Literature Library

Currently indexing 8373 titles

Sea-ice response to climate change in the Bering Sea during the Mid-Pleistocene Transition

Worne S, Stroynowski Z, Kender S, Swann GEA. Sea-ice response to climate change in the Bering Sea during the Mid-Pleistocene Transition. Quaternary Science Reviews [Internet]. 2021 ;259:106918. Available from: https://www.sciencedirect.com/science/article/pii/S0277379121001256?dgcid=raven_sd_search_email
Freely available?: 
Yes
Summary available?: 
No
Type: Journal Article

Sea-ice is believed to be an important control on climatic changes through the Mid-Pleistocene Transition (MPT; 0.6–1.2 Ma). However, the low resolution/short timescale of existing reconstructions prevents a full evaluation of these dynamics. Here, diatom assemblages from the Bering Sea are used to investigate sea-ice evolution on millennial timescales. We find that sea-ice was primarily controlled by ice-sheet/sea level fluctuations that modulated warm water flow into the Bering Sea. Facilitated by an amplified Walker circulation, sea-ice expansion began at ∼1.05 Ma with a step-increase during the 900 kyr event. Maximal pack ice was simultaneous with glacial maxima, suggesting sea-ice was responding to, rather than modulating ice-sheet dynamics, as proposed by the sea-ice switch hypothesis. Significant pack ice, coupled with Bering Strait closure at 0.9 Ma, indicates that brine rejection played an integral role in the glacial expansion/deglacial collapse of intermediate waters during the MPT, regulating subarctic ocean-atmospheric exchanges of CO2.

Phytoplankton shifts in the Central Bohai Sea over the last 250 years reflect eutrophication and input from the Yellow River

Li L, Wang Y, Liu D. Phytoplankton shifts in the Central Bohai Sea over the last 250 years reflect eutrophication and input from the Yellow River. Ecological Indicators [Internet]. 2021 ;126:107676. Available from: https://www.sciencedirect.com/science/article/pii/S1470160X21003411?dgcid=raven_sd_search_email
Freely available?: 
Yes
Summary available?: 
No
Type: Journal Article

Phytoplankton shifts driven by the environmental changes can significantly impact the functioning of marine ecosystems. Analyzing time series data is an important way to understand how phytoplankton responds to environmental changes. Here, multiple indicators, including diatoms and dinoflagellate cysts, total organic matter, carbon and nitrogen isotopes, and biosilicate, were analyzed in the sediment core from the Central Bohai Sea. A 250-year palaeo-environment was reconstructed based on these indicators to examine the responses of phytoplankton assemblages to environmental events. Two significant shifting points were identified from the varying trend of diatoms and cysts. The first one occurred in the 1850s, when the Yellow River outlet relocated from the southern Yellow Sea to the Bohai Sea, as evidenced by finer grain size and lower sea salinity, causing a significant increase in total biomass and brackish species. The other shift happened in the 1970s, when significantly increased fertilizer usage and wastewater discharge led to more organic matter in the core and nitrogen enrichment in the water column up to the 2010s, causing a marked increase in total biomass, small-sized species, and harmful algal bloom species. Redundancy analysis between major community shifts and environmental factors indicated that the Yellow River input and nutrient enrichment had a more important role in regulating phytoplankton shifts than rising temperature after the 1970s.

Rapid deterministic wave prediction using a sparse array of buoys

Fisher A, Thomson J, Schwendeman M. Rapid deterministic wave prediction using a sparse array of buoys. Ocean Engineering [Internet]. 2021 ;228:108871. Available from: https://www.sciencedirect.com/science/article/pii/S0029801821003061?dgcid=raven_sd_search_email
Freely available?: 
Yes
Summary available?: 
No
Type: Journal Article

A long-standing problem in maritime operations and ocean development projects has been the prediction of instantaneous wave energy. Wave measurements collected using an array of freely drifting arrays of Surface Wave Instrument Float with Tracking (SWIFT) buoys are used to test methods for phase-resolved wave prediction in a wide range of observed sea states. Using a linear inverse model in directionally-rich, broadbanded wave fields can improve instantaneous heave predictions by an average of 63% relative to statistical forecasts based on wave spectra. Numerical simulations of a Gaussian sea, seeded with synthetic buoys, were used to supplement observations and characterize the spatiotemporal extent of reconstruction accuracy. Observations and numerical results agree well with theoretical deterministic prediction zones proposed in previous studies and suggest that the phase-resolved forecast horizon is between 1–3 average wave periods for a maximum measurement interval of 10 wave periods for ocean wave fields observed during the experiment. Prediction accuracy is dependent on the geometry and duration of the measurements and is discussed in the context of the nonlinearity and bandwidth of incident wave fields.

Payments for nutrient uptake in the blue bioeconomy – When to be careful and when to go for it

Hasselström L, Gröndahl F. Payments for nutrient uptake in the blue bioeconomy – When to be careful and when to go for i. Marine Pollution Bulletin [Internet]. 2021 ;167:112321. Available from: https://www.sciencedirect.com/science/article/pii/S0025326X21003556?dgcid=raven_sd_search_email
Freely available?: 
Yes
Summary available?: 
No
Type: Journal Article

Harvesting of marine biomass for various applications may generate ecosystem services that currently lack a market price. One of these is nutrient uptake, which could counteract eutrophication. Market-based instruments (MBIs) such as cap & trade, compensatory mitigation, and payment for ecosystem services could help internalize such positive externalities. However, activities of the blue bioeconomy are diverse. We show that identifiable market characteristics can provide guidance concerning when to use these instruments and not. We find that the activities most suitable for MBIs are those that have positive environmental impacts but that are not (yet) financially viable. For activities that are already profitable on the biomass market, ensuring ‘additionality’ may be a significant problem for MBIs, especially for cap & trade systems or compensatory mitigation. We provide an overview of how some current biomass options fit into this framework and give suggestions on which biomass types to target.

Key climate change stressors of marine ecosystems along the path of the East African coastal current

Jacobs ZL, Yool A, Jebri F, Srokosz M, van Gennip S, Kelly SJ, Roberts M, Sauer W, Queirós AM, Osuka KE, et al. Key climate change stressors of marine ecosystems along the path of the East African coastal current. Ocean & Coastal Management [Internet]. 2021 ;208:105627. Available from: https://www.sciencedirect.com/science/article/pii/S0964569121001125?dgcid=raven_sd_search_email
Freely available?: 
Yes
Summary available?: 
No
Type: Journal Article

For the countries bordering the tropical Western Indian Ocean (TWIO), living marine resources are vital for food security. However, this region has largely escaped the attention of studies investigating potential impacts of future climate change on the marine environment. Understanding how marine ecosystems in coastal East Africa may respond to various climatic stressors is vital for the development of conservation and other ocean management policies that can help to adapt to climate change impacts on natural and associated human systems. Here, we use a high-resolution (1/4°) ocean model, run under a high emission scenario (RCP 8.5) until the end of the 21st century, to identify key regionally important climate change stressors over the East African Coastal Current (EACC) that flows along the coasts of Kenya and Tanzania. We also discuss these stressors in the context of projections from lower resolution CMIP5 models. Our results indicate that the main drivers of dynamics and the associated ecosystem response in the TWIO are different between the two monsoon seasons. Our high resolution model projects weakening of the Northeast monsoon (December–February) winds and slight strengthening of the Southeast monsoon (May–September) winds throughout the course of the 21st century, consistent with CMIP5 models. The projected shallower mixed layers and weaker upwelling during the Northeast Monsoon considerably reduce the availability of surface nutrients and primary production. Meanwhile, primary production during the Southeast monsoon is projected to be relatively stable until the end of the century. In parallel, a widespread warming of up to 5 °C is projected year-round with extreme events such as marine heatwaves becoming more intense and prolonged, with the first year-long event projected to occur as early as the 2030s. This extreme warming will have significant consequences for both marine ecosystems and the coastal populations dependent on these marine resources. These region-specific stressors highlight the importance of dynamic ocean features such as the upwelling systems associated with key ocean currents. This indicates the need to develop and implement a regional system that monitors the anomalous behaviour of such regionally important features. Additionally, this study draws attention to the importance of investment in decadal prediction methods, including high resolution modelling, that can provide information at time and space scales that are more directly relevant to regional management and policy making.

The implementation gap in Canadian fishery policy: Fisheries rebuilding and sustainability at risk

Archibald DW, McIver R, Rangeley R. The implementation gap in Canadian fishery policy: Fisheries rebuilding and sustainability at risk. Marine Policy [Internet]. 2021 ;129:104490. Available from: https://www.sciencedirect.com/science/article/pii/S0308597X21001019?dgcid=raven_sd_search_email
Freely available?: 
Yes
Summary available?: 
No
Type: Journal Article

Fisheries and Oceans Canada (DFO) established the Sustainable Fisheries Framework (SFF) in 2009 to help meet Canada’s international commitments towards sustainable fisheries management. The SFF is a suite of policies and tools intended to ensure the precautionary approach (PA) is incorporated into fisheries management. Seven years later (2016) a federal government audit by the Canadian Commissioner of the Environment and Sustainable Development (CESD) found that although DFO had identified key components necessary for successful fisheries management in the SFF, it had failed to put these components in place for many stocks and did not always apply them even when they were in place. The DFO response to the CESD audit included a commitment to develop work plans with deliverables outlining priorities and timelines for implementing key aspects of the SFF: reference points, harvest control rules, management plans and rebuilding plans for critically depleted stocks. The present study evaluated progress towards meeting this commitment and found that only 38% of the expected products were completed, 14% are in progress, 40% have progress delayed and are not proceeding as anticipated, while the remaining 8% were suspended. This weak performance highlights a larger trend of inadequate and slow implementation of legislative and policy tools in the management of Canada’s fisheries and oceans. With declining health status of Canadian stocks and less than half of critical stocks with rebuilding plans, these failures are having a significant impact on the ability of good policy to promote the long-term health of Canada’s fisheries and fishing communities.

Key climate change stressors of marine ecosystems along the path of the East African coastal current

Jacobs ZL, Yool A, Jebri F, Srokosz M, van Gennip S, Kelly SJ, Roberts M, Sauer W, Queirós AM, Osuka KE, et al. Key climate change stressors of marine ecosystems along the path of the East African coastal current. Ocean & Coastal Management [Internet]. 2021 ;208:105627. Available from: https://www.sciencedirect.com/science/article/pii/S0964569121001125?dgcid=raven_sd_search_email
Freely available?: 
Yes
Summary available?: 
No
Type: Journal Article

For the countries bordering the tropical Western Indian Ocean (TWIO), living marine resources are vital for food security. However, this region has largely escaped the attention of studies investigating potential impacts of future climate change on the marine environment. Understanding how marine ecosystems in coastal East Africa may respond to various climatic stressors is vital for the development of conservation and other ocean management policies that can help to adapt to climate change impacts on natural and associated human systems. Here, we use a high-resolution (1/4°) ocean model, run under a high emission scenario (RCP 8.5) until the end of the 21st century, to identify key regionally important climate change stressors over the East African Coastal Current (EACC) that flows along the coasts of Kenya and Tanzania. We also discuss these stressors in the context of projections from lower resolution CMIP5 models. Our results indicate that the main drivers of dynamics and the associated ecosystem response in the TWIO are different between the two monsoon seasons. Our high resolution model projects weakening of the Northeast monsoon (December–February) winds and slight strengthening of the Southeast monsoon (May–September) winds throughout the course of the 21st century, consistent with CMIP5 models. The projected shallower mixed layers and weaker upwelling during the Northeast Monsoon considerably reduce the availability of surface nutrients and primary production. Meanwhile, primary production during the Southeast monsoon is projected to be relatively stable until the end of the century. In parallel, a widespread warming of up to 5 °C is projected year-round with extreme events such as marine heatwaves becoming more intense and prolonged, with the first year-long event projected to occur as early as the 2030s. This extreme warming will have significant consequences for both marine ecosystems and the coastal populations dependent on these marine resources. These region-specific stressors highlight the importance of dynamic ocean features such as the upwelling systems associated with key ocean currents. This indicates the need to develop and implement a regional system that monitors the anomalous behaviour of such regionally important features. Additionally, this study draws attention to the importance of investment in decadal prediction methods, including high resolution modelling, that can provide information at time and space scales that are more directly relevant to regional management and policy making.

Comparative sensitivity of the early life stages of a coral to heavy fuel oil and UV radiation

F. Nordborg M, Brinkman DL, Ricardo GF, Agusti S, Negri AP. Comparative sensitivity of the early life stages of a coral to heavy fuel oil and UV radiation. Science of The Total Environment [Internet]. 2021 ;781:146676. Available from: https://www.sciencedirect.com/science/article/pii/S0048969721017447?dgcid=raven_sd_search_email
Freely available?: 
Yes
Summary available?: 
No
Type: Journal Article

During an oil spill, shallow, tropical coral reefs are likely to be simultaneously exposed to high intensities of ultraviolet radiation (UVR), which can exacerbate the toxicity of petroleum oils. While successful recruitment of corals is critical for reef recovery following disturbances, the sensitivity of several early life stages of coral to petroleum hydrocarbons has not been investigated, particularly for UVR co-exposure. Here we present the first dataset on the relative sensitivity of three early life stages (gametes, embryos and planula larvae) in a model broadcast spawning coral species, Acropora millepora, to the dissolved fraction of a heavy fuel oil (HFO), both in the absence and presence of UVR. All early life stages were negatively impacted by HFO exposure but exhibited distinct sensitivities. Larval metamorphosis was the most sensitive endpoint assessed with a 10% effect concentration of 34 μg L−1 total aromatic hydrocarbons (TAH) in the absence of UVR. The impact on fertilisation success was highly dependent on sperm density, while the fragmentation of embryos masked embryo mortality. Larval metamorphosis was conclusively the most reliable endpoint for use in risk assessments of the endpoints investigated. Putative critical target lipid body burdens (CTLBBs) were calculated for each life stages, enabling a comparison of their sensitivities against species in the Target Lipid Model (TLM) database. A. millepora had a putative CTLBB of 4.4 μmol g−1 octanol for larval metamorphosis, indicating it is more sensitive than any species currently included in the TLM database. Coexposure to UVR reduced toxicity thresholds by 1.3-fold on average across the investigated life stages and endpoints. This increase in sensitivity in the presence of UVR highlights the need to incorporate UVR co-exposure (where ecologically relevant) when assessing oil toxicity thresholds, otherwise the risks posed by oil spills to shallow coral reefs are likely to be underestimated.

Potential environmental effects of deepwater floating offshore wind energy facilities

Farr H, Ruttenberg B, Walter RK, Wang Y-H, White C. Potential environmental effects of deepwater floating offshore wind energy facilities. Ocean & Coastal Management [Internet]. 2021 ;207:105611. Available from: https://www.sciencedirect.com/science/article/pii/S096456912100096X?dgcid=raven_sd_search_email
Freely available?: 
Yes
Summary available?: 
No
Type: Journal Article

Over the last few decades, the offshore wind energy industry has expanded its scope from turbines mounted on foundations driven into the seafloor and standing in less than 60 m of water, to floating turbines moored in 120 m of water, to prospecting the development of floating turbines moored in ~1,000 m of water. Since there are few prototype turbines and mooring systems of these deepwater, floating offshore wind energy facilities (OWFs) currently deployed, their effects on the marine environment are speculative. Using the available scientific literature concerning appropriate analogs, including fixed-bottom OWFs, land-based wind energy facilities, wave and tidal energy devices, and oil and gas platforms, we conducted a qualitative systematic review to estimate the potential environmental effects of deepwater, floating OWFs during operation, as well as potential mitigation measures to address some of the effects. We evaluated six categories of potential effects: changes to atmospheric and oceanic dynamics due to energy removal and modifications, electromagnetic field effects on marine species from power cables, habitat alterations to benthic and pelagic fish and invertebrate communities, underwater noise effects on marine species, structural impediments to wildlife, and changes to water quality. Our synthesis of 89 articles selected for the review suggests that many of these potential effects could be mitigated to pose a low risk to the marine environment if developers adopt appropriate mitigation strategies and best-practice protocols. This review takes the necessary first steps in summarizing the available information on the potential environmental effects of deepwater, floating OWFs and can serve as a reference document for marine scientists and engineers, the energy industry, permitting agencies and regulators of the energy industry, project developers, and concerned stakeholders such as coastal residents, conservationists, and fisheries.

Assessment of ecological stress caused by maritime vessels based on a comprehensive model using AIS data: Case study of the Bohai Sea, China

Liu B, Wu X, Liu X, Gong M. Assessment of ecological stress caused by maritime vessels based on a comprehensive model using AIS data: Case study of the Bohai Sea, China. Ecological Indicators [Internet]. 2021 ;126:107592. Available from: https://www.sciencedirect.com/science/article/pii/S1470160X21002570?dgcid=raven_sd_search_email
Freely available?: 
Yes
Summary available?: 
No
Type: Journal Article

Increased maritime vessel activity has adversely affected the conservation of marine environments. The mobility and diverse operations of vessels increase the difficulty of marine spatial planning and protected-area management. This study proposed a “source-pathway-carrier-impact-response” (SPCIR) model to describe marine ecological stress caused by vessels (VES) and constructed a comprehensive assessment index system. The method was applied to the Bohai Sea in China using automatic identification system (AIS) data and geographic information system (GIS) spatial analysis. The results showed an obvious increase in VES from 2014 to 2018, with noise pollution, light pollution, and hydrodynamic interaction being the most prominent. Cargo vessels and oil tankers were the main stressors. Vessel activity seriously affected agriculture and fishery functions as well as marine-reserved zones in the Bohai Sea. The proposed SPCIR model can effectively identify the level and spatiotemporal characteristics of various vessel-related impacts and efficiently determine management priorities. It can provide a theoretical basis for marine area management and be conveniently adopted by management departments in various regions.

Application of the Ocean Health Index to assess ecosystem health for the coastal areas of Shanghai, China

Wu Z, Chen R, Meadows ME, Liu X. Application of the Ocean Health Index to assess ecosystem health for the coastal areas of Shanghai, China. Ecological Indicators [Internet]. 2021 ;126:107650. Available from: https://www.sciencedirect.com/science/article/pii/S1470160X21003150?dgcid=raven_sd_search_email
Freely available?: 
Yes
Summary available?: 
No
Type: Journal Article

The ocean delivers many ecosystem services to human society in providing food, livelihoods, and recreation and is crucial for regulating the global climate. Coastal cities, which have become the backbone of national economies, are highly dependent on the ecosystem services supported by the ocean. As a global coastal megacity, Shanghai has benefited enormously from its relationship with the ocean but its burgeoning population and rampant economic development in recent decades have applied great pressures on the associated coastal ecosystems and have reduced the ocean's capacity to provide ecosystem services and, meanwhile, have led to the demand for greater investment in ocean ecosystem restoration. To support the goal of long-term sustainability and facilitate appropriate management decisions, it is essential to assess the current health status of the coastal ecosystems of Shanghai and evaluate potential future risks. Here we apply the Ocean Health Index (OHI) framework, with indicators and reference points adjusted based on the unique coastal environment in Shanghai. The results reveal that the city obtained an overall OHI of 59 (out of 100) for the period 2012 to 2016. Individual indicators for Clean Waters (22) and Fisheries (39) exhibit particularly low values, indicating that the coastal waters around Shanghai are heavily polluted and that marine fishing is unsustainable. The city’s highest OHI scores are in the sectors of Coastal Livelihoods and Economies (93), and Tourism and Recreation (93), indicating that Shanghai’s coastal ecosystems contribute significantly to people’s livelihoods and regional economies, while marine recreational areas and related leisure activities add considerably to the quality of life in the region. This study demonstrates the value of the OHI in assessing ocean health at the city scale and reveals its potential for application in other coastal localities. In so doing, the findings provide a valuable benchmark against which to measure progress towards the sustainable development of Shanghai's oceans.

Can vertical separation of species in trawls be utilized to reduce bycatch in shrimp fisheries?

Larsen RB, Herrmann B, Brčić J, Sistiaga M, Cerbule K, Nielsen KNolde, Jacques N, Lomeli MJM, Tokaç A, Cuende E. Can vertical separation of species in trawls be utilized to reduce bycatch in shrimp fisheries? Kimirei IAaron. PLOS ONE [Internet]. 2021 ;16(3):e0249172. Available from: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0249172
Freely available?: 
Yes
Summary available?: 
No
Type: Journal Article

Several shrimp trawl fisheries use a Nordmöre sorting grid to avoid bycatch of fish. However, small fish can pass through the grid. Therefore, the retention of juvenile fish often remains an issue during shrimp trawling. We investigated the vertical distribution of deepwater shrimp (Pandalus borealis) and dominant bycatch species at the point where the Nordmöre grid section is installed. This was achieved using a separator frame which split the net vertically into three compartments of equal entry size. Our results showed that shrimp predominately follow the lower part of the trawl belly, whereas species such as redfish (Sebastes spp.), cod (Gadus morhua), polar cod (Boreogadus saida) and American plaice (Hippoglossoides platessoides) preferred the mid-section in the aft of the trawl. Haddock (Melanogrammus aeglefinus) primarily entered through the upper section of the trawl belly. Using these results, we predict that a vertical separation device installed forward of a 19 mm Nordmöre grid combined with a 35 mm codend would result in a significant reduction in bycatch with only minor loss of shrimp.

Ungovernable systems: The strength of informal institutions in the sea cucumber fishery in Yucatan, Mexico

Pedroza-Gutiérrez C, López-Rocha JA. Ungovernable systems: The strength of informal institutions in the sea cucumber fishery in Yucatan, Mexico Xin B. PLOS ONE [Internet]. 2021 ;16(3):e0249132. Available from: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0249132
Freely available?: 
Yes
Summary available?: 
No
Type: Journal Article

Formal and informal institutions govern fisheries around the world. Yucatan’s sea cucumber fishery is not an exemption, the sudden and fast development of the fishery in 2010 has motivated the creation of informal and illegal forms of organization. The prices, buyers’ interest and the fishing effort substantially increased, being followed by illegal fishing-fishers and traders, creating informal fishing-trade channels and severe social and biological concerns. This article aims to give account of the emergence and dynamics of the informal institutions which currently dominate this fishery. It was sought to identify the extent to which rules and regulations are not being respected and how they are affecting fish resources and coastal communities. We considered the case of the port of Sisal, Yucatan, Mexico to illustrate our argument and here we applied a mixture of qualitative and quantitative methodologies including informal and in-depth interviews applied to 17 key informants, a questionnaire applied to 47 fishers and an estimation of the degree of compliance from three of the main management measures. Socio-biological negative impacts were identified in Yucatan’s coastal communities and its fisheries. Foreign buyers and local middlemen exert high pressure on fishers to exceed the quota and catch the highest possible volumes facilitating the fisheries decline. This and the growing economic interest motivated the development of strong informal institutions supporting illegal fishing and informal trade. Social problems emerged and women were particularly affected. The economic power of the fishery is likely to overcome any type of governance structure. The enforcement of entry rules was not effective, so the governance base was around informality and illegal actions. Local and foreign buyers are exerting pressure to increase the catch volume thus it is recommended that rules and regulations be directed at buyers and exporting companies rather than at fishers.

Understanding shifts in estuarine fish communities following disturbances using an ensemble modeling framework

Lewis DM, Thompson KA, MacDonald TC, Cook GS. Understanding shifts in estuarine fish communities following disturbances using an ensemble modeling framework. Ecological Indicators [Internet]. 2021 ;126:107623. Available from: https://www.sciencedirect.com/science/article/pii/S1470160X21002880?dgcid=raven_sd_search_email
Freely available?: 
Yes
Summary available?: 
No
Type: Journal Article

Ecological disturbances may result in mortality events that alter biotic communities and ecosystems. In many coastal zones disturbances are increasing, including algal blooms and fish kills. These two disturbances are often related, with blooms releasing toxins or depleting oxygen, ultimately killing fish. Depending on the intensity, duration, and geographic extent of an algal bloom, the fish community can take days to years to recover from disturbances. To explore the relationship among environmental disturbances, sport fish, and forage fish communities, this study examines a non-toxic brown algal bloom (Aureoumbra lagunensis) occurring from December 2015 through March 2016. Using an ensemble modelling framework combining generalized linear models (GLM), Bayesian modelling, and Bayesian structural equation modeling (SEM), this complementary framework helped elucidate complex relationships among environmental variables and the fish community following a disturbance. The algal bloom crashed over a three-day period in March 2016 and resulted in a fish kill when dissolved oxygen concentrations dropped below hypoxic levels (DO < 2 mg/L). The bloom and subsequent fish kill led to shifts in both forage and sport fish communities, and their relationships, when compared to non-disturbed years. Both sport fish and forage fish abundances decreased following the bloom, but the response of the forage fish community was more rapid. When looking at direct correlations between individual sport fish and forage fish community metrics during the bloom, a large amount of variation in sport fish abundance was explained by forage fish abundance (R2 = 0.34). Also, the variation in forage fish abundance was explained well by pH (R2 = 0.72). Forage fish community dynamics were more closely related to water quality metrics than sport fish communities during non-disturbed periods. However, during this algal bloom, sport fish community dynamics were more closely associated with water quality metrics than forage fish community dynamics. Furthermore, sport fish community dynamics were strongly related to bloom dynamics during the three months prior to the fish kill. In the three months following the kill, the forage and sport fish communities were less strongly linked than in non-disturbed years. These large shifts in community dynamics and relationships following a disturbance suggest both forage and sport fish communities, food webs, and trophic dynamics may be at increasing risk of crossing ecological thresholds as algal blooms become more common in coastal ecosystems.

Politics of vulnerability: Impacts of COVID-19 and Cyclone Harold on Indo-Fijians engaged in small-scale fisheries

Mangubhai S, Nand Y, Reddy C, Jagadish A. Politics of vulnerability: Impacts of COVID-19 and Cyclone Harold on Indo-Fijians engaged in small-scale fisheries. Environmental Science & Policy [Internet]. 2021 ;120:195 - 203. Available from: https://www.sciencedirect.com/science/article/pii/S1462901121000745?dgcid=raven_sd_search_email
Freely available?: 
Yes
Summary available?: 
No
Type: Journal Article

The global COVID-19 pandemic has exposed the shortcomings of our health, social, and economic systems. While responding to the health crisis, governments are scrambling to understand and address the knock-on economic effects from market disruptions, and respond to other major disturbances (e.g. natural disasters). We conducted 61 key informant interviews with Indo-Fijian small-scale fisheries (SSF) actors (i.e. fishers, boat owners (that may or may not fish), crew members, and traders) in May 2020, two months after Fiji got its first case of COVID-19 and a month after Cyclone Harold hit the country. We examined how these SSF groups whose access to resources depends on their ability to navigate existing social relations of power, have lived through, experienced, and responded to the two stresses. We found the main impact of COVID-19 on SSF actors was the reduction in sales of fish (73.8 % of respondents) likely a result of reduction in local consumption and/or the loss of tourism markets. Loss of purchasing power meant almost a fifth of Indo-Fijian SSF actors interviewed (comprising 44.4 % of crew members, 16.4 % fishers, 11.5 % boat owners, 8.3 % traders) were unable to obtain sufficient food to meet their families’ daily needs. Many of these SSF actors do not have access to social security or similar safety nets leaving them vulnerable to the current crisis as well as to other shocks and changes. Furthermore, social inequities and power relations surrounding access to fisheries resources and government aid contributed to their vulnerability to economic stresses from COVID-19 and a severe cyclone. An understanding of early impacts of COVID-19 on SSF through an intersectional lens can assist decision-makers to quickly mobilise assistance to help people who are most vulnerable, and avoid widening inequities among social groups.

Large inter-stock differences in catch size-at-age of mature Atlantic salmon observed by using genetic individual origin assignment from catch data

Koljonen M-L, Masuda M, Kallio-Nyberg I, Koskiniemi J, Saloniemi I. Large inter-stock differences in catch size-at-age of mature Atlantic salmon observed by using genetic individual origin assignment from catch data Palsson A. PLOS ONE [Internet]. 2021 ;16(4):e0247435. Available from: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0247435
Freely available?: 
Yes
Summary available?: 
No
Type: Journal Article

Genetic individual assignment of river stock of origin of mixed stock catch fish offers a tool to analyze size differences among river stocks. Data on the genetically identified river stock of origin of individual fish from commercial mixed stock catches were used to compare the catch size-at-age of mature Atlantic salmon catch fish (Salmo salar) from different rivers in the Baltic Sea. In this application of genetic mixed stock modeling, individual assignments of the river stock of origin were analyzed together with length- and weight-at-age data for individual catch fish. The use of four genetic stock identification based methods was compared for defining the length distributions of caught mature salmon in different river stocks. The catch data included information on maturing salmon in the northern Baltic Sea over the years 2000–2013. DNA microsatellite data on 17 loci and information on the smoltification age were used to assign spawners to their stock of origin. All of the compared methods for using probabilistic stock of origin data in our case yielded very similar estimates of the final mean length distributions of the stocks. The Bayesian mixture model yielded slightly more conservative estimates than the direct probability method, threshold method, or the modified probability method. The catch size between spawners of a same sex and age from river stocks differed significantly and the differences were large. The mean catch weight of 1-sea-winter old mature males in different rivers varied from 1.9 kg to 2.9 kg, from 5.1 kg to 7.5 kg for 2-sea-winter old males, from 5.0 kg to 7.2 kg for 2-sea-winter old females, and from 8.2 kg to 10.8 kg for 3-sea-winter-old females. The mean size of caught wild salmon spawners in each year-class was on average smaller than that of the hatchery-reared and sea ranched stocks.

Better educational signage could reduce disturbance of resting dolphins

Donnelly RE, Prots A, Donnelly CA. Better educational signage could reduce disturbance of resting dolphins Halliday WDavid. PLOS ONE [Internet]. 2021 ;16(4):e0248732. Available from: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0248732
Freely available?: 
Yes
Summary available?: 
No
Type: Journal Article

Spinner dolphins on Hawai‘i Island’s west coast (Stenella longirostris longirostris) rest by day in protected bays that are increasingly popular for recreation. Because more frequent interactions of people with these dolphins is likely to reduce rest for dolphins and to explain recent decline in dolphin abundance, the National Oceanic and Atmospheric Administration (NOAA) proposed stricter rules regarding interactions with spinner dolphins near the main Hawaiian Islands and plans to increase enforcement. Simultaneous investment in public education about both interaction rules and their biological rationale has been and is likely to be relatively low. To test the hypothesis that more educational signage will reduce human-generated disturbance of dolphins, a paper questionnaire was distributed to 351 land-based, mostly unguided visitors at three dolphin resting bays on Hawai‘i Island’s west coast. Responses indicated that visitors wanted to see dolphins, were ignorant of interaction rules, were likely to read signs explaining rules and their biological rationales, and were likely to follow known rules. Therefore, investment in effective educational signage at dolphin resting bays is recommended as one way to support conservation of spinner dolphins on Hawai‘i Island’s west coast and similar sites in the Hawaiian archipelago.

Meta-Analysis of Salmon Trophic Ecology Reveals Spatial and Interspecies Dynamics Across the North Pacific Ocean

Graham C, Pakhomov EA, Hunt BPV. Meta-Analysis of Salmon Trophic Ecology Reveals Spatial and Interspecies Dynamics Across the North Pacific Ocean. Frontiers in Marine Science [Internet]. 2021 ;8. Available from: https://www.frontiersin.org/articles/10.3389/fmars.2021.618884/full?utm_source=F-AAE&utm_medium=EMLF&utm_campaign=MRK_1585058_45_Marine_20210325_arts_A
Freely available?: 
Yes
Summary available?: 
No
Type: Journal Article

We examined spatial patterns in diet, trophic niche width and niche overlap for chum, pink and sockeye salmon across the North Pacific during 1959–1969. This is a baseline period before major hatchery enhancement occurred coinciding with a negative phase of the Pacific Decadal Oscillation. Large-scale (between regions) and fine-scale (within regions) spatial and interspecies differences were apparent. In the Western Subarctic, all species tended to consume zooplankton. In the Bering Sea, chum consumed zooplankton, while sockeye and pink alternated between zooplankton and micronekton. In the Gulf of Alaska/Eastern Subarctic, chum and sockeye specialized on gelatinous zooplankton and cephalopod prey, respectively, while pink consumed a mixture of zooplankton and micronekton. The highest diet overlap across the North Pacific was between pink and sockeye (46.6%), followed by chum and pink (31.8%), and chum and sockeye (30.9%). Greater diet specialization was evident in the Gulf of Alaska/Eastern Subarctic compared to the Western Pacific. Generally, species had higher niche width and overlap in areas of high prey availability, and this was particularly evident for chum salmon. In addition to the large-scale trophic patterns, our data revealed novel fine-scale spatial patterns, including latitudinal, onshore-offshore, and cross-gyre gradients. Our results showed that pink tended to be more generalist consumers, and their diets may be a better reflection of overall prey presence and abundance in the environment. Conversely, chum and sockeye tended to be more specialist consumers, and their diets may provide a better reflection of interspecies dynamics or prey availability. This study provides a baseline for comparison with current and future changes in salmon marine ecology and North Pacific ecosystems. Finally, we identify two important data gaps that need addressing, that of improved taxonomic resolution diet data for Pacific salmon and focused research on sub-mesoscale oceanographic features that may play an important role in salmon health and productivity.

Crab Diets Differ Between Adjacent Estuaries and Habitats Within a Sheltered Marine Embayment

Campbell TI, Tweedley JR, Johnston DJ, Loneragan NR. Crab Diets Differ Between Adjacent Estuaries and Habitats Within a Sheltered Marine Embayment. Frontiers in Marine Science [Internet]. 2021 ;8. Available from: https://www.frontiersin.org/articles/10.3389/fmars.2021.564695/full?utm_source=F-AAE&utm_medium=EMLF&utm_campaign=MRK_1585058_45_Marine_20210325_arts_A
Freely available?: 
Yes
Summary available?: 
No
Type: Journal Article

Portunid crabs contribute to significant commercial and recreational fisheries globally and are commonly fished in estuaries and/or marine embayments, which are amongst the most degraded of all aquatic ecosystems. Portunus armatus were collected seasonally between April and February from five locations across three systems in temperate south-western Australia. The dietary composition of crabs was quantified and compared between two estuaries (Peel-Harvey and Swan-Canning) and a sheltered marine embayment (Cockburn Sound) containing three distinct habitats: shallow seagrass, shallow sand and deep sand. Overall, crabs ingested large volumes of bivalves (both live organisms and dead shell), polychaetes, crustaceans (e.g., amphipods, small decapods), and smaller volumes of teleosts, echinoderms and plant material (seagrass, algae). Analysis of Similarities showed that dietary composition varied significantly among the five locations (two estuaries and three habitats within Cockburn Sound) and seasons, with greater location than seasonal differences in the two estuaries. Diets were most distinct in the Cockburn Sound seagrass due to greater volumes of decapods and teleosts and smaller volumes of bivalve shell consumed in this habitat. Crabs from both estuaries consumed greater quantities of bivalves than those from Cockburn Sound. Seasonal differences in both estuaries were greatest between summer and winter, with a more diverse range of prey and large quantities of bivalves ingested in summer, whereas small bivalves and bivalve shell in the Peel-Harvey and polychaetes and other crustaceans in the Swan-Canning, were consumed in greater quantities in winter. The summer diet in the Peel-Harvey Estuary in the current study was compared to that 20 years previous and with documented change in the benthic macroinvertebrate fauna. Currently, crabs consume smaller volumes of high-calorie prey, i.e., polychaetes, small bivalves and teleosts, and instead ingest greater proportions of calcareous material than previously. This marked shift in dietary composition parallels changes in benthic macroinvertebrates in the Peel-Harvey Estuary. Overall, prey availability appears to be the major factor influencing the spatial and temporal differences in P. armatus diets in these three coastal systems.

Disentangling the Influence of Three Major Threats on the Demography of an Albatross Community

Cleeland JB, Pardo D, Raymond B, Tuck GN, McMahon CR, Phillips RA, Alderman R, Lea M-A, Hindell MA. Disentangling the Influence of Three Major Threats on the Demography of an Albatross Community. Frontiers in Marine Science [Internet]. 2021 ;8. Available from: https://www.frontiersin.org/articles/10.3389/fmars.2021.578144/full?utm_source=F-AAE&utm_medium=EMLF&utm_campaign=MRK_1585058_45_Marine_20210325_arts_A
Freely available?: 
Yes
Summary available?: 
No
Type: Journal Article

Climate change, fisheries and invasive species represent three pervasive threats to seabirds, globally. Understanding the relative influence and compounding nature of marine and terrestrial threats on the demography of seabird communities is vital for evidence-based conservation. Using 20 years of capture-mark-recapture data from four sympatric species of albatross (black-browed Thalassarche melanophris, gray-headed T. chrysostoma, light-mantled Phoebetria palpebrata and wandering Diomedea exulans) at subantarctic Macquarie Island, we quantified the temporal variability in survival, breeding probability and success. In three species (excluding the wandering albatross because of their small population), we also assessed the influence of fisheries, oceanographic and terrestrial change on these rates. The Southern Annular Mode (SAM) explained 20.87–29.38% of the temporal variability in survival in all three species and 22.72–28.60% in breeding success for black-browed and gray-headed albatross, with positive SAM events related to higher success. The El Niño Southern Oscillation (ENSO) Index explained 21.14–44.04% of the variability in survival, with higher survival rates following La Niña events. For black-browed albatrosses, effort in south-west Atlantic longline fisheries had a negative relationship with survival and explained 22.75–32.21% of the variability. Whereas increased effort in New Zealand trawl fisheries were related to increases in survival, explaining 21.26–28.29 % of variability. The inclusion of terrestrial covariates, reflecting extreme rainfall events and rabbit-driven habitat degradation, explained greater variability in trends breeding probability than oceanographic or fisheries covariates for all three species. These results indicate managing drivers of demographic trends that are most easily controlled, such as fisheries and habitat degradation, will be a viable option for some species (e.g., black-browed albatross) but less effective for others (e.g., light-mantled albatross). Our results illustrate the need to integrate fisheries, oceanographic and terrestrial processes when assessing demographic variability and formulating the appropriate management response.

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