Chronic anthropogenic disturbances on coral reefs in the form of overfishing and pollution can shift benthic community composition away from stony corals and toward macroalgae. The use of reefs for recreational snorkeling and diving potentially can lead to similar ecological impacts if not well-managed, but impacts of snorkeling on benthic organisms are not well understood. We quantified variation in benthic community structure along a gradient of snorkeling frequency in an intensively-visited portion of the Mesoamerican Barrier Reef. We determined rates of snorkeling in 6 water sections and rates of beach visitation in 4 adjacent land sections at Akumal Bay, Mexico. For each in-water section at 1–3 m depth, we also assessed the percent cover of benthic organisms including taxa of stony corals and macroalgae. Rates of recreational snorkeling varied from low in the southwestern to very high (>1000 snorkelers d-1) in the northeastern sections of the bay. Stony coral cover decreased and macroalgal cover increased significantly with levels of snorkeling, while trends varied among taxa for other organisms such as gorgonians, fire corals, and sea urchins. We conclude that benthic organisms appear to exhibit taxon-specific variation with levels of recreational snorkeling. To prevent further degradation, we recommend limitation of snorkeler visitation rates, coupled with visitor education and in-water guides to reduce reef-damaging behaviors by snorkelers in high-use areas. These types of management activities, integrated with reef monitoring and subsequent readjustment of management, have the potential to reverse the damage potentially inflicted on coral reefs by the expansion of reef-based recreational snorkeling.
Methods to quantify biodiversity impacts through life cycle assessment (LCA) are evolving for both land- and marine-based production systems, although typically independently from each other. An indicator for terrestrial food production systems that may be suitable to assess marine biodiversity, and is applicable across all food production systems, is a measure of hemeroby or distance from the natural state. We explore the possibility of adapting this approach to marine systems to assess the impact of fishing on seawater column and seafloor systems.
The terrestrial hemeroby concept is adapted here for marine ecosystems. Two commercial fishery case studies are used to trial the effectiveness of hemeroby in measuring the influence exerted by fishing practices on marine biodiversity. Available inventory data are used to score areas to a hemeroby class, following a semi-quantitative scoring matrix and a seven-point scale, to determine how far the seafloor and seawater column are from their natural state. Assessment can progress to the impact assessment stage involving characterisation of the hemeroby score, to determine the Naturalness Degradation Potential (NDP) for use in calculating the Naturalness Degradation Indicator (NDI). The method builds on well-established processes for assessing fisheries within the ecosystem-based fisheries management framework and is designed to enhance assessment of fishing impacts within LCA.
Results and discussion
Australian fisheries case studies were used to demonstrate the application of this method. The naturalness of these fisheries was scored to a hemeroby level using the scoring matrix. The seafloor of the Northern Prawn Fishery and the seawater column of the South Australian Sardine Fishery were both classified as partially close to nature. Impact assessment was carried out following the process outlined for the NDI. The naturalness degradation results were highly sensitive to area calculation method and data. There was also variation in results when using annual or averaged data for catch. Results should therefore be interpreted in the context of these sensitivities.
Adaptation of the hemeroby concept to marine habitats may present an opportunity for more informed comparison of impacts between terrestrial and marine systems. Incorporating a measure of naturalness into assessments of food production can be useful to better understand the cost, in terms of transforming ecosystems from natural to more artificial, of meeting growing food demand. Biodiversity is a broad concept not easily captured through one indicator, and this method can complement emerging biotic LCA indicators, to provide a suite of indicators capable of capturing the full impact of fishing on marine biodiversity.
- On a global scale, most of the coastal zones in the world are undergoing rapid and accelerating changes. This coastal syndrome combines two major trends: one linked to the growth of coastal populations, habitat, transport and industrial infrastructures (assets); the other linked to the influence of climate change and its effects in terms of sea-level rise, increased frequency of extreme weather events, acidification and increase in ocean surface temperature, both affecting the health of coastal ecosystems. This situation is also reflected in the increase in coastal engineering solutions, which have significant impacts on coastal hydrodynamics and natural ecosystems.
- This extremely dynamic context calls for an evolution in conservation and spatial planning strategies in order to better anticipate changes that may affect not only the sustainability of both the distribution and health of natural ecosystems, but also the relevance of conservation efforts. Marine and coastal protected areas help preserve ecological services, and reduce the risks faced by coastal communities. Therefore, it can be argued that the effectiveness of these conservation units will depend on the ability, (i) to take into account their territorial context, and also (ii) to base the management decisions on a prospective and sufficiently anticipated (future-oriented) approach. MPA management must be proactive to cope with such rapid changes.
- The Nexus approach, promoted by the IUCN Commission on Ecosystem Management - coastal ecosystem group (CEM/CEG), places marine and coastal spatial planning as a key integrative element linking conservation, adaptation to climate change and coastal risk reduction, and as a part of no-regret adaptation strategies. This paper highlights the main factors that characterize current coastal dynamics, and then briefly presents three future-oriented pilot operations, implemented in Western Africa at different scales. These operations illustrate how MPAs must become structuring elements for the organization and development of coastal territories if they are to contribute to the resilience of coastal systems and to ensure their own long-term sustainability.
Using twelve years of high resolution global lightning stroke data from the World Wide Lightning Location Network (WWLLN), we show that lightning density is enhanced by up to a factor of two directly over shipping lanes in the northeastern Indian Ocean and the South China Sea as compared to adjacent areas with similar climatological characteristics. The lightning enhancement is most prominent during the convectively active season, November-April for the Indian Ocean and April-December in the South China Sea, and has been detectable from at least 2005 to the present. We hypothesize that emissions of aerosol particles and precursors by maritime vessel traffic lead to a microphysical enhancement of convection and storm electrification in the region of the shipping lanes. These persistent localized anthropogenic perturbations to otherwise clean regions are a unique opportunity to more thoroughly understand the sensitivity of maritime deep convection and lightning to aerosol particles.
- Oceans and coasts provide a wide array of services to humans, including climate regulation, food security, and livelihoods. Managing them well is vital to human well-being as well as the maintenance of marine biodiversity and ocean-dependent economies.
- Carbon sequestration and storage is increasingly recognized as a valuable service provided by coastal vegetation. Carbon sequestered and stored by mangrove forests, tidal marshes, and seagrass meadows is known as ‘blue’ carbon. These habitats capture and store carbon within the plants themselves and in the sediment below them. When the habitats are destroyed, much of their carbon is released back to the atmosphere and ocean contributing to global climate change.
- Therefore, blue carbon ecosystem protection is becoming a greater priority in marine management and is an area of interest to scientists, policy makers, coastal communities, and the private sector including those that contribute to ecosystem degradation but also those that are looking to reduce their carbon footprint. A range of policy and management responses aim to reduce coastal ecosystem loss, including the establishment of marine protected areas (MPAs).
- This paper explores how MPA design, location, and management could be used to protect and increase carbon sequestration and ensure integrity of carbon storage through conservation and restoration activities. While additional research is necessary to validate the proposed recommendations, this paper describes much needed first steps and highlights the potential for blue carbon finance mechanisms to provide sustainable funding for MPAs.
- Coastal blue carbon activities are being implemented by a variety of countries, using different approaches. Existing regulatory regimes, including on coastal protection, are still very useful tools to protect and conserve mangroves, seagrasses and saltmarshes, and preserve their carbon value and role. These approaches suffer, however, from ‘traditional’ issues such as lack of enforcement, human and financial constraints as well as unclear or misguiding government mandates.
- Successes are witnessed using a community-based carbon project approach, ensuring high stakeholder participation via direct or indirect incentive programmes. Comprehensive coastal zone management approaches seem very promising, but success overall, and regarding carbon specifically, are yet to be reported.
- The Paris Agreement has introduced new tools which could serve as means to trigger more and better coastal adaptation and mitigation efforts. Their implementation details are, however, still under negotiation and their impacts can only be expected in a few years.
- Innovative financing, that is the development of new funding sources and mechanisms including from the private sector, can be used to deliver promising ocean conservation opportunities. Capital markets are increasingly accessible for sustainable development and climate finance, and are gaining traction for biodiversity conservation. Such financing concepts could also be applied in the High Seas. Drawing on natural capital economics as a way to ascribe economic value, specific marine investment opportunities can be identified and made accessible to new financiers and funding processes.
- International waters cover nearly half of the planet's surface, yet governance deficiencies have meant that marine habitats and ecosystems are rapidly deteriorating. Improved governance through the proposed Marine Biodiversity Implementing Agreement discussed under the 1982 UN Convention on the Law of the Sea and delivery of the Sustainable Development Goals, in particular ocean goal 14, will require additional financial support for High Seas solutions, including for the effective management of marine reserves.
- For projects to be attractive to funders they need to be clearly structured and deliver quantifiable benefits. A comprehensive ocean data infrastructure could be put in place to support large-scale marine conservation monitoring cost-effectively. This infrastructure could serve also other ocean users, thereby defraying the cost and could be delivered through public–private partnerships. Development finance and climate finance provide examples for relevant pathways for such integrated approaches.
- Existing efforts to find additional funding for ocean solutions can be enhanced through the range of specific innovative ocean finance mechanisms that are identified. These offer the prospect of long-term support.
- This review draws on progress made at the IUCN World Conservation Congress in Honolulu, Hawai'i in September 2016 and builds on the momentum created by the Paris Agreement and the Sustainable Development Goals.
The sensitivity of corals and their Symbiodinium to warming has been extensively documented; however very few studies considered that anthropogenic inputs such as metal pollution have already an impact on many fringing reefs. Thus, today, nickel releases are common in coastal ecosystems. In this study, two major reef-building species Acropora muricata and Pocillopora damicornis were exposed in situ to ambient and moderate nickel concentrations on a short-term period (1 h) using benthic chamber experiments. Simultaneously, we tested in laboratory conditions the combined effects of a chronic exposure (8 weeks) to moderate nickel concentrations and ocean warming on A. muricata. The in situ experiment highlighted that nickel enrichment, at ambient temperature, stimulated by 27 to 47% the calcification rates of both species but not their photosyntheticperformances. In contrast, an exposure to higher nickel concentration, in combination with elevated temperature simulated in aquaria, severely depressed by 30% the growth of A. muricata.
Ecosystem-based management is an increasingly prominent paradigm for the management of living marine resources with a focus on maintaining ecosystem level properties and processes. Although highly migratory marine and anadromous fish species often disproportionately contribute to the structure and function of ecosystems, incorporating these species into ecosystem-based management policies remains difficult because they spend a considerable portion of time outside the boundaries that define a particular management area. In this paper, two case studies are used to examine how the challenges of ecosystem openness, imperfect information, and ecosystem complexity can impede efforts to integrate highly migratory Pacific salmon into ecosystem-based management policies. This analysis highlights three main factors that hinder more effective integration: (1) uncertainties about impacts of human activities and ecological processes that occur in geographically distant jurisdictional areas or at spatial scales larger than the ecosystem-based management area, (2) spatial asymmetries in the distribution of costs and benefits associated with management decisions (i.e., positive or negative externalities), and (3) static management policies that prevent updating management decisions in a timely manner when ecosystem conditions change or new information becomes available. Given these factors, two potential strategies to address migratory challenges are suggested. First, the creation of an international ecosystem synthesis group is recommended to facilitate the collection, analysis, and dissemination of ecological, social, and policy information across national and other jurisdictional boundaries. Second, the expanded use of dynamic in-season management policies is recommended, which allow for rapid updating of management decisions based on evolving information about ecosystem conditions.
Ecosystem-based management (EBM) in marine ecosystems considers impacts caused by complex interactions between environmental and anthropogenic pressures (i.e., oceanographic, climatic, socio-economic) and marine communities. EBM depends, in part, on ecological indicators that facilitate understanding of inherent properties and the dynamics of pressures within marine communities. Thresholds of ecological indicators delineate ecosystem status because they represent points at which a small increase in one or many pressure variables results in an abrupt change of ecosystem responses. The difficulty in developing appropriate thresholds and reference points for EBM lies in the multidimensionality of both the ecosystem responses and the pressures impacting the ecosystem. Here, we develop thresholds using gradient forest for a suite of ecological indicators in response to multiple pressures that convey ecosystem status for large marine ecosystems from the US Pacific, Atlantic, sub-Arctic, and Gulf of Mexico. We detected these thresholds of ecological indicators based on multiple pressures. Commercial fisheries landings above approximately 2–4.5 t km−2 and fisheries exploitation above 20–40% of the total estimated biomass (of invertebrates and fish) of the ecosystem resulted in a change in the direction of ecosystem structure and functioning in the ecosystems examined. Our comparative findings reveal common trends in ecosystem thresholds along pressure gradients and also indicate that thresholds of ecological indicators are useful tools for comparing the impacts of environmental and anthropogenic pressures across multiple ecosystems. These critical points can be used to inform the development of EBM decision criteria.
Proponents of marine renewable energy worldwide highlight that regulatory and consenting procedures are a significant barrier to the upscaling of infrastructure required to transform the energy generation sector. Uncertainties about the cumulative effects of marine renewable energy developments cause substantial delays during the consenting process, which are exacerbated by the lack of clarity about how to assess cumulative effects. These obstacles have contributed to perceptions that this essential emerging industry receives disproportionate scrutiny relative to established maritime activities. However, alongside legislated targets to reduce carbon emissions, there are legal obligations to protect, maintain and improve the condition of the marine environment. As the imperative to halt the decline in the condition of the environment increases, so expectations of cumulative impact assessments grow and the risk of consenting delays persists. To investigate how robust current cumulative impact assessment practise is, a novel evaluation framework was developed and applied to Environmental Statements of the world's largest offshore wind farms, currently in United Kingdom waters. The framework was designed to evaluate cumulative impact assessments relative to the information needs of decision-makers tasked with managing cumulative effects. We found that current practise does not meet those needs, that there is dissonance between science and practise, and problematic variability between assessments was observed. Straightforward recommendations for improved practise are provided, which if implemented may ease the perceived regulatory burden by clarifying practise. We also highlight additional steps that could enable project-led cumulative impact assessments to better support regional marine management. The results and recommendations will be of interest to countries worldwide where marine renewable energy is emerging alongside ecosystem-approach and marine spatial planning aspirations.
There has been a strong push within natural resource management to incorporate spatial structure into management regimes. However, discussions surrounding the appropriate designs of spatial management have largely been conceptual. This paper develops a spatial econometric model of fishing location choice using non-confidential data from the Great Barrier Reef coral trout commercial fishery. Harvest location decisions are modeled as a function of spatial patterns of expected economic returns. The preferred spatially dependent econometric model is shown to outperform ordinary least squares and fixed effects models in out-of-sample forecasting. Estimates from the spatial model reveal spatial spillover effects in fleet harvest location behavior. In particular, harvest activity at any given site is equally sensitive to same-site economic returns and surrounding-site economic returns. The econometric results are illustrated using a fee-based policy simulation. Results suggest non-spatial management is characterized by two inefficiencies. First, heterogeneity between sites is averaged, resulting a fee that is too high or too low across space. Second, fees that are too high or too low affect the fishing effort in nearby locations.
Marine debris is the most conspicuous pollutant that makes beaches aesthetically unappealing to users. The perceptions and reactions of beach users to stranded litter were compared between second-home owners and users (SHOU) and non-recurrent tourists (T). A questionnaire was applied to obtain socio-economic characteristics; assessment of the overall beach quality and perception of beach litter pollution (perception); hypothetical scenarios of marine litter pollution and deterrence (reaction); and potential alternative destinations in the case of deterrence (economic effect). Questionnaires (n = 319) were applied at two Brazilian subtropical beaches, with different physiographical settings (Pontal do Sul, PS, estuarine beach; Ipanema, I, open-ocean beach). Beach users’ groups differed regarding daily expenses (T > SHOU), period of permanence per trip (SHOU > T) and trip frequency (SHOU > T). The open-ocean beach (I) was rated the worst regarding overall beach quality. Marine debris generation was mainly attributed to local “beach users”, in the open-ocean beach (I). “Marine” (or non-local) sources were four times more frequently cited in the estuarine beach (PS). Perception on actual litter pollution and litter deterrence scenarios, did not vary between beaches or groups. More than 85% of beachgoers would avoid a beach visit if a worst scenario (> 15items/m2) occurred and most users would choose a neighboring state beach destination. Stranded litter may potentially reduce local tourism income by 39.1%, representing losses of up to US$ 8.5 million per year. These figures are proxies to support the trade-off local authority's make between investments to prevent/remove beach litter and the potential reduction in income from a tourist destination change.
We have little empirical evidence of how large-scale overlaps between large numbers of marine species may have altered in response to human impacts. Here, we synthesized all available distribution data (>1 million records) since 1992 for 61 species of the East Australian marine ecosystem, a global hot spot of ocean warming and continuing fisheries exploitation. Using a novel approach, we constructed networks of the annual changes in geographical overlaps between species. Using indices of changes in species overlap, we quantified changes in the ecosystem stability, species robustness, species sensitivity and structural keystone species. We then compared the species overlap indices with environmental and fisheries data to identify potential factors leading to the changes in distributional overlaps between species. We found that the structure of the ecosystem has changed with a decrease in asymmetrical geographical overlaps between species. This suggests that the ecosystem has become less stable and potentially more susceptible to environmental perturbations. Most species have shown a decrease in overlaps with other species. The greatest decrease in species overlap robustness and sensitivity to the loss of other species has occurred in the pelagic community. Some demersal species have become more robust and less sensitive. Pelagic structural keystone species, predominately the tunas and billfish, have been replaced by demersal fish species. The changes in species overlap were strongly correlated with regional oceanographic changes, in particular increasing ocean warming and the southward transport of warmer and saltier water with the East Australian Current (EAC), but less correlated with fisheries catch. Our study illustrates how large-scale multispecies distribution changes can help identify structural changes in marine ecosystems associated with climate change.
This article explores the concept of “other effective area-based conservation measures” (OECMs) in the context of the UN Convention on Biological Diversity (CBD) Aichi Biodiversity Target 11 on marine protected areas and OECMs and its linkages to the Sustainable Development Goals (SDGs). It argues that mainstreaming biodiversity through CBD Aichi Biodiversity Targets’ implementation into the SDGs can contribute to a more systemic and comprehensive implementation of SDG 14.5 on conservation of at least 10% of marine and coastal areas. It argues that OECMs can complement MPAs and contribute to ecologically representative and effectively managed marine protected areas systems integrated into broader governance systems such as marine spatial planning. Selected global and local sectoral conservation measures are therefore highlighted in this analysis as potential forms of OECMs. At the local level, a case study of ecologically or biologically significant marine areas managed as locally managed marine areas (LMMAs) in Mozambique is discussed. This case study explores how multiple-use LMMAs, which respond to short-term fisher's needs and targeted biodiversity conservation, could contribute to the achievement of specific SDGs on food security, poverty elimination and resilient ecosystems if properly supported by long-term investments, strong institutions and integrated oceans management.
Marine ecosystems are increasingly threatened by the cumulative effects of multiple human pressures. Cumulative effect assessments (CEAs) are needed to inform environmental policy and guide ecosystem-based management. Yet, CEAs are inherently complex and seldom linked to real-world management processes. Therefore we propose entrenching CEAs in a risk management process, comprising the steps of risk identification, risk analysis and risk evaluation. We provide guidance to operationalize a risk-based approach to CEAs by describing for each step guiding principles and desired outcomes, scientific challenges and practical solutions. We reviewed the treatment of uncertainty in CEAs and the contribution of different tools and data sources to the implementation of a risk based approach to CEAs. We show that a risk-based approach to CEAs decreases complexity, allows for the transparent treatment of uncertainty and streamlines the uptake of scientific outcomes into the science-policy interface. Hence, its adoption can help bridging the gap between science and decision-making in ecosystem-based management.
Ecosystems influence human societies, leading people to manage ecosystems for human benefit. Poor environmental management can lead to reduced ecological resilience and social–ecological collapse. We review research on resilience and collapse across different systems and propose a unifying social–ecological framework based on (i) a clear definition of system identity; (ii) the use of quantitative thresholds to define collapse; (iii) relating collapse processes to system structure; and (iv) explicit comparison of alternative hypotheses and models of collapse. Analysis of 17 representative cases identified 14 mechanisms, in five classes, that explain social–ecological collapse. System structure influences the kind of collapse a system may experience. Mechanistic theories of collapse that unite structure and process can make fundamental contributions to solving global environmental problems.
As social–ecological systems enter a period of rapid global change, science must predict and explain ‘unthinkable’ social, ecological, and social–ecological collapses.
Existing theories of collapse are weakly integrated with resilience theory and ideas about vulnerability and sustainability.
Mechanisms of collapse are poorly understood and often heavily contested. Progress in understanding collapse requires greater clarity on system identity and alternative causes of collapse.
Archaeological theories have focused on a limited range of reasons for system collapse. In resilience theory, the adaptive cycle has been used to describe collapse but offers little insight into the mechanisms that cause it.
Theories of collapse should connect structure and process. Mechanistic, structure–process–function theories of collapse suggest new avenues for understanding and improving resilience.
Globally, many temperate marine communities have experienced significant temperature increases over recent decades in the form of gradual warming and heatwaves. As a result, these communities are shifting towards increasingly subtropical and tropical species compositions. Expanding coral populations have been reported from several temperate reef ecosystems along warming coastlines; these changes have been attributed to direct effects of gradual warming over decades. In contrast, increases in coral populations following shorter-term extreme warming events have rarely been documented. In this study, we compared coral populations on 17 temperate reefs in Western Australia before (2005/06) and after (2013) multiple marine heatwaves (2010–2012) affected the entire coastline. We hypothesised that coral communities would expand and change as a consequence of increasing local populations and recruitment of warm-affinity species. We found differences in coral community structure over time, driven primarily by a fourfold increase of one local species, Plesiastrea versipora, rather than recruitment of warm-affinity species. Coral populations became strongly dominated by small size classes, indicative of recent increased recruitment or recruit survival. These changes were likely facilitated by competitive release of corals from dominant temperate seaweeds, which perished during the heatwaves, rather than driven by direct temperature effects. Overall, as corals are inherently warm-water taxa not commonly associated with seaweed-dominated temperate reefs, these findings are consistent with a net tropicalisation. Our study draws attention to processes other than gradual warming that also influence the trajectory of temperate reefs in a changing ocean.
The world's oceans today have become a place for the disposal of toxic waste, which leads to the degradation of marine mammal habitats and populations. Marine mammal cell cultures have proven to be a multifunctional tool for studying the peculiarities of the cell physiology and biochemistry of these animals as well as the destructive effects of anthropogenic and natural toxicants. This review describes the sources of marine mammal live tissues and the methods required for establishing cell cultures, their use, and long-term storage. Approaches to conserving rare animal species by applying cell biology methodologies are also discussed.