The susceptibility of reef-building corals to climatic anomalies is well documented and a cause of great concern for the future of coral reefs. Reef corals are normally considered to tolerate only a narrow range of climatic conditions with only a small number of species considered heat-tolerant. Occasionally however, corals can be seen thriving in unusually harsh reef settings and these are cause for some optimism about the future of coral reefs. Here we document for the first time a diverse assemblage of 225 species of hard corals occurring in the intertidal zone of the Bonaparte Archipelago, north western Australia. We compare the environmental conditions at our study site (tidal regime, SST and level of turbidity) with those experienced at four other more typical tropical reef locations with similar levels of diversity. Physical extremes in the Bonaparte Archipelago include tidal oscillations of up to 8 m, long subaerial exposure times (>3.5 hrs), prolonged exposure to high SST and fluctuating turbidity levels. We conclude the timing of low tide in the coolest parts of the day ameliorates the severity of subaerial exposure, and the combination of strong currents and a naturally high sediment regime helps to offset light and heat stress. The low level of anthropogenic impact and proximity to the Indo-west Pacific centre of diversity are likely to further promote resistance and resilience in this community. This assemblage provides an indication of what corals may have existed in other nearshore locations in the past prior to widespread coastal development, eutrophication, coral predator and disease outbreaks and coral bleaching events. Our results call for a re-evaluation of what conditions are optimal for coral survival, and the Bonaparte intertidal community presents an ideal model system for exploring how species resilience is conferred in the absence of confounding factors such as pollution.
The following titles are freely-available, or include a link to a preprint or postprint.
Concern for the future of reef-building corals in conditions of rising sea temperatures combined with recent technological advances has led to a renewed interest in documenting the biodiversity of mesophotic coral ecosystems (MCEs) and their potential to provide lineage continuation for coral taxa. Here, we examine species diversity of staghorn corals (genera Acropora and Isopora) in the mesophotic zone (below 30 m depth) of the Great Barrier Reef and western Coral Sea. Using specimen-based records we found 38 staghorn species in the mesophotic zone, including three species newly recorded for Australia and five species that only occurred below 30 m. Staghorn corals became scarce at depths below 50 m but were found growing in-situ to 73 m depth. Of the 76 staghorn coral species recorded for shallow waters (depth ≤ 30 m) in north-east Australia, 21% extended to mesophotic depths with a further 22% recorded only rarely to 40 m depth. Extending into the mesophotic zone provided shallow water species no significant advantage in terms of their estimated global range-size relative to species restricted to shallow waters (means 86.2 X 106 km2 and 85.7 X 106 km2 respectively, p = 0.98). We found four staghorn coral species at mesophotic depths on the Great Barrier Reef that were previously considered rare and endangered on the basis of their limited distribution in central Indonesia and the far western Pacific. Colonies below 40 m depth showed laterally flattened branches, light and fragile skeletal structure and increased spacing between branches and corallites. The morphological changes are discussed in relation to decreased light, water movement and down-welling coarse sediments. Staghorn corals have long been regarded as typical shallow-water genera, but here we demonstrate the significant contribution of this group to the region’s mesophotic fauna and the importance of considering MCEs in reef biodiversity estimates and management.
Understanding the influence of synergisms on natural processes is a critical step toward determining the full-extent of anthropogenic stressors. As carbon emissions continue unabated, two major stressors—warming and acidification—threaten marine systems on several scales. Here, we report that a moderate temperature increase (from 30°C to 32°C) is sufficient to slow— even hinder—the ability of dissolved organic matter, a major carbon pool, to self-assemble to form marine microgels, which contribute to the particulate organic matter pool. Moreover, acidification lowers the temperature threshold at which we observe our results. These findings carry implications for the marine carbon cycle, as self-assembled marine microgels generate an estimated global seawater budget of ~1016 g C. We used laser scattering spectroscopy to test the influence of temperature and pH on spontaneous marine gel assembly. The results of independent experiments revealed that at a particular point, both pH and temperature block microgel formation (32°C, pH 8.2), and disperse existing gels (35°C). We then tested the hypothesis that temperature and pH have a synergistic influence on marine gel dispersion. We found that the dispersion temperature decreases concurrently with pH: from 32°C at pH 8.2, to 28°C at pH 7.5. If our laboratory observations can be extrapolated to complex marine environments, our results suggest that a warming–acidification synergism can decrease carbon and nutrient fluxes, disturbing marine trophic and trace element cycles, at rates faster than projected.
Understanding the effects of environmental change on ecosystems requires the identification of baselines that may act as reference conditions. However, the continuous change of these references challenges our ability to define the true natural status of ecosystems. The so-called sliding baseline syndrome can be overcome through the analysis of quantitative time series, which are, however, extremely rare. Here we show how combining historical quantitative data with descriptive ‘naturalistic’ information arranged in a chronological chain allows highlighting long-term trends and can be used to inform present conservation schemes. We analysed the long-term change of a coralligenous reef, a marine habitat endemic to the Mediterranean Sea. The coralligenous assemblages of Mesco Reef (Ligurian Sea, NW Mediterranean) have been studied, although discontinuously, since 1937 thus making available both detailed descriptive information and scanty quantitative data: while the former was useful to understand the natural history of the ecosystem, the analysis of the latter was of paramount importance to provide a formal measure of change over time. Epibenthic assemblages remained comparatively stable until the 1990s, when species replacement, invasion by alien algae, and biotic homogenisation occurred within few years, leading to a new and completely different ecosystem state. The shift experienced by the coralligenous assemblages of Mesco Reef was probably induced by a combination of seawater warming and local human pressures, the latter mainly resulting in increased water turbidity; in turn, cumulative stress may have favoured the establishment of alien species. This study showed that the combined analysis of quantitative and descriptive historical data represent a precious knowledge to understand ecosystem trends over time and provide help to identify baselines for ecological management.
For many species securing territories is important for feeding and reproduction. Factors such as competition, habitat availability, and male characteristics can influence an individual’s ability to establish and maintain a territory. The risk of predation can have an important influence on feeding and reproduction; however, few have studied its effect on territoriality. We investigated territoriality in a haremic, polygynous species of coral reef herbivore, Sparisoma aurofrenatum (redband parrotfish), across eight reefs in the Florida Keys National Marine Sanctuary that were either protected or unprotected from fishing of piscivorous fishes. We examined how territory size and quality varied with reef protection status, competition, predation risk, and male size. We then determined how territory size and quality influenced harem size and female size to understand the effect of territoriality on reproductive potential. We found that protected reefs trended towards having more large predatory fishes and that territories there were smaller but had greater algal nutritional quality relative to unprotected reefs. Our data suggest that even though males in protected sites have smaller territories, which support fewer females, they may improve their reproductive potential by choosing nutritionally rich areas, which support larger females. Thus, reef protection appears to shape the trade-off that herbivorous fishes make between territory size and quality. Furthermore, we provide evidence that males in unprotected sites, which are generally less complex than protected sites, choose territories with higher structural complexity, suggesting the importance of this type of habitat for feeding and reproduction in S. aurofrenatum. Our work argues that the loss of corals and the resulting decline in structural complexity, as well as management efforts to protect reefs, could alter the territory dynamics and reproductive potential of important herbivorous fish species.
Table of Contents:
- Sound and regular monitoring is essential to effective MPA management;
- Monitoring should focus on protected features, pressures and socioeconomic effects of conservation measures;
- Most existing MPA monitoring programmes are still scarce, short-term, poorly funded and inconsistent;
- Partnering with research institutions, securing monitoring funds and citizen science can help to streamline MPA monitoring efforts.
The Task Force to Study the Impact of Ocean Acidification on State Waters was formed by the Maryland General Assembly during its 2014 session through House Bill 118 (http://mgaleg.maryland.gov/2014RS/bills/hb/hb0118e.pdf). The bill states, “The Task Force shall: analyze the best available science regarding ocean acidification and the potential effects of acidification on the ecology of State waters and on State fisheries; and make recommendations regarding potential strategies to mitigate the effects of acidification on State waters and on State fisheries.”
Beginning July 2014, the Task Force comprised of representatives from the Maryland Senate, the Maryland House of Delegates, the National Aquarium, the Aquaculture Industry, the Maryland Watermen’s Association, the Maryland Departments of Natural Resources (DNR) and the Environment (MDE), the University of Maryland Center for Environmental Science (UMCES), the Chesapeake Bay Foundation, and several outside experts and interested stakeholders met on a monthly basis to evaluate the basic science and problems of acidification in Maryland waters. Much is known about the ocean becoming more acidic from increased introduction of carbon dioxide (CO2) in the atmosphere, and the importance of upwelling events in the coastal ocean off of Washington State that have impacted the success of shellfish aquaculture facilities. Much less is known about the more complex acidification processes in shallow estuarine environments like Maryland’s Chesapeake and Coastal Bays, which are highly sensitive to terrestrial inputs, and the potential impacts that may be posed to the aquaculture industry and important fisheries such as oysters, crabs, striped bass, and other aquatic resources.
The information gaps to understanding the impacts of acidification in Maryland’s waters are large. Key findings from Maryland’s Task Force focus on seven areas that should be addressed in order to enhance our acidification understanding, its impacts to Maryland aquatic industries, and to leverage resources to capitalize on federal and other state acidification research and monitoring programs.
- This science advisory report is intended to provide general advice on how shipping activities may potentially impact the marine and freshwater environment. The Pathways of Effects (PoE) models included in this report are general and simply illustrate linkages that may not be universally applicable. The potential impacts of shipping can be widespread or localised, and may be chronic or acute.
- The PoE components included in this report (i.e., movement underway, discharge, oil spills, anchoring, and grounding) are independent of time and space constraints, and do not address the frequency, likelihood of occurrence, nor magnitude of potential impact(s) on an ecosystem. In no way should this advice or the PoE components be interpreted as risk or threat assessments.
- A suite of stressors resulting from movement underway (i.e. water mixing, substrate disturbance, noise emissions, icebreaking, strikes, wake, and light emission) may lead to changes in habitat, community structure, and the health (fitness) and survival (mortality) of organisms.
- Operational and incidental or accidental discharges associated with shipping can result in the discharge of aquatic invasive species, debris, oils and other aquatic or atmospheric contaminants, and nutrients (e.g., via grey water, sewage). Such discharges can result in changes to habitat, community structure, the fitness, mortality, and/or function of aquatic organisms.
- Oil spills are one of the most damaging events in the aquatic environment, affecting multiple species and habitats. Spill recovery measures are often largely ineffective and long-term chronic ecosystem effects often result.
- Anchoring may create vertical obstructions in the water column and/or may result in substantial changes to the substrate composition and structure resulting from crushing and/or sediment re-suspension. Changes to the substrate as a result of anchoring may alter benthic habitats and may result in sub-lethal impacts or an increase in mortality of benthic organisms.
- Vessel grounding can affect the substrate, habitat, and benthic organisms. Groundings are more likely near shore when approaching ports but could also occur offshore (e.g., where shallow seamounts or ridges are located).
- The environmental effects of shipping are multifaceted, with potential consequences on all structures and components of the ecosystem. As such, PoE models can be strongly inter-related leading to linkages at various levels. However, given many of the linkages have limited documentation of varying quality and quantity, predicting the PoEs can be challenging. The PoE components included in this report were developed based on the current state of knowledge with many potential linkages remaining to be thoroughly quantified.
Societal and scientific challenges foster the implementation of the ecosystem approach to marine ecosystem analysis and management, which is a comprehensive means of integrating the direct and indirect effects of multiple stressors on the different components of ecosystems, from physical to chemical and biological and from viruses to fishes and marine mammals. Ecopath with Ecosim (EwE) is a widely used software package, which offers great capability for a dynamic description of the multiple interactions occurring within a food web, and potentially, a crucial component of an integrated platform supporting the ecosystem approach. However, being written for the Microsoft .NET framework, seamless integration of this code with Fortran-based physical oceanographic and/or biogeochemical models is technically not straightforward. In this work we release a re-coding of EwE in Fortran (EwE-F). We believe that the availability of a Fortran version of EwE is an important step towards setting-up integrated end-to-end (E2E) modelling schemes utilising this widely adopted software because it (i) increases portability of the EwE models, (ii) provides greater flexibility towards integrating EwE with Fortran-based modelling schemes. Furthermore, EwE-F might help modellers using Fortran programming language to get close to the EwE approach. In the present work, first the fundamentals of EwE-F are introduced, followed by validation of EwE-F against standard EwE utilising sample models. Afterwards, an E2E ecological representation of the Trieste Gulf (Northern Adriatic Sea) ecosystem is presented as an example of online two-way coupling between an EwE-F food web model and a biogeochemical model. Finally, the possibilities that having EwE-F opens up for are discussed.
Numerous assessments have quantified, mapped, and valued the services provided by ecosystems that are important for human wellbeing. However, much of the literature does not clarify how the information gathered in such assessments could be used to inform decisions that will impact ecosystem services. We propose that the process of making management decisions for ecosystem services comprises five core steps: identification of the problem and its social–ecological context; specification of objectives and associated performance measures; defining alternative management actions and evaluating the consequences of these actions; assessment of trade-offs and prioritization of alternative management actions; and making management decisions. We synthesize the degree to which the peer-reviewed ecosystem services literature has captured these steps. For the ecosystem service paradigm to gain traction in science and policy arenas, future ecosystem service assessments should have clearly articulated objectives, seek to evaluate the consequences of alternative management actions, and facilitate closer engagement between scientists and stakeholders.
The National Marine Fisheries Service (NMFS) is responsible for the stewardship of the nation's living marine resources and their habitat. As part of this charge, NMFS conducts stock assessments of the abundance and composition of fish stocks in several bodies of water. At present, stock assessments rely heavily on human data-gathering and analysis. Automatic means of fish stock assessments are appealing because they offer the potential to improve efficiency and reduce human workload and perhaps develop higher-fidelity measurements. The use of images and video, when accompanies by appropriate statistical analyses of the inferred data, is of increasing importance for estimating the abundance of species and their age distributions.
Robust Methods for the Analysis of Images and Videos for Fisheries Stock Assessment is the summary of a workshop convened by the National Research Council Committee on Applied and Theoretical Statistics to discuss analysis techniques for images and videos for fisheries stock assessment. Experts from diverse communities shared perspective about the most efficient path toward improved automation of visual information and discussed both near-term and long-term goals that can be achieved through research and development efforts. This report is a record of the presentations and discussions of this event.
Fishery management is increasingly moving toward management that accounts for environmental and social dimensions. Such an approach requires the integration of natural and social science information into planning and decision-making processes. The actual integration of social science information, however, remains limited in many policy and decision-making processes within fisheries. Our study provides insights into factors that influence the intention to use social science information among fishery managers and the actual integration of such information into fishery management. Based on interviews with fishery managers in the Great Lakes, we find that the lack of social science expertise in fishery management agencies leads to multiple negative beliefs and attitudes, and subsequently a low intention to use social science information in decision-making processes. At the same time, the paper finds that more expertise in decision-making tools and basing social science on equal footing with natural sciences within fishery management institutions appears critical to advance the actual integration of social science information in fishery management.
Among the various shark species that are captured as bycatch in commercial fishing operations, the group of pelagic sharks is still one of the least studied and known. Within those, the crocodile shark, Pseudocarcharias kamoharai, a small-sized lamnid shark, is occasionally caught by longline vessels in certain regions of the tropical oceans worldwide. However, the population dynamics of this species, as well as the impact of fishing mortality on its stocks, are still unknown, with the crocodile shark currently one of the least studied of all pelagic sharks. Given this, the present study aimed to assess the population structure of P. kamoharai in several regions of the Atlantic and Indian Oceans using genetic molecular markers. The nucleotide composition of the mitochondrial DNA control region of 255 individuals was analyzed, and 31 haplotypes were found, with an estimated diversity Hd = 0.627, and a nucleotide diversity π = 0.00167. An analysis of molecular variance (AMOVA) revealed a fixation index ΦST = -0.01118, representing an absence of population structure among the sampled regions of the Atlantic Ocean, and between the Atlantic and Indian Oceans. These results show a high degree of gene flow between the studied areas, with a single genetic stock and reduced population variability. In panmictic populations, conservation efforts can be concentrated in more restricted areas, being these representative of the total biodiversity of the species. When necessary, this strategy could be applied to the genetic maintenance of P. kamoharai.
Despite the significance of marine habitat-forming organisms, little is known about their large-scale distribution and abundance in deeper waters, where they are difficult to access. Such information is necessary to develop sound conservation and management strategies. Kelps are main habitat-formers in temperate reefs worldwide; however, these habitats are highly sensitive to environmental change. The kelp Ecklonia radiate is the major habitat-forming organism on subtidal reefs in temperate Australia. Here, we provide large-scale ecological data encompassing the latitudinal distribution along the continent of these kelp forests, which is a necessary first step towards quantitative inferences about the effects of climatic change and other stressors on these valuable habitats. We used the Autonomous Underwater Vehicle (AUV) facility of Australia’s Integrated Marine Observing System (IMOS) to survey 157,000 m2 of seabed, of which ca 13,000 m2 were used to quantify kelp covers at multiple spatial scales (10–100 m to 100–1,000 km) and depths (15–60 m) across several regions ca 2–6° latitude apart along the East and West coast of Australia. We investigated the large-scale geographic variation in distribution and abundance of deep-water kelp (>15 m depth) and their relationships with physical variables. Kelp cover generally increased with latitude despite great variability at smaller spatial scales. Maximum depth of kelp occurrence was 40–50 m. Kelp latitudinal distribution along the continent was most strongly related to water temperature and substratum availability. This extensive survey data, coupled with ongoing AUV missions, will allow for the detection of long-term shifts in the distribution and abundance of habitat-forming kelp and the organisms they support on a continental scale, and provide information necessary for successful implementation and management of conservation reserves.
Complex networks are everywhere, such as the power grid network, the airline network, the protein-protein interaction network, and the road network. The networks are ‘robust yet fragile’, which means that the networks are robust against random failures but fragile under malicious attacks. The cascading failures, system-wide disasters and intentional attacks on these networks are deserving of in-depth study. Researchers have proposed many solutions to improve the robustness of these networks. However whilst many solutions preserve the degree distribution of the networks, little attention is paid to the community structure of these networks. We argue that the community structure of a network is a defining characteristic of a network which identifies its functionality and thus should be preserved. In this paper, we discuss the relationship between robustness and the community structure. Then we propose a 3-step strategy to improve the robustness of a network, while retaining its community structure, and also its degree distribution. With extensive experimentation on representative real-world networks, we demonstrate that our method is effective and can greatly improve the robustness of networks, while preserving community structure and degree distribution. Finally, we give a description of a robust network, which is useful not only for improving robustness, but also for designing robust networks and integrating networks.
Knowledge of the spatial distribution and habitat associations of species in relation to the environment is essential for their management and conservation. Habitat suitability models are useful in quantifying species-environment relationships and predicting species distribution patterns. Little is known, however, about the stability and performance of habitat suitability models when projected into new areas (spatial transferability) and how this can inform resource management. The aims of this study were to model habitat suitability of Norway lobster (Nephrops norvegicus) in five fished areas of the Northeast Atlantic (Aran ground, Irish Sea, Celtic Sea, Scotland Inshore and Fladen ground), and to test for spatial transferability of habitat models among multiple regions. Nephrops burrow density was modelled using generalised additive models (GAMs) with predictors selected from four environmental variables (depth, slope, sediment and rugosity). Models were evaluated and tested for spatial transferability among areas. The optimum models (lowest AICc) for different areas always included depth and sediment as predictors. Burrow densities were generally greater at depth and in finer sediments, but relationships for individual areas were sometimes more complex. Aside from an inclusion of depth and sediment, the optimum models differed between fished areas. When it came to tests of spatial transferability, however, most of the models were able to predict Nephrops density in other areas. Furthermore, transferability was not dependent on use of the optimum models since competing models were also able to achieve a similar level of transferability to new areas. A degree of decoupling between model ‘fitting’ performance and spatial transferability supports the use of simpler models when extrapolating habitat suitability maps to different areas. Differences in the form and performance of models from different areas may supply further information on the processes shaping species’ distributions. Spatial transferability of habitat models can be used to support fishery management when the information is scarce but caution needs to be applied when making inference and a multi-area transferability analysis is preferable to bilateral comparisons between areas.
- After almost 10 years of discussions, States finally agreed to launch negotiations for the elaboration of an international legally binding instrument dedicated to the conservation and sustainable use of marine biodiversity in ABNJ.
- The process will take a two-step approach: (1) a Preparatory Committee (PrepCom) will make recommendations to the UNGA on the elements of a draft text by the end of 2017; (2) the UNGA will then decide on the convening and date of an intergovernmental conference by the end of its 72nd session (i.e. September 2018).
- The historic nature of the decision taken by the States, and the enthusiasm demonstrated by many delegations and observers, does not mean the forthcoming negotiation process will be easy. The road ahead is paved with difficult choices and complex challenges.
Marine ecosystems can experience regime shifts, in which they shift from being organized around one set of mutually reinforcing structures and processes to another. Anthropogenic global change has broadly increased a wide variety of processes that can drive regime shifts. To assess the vulnerability of marine ecosystems to such shifts and their potential consequences, we reviewed the scientific literature for 13 types of marine regime shifts and used networks to conduct an analysis of co-occurrence of drivers and ecosystem service impacts. We found that regime shifts are caused by multiple drivers and have multiple consequences that co-occur in a non-random pattern. Drivers related to food production, climate change and coastal development are the most common co-occurring causes of regime shifts, while cultural services, biodiversity and primary production are the most common cluster of ecosystem services affected. These clusters prioritize sets of drivers for management and highlight the need for coordinated actions across multiple drivers and scales to reduce the risk of marine regime shifts. Managerial strategies are likely to fail if they only address well-understood or data-rich variables, and international cooperation and polycentric institutions will be critical to implement and coordinate action across the scales at which different drivers operate. By better understanding these underlying patterns, we hope to inform the development of managerial strategies to reduce the risk of high-impact marine regime shifts, especially for areas of the world where data are not available or monitoring programmes are not in place.
Overfishing of large predatory fish populations has resulted in lasting restructurings of entire marine food webs worldwide, with serious socio-economic consequences. Fortunately, some degraded ecosystems show signs of recovery. A key challenge for ecosystem management is to anticipate the degree to which recovery is possible. By applying a statistical food-web model, using the Baltic Sea as a case study, we show that under current temperature and salinity conditions, complete recovery of this heavily altered ecosystem will be impossible. Instead, the ecosystem regenerates towards a new ecological baseline. This new baseline is characterized by lower and more variable biomass of cod, the commercially most important fish stock in the Baltic Sea, even under very low exploitation pressure. Furthermore, a socio-economic assessment shows that this signal is amplified at the level of societal costs, owing to increased uncertainty in biomass and reduced consumer surplus. Specifically, the combined economic losses amount to approximately 120 million € per year, which equals half of today's maximum economic yield for the Baltic cod fishery. Our analyses suggest that shifts in ecological and economic baselines can lead to higher economic uncertainty and costs for exploited ecosystems, in particular, under climate change.
Concerns are growing at multiple levels of government about the effects of ocean acidification and increasing hypoxia events on ecosystems along the coasts of California, Oregon, Washington, and British Columbia. Thoughtful and strategic research and monitoring will be essential to improve understanding of these impacts and to develop effective management and mitigation options.
This report seeks to assist decision-makers across the public sector in supporting science to address ocean acidification and hypoxia. Working with the West Coast Ocean Acidification and Hypoxia Science Panel and other thought leaders, the California Ocean Science Trust has developed this vision for the future state of knowledge and role of science in improving our ability to understand and manage these threats on the West Coast.