Current Large Marine Ecosystem Research Articles

Carbon Transfer Efficiency and Risk of Fisheries Collapse in Three Large Marine Ecosystems Around China

Fisheries catch is determined by a complex combination of biological and industrial factors. In this study, using data from the online database Sea Around Us from 1950 to 2018, the risk of fisheries collapse was assessed for the three large marine ecosystems (LMEs) around China by analyzing the carbon transfer efficiency, mean trophic level, and mean maximum length of fisheries catch and expansion factor. In addition, these were compared with the corresponding values for other LMEs, especially the Humboldt Current and the North Sea LMEs, which experienced fisheries collapse.Our results revealed high carbon transfer efficiencies in LMEs around China, suggesting large fishing efforts compared with LMEs with similar primary production. Although marine fish landings did not decline significantly, they were maintained by potential resources associated with offshore and deep expansion and fishing of lower–trophic-level species and juvenile fish. However, the potential resources have been largely consumed in the East China Sea and South China Sea LMEs, where the ratio of the primary production required to sustain catches to the total primary production (%PPR) was greater than 50%. In contrast, this ratio in the Yellow Sea LME was lower; however, this value was still higher than the sustainable ratio in the Humboldt Current LME. Without proper fisheries management, the three fisheries around China are likely to collapse, as observed in case of the North Sea LME in the 1970s.

Applying Acoustic Scattering Layer Descriptors to Depict Mid-Trophic Pelagic Organisation: The Case of Atlantic African Large Marine Ecosystems Continental Shelf

To identify key nonspecific organisational characteristics of the mid-trophic pelagic communities, which remain a challenge, we work with sound scattering layers (SSLs). Application was tested in the three African Atlantic Large Marine Ecosystems (AALMEs) to assess the utility of adapting and developing new acoustic variables. Our methodology allowed comparison between Large Marine Ecosystems (LMEs) based on 14 morphological, spatial and acoustic variables to characterize SSLs over time. These original variables were effective in monitoring and comparing the LMEs, and even allowed us to discriminate different organisations inside the Canary Current LME. Common traits identified for all AALMEs included the importance of the shallowest SSL. However, we identified an unexpected night-time pattern in SSL distributions in the Benguela Current LME which reflect a major difference in diel vertical migration mechanisms relative to other AALMEs. We also highlighted the predominance of elementary sampling unit (ESUs) with a single SSL and an unoccupied tiny layer close to the bottom, even if some ESUs presented up to six SSLs. Inter-annual changes in SSL organisation are highlighted by adaptation of original variables as the proportion of the water column occupied by SSLs and the relative importance of the shallowest SSL. SSL variables have been used mostly in deep water; here, we applied them on the continental shelf. SSL variables can be used to standardize the monitoring of marine ecosystems and capture change in spatial structure and function of mid-trophic pelagic marine ecosystems worldwide, even in data-poor areas where species identification of lower-trophic pelagic organism remains a challenge.

Valuation of coastal ecosystem services in the Large Marine Ecosystems of Africa

The African coastline is bordered by highly valuable marine ecosystems, but the environmental degradation due to anthropogenic pressure alter the benefits that they render to people. Our paper aims at assessing the value of ecosystem services provided by mangroves, seagrass beds, coral reefs, and kelp forests present in the Large Marine Ecosystems (LMEs) of Africa. After the mapping of coastal marine habitats, our valuation relies on the transfer of value of all ecosystem services from reference monetary unit values, extracted from the literature. A habitat functionality index based on the assumption that a higher population density and a higher demographic growth rate lead to a decrease in the functionality and services of marine habitats was then defined and incorporated into the valuation. The surveyed coastal habitats cover about 117,000 km2, with seagrass beds being by far the most extensive habitat. Present all along the coasts of Africa, their surface area represents about 62% of surveyed coastal habitats, followed by the mangroves (23%), coral reefs (15%). Kelp forests are only present in the southern Benguela Current LME. We estimated the annual value of the LME's coastal ecosystem services at 814 billion USD. Coral reefs have the highest value (588 billion USD/year), followed by seagrass beds (135 billion USD/year), mangroves (91 billion USD/year), and kelp forests (0.4 billion USD/year). The results show that ecosystem services from the four coastal habitat types had the highest value in the Agulhas Current LME, representing 38% of the total value, followed by the Red Sea LME (28%) and the Somali Coastal Current LME (10%). The three LMEs of the Atlantic side represent 15% of the total estimated value. Our paper highlighted many gaps that remain to be filled in terms of mapping and ecosystem services assessment in Africa. Nonetheless, our estimated values can facilitate dialogue between decision-makers and managers, and between countries sharing the same habitats and marine resources, toward better management of these ecosystems.

Comparative fishery yields of African Large Marine Ecosystems

Fisheries around Africa have historically suffered from the erroneous perception that there is little to no data on or knowledge about these activities, beyond the sometimes questionable or sparse official reported capture statistics. However, concerted efforts by scientists in and associated with Africa have changed this over the last decades. This includes the decade long efforts of the global Sea Around Us initiative to reconstruct comprehensive estimates of total fisheries catches in the waters of each African country, and create indicators using these data. Here, we build on these and other efforts, and review the main catch features, and landed values over the last 65 years generated by the fisheries in the seven Large Marine Ecosystems (LMEs) that surround the African continent, i.e., Canary Current, Guinea Current, Benguela Current, Agulhas Current, Somali Coastal Current, Red Sea, and Mediterranean Sea LMEs. Note that the small African coastal area (north coast of Somalia and Djibouti) covered by the Arabian Sea LME is excluded here due to its negligible contribution to the Arabian Sea LME. We illustrate which countries or geographic regions extract catches in each LME, with focus on African versus non-African fishing countries; examine the potential for fishing down the food web in each LME; as well as the time trends in the status of stocks. Finally, we present comprehensive economic data describing the fisheries around Africa. Jointly, these data and indicators suggest that the fisheries around Africa have reached their peak, and in many cases, moved beyond peak catches to a declining trend. Indeed, these fisheries mostly rely on overfished resources in all LMEs. Thus, better management, monitoring, compliance and policy efforts are needed around Africa, with a strong emphasis on regional cooperation, to help rebuild their stocks. Clearly, this is a challenging prospect, but seems to be the only rational way to maintain what is, for Africa, a crucial economic resource as well as food security base.

Sex differences in migration and demography of a wide-ranging seabird, the northern gannet

Marine vertebrates show a diversity of migration strategies, including sex differences. This may lead to differential demography, but the consequences of such between-sex variation are little understood. Here, we studied the migration of known-sex northern gannets Morus bassanus—a partial migrant with females ~8% heavier than males. We used geolocators to determine wintering areas of 49 breeding adults (19 females and 30 males) from 2 colonies in the northeast Atlantic (Bass Rock and Grassholm, UK). We also tested for sex-specific survival probabilities using capture-mark-recapture methods (n = 72 individuals Bass Rock, n = 229 individuals Grassholm; 2010-2018) and applied sex-specific population projection matrices (PPMs) to quantify population-level effects. Tracked gannets wintered in a range of large marine ecosystems (LMEs): Canary Current LME (CCLME; 69%), Celtic-Biscay Shelf LME (16%), Iberian Coastal LME (8%), North Sea LME (4%) or Mediterranean LME (2%). Migratory destination differed between the sexes: 90% of females vs. 57% of males wintered in the CCLME. Survival was similar between the sexes at Bass Rock (mean ± 95% CI = 0.951 ± 0.053 and 0.956 ± 0.047 for females and males, respectively). At Grassholm, there was evidence of slight sex differences in breeder survival: females had lower annual survival (0.882 ± 0.040) than males (0.946 ± 0.026). At Bass Rock, PPMs with no sex effect best fitted the observed population increase (1994-2014). Sex-specific PPMs fitted the population estimates for Grassholm (1995-2015). Our results reveal that female gannets are more likely to travel further than males to winter in the CCLME. This difference is unlikely due to morphological differences, unlike in other bird species. However, the reason for slightly higher over-winter female mortality at Grassholm is unclear.

Existing global marine protected area network is not representative or comprehensive measured against seafloor geomorphic features and benthic habitats

The Aichi targets of the Convention on Biological Diversity leverage the use of protected areas to halt the loss of global biodiversity. Target 11 recommends that ecologically representative portions (10%) of important coastal and marine areas be set aside within MPAs. Despite global progress in attaining the 10% target, few areas are set aside with consideration of ecological representation (area and diversity of features) as a conservation goal. Using publicly available datasets of marine geomorphic features and benthic habitats, we assessed the relative representativeness of features, by assessing feature coverage and diversity, within existing protected areas of both Large Marine Ecosystem (LMEs) and Exclusive Economic Zones (EEZs). Only 18 of the 66 LMEs contained greater than 10% of their marine geomorphic features and benthic habitats within MPAs. The Caribbean, Pacific Central, Mediterranean and Canary Current LMEs were identified as areas that protected the most diversity, while the geomorphically diverse Arctic Ocean had the least area of features within MPAs. Less than one quarter of EEZs (46 out of 230) had more than 10% of their geomorphic features and benthic habitats within MPAs. The coral triangle and other warm water reef areas are clear priorities for conservation, exhibiting high diversity of geomorphic features and benthic habitats, yet, most LMEs and EEZs in these areas fail to achieve representativeness or 10% feature coverage. Australia, New Zealand and the United States and areas in Europe and the South Pacific achieve relative representativeness scoring highly in coverage and diversity of features protected. Assessing the coverage and diversity of protected features within EEZs and LMEs can assist nation states and ecosystem management regions to better assess representativeness in achieving the 2020 Aichi targets.

Megaregions among the large marine ecosystems of the Americas

We organized environmental observations (Sea Surface Temperature, chlorophyll concentration, and primary productivity) and biological diversity indices based on reconstructed fisheries landings obtained from the Sea Around Us project to address two objectives: 1) to understand whether adjacent Large Marine Ecosystems (LMEs) of the Americas form megaregions for assemblages of commercially-valuable fish; and 2) to assess changes in the diversity of fisheries landings in LMEs of the Americas over time (1982 to 2010). To test for similarities between LMEs, we used the seascape approach of unsupervised clustering of annual mean environmental observations and fisheries-derived diversity indices. Beta-diversity estimates based on fisheries landings were used to evaluate the degree to which species spanned LMEs. Temporal trends were computed for each dataset by linear least-squares. Three megaregions emerged when considering similarities in species composition of fisheries landings, fisheries-derived diversity indices, and characteristic environmental conditions among LMEs. These include (A) the South Brazil Shelf, East Brazil Shelf, and North Brazil Shelf LMEs, (B) the Gulf of Mexico and Southeast U.S. Continental Shelf LMEs, and (C) the Northeast U.S. Continental Shelf, Scotian Shelf, and Newfoundland-Labrador Shelf LMEs. No megaregions emerged for the Pacific Ocean. While there were some shared species assemblages between the California Current and the Gulf of Alaska, the Gulf of California, and the Pacific Central-American Coastal LMEs, these showed different average environmental conditions and fishery-derived diversity indices, so they did not cluster as a megaregion. In the Pacific Ocean, the high dissimilarity in the fisheries is in part related to different top-down pressures and strong regional differences in oceanographic properties, including upwelling and impacts of El-Niño Southern Oscillation events. Overall, between 1982 and 2010, seven LMEs diversified their fisheries (Pacific Central-America Coastal, Patagonian Shelf, South Brazil Shelf, East Brazil Shelf, North Brazil Shelf, Southeast U.S. Continental Shelf, and Newfoundland-Labrador Shelf). This may be due to a number of reasons including decreasing fishing pressure but expansion of target stocks due to management quotas, changes in regional markets, competition, effort, or a decrease in particular target stocks. Three LMEs showed increasingly less diversified fisheries, namely the California Current, the Northeast U.S. Continental Shelf, and the Caribbean Sea LMEs. While in some cases this may be related to historical overfishing, such as in the Northeast U.S. Continental Shelf LME, the California Current LME has been subjected to strong and conservative management practices. The Caribbean Sea LME was likely subjected to heavy fishing at a time of rapid environmental change.

Collaboration between the Nansen Programme and the Large Marine Ecosystem Programmes

Norwegian development cooperation in fisheries has been taken place since the early 1950s and the Nansen Programme, now operating as the EAF-Nansen Project, has been one of its major representatives. The Nansen Programme has cooperated with developing nations, institutions and national and regional projects over the last forty years, representing an important mechanism for development assistance in the field of fisheries for the Norwegian Agency for Development Cooperation (Norad). The scope of the cooperation has changed over the years to respond to emerging needs and challenges in partner countries. Since the Large Marine Ecosystem (LME) concept appeared in the global marine science and governance agenda, the Nansen Programme was seen as an important partner for the regional projects in Africa that emerged from the concept. The Nansen Programme has collaborated with the Agulhas and Somali Currents LME (ACSLME) project, the Benguela Current LME (BCLME) project and its successor the Benguela Current Commission (BCC) as well as the Canary Current LME (CCLME) project and the Guinea Current LME (GCLME) project. In South Asia, the Nansen Programme has also collaborated with the Bay of Bengal LME (BoBLME) project. This paper chronicles the nature of the collaboration and the mutual benefits accruing to all the parties.

Fisheries catch under-reporting in The Gambia, Liberia and Namibia and the three large marine ecosystems which they represent

Fisheries catches from the Exclusive Economic Zones of three West African countries, each representing a Large Marine Ecosystem (LME), were reconstructed to cover all fishing sectors over a 6-decade period. While there are strong differences in terms of target species and the ecosystems within which they are embedded, there are similarities in the manner that domestic catches in The Gambia, Liberia and Namibia are under-reported. For The Gambia, catches by all domestic sectors were assessed to be twice the data supplied by The Gambia to the Food and Agriculture Organization of the United Nations (FAO). This is similar to the trend observed for Liberia, representing the Guinea Current LME, and where there is a larger margin for improvement, as the Liberian small-scale sector on its own is twice the entirety of the catches reported to the FAO. In Namibia, representing the Benguela Current LME, reconstructed catches were only 9% higher than the data reported by the FAO on behalf of Namibia, implying that the drastic measures implemented by Namibia to prevent illegal fishing are bearing fruits. Important lessons can be drawn from the present study for other countries in West Africa, notably for combating illegal foreign fishing, still rampant in the CCLME and the GCLME, and in managing small-scale fisheries, which require, as a starting point a detailed knowledge of their catch. These latter points are illustrated, finally, by catch time series for these three LMEs, reconstructed by taking account of the other 20 West African countries.

An overview of the large marine ecosystem programs at work in Africa today

This paper highlights the efforts of four African Large Marine Ecosystem (LME) (Agulhas and Somali, Benguela, Canary and Guinea Current LME) Programs, which are in various stages of implementation across the continent are making in adapting and integrating the LME approach into diagnostic and strategic documents required by the Global Environment Facility (GEF) and using these documents to restore and manage the LMEs. The African LMEs are some of the most productive in the world and are shared by 33 coastal states and 600 million people. The total economic value of environmental goods and services from these LMEs is estimated at US$139 billion per year; while the total production of capture fisheries in 2013 was 5698 million tonnes. Countries sharing each LME have adopted a phased approach and systematic process in applying the LME approach. Strategically important advancements are being made by the Programs in regional policy and institutional harmonization, science and capacity building through the implementation of science projects, the conduct of environmental monitoring and offshore research cruises; economic valuation of the goods and services in the respective LMEs and training scientists and technicians on the key transboundary concerns. The Benguela Current Commission, the world’s first LME-based institution was established by treaty and is functional. Institutional arrangements also exist for the GCLME and ASCLME. While limited in scope, the outputs serve to sensitize, engender confidence, strengthen capacity and empower stakeholders about the importance of the LMEs and the need to promote coordinated and integrated approach in their management.

Patterns of interannual climate variability in large marine ecosystems

The purpose of this study is to investigate the vulnerability of the Brazilian and western African Large Marine Ecosystems (LMEs) to local and remote forcing, including the Pacific Decadal Oscillation (PDO) regime shift. The analyses are based on the total and partial correlation between climate indices (Niño3, tropical South Atlantic (TSA), tropical North Atlantic (TNA) and Antarctic oscillation (AAO) and oceanic and atmospheric variables (sea surface temperature (SST), wind stress, Ekman transport, sea level pressure and outgoing longwave radiation). Differences in the correlation fields between the cold and warm PDO indicate that this mode exerts a significant impact on the thermodynamic balance of the ocean–atmosphere system on the South Atlantic ocean, mainly in the South Brazil and Benguela LMEs. The PDO regime shift also resulted in an increase in the spatial variability of SST and wind stress anomalies, mainly along the western African LMEs. Another important finding is the strong AAO influence on the SST anomalies (SSTA) in the South Brazil LME. It is also striking that TSA modulates the relation between El Niño–Southern Oscillation (ENSO) and SSTA, by reducing the influence of ENSO on SSTA during the warm PDO period in the North and East Brazil LMEs and in the Guinea Current LME. The relation between AAO and SSTA on the tropical area is also influenced by the TSA. The results shown here give a clear indication that future ecosystem-based management actions aimed at the conservation of marine resources under climate change need to consider the high complexity of basin-scale interactions between local and remote climate forcings, including their effects on the ocean-atmosphere system of the South Atlantic ocean.

Large-scale movements and high-use areas of western Pacific leatherback turtles,Dermochelys coriacea

The western Pacific leatherback turtle (Dermochelys coriacea), one of three genetically distinct stocks in the Indo-Pacific region, has declined markedly during past decades. This metapopulation nests year-round at beaches of several western Pacific island nations and has been documented through genetic analysis and telemetry studies to occur in multiple regions of the Pacific Ocean. To provide a large-scale perspective of their movements, high-use areas, and habitat associations, we report and synthesize results of 126 satellite telemetry deployments conducted on leatherbacks at western Pacific nesting beaches and at one eastern Pacific foraging ground during 2000–2007. A Bayesian switching state-space model was applied to raw Argos-acquired surface locations to estimate daily positions and behavioral mode (either transiting or area-restricted search) for each turtle. Monthly areas of high use were identified for post-nesting periods using kernel density estimation. There was a clear separation of migratory destinations for boreal summer vs. boreal winter nesters. Leatherbacks that nested during boreal summer moved into Large Marine Ecosystems (LMEs) of the temperate North Pacific Ocean or into tropical waters of the South China Sea. Turtles that nested during boreal winter moved into temperate and tropical LMEs of the southern hemisphere. Area-restricted search occurred in temperate and tropical waters at diverse pelagic and coastal regions exhibiting a wide range of oceanographic features, including mesoscale eddies, coastal retention areas, current boundaries, or stationary fronts, all of which are known mechanisms for aggregating leatherback prey. Use of the most distant and temperate foraging ground, the California Current LME, required a 10–12 month trans-Pacific migration and commonly involved multiple years of migrating between high-latitude summer foraging grounds and low-latitude eastern tropical Pacific wintering areas without returning to western Pacific nesting beaches. In contrast, tropical foraging destinations were reached within 5–7 months and appeared to support year-round foraging, potentially allowing a more rapid return to nesting beaches. Based on these observations, we hypothesize that demographic differences are likely among nesting females using different LMEs of the Indo-Pacific. The differences in movements and foraging strategies underscore the importance of and the need for ecosystem-based management and coordinated Pacific-wide conservation efforts.