure be abandoned in situ, repurposed, partially removed, or fully removed? Environmental contaminants around oil and gas infrastructure could influence these decisions because contaminants in sediments could degrade the value of the infrastructure as habitat, enter the seafood supply if the area is re-opened for commercial and/or recreational fishing, or be made biologically available as sediment is resuspended when the structures are moved. An initial risk hypothesis, however, may postulate that these concerns are only relevant if contaminant concentrations are above screening values that predict the possibility of environmental harm or contaminant bioaccumulation. To determine whether a substantive contaminants-based risk assessment is needed for infrastructure in the Gippsland Basin (South-eastern Australia), we measured the concentration of metals and polycyclic aromatic hydrocarbons (PAHs) in benthic sediments collected around eight platforms earmarked for decommissioning. The measurements were compared to preset screening values and to background contaminant concentrations in reference sites. Lead (Pb), zinc (Zn), PAHs and other contaminants were occasionally measured at concentrations that exceeded reference values, most often within 150 m of the platforms. The exceedance of a few screening values by contaminants at some platforms indicates that these platforms require further analysis to determine the contaminant risks associated with any decommissioning option.

Shell cover, rugosity, and tidal elevation impact native and non-indigenous oyster recruitment: Implications for reef ball design

Article

Jul 2023
ECOL ENG

Population structure and reproductive states of the dogwhelk Nucella lapillus differ between artificial structures and natural rocky shores

Article

Jun 2023
MAR ENVIRON RES

Artificial structures are an increasingly common feature of coastal marine environments. These structures are poor surrogates of natural rocky shores, and generally support less diverse communities and reduced population sizes. Little is known about sub-lethal effects of such structures in terms of demographic properties and reproductive potential, both of which may influence the dynamics and long-term viability of populations. This study examines the population structure, reproductive states and embryo production of Nucella lapillus populations on artificial structures and natural shores in Ireland and Wales. Population density was measured twice at six natural shores and six artificial structures: once in winter and once in spring. At each sampling, the shell height of 100 individuals from each site was measured. Monthly collections of adult specimens and egg capsules were made at each site from November-January and from March-May, in order to determine sex ratios, reproductive states, and embryo abundances. Artificial structures supported larger individuals and very few juveniles compared to natural shores. Between December and January, natural shores experienced a distinctive pulse in spawning activity followed by a decline in the proportion of females in a reproductive state, whereas on artificial structures the proportion of reproductive females remained relatively stable. Differences observed may be due to a lack of microhabitats on artificial structures, along with subtle variations in structure slope. Eco-engineering interventions, including the addition of refugia such as cracks and crevices, may allow N. lapillus populations on artificial structures to approximate those on natural shores.

Artificial rockpools: Seaweed colonisation and productivity vary between sites but are consistent across environmental contexts

Article

May 2023
MAR ENVIRON RES

Artificial structures are widespread features of coastal environments, but are poor surrogates of natural rocky shores because they generally support depauperate assemblages with reduced population sizes. This has generated significant interest in eco-engineering solutions, including retrofitting seawalls with artificial rockpools to increase water retention and provide microhabitats. Although these have proven effective at individual sites, widespread uptake is contingent on evidence of consistent benefits across a range of contexts. In this study, Vertipools™ were retrofitted on eight seawalls in different environmental contexts (urban v rural and estuarine v marine) along the Irish Sea coastline and were monitored regularly for two years. Seaweed colonisation proceeded in a manner similar to patterns described for natural and artificial intertidal systems in general, consisting of early dominance by ephemeral species followed by the appearance and eventual establishment of perennial habitat-formers. After 24 months, species richness did not differ between contexts, but differed between sites. The units supported populations of large habitat-forming seaweeds at all sites. Productivity and community respiration of the colonising communities differed between sites by up to 0.5 mg O2 L−1 min−1, but not across environmental contexts. This study demonstrates that bolt-on rockpools attract similar levels of biotic colonisation and functioning in a variety of temperate environmental contexts, and could be considered for widespread implementation as an eco-engineering solution.

The Clam Before the Storm: A Meta Analysis Showing the Effect of Combined Climate Change Stressors on Bivalves

Preprint

Full-text available

Mar 2023

Impacts of a range of climate change on marine organisms have been analysed in laboratory and experimental studies. The use of different taxonomic groupings, and assessment of different processes, though, makes identifying overall trends challenging, and may mask phylogenetically different responses. Bivalve molluscs are an ecologically and economically important data-rich clade, allowing for assessment of individual vulnerability and across developmental stages. We use meta-analysis of 203 unique experimental setups to examine how bivalve growth rates respond to increased water temperature, acidity, deoxygenation, changes to salinity, and combinations of these drivers. Results show that anthropogenic climate change will affect different families of bivalves disproportionally but almost unanimously negatively. Almost all drivers and their combinations have significant negative effects on growth. Combined deoxygenation, acidification, and temperature shows the largest negative effect size. Eggs/larval bivalves are more vulnerable overall than either juveniles or adults. Infaunal taxa, including Tellinidae and Veneridae, appear more resistant to warming and oxygen reduction than epifaunal or free-swimming taxa but this assessment is based on a small number of datapoints. The current focus of experimental set-ups on commercially important taxa and families within a small range of habitats creates gaps in understanding of global impacts on these economically important foundation organisms.

Facilitation of non-indigenous ascidian by marine eco-engineering interventions at an urban site

Article

Mar 2023
BIOFOULING

Marine artificial structures often support lower native species diversity and more non-indigenous species (NIS), but adding complex habitat and using bioreceptive materials have the potential to mitigate these impacts. Here, the interacting effects of structural complexity (flat, complex with pits) and concrete mixture (standard, or with oyster shell or vermiculite aggregate) on recruitment were assessed at two intertidal levels at an urban site. Complex tiles had less green algal cover, oyster shell mixtures had less brown (Ralfsia sp.) algal cover. At a low tidal elevation, the non-indigenous ascidian Styela plicata dominated complex tiles. Additionally, mixtures with oyster shell supported higher total cover of sessile species, and a higher cover of S. plicata. There were no effects of complexity or mixture on biofilm communities and native and NIS richness. Overall, these results suggest that habitat complexity and some bioreceptive materials may facilitate colonisation by a dominant invertebrate invader on artificial structures.

Surface Integrity Could Limit the Potential of Concrete as a Bio-Enhanced Material in the Marine Environment

Preprint

Mar 2023

Coastal sprawl is among the main drivers of global degradation of shallow marine ecosystems. Among artificial substrates, quarry rock can have faster recruitment of benthic organisms than traditional concrete, which is instead more versatile for construction. However, the factors driving these differences are poorly understood. In this context, this study was designed to compare the intertidal and subtidal benthic and epibenthic assemblages on concrete and artificial basalt boulders in six locations of Madeira Island (northeastern Atlantic, Portugal). To assess the size of the habitat, the shorelines in the study area were quantified using satellite images, resulting in 33% of the south coast of Madeira being artificial. Benthic assemblages differed primarily between locations and secondarily substrates. Generally, assemblages differed between substrates in the subtidal, with lower biomass and abundance in concrete than basalt. We conclude that differences are not related to chemical effects (e.g., heavy metals) but to a higher detachment rate of calcareous biocrusts from concrete, as surface abrasion is faster in concrete than basalt. Therefore, surface integrity could be a factor of ecological significance in coastal constructions. This study advances knowledge on the impact and ecology of artificial shorelines and provides a baseline for future research towards ecological criteria for coastal protection and management.

Designing urban ports for improved coastal ecosystem services: Lessons learnt for enhancing biodiversity and reducing social-ecological conflicts

Article

Feb 2023

Ports are expanding urban systems worldwide because provide important economic benefits to local economies. But port land reclamation together with infrastructure deployment and operations, produce unprecedented pressure on surrounding coastal ecosystems. Thus, the implementation of effective management strategies to deal with social-environmental conflicts is often required. Only a few studies addressed the socio-ecological link between port impact on coastal ecosystem services and how this related to social conflicts. Here, we use multidisciplinary research to address these questions considering two ports located in Coquimbo city-port (29°S) in Chile, as our study port-system. Index scores of port impacts on urban natural ecosystem services and the city were calculated from known drivers of decline. Questionnaires were used to identify local citizens’ concerns about port operations and expansion. Our results demonstrated significant pressures from port infrastructure and operations on maritime but also in shoreland coastal ecosystem services, which were perceived as a critical environmental concern by local respondents. There was low knowledge, but positive appreciation, of eco-engineering initiatives in urban environments to rehabilitee ecosystem attributes. Field experiments showed that biodiversity enhancement of port infrastructure is effective, and might be a good initiative to link people with the port. Our results suggest that port industries must engage in more explicit initiatives to compensate for the environmental impacts of the expansion of built infrastructure, resulting in more effective integration of these urban systems with natural ecosystems.

Timing of deployment does not affect the biodiversity outcomes of ecological enhancement of coastal flood defences in northern Europe

Article

Full-text available

Feb 2023

Structure in the sea

Chapter

Jan 2023

William Seaman

Coastal urbanization, an issue for marine conservation

Chapter

Full-text available

Feb 2023

Coastal zones provide about 70% of the world’s ecosystem services. However, more than 25% of these habitats have been modified by human activity at both land and sea. At the intertidal eco-tonal zone, habitat modification is equally severe, as almost 20% of the world’s shoreline is now artificial. Coastal defense structures are more abundant in areas where the ecosystem richness, diversity and productivity are higher, such as coastal lagoons, estuaries and bays. As these degrad-ed areas are under high human pressure, their protection should be prioritized. Coastal infrastruc-ture, particularly those enclosing highly modified water bodies, such as ports and marinas, are hubs for pollution and human activities, such as trade and leisure. These have become a serious threat to marine coastal communities, due to habitat degradation and disease spread, and ecolog-ical-engineering interventions are now an imperative to integrate urban with nature and improve life and ecosystem quality for coastal settlements.

The elephant in the room: Introduced species also profit from refuge creation by artificial fish habitats

Article

Mar 2023
MAR ENVIRON RES

Increasingly, ecological rehabilitation is envisioned to mitigate and revert impacts of ocean sprawl on coastal marine biodiversity. While in the past studies have demonstrated the positive effects of artificial fish habitats in port areas on fish abundance and diversity, benthic colonization of these structures has not yet been taken into consideration. This could be problematic as they may provide suitable habitat for Non-Indigenous Species (NIS) and hence facilitate their spreading. The present study aimed to examine communities developing on artificial fish habitats and to observe if the number of NIS was higher than in surrounding equivalent habitats. The structures were colonized by communities that were significantly different compared to those surrounding the control habitat, and they were home to a greater number of NIS. As NIS can cause severe ecological and economical damages, our results imply that in conjunction with the ecosystem services provided by artificial fish habitats, an ecosystem disservice in the form of facilitated NIS colonization may be present. These effects have not been shown before and need to be considered to effectively decide in which situations artificial structures may be used for fish rehabilitation.

Eco-creative nature-based solutions to transform urban coastlines, local coastal communities and enhance biodiversity through the lens of scientific and Indigenous knowledge

Article

Full-text available

Dec 2022

Increasing anthropogenic pressure on the sea and alteration of coastscapes challenge the functioning of marine ecosystems and long-term reliance on blue economies, especially for developing southern economies. The structural hardening of shores can result in ecological disruptions, with cascading effects on the wellbeing and livelihoods of marginalised groups who depend on marine resources. Mitigation, adaptation and rehabilitation options for coastal developments should include innovative, socially responsible solutions to be used to modify shorelines and ensure long-term functionality of metropolitan coastal ecosystems. Nature-based innovations are being developed to improve surrogacy for natural marine ecosystems. The co-creation of nature-based structures, entailing partnerships between scientists and a local rural community is currently being considered in South Africa and we present this regional case study as a transdisciplinary framework for research in nature-based, ecological engineering of coastal systems. Novel transdisciplinary approaches include ecomusicological interventions, where traditional cultural expressions (TCEs) create opportunities for transgressive pedagogy. This step aims to ensure that the knowledge gathered through nature-based scientific research remains a part of community developed Indigenous knowledge systems. The merging of innovative, eco-creative approaches and TCEs has the potential to sustainably and ethically improve the functioning and diversity of coastal urban habitats. This review tackles the potential of transdisciplinary settings to transform urban coastlines using “low-tech” engineering and Indigenous eco-creative innovations to pedagogy, to benefit the people and biological communities as well as reduce social and gender inequalities.

The Smart Sea concept and its application for ocean management in a changing climate

Article

Full-text available

Sep 2022

Global environmental change is a defining issue of our time. The ocean is a key component of the Earth system, and yet, in-depth understanding of its roles in sustaining life has not received the attention which it deserves. Humanity must develop a new relationship with the ocean characterized by protection, sustainable production, and prosperity. Society has too much to gain by implementing sustainability solutions and too much to lose by ignoring them. Our actions or inaction now will have far-reaching implications for future of all life on Earth. Ocean blueprint that calls for enforcing 30% Marine Protected Areas by 2030 requires real transformative action. This paper contains new ideas for combining the efforts of natural and social scientists, and traditional users of sea, and explores the potential of modern technologies to assist in this campaign. ‘Smart Sea’ concept introduced in this paper envisages synergies among the problem-solving approaches including digital tools, and eco-engineering and eco-mimicry solution options. Knowledge gaps have been highlighted and relevance of new knowledge systems emphasized together with enabling conditions to address the uncertainties associated with the ocean ecosystem. The ocean has a central position in actions towards preventing global warming of 1.5oC but measures to achieve it should consider that the ocean carbon sink is dynamic and is adversely affected when excessive carbon dioxide produces acidification. The selected measures are likely to have trade-offs, requiring analysis of multiple dimensions, for ensuring sustainable outcomes. The prevailing ocean health and urgency to mitigate it calls for combining global and local solutions, technologies and actions driven by safe and innovative solutions, and wherever possible, based on proof-of-concept. Deviating from the on-going incremental data collection systems to new forms of data-sharing using modern technological tools will contribute to addressing the glaring vacuum in knowledge of the ocean and facilitating a concerted global action for maintaining its ecosystem services. An attempt has been made in this paper to consolidate different opinions and experiences in moving from generalities to specifics for sustainable solutions that support economies, food security and the society.

Microhabitat thermal environment controls community structure of macrobenthos on coastal infrastructures

Article

Sep 2022
ESTUAR COAST SHELF S

The proliferation of coastal infrastructure in the context of coastal development, urbanization, and global change is inevitably related to the transformation of coastal community structure. For restoration of biodiversity in these human-disturbed coastal ecosystems, it is vital to untangle the community structure and thermal environments, with the consideration of the microhabitat-scale thermal environment variations. In the present study, we measured the species richness, α-diversity (i.e. the species composition of each surface of breakwaters), and β-diversity (i.e. the dissimilarities among macrobenthic communities of different surfaces of breakwater) of macrobenthos on the breakwaters on a tropical shore for understanding the variation of the community structure of macrobenthos; we also monitored the operative temperatures in different surfaces of the breakwaters during the experimental period for investigating the roles of microhabitat thermal environment on the community structure of macrobenthos on the artificial infrastructure. Our results showed that there were higher species richness and abundance in the thermally benign microhabitats. The variations of β-diversity indicated that the community structure underwent dramatic changes in different microhabitats and seasons. The population dynamics of thermal-sensitive species (e.g. Patelloida pygmaea, Cellana toreuma, and Siphonaria japonica) largely contributed to the changes in community structure. Redundancy analysis (RDA) results showed that maximum temperature, temperature predictability (i.e. the degree to which a temperature data point in a time series is influenced by its historical values), and heating rate were important thermal characteristics driving community structure on the artificial infrastructure. These results indicate the heterogeneity of thermal environments among different microhabitats is crucial for maintaining the community structure of macrobenthos on the artificial infrastructure and suggest that structural complexity should be considered for biodiversity conservation in the design and construction of coastal infrastructure.

The ecological benefits of adding topographic complexity to seawalls vary across estuarine gradients

Article

Sep 2022
ECOL ENG

Artificial structures such as seawalls increasingly dominate marine urban environments. As compared to natural rocky shore habitats, seawalls are usually flat, featureless, vertical surfaces that support reduced biodiversity. One approach to increase their biodiversity is to add topographic complexity (‘complexity’) that increases microhabitat diversity and surface area. Initial investigations of the effects of complexity on the biodiversity of marine built structures found positive relationships, but more recently spatially variable effects have been found at a biogeographical scale. The present study tested whether at the scale of sites within an estuary (in this case Sydney Harbour), effects of complexity also spatially vary, and whether pollution and estuarine gradients are good predictors of this variation. Comparisons of intertidal communities colonising flat and complex (creviced / ridged) tiles, affixed to seawalls confirmed that effects of complexity were spatially variable at the site-scale, ranging from neutral to highly positive. Proximity to stormdrains, a point source of contaminants including metals, was a poor predictor of complexity effects, but effects were generally greater in the outer harbour, where biodiversity was overall greater, than the inner harbour. These results suggest that eco-engineering interventions based on complexity will not have universally positive effects and instead vary between sites separated by as little as hundreds of meters. Knowledge of spatial variation in physico-chemical conditions and the size and composition of the species pool of available colonists may assist in predicting when and where adding complexity to marine built structures will be of ecological benefit.

The intrinsic primary bioreceptivity of concrete in the coastal environment – A review

Article

Full-text available

May 2022

The proliferation of artificial concrete structures (ACSs) in the marine environment causes intertidal habitat loss and is a poor surrogate for natural rocky shores in terms of species richness, abundance, and community composition. As hard engineered coastlines increase, there is growing interest in how new concrete structures can facilitate improved habitat and biodiversity compared to existing concrete structures. Experiments that have substituted cement binder and aggregates in varying proportions and combinations have demonstrated that it is possible to enhance the primary bioreceptivity of concrete, either chemically or via microtopographical texture. This review synthesises key literature and identifies which concrete formulas prove most effective at enhancing bioreceptivity and those that have limited value, providing recommendations for coastal practitioners and for formulas that warrant further study. It is evident that the efficacy of chemical bioreceptivity of concrete is likely to be spatio-temporally limited (months) and enhancing surface roughness should be prioritised as a way to enhance colonisation. However, both chemical and physical methods require further investigation in within in situ marine settings for longer durations (>12 months).

Ecological value of the earliest human manipulated coastal habitats: Preliminary insights into the nursery function of a pre-colonial stonewalled fish trap in South Africa

Article

May 2022

Pre-colonial stonewalled fish traps, an ancient engineering feat in the intertidal region, represent the earliest proof of human manipulation of the coastline in Southern Africa, specifically by the First Indigenous Peoples of South Africa. We investigated the ecologically functioning of a fish trap located on the southeast coast of South Africa from a larval fish and invertebrate perspective. This research was done in collaboration with the Khoi traditional custodians of the area of study. Samples were collected using a light trap on four separate spring tide occasions, deployed for 3 consecutive nights during 2 full moon trips and 2 new moon trips during the known peak larval settlement period (November 2020–February 2021). Although time-dependent, the importance of this novel microhabitat for the development of coastal fishes and invertebrates was highlighted. Even with the high intertidal location of the stonewalled fish trap sampled at Cape Recife, the presence of a pool of permanent non-stagnant water within the fish trap, even during low spring tide, could provide protection to larvae, in the form of more stable environmental conditions, as well as less exposure to marine predators and harsh physical environmental conditions. This research aims to raise awareness of the stonewalled fish traps located on the southeast of South Africa with a view towards developing a more inclusive management of these marine cultural heritage sites, specifically involving the First Indigenous Peoples of South Africa.

A review of methods and indicators used to evaluate the ecological modifications generated by artificial structures on marine ecosystems

Article

Full-text available

May 2022
J ENVIRON MANAGE

The current development of human activities at sea (e.g. land reclamation, maritime activity and marine renewable energy) is leading to a significant increase in the number of infrastructures installed in marine settings. These artificial structures provide new hard-bottom habitats for many marine organisms and can thus modify the structure and functioning of coastal ecosystems. In order to better evaluate the nature of these modifications as well as the potential benefits and/or impacts generated, it becomes essential to develop assessment methods that can be applied to a wide variety of study sites from harbours to coastal offshore environments. In this context, our study aims to review the different methods and indicators available which are used to measure the modifications of biodiversity and ecological functioning generated by such structures. Among the methods reviewed, we highlight some that were developed specifically for artificial structures, and others intended for various primary uses but which have been successfully transposed to artificial structures. Nevertheless, we also point out the lack of reliable methods concerning some biological ecosystem components impacted by artificial structures. In this context, we require the adaptation or creation of brand-new indicators to achieve a better characterisation of the ecological impacts generated by these structures. Overall, this study highlights a very high number of existing methods, which provide stakeholders with useful tools to study the impacts of artificial structures, and identifies the need to develop integrative indicators to enhance the deployment of new artificial structures.

Northward shift of a biogeographical barrier on China’s coast

Article

Full-text available

Dec 2021
DIVERS DISTRIB

Aim Understanding the formation and maintenance of biogeographical breaks is fundamental for developing analyses related to biodiversity and conservation. Biogeographical patterns along China's coast are changing dramatically in the face of climate change and alterations in land-use. In this paper, we sought to clarify the mechanisms responsible for the formation and maintenance of a biogeographical barrier on China's coast. Location Coastline of northern China. Methods We have reviewed literature of research related to biogeographical and phylogeographical patterns of intertidal macrobenthos along the coast of Jiangsu Province and adjacent areas, summarized the distribution patterns and biogeographical breakers. We have also reviewed literature about the processes and drivers on coastal biogeographical breaks, to clarify the mechanisms acting to the northward shift of the biogeographical break. Results The Yangtze (Changjiang) River Estuary Biogeographical Barrier (YREBB) at 30°–31°N, which serves as a coastal biogeographical boundary for the Cold Temperate Northwest Pacific Province and the Warm Temperate Northwest Pacific Province for marine species, has moved northward to ~33°–34°N due to the changes in habitat continuity, oceanographic circulation and climate factors. Consequently, a new biogeographic barrier for intertidal macrobenthos, the Subei Biogeographical Barrier (SBB) on the central coast of Jiangsu Province, has emerged. Main conclusions The formation and maintenance of the SBB are closely related to the larval dispersal potential, larval settlement success and post-settlement population establishment, all of which have been profoundly influenced by anthropogenic environmental changes. The northward shift of the YREBB and the appearance of the SBB provide an excellent model system for investigating the impacts of climate change and land-use change on coastal biogeographic patterning and for clarifying the mechanisms underlying the formation and maintenance of biogeographical barriers in the face of the unprecedented environmental changes.

Beyond coastal protection: A robust approach to enhance environmental and social outcomes of coastal adaptation

Article

Feb 2022
OCEAN COAST MANAGE

Hard coastal protective infrastructure, such as breakwaters, are a common adaptation strategy to protect assets, increase safety and improve navigation by reducing erosion and flood risks along coastlines globally. However, protective structures can have pervasive impacts on use patterns, aesthetics and associated ecosystems, threatening ecosystem goods and services upon which humans depend. Guided by a recent Australian state Government strategy that aims to plan for “a healthy coast and sea managed for the greatest wellbeing of the community, now and into the future”, we present a decision-making support tool for practitioners to help achieve more sustainable solutions to coastal adaptation into the future. Sustainable coastal adaptation needs to consider the environmental and socio-economic consequences of hard protective infrastructure, as well as the increased vulnerability due to rising sea levels. To demonstrate our arguments, we introduce three different coastal scenarios. We also discuss alternatives to coastal protection and make scenario-specific recommendations to enhance environmental and socio-economic outcomes of coastal adaptation. In general, the implementation of hard protective infrastructure should probably be a last resort after retreat and soft approaches have been ruled out as viable options. Where protective infrastructure is the current best option, environmental and socio-economic outcomes can be enhanced using eco-engineering and multi-use features. In the long term, however, retreat from some coastal areas may be necessary and existing infrastructure might be removed or abandoned.

Making seawalls multifunctional: The positive effects of seeded bivalves and habitat structure on species diversity and filtration rates

Article

Jan 2021
MAR ENVIRON RES

The marine environment is being increasingly modified by the construction of artificial structures, the impacts of which may be mitigated through eco-engineering. To date, eco-engineering has predominantly aimed to increase biodiversity, but enhancing other ecological functions is arguably of equal importance for artificial structures. Here, we manipulated complexity through habitat structure (flat, and 2.5 cm, 5 cm deep vertical and 5 cm deep horizontal crevices) and seeding with the native oyster (Saccostrea glomerata, unseeded and seeded) on concrete tiles (0.25 m x 0.25 m) affixed to seawalls to investigate whether complexity (both orientation and depth of crevices) influences particle removal rates by suspension feeders and colonisation by different functional groups, and whether there are any ecological trade-offs between these functions. After 12 months, complex seeded tiles generally supported a greater abundance of suspension feeding taxa and had higher particle removal rates than flat tiles or unseeded tiles. The richness and diversity of taxa also increased with complexity. The effect of seeding was, however, generally weaker on tiles with complex habitat structure. However, the orientation of habitat complexity and the depth of the crevices did not influence particle removal rates or colonising taxa. Colonisation by non-native taxa was low compared to total taxa richness. We did not detect negative ecological trade-offs between increased particle removal rates and diversity and abundance of key functional groups. Our results suggest that the addition of complexity to marine artificial structures could potentially be used to enhance both biodiversity and particle removal rates. Consequently, complexity should be incorporated into future eco-engineering projects to provide a range of ecological functions in urbanised estuaries.

Interacting effects of habitat structure and seeding with oysters on the intertidal biodiversity of seawalls

Article

Full-text available

Jul 2020
PLOS ONE

The construction of artificial structures, such as seawalls, is increasing globally, resulting in loss of habitat complexity and native species biodiversity. There is increasing interest in mitigating this biodiversity loss by adding topographic habitat to these structures, and/or seeding them with habitat-forming species. Settlement tile experiments, comparing colonisation of species to more and less complex habitats, have been used to inform eco-engineering interventions prior to their large-scale implementation. Most studies have focused on applying one type of intervention (either adding habitat structure or seeding with native organisms), so it is unclear whether there are greater benefits to biodiversity when multiple interventions are combined. Using a fully orthogonal experiment, we assessed the independent and interactive effects of habitat structure (flat vs. crevice/ridges) and seeding with native oysters (unseeded vs. seeded) on the biodiversity of four different functional groups (sessile and mobile taxa, cryptobenthic and pelagic fishes). Concrete tiles (flat unseeded, flat seeded, complex unseeded and complex seeded) were deployed at two sites in Sydney Harbour and monitored over 12 months, for the survival and colonisation of oysters and the species density and abundances of the four functional groups. The survival of seeded oysters was greater on the complex than flat tiles, at one of the two sites, due to the protective role of crevices. Despite this, after 12 months, the species density of sessile invertebrates and the percentage cover of seeded and colonising oysters did not differ between complex and seeded tiles each of which supported more of these variables than the flat unseeded tiles. In contrast, the species density of mobile invertebrates and cryptobenthic fishes and the MaxN of pelagic fishes, at 1 month, were only positively influenced by seeding with oysters, which provided food as well as habitat. Within the complex seeded and unseeded tiles, there was a greater species density of sessile taxa, survival and percentage cover of oysters in the crevices, which were more humid and darker at month 12, had lower high temperature extremes at months 1 and 12, than on the ridges or flat tiles. Our results suggest that eco-engineering projects which seek to maximise the biodiversity of multiple functional groups on seawalls, should apply a variety of different microhabitats and habitat-forming species, to alter the environmental conditions available to organisms.

Greening of grey infrastructure should not be used as a Trojan horse to facilitate coastal development

Article

Full-text available

May 2020

1. Climate change and coastal urbanisation are driving the replacement of natural habitats with artificial structures and reclaimed land globally. These novel habitats are often poor surrogates for natural habitats. 2. The application of integrated greening of grey infrastructure (IGGI) to artificial shorelines demonstrates how multifunctional structures can provide biodiversity benefits whilst simultaneously serving their primary engineering function. IGGI is being embraced globally, despite many knowledge gaps and limitations. It is a management tool to compensate anthropogenic impacts as part of the Mitigation Hierarchy. There is considerable scope for misuse and ‘greenwashing’ however, by making new developments appear more acceptable, thus facilitating the regulatory process. 3. We encourage researchers to exercise caution when reporting on small‐scale experimental trials. We advocate that greater attention is paid to when experiments ‘fail’ or yield unintended outcomes. We advise revisiting, repeating and expanding on experiments to test responses over broader spatio‐temporal scales to improve the evidence base. 4. Synthesis and applications . Where societal and economic demand makes development inevitable, particular attention should be paid to avoiding, minimising and rehabilitating environmental impacts. Integrated greening of grey infrastructure (IGGI) should be implemented as partial compensation for environmental damage. Mutual benefits for both humans and nature can be achieved when IGGI is implemented retrospectively in previously‐developed or degraded environments. We caution however, that any promise of net biodiversity gain from new developments should be scrutinised and any local ecological benefits set in the context of the wider environmental impacts. A ‘greened’ development will always impinge on natural systems, a reality that is much less recognised in the sea than on land.

Design catalogue for eco-engineering of coastal artificial structures: A multifunctional approach for stakeholders and end-users

Article

Full-text available

Apr 2020
Urban Ecosyst

Coastal urbanisation, energy extraction, food production, shipping and transportation have led to the global proliferation of artificial structures within the coastal and marine environments (sensu "ocean sprawl"), with subsequent loss of natural habitats and biodiversity. To mitigate and compensate impacts of ocean sprawl, the practice of eco-engineering of artificial structures has been developed over the past decade. Eco-engineering aims to create sustainable ecosystems that integrate human society with the natural environment for the benefit of both. The science of eco-engineering has grown markedly, yet synthesis of research into a user-friendly and practitioner-focused format is lacking. Feedback from stakeholders has repeatedly stated that a "photo user guide" or "manual" covering the range of eco-engineering options available for artificial structures would be beneficial. However, a detailed and structured "user guide" for eco-engineering in coastal and marine environments is not yet possible; therefore we present an accessible review and catalogue of trialled eco-engineering options and a summary of guidance for a range of different structures tailored for stakeholders and end-users as the first step towards a structured manual. This work can thus serve as a potential template for future eco-engineering guides. Here we provide suggestions for potential eco-engineering designs to enhance biodiversity and ecosystem functioning and services of coastal artificial structures with the following structures covered: (1) rock revetment, breakwaters and groynes composed of armour stones or concrete units; (2) vertical and sloping seawalls; (3) over-water structures (i.e., piers) and associated support structures ; and (4) tidal river walls.

Pollution signature for temperate reef biodiversity is short and simple

Article

Full-text available

May 2018
MAR POLLUT BULL

Latitudinal gradients in ecosystem engineering by oysters vary across habitats

Article

Full-text available

Feb 2016

Ecological theory predicts that positive interactions among organisms will increase across gradients of increasing abiotic stress or consumer pressure. This theory has been supported by empirical studies examining the magnitude of ecosystem engineering across environmental gradients and between habitat settings at local scale. However, predictions that habitat setting, by modifying both biotic and abiotic factors, will determine large-scale gradients in ecosystem engineering have not been tested. A combination of manipulative experiments and field surveys assessed whether along the east Australian coastline: (1) facilitation of invertebrates by the oyster Saccostrea glomerata increased across a latitudinal gradient in temperature; and (2) the magnitude of this effect varied between intertidal rocky shores and mangrove forests. It was expected that on rocky shores, where oysters are the primary ecosystem engineer, they would play a greater role in ameliorating latitudinal gradients in temperature than in mangroves where they are a secondary ecosystem engineer living under the mangrove canopy. On rocky shores, the enhancement of invertebrate abundance in oysters as compared to bare microhabitat decreased with latitude, as the maximum temperatures experienced by intertidal organisms diminished. By contrast, in mangrove forests, where the mangrove canopy resulted in maximum temperatures that were cooler and of greater humidity than on rocky shores, we found no evidence of latitudinal gradients of oyster effects on invertebrate abundance. Contrary to predictions, the magnitude by which oysters enhanced biodiversity was in many instances similar between mangroves and rocky shores. Whether habitat-context modifies patterns of spatial variation in the effects of ecosystem engineers on community structure will depend, in part, on the extent to which the environmental amelioration provided by an ecosystem engineer replicates that of other co-occurring ecosystem engineers. This article is protected by copyright. All rights reserved.

Settlement plates as monitoring devices for non-indigenous species in marine fouling communities

Article

Full-text available

Nov 2017

Non-indigenous species (NIS) are one of the leading forces of change in coastal marine ecosystems and are often associated with fouling communities, especially the artificial structures of marinas and ports. As a result, monitoring of marine fouling communities is crucial to evaluate the introduction and spread of NIS as well as assess the efficacy of legislation aimed to prevent further introductions. Settlement plates have long been used as a means of studying fouling communities. Many factors such as orientation, movement, and substrate type have been shown to influence the number and type of organisms present in fouling communities, but one key question remains poorly studied: how well do settlement plates represent the established fouling community of a marina, especially regarding NIS? We investigated this question, by examining the sessile invertebrates on both marina structures and settlement plates from three marinas in San Francisco Bay (California, USA). Total species richness, NIS richness, and community composition on settlement plates were found to be similar to those on existing marina floating docks. Our results indicate that settlement plates can provide a sensitive and standardized measure of the NIS richness and composition in fouling communities.

Increasing microhabitat complexity on seawalls can reduce fish predation on native oysters

Article

Full-text available

May 2017
ECOL ENG

Increasingly, urbanised coastlines are being armoured by shoreline protection structures, such as seawalls. Seawalls typically lack the complex microhabitats and protective spaces of natural shorelines and consequently organisms that settle on them may be particularly susceptible to predation. We tested whether the addition of complex microhabitats to seawalls enhances the survivorship of oysters, key habitat-forming species on intertidal shores, by reducing the intensity of predation. At two sites in Sydney Harbour, we compared the magnitude and sources of mortality of juvenile oysters among (1) flat tiles, without crevices or ridges; (2) complex tiles, with 2.5 cm high ridges, separated by crevices; and (3) complex tiles, with 5 cm high ridges, separated by crevices. We also compared predatory fish visitation and feeding among sites and treatments using GoPro® cameras. The abundance and feeding of predatory fish was much greater at one of the study sites than the other, but at neither site differed among treatments. At the site with greater predatory fish abundances, survivorship of juvenile oysters was 50% greater on the 5 cm complex tiles than flat tiles, and on complex tiles approximately 300% greater in crevices than on ridges. Of the dead oysters, almost all were cracked, indicative of fish predation. In contrast, at the site with fewer predatory fish, there were no detectable differences in oyster survivorship between treatments. These results suggest that the addition of complex habitat to seawalls could be an effective strategy in reducing fish predation pressure on juvenile oysters at sites with abundant predatory fish. A greater understanding of the site-specific pressures is required to enhance the abundances of desirable species and functions on seawalls.

Benches, beaches, and bumps: how habitat monitoring and experimental science can inform urban seawall design

Chapter

Full-text available

Jan 2017

Relationships between structural complexity, coral traits, and reef fish assemblages

Article

Full-text available

Jun 2017
CORAL REEFS

With the ongoing loss of coral cover and the associated flattening of reef architecture, understanding the links between coral habitat and reef fishes is of critical importance. Here, we investigate whether considering coral traits and functional diversity provides new insights into the relationship between structural complexity and reef fish communities, and whether coral traits and community composition can predict structural complexity. Across 157 sites in Seychelles, Maldives, the Chagos Archipelago, and Australia’s Great Barrier Reef, we find that structural complexity and reef zone are the strongest and most consistent predictors of reef fish abundance, biomass, species richness, and trophic structure. However, coral traits, diversity, and life histories provided additional predictive power for models of reef fish assemblages, and were key drivers of structural complexity. Our findings highlight that reef complexity relies on living corals—with different traits and life histories—continuing to build carbonate skeletons, and that these nuanced relationships between coral assemblages and habitat complexity can affect the structure of reef fish assemblages. Seascape-level estimates of structural complexity are rapid and cost effective with important implications for the structure and function of fish assemblages, and should be incorporated into monitoring programs.

The environmental context and traits of habitat-forming bivalves influence the magnitude of their ecosystem engineering

Article

Full-text available

Jan 2016

The effective use of ecosystem engineers in biodiversity conservation is contingent on an understanding of those factors that influence the magnitude and direction of their effects. At patch scales, effects of ecosystem engineers on associated communities can range from positive to negative according to how the ecosystem engineer modifies environmental conditions. In a metaanalysis of 68 empirical studies, we assessed how, for a widespread group of ecosystem engineers- the marine habitat-forming bivalves-bivalve taxon, density, habitat, tidal elevation and latitude, as well as habit, or lifestyle, of associated taxa, influences the magnitude and direction of their effect on associated invertebrates. Overall, marine bivalves had a positive effect on both species abundance and species density, but effect sizes varied considerably according to bivalve traits and environmental setting. Oysters enhanced invertebrate abundance to a greater extent than either mussels or pinnids, perhaps because of the greater habitat heterogeneity they provide. Nevertheless, the effect of mussels on associated communities was generally more responsive to spatial variation in engineer traits and environmental context than the effect of oysters or pinnids. Positive effects of mussels on associated species abundance decreased at high mussel densities, were greater at subtidal than mid-low intertidal elevations and differed among faunal habits depending on habitat setting. Knowledge of those conditions under which positive effects of bivalves on associated biodiversity is greatest will help in identifying which species of ecosystem engineer, at which sites, should be prioritised for conservation and restoration, where the goal is enhancement of biodiversity.

Checklist of Singaporean Bryozoa and Entoprocta

Article

Full-text available

Jun 2016
RAFFLES B ZOOL

A checklist of 118 Singaporean species of Bryozoa (3 Cyclostomata, 7 Ctenostomata, 108 Cheilostomata) and three taxa of Entoprocta is presented, based upon sampling during recent workshops (2012–2014), registered museum material, incidental collecting and historical records. Accordingly, many species are reported for the first time from Singaporean waters, including a freshwater bryozoan (Hislopia malayensis), numerous marine bryozoans and an entoproct (Pedicellina sp.). Several easily collected intertidal species, including a population of the globally rare mangrove epiphyte Amphibiobeania epiphylla and certain alien-invasive taxa, are amenable to research on their biology (growth and reproduction) and ecology.

Distributed under Creative Commons CC-BY 4.0 The interplay between habitat structure and chemical contaminants on biotic responses of benthic organisms

Article

Full-text available

May 2016

Habitat structure influences the diversity and distribution of organisms, potentially affecting their response to disturbances by either affecting their ‘susceptibility’ or through the provision of resources that can mitigate impacts of disturbances. Chemical disturbances due to contamination are associated with decreases in diversity and functioning of systems and are also likely to increase due to coastal urbanisation. Understanding how habitat structure interacts with contaminants is essential to predict and therefore manage such effects, minimising their consequences to marine systems. Here, we manipulated two structurally different habitats and exposed them to different types of contaminants. The effects of contamination and habitat structure interacted, affecting species richness. More complex experimental habitats were colonized by a greater diversity of organisms than the less complex habitats. These differences disappeared, however, when habitats were exposed to contaminants, suggesting that contaminants can override effects of habitats structure at small spatial scales. These results provide insight into the complex ways that habitat structure and contamination interact and the need to incorporate evidence of biotic responses from individual disturbances to multiple stressors. Such effects need to be taken into account when designing and planning management and conservation strategies to natural systems.

Latitudinal gradients in ecosystem engineering by oysters vary across habitats

Article

Full-text available

Dec 2015

Ecological theory predicts that positive interactions among organisms will increase across gradients of increasing abiotic stress or consumer pressure. This theory has been supported by empirical studies examining the magnitude of ecosystem engineering across environmental gradients and between habitat settings at local scale. Predictions that habitat setting, by modifying both biotic and abiotic factors, will determine large-scale gradients in ecosystem engineering have not been tested, however. A combination of manipulative experiments and field surveys assessed whether along the east Australian coastline: (1) facilitation of invertebrates by the oyster Saccostrea glomerata increased across a latitudinal gradient in temperature; and (2) the magnitude of this effect varied between intertidal rocky shores and mangrove forests. It was expected that on rocky shores, where oysters are the primary ecosystem engineer, they would play a greater role in ameliorating latitudinal gradients in temperature than in mangroves, where they are a secondary ecosystem engineer living under the mangrove canopy. On rocky shores, the enhancement of invertebrate abundance in oysters as compared to bare microhabitat decreased with latitude, as the maximum temperatures experienced by intertidal organisms diminished. By contrast, in mangrove forests, where the mangrove canopy resulted in maximum temperatures that were cooler and of greater humidity than on rocky shores, we found no evidence of latitudinal gradients of oyster effects on invertebrate abundance. Contrary to predictions, the magnitude by which oysters enhanced biodiversity was in many instances similar between mangroves and rocky shores. Whether habitat-context modifies patterns of spatial variation in the effects of ecosystem engineers on community structure will depend, in part, on the extent to which the environmental amelioration provided by an ecosystem engineer replicates that of other co-occurring ecosystem engineers.

A Standardised Vocabulary for Identifying Benthic Biota and Substrata from Underwater Imagery: The CATAMI Classification Scheme

Article

Full-text available

Oct 2015
PLOS ONE

Imagery collected by still and video cameras is an increasingly important tool for minimal impact, repeatable observations in the marine environment. Data generated from imagery includes identification, annotation and quantification of biological subjects and environmental features within an image. To be long-lived and useful beyond their project-specific initial purpose, and to maximize their utility across studies and disciplines, marine imagery data should use a standardised vocabulary of defined terms. This would enable the compilation of regional, national and/or global data sets from multiple sources, contributing to broad-scale management studies and development of automated annotation algorithms. The classification scheme developed under the Collaborative and Automated Tools for Analysis of Marine Imagery (CATAMI) project provides such a vocabulary. The CATAMI classification scheme introduces Australian-wide acknowledged, standardised terminology for annotating benthic substrates and biota in marine imagery. It combines coarse-level taxonomy and morphology, and is a flexible, hierarchical classification that bridges the gap between habitat/biotope characterisation and taxonomy, acknowledging limitations when describing biological taxa through imagery. It is fully described, documented, and maintained through curated online databases, and can be applied across benthic image collection methods, annotation platforms and scoring methods. Following release in 2013, the CATAMI classification scheme was taken up by a wide variety of users, including government, academia and industry. This rapid acceptance highlights the scheme's utility and the potential to facilitate broad-scale multidisciplinary studies of marine ecosystems when applied globally. Here we present the CATAMI classification scheme, describe its conception and features, and discuss its utility and the opportunities as well as challenges arising from its use.

Structure of intertidal sessile communities before and after the invasion of Isognomon bicolor (C.B. Adams, 1845) (Bivalvia, Isognomonidae) in southeastern Brazil

Article

Full-text available

Nov 2014

Scientists recognize the importance of ecological data prior to invasion by non-native species in order to evaluate changes in the recipient community. Here we assess the potential impact of the invasion of the bivalve Isognomon bicolor (C.B. Adams, 1845) on Brazilian rocky shores through the use of surveys both before and after the arrival of this non-native species. The invader was mostly distributed across the mid and low shore levels of the intertidal zone with relative abundance ranging from 9.0 to 36.7 percent cover. The mid shore, previously dominated by the native barnacle Tetraclita stalactifera (Lamarck, 1818), was co-dominated by this barnacle species and I. bicolor after invasion. The relative abundance of these species, and presumably the interaction strength between them, differed between sites. At the site where I. bicolor reached the highest abundance (around 30% on average), the abundance of T. stalactifera decreased on average 70% compared to baseline values obtained before the I. bicolor invasion. Finally, conspicuous and extensive I. bicolor beds such as those observed in this study have not been reported in its original distribution range. Beds of I. bicolor may create a much more intricate biogenic matrix than the extents of bare rock and barnacle clumps it replaced. This bivalve may act as an ecosystem engineer and, thus a functionally different component of the intertidal community in its invaded range compared to its native distribution.

Predation, Prey Refuges, and the Structure of Coral-Reef Fish Assemblages

Article

Full-text available

Feb 1993

We studied the influence of piscivorous fishes and prey refuges on assemblages of fishes occupying 52 model reefs in a large seagrass bed off St. Thomas, U.S. Virgin Islands. We conducted three experiments: two involving 6 reefs each, lasting 2 and 5 yr, and one involving 40 reefs, lasting 1 yr. Each experiment included replicate reefs in various combinations of five structural treatments: holeless controls, 12 and 24 small holes, and 12 and 24 large holes. Tagging studies indicated that the reefs were sufficiently isolated from each other to comprise statistically independent replicates, and that resident piscivores occupied home reefs. We observed 97 species on or near the reefs, representing all major foraging guilds, and each holed reef supported hundreds of individuals. We examined four categories of fish: (1) large reef associates (too large for the small holes; most of these fish were both predators on smaller fish and prey for larger transient piscivores), (2) moray eels (piscivores that could fit into the small holes), (3) small reef associates (potential prey that could fit into the small holes), and (4) juvenile grunts (potential prey that sporadically were extremely abundant). We tested five a priori predictions of the general hypothesis that predation is an important process structuring reef-fish assemblages. The first two predictions dealt with the role of prey refuges. First, if reef holes function as prey refuges, then prey fish should be most abundant on reefs providing holes near their body diameters, because such holes would make the prey fish safest from predation. Seven of eight experimental comparisons supported this prediction, and five of them were statistically significant. Second, if refuge availability limits prey abundance, then prey fish should be more abundant on reefs with 12 holes than those with no holes, and should be more abundant on reefs with 24 holes than those with 12 holes. The first part of this prediction was verified by all nine experimental comparisons, seven of which were statistically significant. However, there were no strong differences between 12-hole and 24-hole reefs. Thus, between 0 and 12 holes per reef, holes limited local prey populations; between 12 and 24 holes per reef, the number of holes was not limiting. Several lines of evidence suggested that the latter pattern was due to temporary saturation of the study area with refuges when we added 40 reefs to 12 existing reefs. The remaining three predictions dealt directly with the community-level role of predation. First, predators should affect local prey abundance either chronically, in which case a negative relationship among reefs is predicted between the average abundances of predators and prey, or sporadically, in which case a negative relationship is predicted between the abundance of predators and the maximum number of co-occurring prey ever observed at each predator abundance. The former prediction was falsified, whereas the latter was verified. Observations of extreme type III survivorship of recruit cohorts on reefs with many piscivores and occasional direct observations of piscivory bolstered the conclusion that this relationship was causal. Finally, we predicted that predators should affect the number of prey species on a reef. We observed a significant negative relationship among reefs between predator abundance and maximum prey-species richness. Comparing species' relative abundances on reefs at the extremes of this regression, piscivores appear to have nonselectively reduced and extirpated both common and rare prey species, although this relationship remains purely correlative. In our model system, high local species diversity appears to have been maintained despite rather than because of predation. We propose a conceptual model where the local abundances of coral-reef fishes are determined by the relative magnitudes of recruitment by larvae, colonization by juveniles and adults, predation, and competition for refuges, each of which varies through time and space. Multifactorial field experiments will be necessary to test such pluralistic hypotheses.

Habitat complexity: Approaches and future directions

Article

Full-text available

Apr 2012

Habitat complexity is one of the most important factors structuring biotic assemblages, yet we still lack basic understanding of the underlying mechanisms. Although it is one of the primary targets in conservation management, no methods are available for comparing complexity across ecosystems, and system-specific qualitative assessment predominates. Despite its overwhelming importance for faunal diversity and abundance, there has been surprisingly little interest in examining its effects on other community and ecosystem attributes. We discuss possibilities of such effects, outlining potentially fruitful areas for future research, and argue that complexity may be implicated in community persistence and ecosystem stability by acting as a decoupling mechanism in predator–prey interactions. We provide a brief overview of methods used to quantify complexity in different ecosystems, highlighting contributions of the current issue of Hydrobiologia, and discuss potential application of these approaches for cross-ecosystem comparisons. Better understanding of the role of habitat complexity resulting from such comparisons is critically important for preservation of biodiversity and ecosystem function in an era of unprecedented habitat loss.

Environmental heterogeneity as a universal driver of species richness across taxa, biomes and spatial scales

Article

Full-text available

Apr 2014
ECOL LETT

Environmental heterogeneity is regarded as one of the most important factors governing species richness gradients. An increase in available niche space, provision of refuges and opportunities for isolation and divergent adaptation are thought to enhance species coexistence, persistence and diversification. However, the extent and generality of positive heterogeneity–richness relationships are still debated. Apart from widespread evidence supporting positive relationships, negative and hump-shaped relationships have also been reported. In a meta-analysis of 1148 data points from 192 studies worldwide, we examine the strength and direction of the relationship between spatial environmental heterogeneity and species richness of terrestrial plants and animals. We find that separate effects of heterogeneity in land cover, vegetation, climate, soil and topography are significantly positive, with vegetation and topographic heterogeneity showing particularly strong associations with species richness. The use of equal-area study units, spatial grain and spatial extent emerge as key factors influencing the strength of heterogeneity–richness relationships, highlighting the pervasive influence of spatial scale in heterogeneity–richness studies. We provide the first quantitative support for the generality of positive heterogeneity–richness relationships across heterogeneity components, habitat types, taxa and spatial scales from landscape to global extents, and identify specific needs for future comparative heterogeneity–richness research.

Patterns of the Non-Indigenous Isopod Cirolana harfordi in Sydney Harbour

Article

Full-text available

Jan 2014
PLOS ONE

Biological introductions can alter the ecology of local assemblages and are an important driver of global environmental change. The first step towards understanding the impact of a non-indigenous species is to study its distribution and associations in the invaded area. In Sydney Harbour, the non-indigenous isopod Cirolana harfordi has been reported in densities up to 0.5 individuals per cm(2) in mussel-beds. Abundances of this species have, however, been largely overlooked in other key habitats. The first aim of this study was to evaluate the abundances and distribution of C. harfordi across different habitats representative of Sydney Harbour. Results showed that C. harfordi occurred in oyster and mussel-beds, being particularly abundant in oyster-beds. We also aimed to determine the role of C. harfordi as a predator, scavenger and detritus feeder by investigating the relationships between densities of C. harfordi and (i) the structure of the resident assemblages, and (ii) deposited organic matter in oyster-beds. Densities of C. harfordi were not related to the structure of the assemblages, nor amounts of deposited organic matter. These findings suggested little or no ecological impacts of C. harfordi in oyster-beds. These relationships may, however, affect other variables such as growth of individuals, or be disguised by high variability of assemblages among different locations. Future studies should, therefore, test the impacts of C. harfordi on the size of organisms in the assemblage and use manipulative experiments to control for spatial variation. This study is the first published work on the ecology of the invasion of C. harfordi and provides the starting-point for the study of the impacts of this species in Sydney Harbour.

Community Organization in Temperate and Tropical Rocky Intertidal Habitats: Prey Refuges in Relation to Consumer Pressure Gradients

Article

Full-text available

Dec 1981

The structure of a tropical rocky intertidal community on Taboguilla Island on the Pacific coast of Panama is characterized by extremely low abundances of noncrustose algae and sessile animals, indistinct vertical zonation patterns (a result of the low abundances), and the occur- rence of most invertebrates (except barnacles) and upright algae in holes and crevices (as opposed to open, smooth surfaces). This contrasts strikingly with two temperate rocky intertidal communities, which have high covers of plants and animals, more obvious zones, and invertebrates and upright algae occurring both on relatively homogeneous surfaces and in holes and crevices. Field experiments were done and observations were made in the Panama community to test the effects of different types of consumers (both predators and herbivores) on their prey and on the types of escapes utilized by the prey. Consumer exclusion experiments suggest that (1) predation and herbivory are severe at all times of the year, (2) consumer pressure is a cumulative function of many types and species of predators and herbivores, (3) the primary effect of larger fishes and crabs is to restrict most prey to three-dimensional refuges (holes and crevices), and (4) the primary effect of smaller consumers, mostly invertebrates, is to keep abundances of the prey low. Thus, in the Panama system, three-dimensional space (holes and crevices) appears to be partic- ularly important as a refuge from consumers, while escapes from consumers in body size, time, or two-dimensional space (e.g., in a higher zone) documented so frequently in temperate areas, assume secondary importance for many prey. This restriction of the types of escapes utilized by prey species appears to be a consequence of two main factors: the presence of fast-moving consumers (i.e., herbivorous and predaceous fishes and herbivorous crabs which are absent or rare in the two tem- perate communities), and the year-round foraging of all consumers.

Environmental and ecological changes associated with a marina

Article

Full-text available

Jul 2013
BIOFOULING

Anthropogenic modifications to waterways are common and their ecological consequences must be understood to effectively conserve local biodiversity. The facilitation of recreational boating activities often requires substantial alteration of natural areas, however the environmental and ecological consequences of such alterations are rarely described in the scientific literature. In this study, ecological and physico-chemical conditions were investigated in a recreational boating marina, located inside a marine park on the south-east coast of Australia. Recruitment panels were deployed for 8 weeks both inside and outside the marina, and differences in the composition of the developing fouling communities were observed. The recruitment of taxa, which often have short-lived larvae, was increased inside the marina (bryozoans, spirorbids and sponges) while the recruitment of taxa, which often have longer-lived larvae, was reduced or absent (barnacles, solitary ascidians and non-spirorbid polychaetes). Differences were also observed in environmental conditions inside the marina cf. directly outside. The marina environment had higher turbidity, temperature and pH along with higher concentrations of lead and copper in suspended sediments, while flow rates and trapped sediment loads were reduced inside the marina. The differences observed in the study suggest that there may be marked environmental changes associated with marina developments. The potential ecological consequences of these changes should be a primary consideration during the planning process, particularly for developments in locations of notable ecological value.

Paucity of mobile species on constructed seawalls: Effects of urbanization on biodiversity

Article

Full-text available

Dec 2003

M.G. Chapman

Intertidal seawalls are increasingly being built in urban estuaries, fragmenting and replacing natural intertidal shores. Many species of animals and plants live on seawalls. Previous work in Sydney Harbour has shown that common species live on seawalls and rocky shores, but vary in their relative abundances according to height on the shore and location. The potential value of seawalls to provide viable intertidal habitat will depend on their ability to support the full diversity of intertidal species, including those that are relatively rare. This study examines the diversity of animals and plants at 2 heights on rocky shore and seawalls, at 4 locations in Sydney Harbour, using presence/absence measures in an intensive sampling schedule in each habitat. The total number and types of taxa found were very variable within and among locations, but clear patterns arose when the data were combined (800 quadrats in each habitat). With few exceptions, algae and sessile animals were similarly distributed across habitats, but approximately 50% of the mobile animals were not found on seawalls. In addition, rocky shores had a greater proportion of rare taxa (only found in 1 or very few quadrats). Of the shared taxa, patterns of occurrence were similar on the 2 structures. Potential reasons for these patterns are discussed and ways to improve seawalls as a habitat for mobile animals are proposed.

Benches, Beaches, and Bumps

Chapter

Mar 2017

A Decision Framework for Coastal Infrastructure to Optimize Biotic Resistance and Resilience in a Changing Climate

Article

Oct 2019

Coastal ecosystems are under growing pressure from human activities such as pollution and climate change. Although the rapidly growing numbers of humans living in coastal areas is a large part of the problem, there is great opportunity to improve the resistance and resilience of biotic communities via creative changes to the engineering design of built infrastructure. Here, we apply ecological theories to create a framework for adaptive building in marine systems that can be applied by managers worldwide. We explain how climate effects could be mitigated across different spatial scales with both physical and biological interventions. This requires an approach based on ecological theory that incorporates our understanding of how systems withstand (resistance) or recover (resilience) from impacts and takes into account future local and global environmental conditions. By translating ecological theory into practical application, we propose a framework for the choice and design of coastal infrastructure that can underpin effective, forward-looking conservation strategies.

Sediment metal enrichment and ecological risk assessment of ten ports and estuaries in the World Harbours Project

Article