Since the 1970s, the magnitude of turtle cold-stun strandings have increased dramatically within the northwestern Atlantic. Here, we examine oceanic, atmospheric, and biological factors that may affect the increasing trend of cold-stunned Kemp’s ridleys in Cape Cod Bay, Massachusetts, United States of America. Using machine learning and Bayesian inference modeling techniques, we demonstrate higher cold-stunning years occur when the Gulf of Maine has warmer sea surface temperatures in late October through early November. Surprisingly, hatchling numbers in Mexico, a proxy for population abundance, was not identified as an important factor. Further, using our Bayesian count model and forecasted sea surface temperature projections, we predict more than 2,300 Kemp’s ridley turtles may cold-stun annually by 2031 as sea surface temperatures continue to increase within the Gulf of Maine. We suggest warmer sea surface temperatures may have modified the northerly distribution of Kemp’s ridleys and act as an ecological bridge between the Gulf Stream and nearshore waters. While cold-stunning may currently account for a minor proportion of juvenile mortality, we recommend continuing efforts to rehabilitate cold-stunned individuals to maintain population resiliency for this critically endangered species in the face of a changing climate and continuing anthropogenic threats.
In the northeastern United States, flooding arising from wave overtopping poses a constant threat to coastal communities during storm events. The purpose of this study is to construct a novel integrated atmosphere-ocean-coast modeling framework based on the coupled tide, surge and wave model, ADCIRC-SWAN, to assess risk and facilitate coastal adaptation and resilience to flooding in a changing climate in this region. The integrated modeling system was validated against the field observations of water level, wave height and period during the January 2015 North American blizzard. Water level measurements by a sensor in the Avenues Basin behind the Seawall in Scituate, Massachusetts were combined with the basin volume determined by the USGS LIDAR data to verify the model predictions of wave overtopping volume. At the storm peak, the significant wave height was increased by 0.7 m at the coast by tide and surge. The wave setup along the coast varied from 0.1 m to 0.25 m depending on the coastline geometry. The interaction between tide-surge and waves increased the wave overtopping rate by five folds mainly due to increased wave height at the toe of the seawall. The wave overtopping discharge would approximately double in an intermediate sea level rise scenario of 0.36 m by 2050 for a storm like the January 2015 North American blizzard. The wave overtopping discharge would increase by 1.5 times if the seawall crest elevation was raised by the same amount as sea level rise. An increase of 0.9 m in the seawall crest elevation is required to bring the wave overtopping discharge to the current level under a 0.36 m sea level rise scenario, primarily due to larger waves arriving at the seawall without breaking in the presence of larger water depth.
Systematic conservation planning is essential in the justification and design of protected areas, especially in an era where every piece of land or water is at a high premium. We used satellite tracking data and regular monitoring of Greater flamingos into the spatial prioritization planning tool Marxan to identify the most important zones for the conservation of the greater flamingo and many other species of waterbirds and marine habitats in one of the economically important areas in the coastal zone of Abu Dhabi. Locations from 11 satellite tracked flamingos and monthly count data since 2009 in the Bul Syayeef area showed a predominant use of a relatively small area which when integrated in Marxan provided optimum boundary with minimum cost. Marxan identified 1, 5, 10 and 15 ha planning units and provided the best solution with 15 ha. The reduced total area of 145 km2 is nearly 40% of the originally proposed area for protection, is more pragmatic and easy to establish, given the high importance of the area for economic development. Using approximately the same boundary, the proposed area was declared a Ramsar site in September 2016 and was subsequently declared a protected area through a government decree in September 2017.
Ecological theory predicts that ecosystems with multiple basins of attraction can get locked in an undesired state, which has profound ecological and management implications. Despite their significance, alternative attractors have proven to be challenging to detect and characterize in natural communities. On coral reefs, it has been hypothesized that persistent coral-to-macroalgae “phase shifts” that can result from overfishing of herbivores and/or nutrient enrichment may reflect a regime shift to an alternate attractor, but, to date, the evidence has been equivocal. Our field experiments in Moorea, French Polynesia, revealed the following: (i) hysteresis existed in the herbivory–macroalgae relationship, creating the potential for coral–macroalgae bistability at some levels of herbivory, and (ii) macroalgae were an alternative attractor under prevailing conditions in the lagoon but not on the fore reef, where ambient herbivory fell outside the experimentally delineated region of hysteresis. These findings help explain the different community responses to disturbances between lagoon and fore reef habitats of Moorea over the past several decades and reinforce the idea that reversing an undesired shift on coral reefs can be difficult. Our experimental framework represents a powerful diagnostic tool to probe for multiple attractors in ecological systems and, as such, can inform management strategies needed to maintain critical ecosystem functions in the face of escalating stresses.
Plastic pollution is prevalent worldwide and affects marine wildlife from urbanized beaches to pristine oceanic islands. However, the ecological basis and mechanisms that result in marine animal ingestion of plastic debris are still relatively unknown, despite recent advances. We investigated the relationship between scavenging behavior and plastic ingestion using green turtles, Chelonia mydas, as a model. Diet analysis of C. mydas showed that sea turtles engaging in scavenging behavior ingested significantly more plastic debris than individuals that did not engage in this foraging strategy. We argue that opportunistic scavenging behavior, an adaptive behavior in most marine ecosystems, may now pose a threat to a variety of marine animals due to the current widespread plastic pollution found in oceans.
The data requirements and resources needed to develop effective indicators of fishing impacts on target stocks may often be great, especially for mangrove fisheries where, for example, tidal cycles sequentially flood and drain the habitat as a result of natural processes. Here, we used underwater video systems to evaluate the impact of small-scale fisheries on mangrove fish assemblages at four levels of fishing pressure (low, medium, high, and no pressure). The lowest values of species richness and abundance were recorded in the areas fished most intensively. Conversely, the highest species richness and the occurrence of larger-bodied fish were recorded in areas of reduced fishing activity, which was surprisingly similar to the “no fishing” areas. The slopes of the community size spectra steepened in response to exploitation, while the relative abundance of medium-sized fish (16–25 cm) declined. Fishing for local or regional markets, rather than subsistence, also led to a decrease in the abundance of larger fish (>41 cm). The marked response of population parameters to fishing pressure reflected the impact of unregulated small-scale fisheries on areas of mangroves. Fishery management practices that ignore contemporary changes in these environments are likely to overestimate long-term yields, leading to overfishing. Thus, size-based approaches to evaluating fishing pressure were suitable for detecting negative responses from the mangrove fish assemblages. A next step will be to integrate size- and species-based ecological approaches that provide mechanisms to address pronounced decreases in specific species as a more profitable indicator of fishing impacts on mangrove fish assemblages. This approach will allow the development of effective conservation and management strategies.
Natural resource policies enacted to protect environmental integrity play an important role in promoting sustainability. However, when resources are shared ecologically, economically, or through a common, global interest, policies implemented to protect resource sustainability in one domain can displace, and in some cases magnify, environmental degradation to other domains. Although such displacement has been recognized as a fundamental challenge to environmental and conservation policy within some resource sectors, there has been little cross‐disciplinary and cross‐sectoral integration to address the problem. This suggests that siloed knowledge may be impeding widespread recognition of the ubiquity of displacement and the need for mitigation. Here, we connect research across multiple disciplines to promote a broader discussion and recognition of the processes and pathways that can lead to displaced impacts that countermand or undermine resource policy and outline a number of approaches that can mitigate displacement.
South Pacific albacore is a species of primary importance in the longline fishery of a number of Small Island Developing States in the Western and Central Pacific Ocean. Despite the fact that the stock is assessed as not being subject to overfishing and not overfished, economic returns have declined significantly over the past decade. This has led to calls for management intervention. Given stated biological and economic objectives for the fishery, members of the Pacific Islands Forum Fisheries Agency proposed an interim stock target reference point to the Western and Central Pacific Fisheries Commission that would imply a larger stock size, higher catch rates and a more profitable fishery (FFA Members, 2015). The purpose of this study is to examine the biological and economic consequences along the trajectories of two distinct longline effort reduction regimes that achieve the proposed target reference point within 20 years and review the trade-offs in terms of forgone catch or effort and forgone revenue. The two effort regimes examined are a one-off reduction implemented immediately, and a phased reduction under which effort is reduced by a fixed percent each year. The results are discussed in the light of wider Pacific Island objectives for fishery production and fleet profitability and highlights the importance of moving beyond a purely biological stock-based focus when providing management advice.
The transition of plants and animals from sea to land required adaptation to a very different physical and chemical environment. In this paper, we focus on the consequences of the differences between the magnitude of the variability of ocean and atmospheric dynamics, with the ocean environment (in particular temperature and currents) being two to three orders of magnitude less variable than that on land. We suggest that greater insights on possible responses of marine vs. terrestrial systems to rapid climate change can be gained by considering that terrestrial vertebrates, invertebrates and plants have evolved from marine organisms that, pre-Cambrian, had early life history developmental stages as planktonic larvae. Marine larvae were/are adapted to the predictable and minimal range of temperature changes and regularities in ocean currents, as most organisms utilize the energy in these currents as an “auxiliary” source for predictable gamete and larvae dispersal. Post-Cambrian, on land, no such simple strategy was available; instead, most terrestrial organisms have evolved reproductive strategies and behaviours to eliminate, or at least minimize, the consequences of much larger atmospheric variability. Adapting our future use of these systems sensibly will require greater understanding of how the two regimes respond to rapid climate change.
Dynamic energy budget (DEB) theory offers a comprehensive framework for understanding the overall physiological performance (growth, development, respiration, reproduction, etc.) of an organism over the course of its life cycle. We present here a simplified DEB model for the swimming crab Liocarcinus depurator. To the best of our knowledge, this is the first to be presented for this species. Most applications of the standard DEB model assume continuous growth in all size metrics (length, wet mass, carbon content) of the modelled species. However, in crustaceans growth, measured as an increase of carapace length/width, occurs periodically via moult. To account for this, we have extended the model to track the continuous increase in carbon mass as well as the episodic increase in physical size. Model predictions were consistent with the patterns in the observed data, predicting both the moult increment and the intermoult period of an individual. In addition to presenting the model itself, we also make recommendations for further development, and evaluate the potential applications of such a model, both at the individual level (e.g. aquaculture) and as a potential tool for population level dynamics (e.g. fisheries stock assessment).
In this period of environmental change, understanding how resource users respond to such changes is critical for effective resource management and adaptation planning. Extensive work has focused on natural resource responses to environmental changes, but less has examined the response of resource users to such changes. We used an interdisciplinary approach to analyse changes in resource use among commercial trawl fishing communities in the northwest Atlantic, a region that has shown poleward shifts in harvested fish species. We found substantial community-level changes in fishing patterns since 1996: southern trawl fleets of larger vessels with low catch diversity fished up to 400 km further north, while trawl fleets of smaller vessels with low catch diversity shrank or disappeared from the data set over time. In contrast, trawl fleets (of both large and small vessels) with higher catch diversity neither changed fishing location dramatically or nor disappeared as often from the data set. This analysis suggests that catch diversity and high mobility may buffer fishing communities from effects of environmental change. Particularly in times of rapid and uncertain change, constructing diverse portfolios and allowing for fleet mobility may represent effective adaptation strategies.
Most reporting of stock status accumulated at a national or regional level gives statistics on what proportion of the stocks are below some abundance threshold or above some fishing mortality rate threshold. This approach does not convey useful information on the performance of the fisheries management system in maximizing long-term sustainable yield, which is the primary objective of most national and international fisheries legislation. In this paper, I present a graphical approach for representing how much yield is being lost as a consequence of current suboptimal abundance and fishing pressure. Using the EU stocks assessed by ICES as an example, I show how traditional criteria for overfished and overfishing fail to display realistic information about the performance of the fishery. This approach provides much more useful information for the public and policy makers.
Mandates to execute ecosystem-based management exist but are not implemented sufficiently enough to reap the benefits of a growing blue economy.
The production of marine habitat maps typically relies on the use of habitat classification schemes (HCSs). The choice of which HCS to use for a mapping study is often related to familiarity, established practice, and national desires. Despite a superficial similarity, HCSs differ greatly across six key properties, namely, purpose, environmental and ecological scope, spatial scale, thematic resolution, structure, and compatibility with mapping techniques. These properties impart specific strengths and weaknesses for each HCS, which are subsequently transferred to the habitat maps applying these schemes. This review has examined seven HCSs (that are commonly used and widely adopted for national and international mapping programmes), over the six properties, to understand their influence on marine habitat mapping. In addition, variation in how mappers interpret and apply HCSs introduces additional uncertainties and biases into the final maps. Recommendations are provided for improving HCSs for marine habitat mapping as well as for enhancing the working practices of mappers using habitat classification. It is hoped that implementation of these recommendations will lead to greater certainty and usage within mapping studies and more consistency between studies and adjoining maps.
The appetite for ecosystem-based fisheries management (EBFM) approaches has grown, but the perception persists that implementation is slow. Here, we synthesize progress toward implementing EBFM in the United States through one potential avenue: expanding fish stock assessments to include ecosystem considerations and interactions between species, fleets, and sectors. We reviewed over 200 stock assessments and assessed how the stock assessment reports included information about system influences on the assessed stock. Our goals were to quantify whether and how assessments incorporated broader system-level considerations, and to explore factors that might contribute to the use of system-level information. Interactions among fishing fleets (technical interactions) were more commonly included than biophysical interactions (species, habitat, climate). Interactions within the physical environment (habitat, climate) were included twice as often as interactions among species (predation). Many assessment reports included ecological interactions only as background or qualitative considerations, rather than incorporating them in the assessment model. Our analyses suggested that ecosystem characteristics are more likely to be included when the species was overfished (stock status), the assessment is conducted at a science centre with a longstanding stomach contents analysis program, and/or the species life history characteristics suggest it is likely to be influenced by the physical environment, habitat, or predation mortality (short-lived species, sessile benthic species, or low trophic-level species). Regional differences in stomach contents analysis programs may limit the inclusion of predation mortality in stock assessments, and more guidance is needed on best practices for the prioritization of when and how biophysical information should be considered. However, our results demonstrate that significant progress has been made to use best available science and data to expand single-species stock assessments, particularly when a broad definition of EBFM is applied.
The debate over Brexit and the fisheries question has focused very largely on the expected benefits for the UK's fishing industry to the virtual exclusion of potential implications for the seafood supply chain. This paper refocuses attention on a supply chain now heavily dependent on both imports and exports of fish and fish products mainly to EU markets. Brexit could pose potentially significant problems arising from the imposition of tariff and non-tariff restrictions on trade and limitation on future movements of semi-skilled and unskilled EU migrants into the UK labour market. Three elements of the supply chain are likely to be directly affected: the shellfish and small scale fisheries sectors impacted by tariff and non-tariff restrictions and perhaps most significantly the fish processing industry, similarly affected by trade restrictions and heavily dependent on EU labour. Brexit has also been the catalyst for renewed pressures in Scotland for further devolution of powers relating to the fishing industry that at some future date could see the development of two distinctive seafood supply chains within the UK.
The ability to perceive and recognise a reflected mirror image as self (mirror self-recognition, MSR) is considered a hallmark of cognition across species. Although MSR has been reported in mammals and birds, it is not known to occur in any other major taxon. Potentially limiting our ability to test for MSR in other taxa is that the established assay, the mark test, requires that animals display contingency testing and self-directed behaviour. These behaviours may be difficult for humans to interpret in taxonomically divergent animals, especially those that lack the dexterity (or limbs) required to touch a mark. Here, we show that a fish, the cleaner wrasse Labroides dimidiatus, shows behaviour that may reasonably be interpreted as passing through all phases of the mark test: (i) social reactions towards the reflection, (ii) repeated idiosyncratic behaviours towards the mirror, and (iii) frequent observation of their reflection. When subsequently provided with a coloured tag in a modified mark test, fish attempt to remove the mark by scraping their body in the presence of a mirror but show no response towards transparent marks or to coloured marks in the absence of a mirror. This remarkable finding presents a challenge to our interpretation of the mark test—do we accept that these behavioural responses, which are taken as evidence of self-recognition in other species during the mark test, lead to the conclusion that fish are self-aware? Or do we rather decide that these behavioural patterns have a basis in a cognitive process other than self-recognition and that fish do not pass the mark test? If the former, what does this mean for our understanding of animal intelligence? If the latter, what does this mean for our application and interpretation of the mark test as a metric for animal cognitive abilities?
An operational framework to assess the value of fisheries restricted areas (FRAs) for marine conservation was developed. Such a framework contributes to the wider concept of considering other effective area-based conservation measures (OECMs), as complementing conservation efforts and substantially contributing to effectively and equitably achieving Aichi biodiversity Target 11. A tailor-made multi-criteria decision analysis was designed and applied, for potential OECMs to be carefully assessed on a case-by-case basis and categorized according to their effectiveness in terms of contributing to marine biodiversity conservation. The official documentation and guidance provided by the IUCN were fully respected and made operational, providing a paradigm to managers and decision makers for assessing the contribution of FRAs to marine conservation under the OECM concept. The study also constitutes a review of the conservation status of the Aegean Sea and provides scientific documentation to the managers and decision makers in the area to address spatial conservation targets. By considering Natura 2000 sites as effective marine protected areas (MPAs), the Aichi Target 11 is attained (14.94%) at national level (i.e. within the Greek territorial waters). At ecoregional level (i.e. including international waters of the Aegean Sea) the target is not achieved (6.66%). It is proposed that, by adding all effective FRAs and a number of less effective FRAs, under the condition of increasing their effectiveness for conservation, to the network of MPAs in the area and designating them as OECMs, the conservation target can be attained also at ecoregional level.
The emergence of ecosystem-based fisheries management (EBFM) has broadened the policy scope of fisheries management by accounting for the biological and ecological connectivity of fisheries. Less attention, however, has been given to the economic connectivity of fisheries. If fishers consider multiple fisheries when deciding where, when, and how much to fish, then management changes in one fishery can generate spillover impacts in other fisheries. Catch-share programs are a popular fisheries management framework that may be particularly prone to generating spillovers given that they typically change fishers’ incentives and their subsequent actions. We use data from Alaska fisheries to examine spillovers from each of the main catch-share programs in Alaska. We evaluate changes in participation—a traditional indicator in fisheries economics—in both the catch-share and non–catch-share fisheries. Using network analysis, we also investigate whether catch-share programs change the economic connectivity of fisheries, which can have implications for the socioeconomic resilience and robustness of the ecosystem, and empirically identify the set of fisheries impacted by each Alaska catch-share program. We find that cross-fishery participation spillovers and changes in economic connectivity coincide with some, but not all, catch-share programs. Our findings suggest that economic connectivity and the potential for cross-fishery spillovers deserve serious consideration, especially when designing and evaluating EBFM policies.
The ingestion of plastic marine litter (PML) by sea turtles is widespread and concerning, and the five species that occur in the southwestern Atlantic – green, loggerhead, olive ridley, leatherback and hawksbill – are vulnerable to this pollution. Here, we quantified and characterized PML ingested by these species in southern Brazil, and observed PML ingestion in 49 of 86 sampled individuals (~57.0%). Green turtles presented the highest rates and variety of ingested plastics, and such ingestion has been high at least since 1997. Omnivorous turtles presented higher PML ingestion than carnivorous ones. Loggerheads displayed a negative correlation between body size and number of ingested items. Green turtles ingested mostly flexible transparent and flexible/hard white plastics; loggerheads ate mainly flexible, hard and foam fragments, in white and black/brown colors. These results help us better understand PML ingestion by sea turtles, highlighting the seriousness of this threat and providing information for prevention and mitigation strategies.