Literature Library

Currently indexing 8126 titles

Variation in Seagrass Carbon Stocks Between Tropical Estuarine and Marine Mangrove-Fringed Creeks

Juma GA, Magana AM, Michael GN, Kairo JG. Variation in Seagrass Carbon Stocks Between Tropical Estuarine and Marine Mangrove-Fringed Creeks. Frontiers in Marine Science [Internet]. 2020 ;7. Available from: https://www.frontiersin.org/articles/10.3389/fmars.2020.00696/full?utm_source=F-AAE&utm_medium=EMLF&utm_campaign=MRK_1418755_45_Marine_20200903_arts_A
Freely available?: 
Yes
Summary available?: 
No
Type: Journal Article

Seagrass and associated blue carbon ecosystems are important carbon sinks, and hence understanding their spatial and temporal variability is vital in appreciating their potential roles in climate change mitigation and adaptation. The Indo-Pacific region has the highest seagrass biodiversity, yet little focus has been made to compare seagrass habitat extent and carbon dynamics with their temperate counterparts. The present study assessed habitat characteristics and seagrass species distribution, diversity, and carbon storage in Eastern (marine) and Western (estuarine) mangrove-fringed creeks of Gazi Bay, Kenya. Data on species composition, canopy cover, biomass, and sediment organic carbon were collected in 80 plots of 0.25 × 0.25 m laid along transects established perpendicular to the waterline. Five species formation, viz., Thalassia hemprichiiCymodocea rotundataCymodocea serrulataEnhalus acoroides, and Thalassidendron ciliatum, were encountered as either single or mixed stands. There was a significant difference in total seagrass biomass between creeks (p < 0.01), with the Eastern creek recording a mean of 10.2 ± 0.6 Mg C ha–1 while the Western creek recording 4.3 ± 0.3 Mg C ha–1. In addition, sediment carbon to 1-m depth varied significantly (p < 0.01) between species in the two creeks and ranged from 98 to 302 Mg C ha–1, with the Eastern and Western creeks recording means of 258 ± 90 and 107 ± 21 Mg C ha–1, respectively. The total carbon stock from 50 ha of seagrasses in the Eastern creek was 13,420 Mg C, whereas in the 70 ha of the Western creek it was 7,769 Mg C. The study shows that seagrass community attributes such as species composition and productivity can vary dramatically over a small spatial extent due to differences in biophysical conditions and caution estimations of site-specific carbon stocks using generalized global values.

Marine Heatwave Stress Test of Ecosystem-Based Fisheries Management in the Gulf of Alaska Pacific Cod Fishery

Barbeaux SJ, Holsman K, Zador S. Marine Heatwave Stress Test of Ecosystem-Based Fisheries Management in the Gulf of Alaska Pacific Cod Fishery. Frontiers in Marine Science [Internet]. 2020 ;7. Available from: https://www.frontiersin.org/articles/10.3389/fmars.2020.00703/full?utm_source=F-AAE&utm_medium=EMLF&utm_campaign=MRK_1418755_45_Marine_20200903_arts_A
Freely available?: 
Yes
Summary available?: 
No
Type: Journal Article

In 2014–2016 an unprecedented warming event in the North Pacific Ocean triggered changes in ecosystem of the Gulf of Alaska (GOA) impacting fisheries management. The marine heatwave was noteworthy in its geographical extent, depth range, and persistence, with evidence of shifts in species distribution and reduced productivity. In 2017 a groundfish survey indicated that GOA Pacific cod (Gadus macrocephalus) had experienced a 71% decline in abundance from the previous 2015 survey. The GOA Pacific cod fishery supports a $103 million fishery which is 29% of the groundfish harvest value in the GOA. In this paper, we demonstrate that an increase in metabolic demand during this extended marine heatwave as well as a reduced prey supply can explain the decline in GOA Pacific cod biomass. Although increased mortality likely led to the decline in the Pacific cod population, historically low recruitment concurrent with the heatwave portends a slow recovery for the stock and gives a preview of impacts facing this region due to climate change. We evaluate the intersection of climate change with ecosystem-based fisheries management in the context of GOA Pacific cod with a description of the sensitivities of the ecosystem, how the changes in the ecosystem affected the Pacific cod stock, and a description of how the management system in the North Pacific handled this shock. We also provide suggestions on how fisheries management systems could be improved to better contend with the impacts of climate change such as the effects of heatwaves like that experienced in 2014–2016.

 

Stakeholder perspectives on large-scale marine protected areas

Artis E, Gray NJ, Campbell LM, Gruby RL, Acton L, Zigler SBess, Mitchell L. Stakeholder perspectives on large-scale marine protected areas Hewitt J. PLOS ONE [Internet]. 2020 ;15(9):e0238574. Available from: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0238574
Freely available?: 
Yes
Summary available?: 
No
Type: Journal Article

Large-scale marine protected areas (LSMPAs), MPAs greater than 100,000km2, have proliferated in the past decade. However, the value of LSMPAs as conservation tools is debated, in both global scientific and policy venues as well as in particular sites. To add nuance and more diverse voices to this debate, this research examines the perspectives of stakeholders directly engaged with LSMPAs. We conducted a Q Method study with forty LSMPA stakeholders at five sites, including three established LSMPAs (the Marianas Trench Marine National Monument, United States; the Phoenix Islands Protected Area, Kiribati; the National Marine Sanctuary, Palau) and two sites where LSMPAs had been proposed at the time of research (Bermuda and Rapa Nui (Easter Island), Chile). The analysis reveals five distinct viewpoints of LSMPAs. These include three more optimistic views of LSMPAs we have named EnthusiastPurist, and Relativist. It also depicts two more cautious views of LSMPAs, which we have named Critic and Skeptic. The findings demonstrate the multi-dimensionality of stakeholder viewpoints on LSMPAs. These shared viewpoints have implications for the global LSMPA debate and LSMPA decision-makers, including highlighting the need to focus on LSMPA consultation processes. Better understanding of these viewpoints, including stakeholder beliefs, perspectives, values and concerns, may help to facilitate more nuanced dialogue amongst LSMPA stakeholders and, in turn, promote better governance of LSMPAs.

Artificial habitats host elevated densities of large reef-associated predators

Paxton AB, Newton EA, Adler AM, Van Hoeck RV, Iversen ES, J. Taylor C, Peterson CH, Silliman BR. Artificial habitats host elevated densities of large reef-associated predators Chapman MGeraldine. PLOS ONE [Internet]. 2020 ;15(9):e0237374. Available from: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0237374
Freely available?: 
Yes
Summary available?: 
No
Type: Journal Article

Large predators play important ecological roles, yet many are disproportionately imperiled. In marine systems, artificial reefs are often deployed to restore degraded reefs or supplement existing reefs, but it remains unknown whether these interventions benefit large predators. Comparative field surveys of thirty artificial and natural reefs across ~200 km of the North Carolina, USA coast revealed large reef-associated predators were more dense on artificial than natural reefs. This pattern was associated with higher densities of transient predators (e.g. jacks, mackerel, barracuda, sharks) on artificial reefs, but not of resident predators (e.g., grouper, snapper). Further analyses revealed that this pattern of higher transient predator densities on artificial reefs related to reef morphology, as artificial reefs composed of ships hosted higher transient predator densities than concrete reefs. The strength of the positive association between artificial reefs and transient predators increased with a fundamental habitat trait–vertical extent. Taller artificial reefs had higher densities of transient predators, even when accounting for habitat area. A global literature review of high trophic level fishes on artificial and natural habitats suggests that the overall pattern of more predators on artificial habitats is generalizable. Together, these findings provide evidence that artificial habitats, especially those like sunken ships that provide high vertical structure, may support large predators.

Shorebirds Affect Ecosystem Functioning on an Intertidal Mudflat

Booty JM, Underwood GJC, Parris A, Davies RG, Tolhurst TJ. Shorebirds Affect Ecosystem Functioning on an Intertidal Mudflat. Frontiers in Marine Science [Internet]. 2020 ;7. Available from: https://www.frontiersin.org/articles/10.3389/fmars.2020.00685/full?utm_source=F-AAE&utm_medium=EMLF&utm_campaign=MRK_1418755_45_Marine_20200903_arts_A
Freely available?: 
Yes
Summary available?: 
No
Type: Journal Article

Ecosystem functioning and services have provided a rationale for conservation over the past decades. Intertidal muddy sediments, and the microphytobenthic biofilms that inhabit them, perform crucial ecosystem functions including erosion protection, nutrient cycling and carbon sequestration. It has been suggested that predation on sediment macrofauna by shorebirds may impact biofilms, and shorebirds are known to consume biofilm, potentially causing significant top-down effects on mudflat ecosystem functioning. We carried out an exclusion experiment on the Colne Estuary, Essex, to examine whether shorebird presence significantly affects sediment erodibility measured with a Cohesive Strength Meter (CSM) and microphytobenthos biomass measured using PAM fluorescence (Fo) and chlorophyll a content. We also tested for treatment effects on sediment-water nutrient fluxes [nitrate, nitrite, ammonia, phosphate and dissolved organic carbon (DOC)] during periods of both dark and light incubation. Excluding shorebirds caused statistically significant changes in regulating and provisioning ecosystem functions, including mudflat erodibility and nutrient fluxes. The presence of shorebirds lowered the sediment critical erosion threshold τcr, reduced nitrate fluxes into the sediment under illumination, lowered nitrate efflux, and reduced phosphate uptake, compared to sediments where birds were excluded. There were no significant differences in macrofauna community composition within the sediment between treatments after 45 days of bird exclusion, suggesting a direct link between shorebird presence or absence and the significant differences in biofilm-related variables. This study introduces previously unknown effects of shorebird presence on ecosystem functions within this system and highlights an area of shorebird science that could aid joint conservation and human provisioning action.

Perceptions of Marine Environmental Issues by Saudi Citizens

Almahasheer H, Duarte CM. Perceptions of Marine Environmental Issues by Saudi Citizens. Frontiers in Marine Science [Internet]. 2020 ;7. Available from: https://www.frontiersin.org/articles/10.3389/fmars.2020.00600/full?utm_source=F-AAE&utm_medium=EMLF&utm_campaign=MRK_1418755_45_Marine_20200903_arts_A
Freely available?: 
Yes
Summary available?: 
No
Type: Journal Article

We depend on the sea, economically, social well-being, and for the quality of our lives, yet direct and indirect human activities have affected the marine environment, causing many problems such as overfishing and pollution at the local scale and ocean warming and acidification at the global one. Hence, addressing the cumulative effects of these activities is required to conserve the marine environment for our current and future generations. Social commitment and support for these actions depend, however, on awareness and requires, therefore, an understanding of citizens’ awareness and perceptions on these issues. We assessed the awareness and the perceptions of Saudi citizens on ocean issues through an online questionnaire about environmental issues globally and in the country. The survey was completed by 1,524 Saudi citizens 18 years old and above, with different geographic distributions, gender, and educational status. The participants identified climate change within the top three global problems, with variable level of information and trust on different sources of environmental information. Littering, sewage pollution, and chemical pollution were identified as the top three major marine issues in Saudi Arabia, with the respondents demanding an immediate action through imposing fines to polluters and more regulatory constraints to activities that act as sources of pollution as well as supporting research in science and technologies to address these environmental issues.

Switching Gillnets to Longlines: An Alternative to Mitigate the Bycatch of Franciscana Dolphins (Pontoporia blainvillei) in Argentina

Berninsone LG, Bordino P, Gnecco M, Foutel M, Mackay AI, Werner TB. Switching Gillnets to Longlines: An Alternative to Mitigate the Bycatch of Franciscana Dolphins (Pontoporia blainvillei) in Argentina. Frontiers in Marine Science [Internet]. 2020 ;7. Available from: https://www.frontiersin.org/articles/10.3389/fmars.2020.00699/full?utm_source=F-AAE&utm_medium=EMLF&utm_campaign=MRK_1418755_45_Marine_20200903_arts_A
Freely available?: 
Yes
Summary available?: 
No
Type: Journal Article

The franciscana dolphin (Pontoporia blainvillei) is considered the most threatened cetacean in the South Western Atlantic due to bycatch in gillnet fisheries of Argentina, Uruguay, and Brazil. As gillnet fisheries operate in the same areas inhabited by dolphins, methods and strategies to reduce bycatch require particular attention. This study investigated the potential of switching gillnets to bottom longlines to reduce franciscana bycatch rates while maintaining economic returns in a small-scale artisanal fishery in Argentina. Trials were conducted in Bahía Samborombón and Cabo San Antonio between October 2004 and January 2007, in cooperation with artisanal fishermen who simultaneously fished using bottom longlines and gillnets. Target and non-target catch composition, fishing yield, catch size distribution and quality of catch, as well as bycatch of dolphins, sea turtles, and interaction with sea lions were compared between the two fishing methods to assess the profitability of switching fishing gears. Hauls of both gear types deployed simultaneously in the same locations showed similar fish catch composition and catch size with both gears but reduced catch of juvenile fishes in longlines. Bycatch of franciscana in bottom longlines was limited to only one dolphin in three consecutive years of trials, and no direct interaction between turtles and hooks were recorded. The economic analysis showed financially acceptable perspectives under a 5-year scenario. Reducing gillnet effort by switching to bottom longlines appears a practical approach to creating a sustainable fishery that could result in significant mitigation of current bycatch of franciscana dolphins in Argentina. However, implementation requires acceptance and compliance by the artisanal gillnet fishery.

Mapping the Marine Environment Through a Cross-Cultural Collaboration

Davies HN, Gould J, Hovey RK, Radford B, Kendrick GA. Mapping the Marine Environment Through a Cross-Cultural Collaboration. Frontiers in Marine Science [Internet]. 2020 ;7. Available from: https://www.frontiersin.org/articles/10.3389/fmars.2020.00716/full?utm_source=F-AAE&utm_medium=EMLF&utm_campaign=MRK_1418755_45_Marine_20200903_arts_A
Freely available?: 
Yes
Summary available?: 
No
Type: Journal Article

There is a growing emphasis on formally recognizing the connection to the marine environment of Indigenous peoples and the traditional ecological knowledge (TEK) these strong connections cultivate. The potential for TEK to significantly enrich the scientific comprehension of the marine environment, whilst also celebrating the rich bio-cultural knowledge in its own right, is indisputable. Here, we present a scientifically robust and culturally appropriate participatory mapping methodology for the marine environment which can effectively achieve genuine cross-cultural ecological knowledge transfer between scientists and Indigenous Peoples. Through a case study working with the Anindilyakwa people of the Groote Eylandt Archipelago, we mapped the TEK of benthic habitats off Australia’s poorly surveyed northern coast. Representatives from 14 Anindilyakwa clan groups participated in the marine mapping (n = 53), resulting in 22 individual maps. Eleven broad-scale habitat classifications, predominately in the intertidal and nearshore marine environment, were described in both Anindilyakwa and English. The information gathered was then used to develop benthic habitat maps covering a combined area of ∼1800 km2 and was assessed for accuracy against in situ observations. We found that despite the difficulties in working across two different world views, through the application of this carefully refined methodology, scientists can effectively document the rich TEK of the marine environment in a manner suitable for conservation and management planning while also supporting the prioritization of Indigenous values within the decision-making process.

Growing Into Poverty: Reconstructing Peruvian Small-Scale Fishing Effort Between 1950 and 2018

De la Puente S, de la Lama RLópez, Benavente S, Sueiro JCarlos, Pauly D. Growing Into Poverty: Reconstructing Peruvian Small-Scale Fishing Effort Between 1950 and 2018. Frontiers in Marine Science [Internet]. 2020 ;7. Available from: https://www.frontiersin.org/articles/10.3389/fmars.2020.00681/full?utm_source=F-AAE&utm_medium=EMLF&utm_campaign=MRK_1418755_45_Marine_20200903_arts_A
Freely available?: 
Yes
Summary available?: 
No
Type: Journal Article

Small-scale fisheries are globally marginalized by management institutions; thus, they have to endure the consequences of ineffective regulations, environmental uncertainty, social traps and market inequity. Small-scale fisheries in Peru, one of the world’s leading fishing countries, are important contributors to national employment, food security and gross domestic product. Yet, relatively little is known about these fisheries and their evolution, except for the fact that the Peruvian small-scale fleet size is rapidly increasing. Here, we reconstructed small-scale fishing effort across time and developed several indicators using it to assess changes in the fleet’s fishing efficiency and economic performance. Segmented regression analysis was used to identify statistically significant breakpoints and changes in their trajectories between 1950 and 2018. Our results suggest that fishing effort has strongly increased, and at much faster rates than the catches, particularly since 2006. The combined effect of these trends results in significant declines in the fleet’s ratio indicators (i.e., catch per unit of effort, revenue per unit of effort, and fisher’s incomes relative to Peru’s minimum wage), suggesting that the growing fishing effort is unsustainable and uneconomic. The behavior of these indicators differs within the fleet, depending on the vessel’s main fishing method. Most small-scale fishers are currently living in relative poverty. Yet, fishers using the least selective fishing gears, or engaged in illegal fishing, had the most stable incomes over the past decade. These findings are discussed in detail by exploring the social, legal and economic drivers fostering fleet growth. Finally, a list of general recommendations aimed at improving fisheries sustainability and fisher’s wellbeing was produced, based on the local context, fisheries literature and common sense.

The Globalization of Cultural Eutrophication in the Coastal Ocean: Causes and Consequences

Malone TC, Newton A. The Globalization of Cultural Eutrophication in the Coastal Ocean: Causes and Consequences. Frontiers in Marine Science [Internet]. 2020 ;7. Available from: https://www.frontiersin.org/articles/10.3389/fmars.2020.00670/full?utm_source=F-AAE&utm_medium=EMLF&utm_campaign=MRK_1418755_45_Marine_20200903_arts_A
Freely available?: 
Yes
Summary available?: 
No
Type: Journal Article

Coastal eutrophication caused by anthropogenic nutrient inputs is one of the greatest threats to the health of coastal estuarine and marine ecosystems worldwide. Globally, ∼24% of the anthropogenic N released in coastal watersheds is estimated to reach coastal ecosystems. Seven contrasting coastal ecosystems subject to a range of riverine inputs of freshwater and nutrients are compared to better understand and manage this threat. The following are addressed: (i) impacts of anthropogenic nutrient inputs on ecosystem services; (ii) how ecosystem traits minimize or amplify these impacts; (iii) synergies among pressures (nutrient enrichment, over fishing, coastal development, and climate-driven pressures in particular); and (iv) management of nutrient inputs to coastal ecosystems. This comparative analysis shows that “trophic status,” when defined in terms of the level of primary production, is not useful for relating anthropogenic nutrient loading to impacts. Ranked in terms of the impact of cultural eutrophication, Chesapeake Bay ranks number one followed by the Baltic Sea, Northern Adriatic Sea, Northern Gulf of Mexico, Santa Barbara Channel, East China Sea, and the Great Barrier Reef. The impacts of increases in anthropogenic nutrient loading (e.g., development of “dead zones,” loss of biologically engineered habitats, and toxic phytoplankton events) are, and will continue to be, exacerbated by synergies with other pressures, including over fishing, coastal development and climate-driven increases in sea surface temperature, acidification and rainfall. With respect to management, reductions in point source inputs from sewage treatment plants are increasingly successful. However, controlling inputs from diffuse sources remains a challenging problem. The conclusion from this analysis is that the severity of coastal eutrophication will likely continue to increase in the absence of effectively enforced, ecosystem-based management of both point and diffuse sources of nitrogen and phosphorus. This requires sustained, integrated research and monitoring, as well as repeated assessments of nutrient loading and impacts. These must be informed and guided by ongoing collaborations among scientists, politicians, managers and the public.

Plastic Ingestion in Post-hatchling Sea Turtles: Assessing a Major Threat in Florida Near Shore Waters

Eastman CB, Farrell JA, Whitmore L, Ramia DRRollins, Thomas RS, Prine J, Eastman SF, Osborne TZ, Martindale MQ, Duffy DJ. Plastic Ingestion in Post-hatchling Sea Turtles: Assessing a Major Threat in Florida Near Shore Waters. Frontiers in Marine Science [Internet]. 2020 ;7. Available from: https://www.frontiersin.org/articles/10.3389/fmars.2020.00693/full?utm_source=F-AAE&utm_medium=EMLF&utm_campaign=MRK_1418755_45_Marine_20200903_arts_A
Freely available?: 
Yes
Summary available?: 
No
Type: Journal Article

Pollution from anthropogenic marine debris, particularly buoyant plastics, is ubiquitous across marine ecosystems. Due to the persistent nature of plastics in the environment, their buoyancy characteristics, degradation dynamics, and ability to mimic the behavior of natural prey, there exists significant opportunity for marine organisms to ingest these man-made materials. In this study we examined gastrointestinal (GI) tracts of 42 post-hatchling loggerhead (Caretta caretta) sea turtles stranded in Northeast Florida. Necropsies revealed abundant numbers of plastic fragments ranging from 0.36 to 12.39 mm in size (length), recovered from the GI tracts of 39 of the 42 animals (92.86%), with GI burdens ranging from 0 to 287 fragments with a mass of up to 0.33 g per turtle. Post-hatchlings weighed from 16.0 to 47.59 g yielding a plastic to body weight percentage of up to 1.23%. Several types of plastic fragments were isolated, but hard fragments and sheet plastic were the most common type, while the dominant frequency of fragment color was white. Fragment size and abundance mixed with natural gut contents suggests significant negative health consequences from ingestion in animals at this life stage. Gaining greater insight into the prevalence of plastic ingestion, the types of plastic and the physiological effects of plastic consumption by multiple life-stages of sea turtles will aid the prioritization of mitigation efforts for the growing marine debris problem. This report demonstrates that plastic ingestion is a critical issue for marine turtles from the earliest stages of life.

Large-Scale Variability of Physical and Biological Sea-Ice Properties in Polar Oceans

Castellani G, Schaafsma FL, Arndt S, Lange BA, Peeken I, Ehrlich J, David C, Ricker R, Krumpen T, Hendricks S, et al. Large-Scale Variability of Physical and Biological Sea-Ice Properties in Polar Oceans. Frontiers in Marine Science [Internet]. 2020 ;7. Available from: https://www.frontiersin.org/articles/10.3389/fmars.2020.00536/full?utm_source=F-AAE&utm_medium=EMLF&utm_campaign=MRK_1406443_45_Marine_20200818_arts_A
Freely available?: 
Yes
Summary available?: 
No
Type: Journal Article

In this study, we present unique data collected with a Surface and Under-Ice Trawl (SUIT) during five campaigns between 2012 and 2017, covering the spring to summer and autumn transition in the Arctic Ocean, and the seasons of winter and summer in the Southern Ocean. The SUIT was equipped with a sensor array from which we retrieved: sea-ice thickness, the light field at the underside of sea ice, chlorophyll a concentration in the ice (in-ice chl a), and the salinity, temperature, and chl a concentration of the under-ice water. With an average trawl distance of about 2 km, and a global transect length of more than 117 km in both polar regions, the present work represents the first multi-seasonal habitat characterization based on kilometer-scale profiles. The present data highlight regional and seasonal patterns in sea-ice properties in the Polar Ocean. Light transmittance through Arctic sea ice reached almost 100% in summer, when the ice was thinner and melt ponds spread over the ice surface. However, the daily integrated amount of light under sea ice was maximum in spring. Compared to the Arctic, Antarctic sea-ice was thinner, snow depth was thicker, and sea-ice properties were more uniform between seasons. Light transmittance was low in winter with maximum transmittance of 73%. Despite thicker snow depth, the overall under-ice light was considerably higher during Antarctic summer than during Arctic summer. Spatial autocorrelation analysis shows that Arctic sea ice was characterized by larger floes compared to the Antarctic. In both Polar regions, the patch size of the transmittance followed the spatial variability of sea-ice thickness. In-ice chl a in the Arctic Ocean remained below 0.39 mg chl a m−2, whereas it exceeded 7 mg chl a m−2 during Antarctic winter, when water chl a concentrations remained below 1.5 mg chl a m−2, thus highlighting its potential as an important carbon source for overwintering organisms. The data analyzed in this study can improve large-scale physical and ecosystem models, habitat mapping studies and time series analyzed in the context of climate change effects and marine management.

From plentiful to critically endangered: Demographic evidence of the artisanal fisheries impact on the smalltail shark (Carcharhinus porosus) from Northern Brazil

Santana FMarcante, Feitosa LManir, Lessa RPaula. From plentiful to critically endangered: Demographic evidence of the artisanal fisheries impact on the smalltail shark (Carcharhinus porosus) from Northern Brazil Lucifora L. PLOS ONE [Internet]. 2020 ;15(8):e0236146. Available from: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0236146
Freely available?: 
Yes
Summary available?: 
No
Type: Journal Article

The smalltail shark, Carcharhinus porosus, was the most abundant elasmobranch species in fisheries off Brazil’s northern coast (BNC) in the 1980s, but its population has been declining since the 1990s. For this reason, a demographic analysis is necessary to determine the extent of this decline and the fishing effect on the BNC’s population. Therefore, we performed a stochastic demographic analysis of the population in the BNC, and considered its global center of abundance. Smalltail shark specimens (n = 937) were collected with gillnets in Maranhão state, eastern BNC, in the 1980s with sizes ranging between 29.6 and 120.0 cm total length. Most of the individuals (90.6%) caught were juveniles (< 6 years-old), and the mortality and exploitation rates showed that the species was overexploited (92.3% above the fishing mortality corresponding to the population equilibrium threshold). The smalltail shark’s biological characteristics, such as slow growth and low fecundity, demonstrate that it is one of the least resilient species among similar sized coastal sharks in the region. All these factors yielded an annual decrease of 28% in the intrinsic population growth rate, resulting in a population decline of more than 90% in only 10 years, and much higher for the current period. This set of features comprising fishing recruitment occurring upon juveniles, overfishing, and intrinsically low resilience make the population unable to sustain fishing pressure and severely hamper biological recruitment, thus causing this drastic population decline. Furthermore, several local extinctions for this species in the northeastern and southeastern regions of Brazil highlight its concerning conservation scenario. Therefore, since similar fisheries characteristics occur throughout its distribution range, Cporosus fits the criteria E of the IUCN Red List for a critically endangered species and urgent conservation measures are needed to prevent its extinction in the near future.

Impact of climate change on the primary production and related biogeochemical cycles in the coastal and sea ice zone of the Southern Ocean

Kim S-U, Kim K-Y. Impact of climate change on the primary production and related biogeochemical cycles in the coastal and sea ice zone of the Southern Ocean. Science of The Total Environment [Internet]. 2021 ;751:141678. Available from: https://www.sciencedirect.com/science/article/pii/S0048969720352074?dgcid=raven_sd_search_email
Freely available?: 
Yes
Summary available?: 
No
Type: Journal Article

Climate change in the Southern Hemisphere has exerted impact on the primary production in the Southern Ocean (SO). Using a recently released reanalysis dataset on global biogeochemistry, a comprehensive analysis was conducted on the complex biogeochemical seasonal cycle and the impact of climate change with a focus in areas within the meridional excursion of the sea ice boundary—coastal and continental shelf zone (CCSZ) and seasonal sea ice zone (SIZ). The seasonal cycles of primary production and related nutrients are closely linked with the seasonal changes in sea ice and sea surface temperatures. As sea ice retreats and allows energy and gas exchange across the sea surface, phytoplankton growth is initiated, consuming accumulated nutrients within the shallow depth of ~40 m. The seasonal evolutions of physical, biological and chemical variables show both spatial and temporal consistency with each other. Climate change has altered the timing and amplitude of the seasonal cycle. While primary production has generally increased along with an intensified uptake of CO2, some areas show a reduction in production (e.g., Prydz Bay, eastern Indian Ocean). In the CCSZ, increased iron utilization and light availability allowed production to be increased. However, the mechanism by which these factors are altered varies from one location to another, including changes in sea ice cover, surface stratification, and downwelling/upwelling. In the SIZ, where iron is generally a limiting factor, iron supply is a key driver of changes in primary production regardless of other nutrients. There is a clear influence of climatic change on the biogeochemical cycle although the signal is still weak.

Combined impact of summer heat waves and coastal upwelling in the Baltic Sea

Suursaar Ü. Combined impact of summer heat waves and coastal upwelling in the Baltic Sea. Oceanologia [Internet]. In Press . Available from: https://www.sciencedirect.com/science/article/pii/S0078323420300622?dgcid=raven_sd_search_email
Freely available?: 
Yes
Summary available?: 
No
Type: Journal Article

Under warming climates, heat waves (HWs) have occurred in increasing intensity in Europe. Also, public interest towards HWs has considerably increased over the last decades. The paper discusses the manifestations of the summer 2014 HW and simultaneously occurring coastal upwelling (CU) events in the Gulf of Finland. Caused by an anticyclonic weather pattern and persisting easterly winds, CUs evolved along the southern coast of the Gulf in four episodes from June to August. Based on data from coastal weather stations, 115 days-long measurements with a Recording Doppler Current Profiler (RDCP) oceanographic complex and sea surface temperature (SST) satellite images, the partly opposing impacts of these events are analysed. Occurring on the background of a marine HW (up to 26°C), the CU-forced SST variations reached about 20 degrees. At the 10 m deep RDCP mooring location, a drop from 21.5 to 2.9°C occurred within 60 hours. Salinity varied between 3.6 and 6.2 and an alongshore coastal jet was observed; the statistically preferred westerly current frequently flowed against the wind. Locally, the cooling effect of the CUs occasionally mitigated the overheating effects by the HWs both in the sea and on the marine-land boundary. However, in the elongated channel-like Gulf of Finland, upwelling at one coast is usually paired with downwelling at the opposite coast, and simultaneously or subsequently occurring HWs and CUs effectively contribute to heat transfer from the atmosphere to the water mass. Rising extremes of HWs and rapid variations by CUs may put the ecosystems under increasing stress.

Does Lack of Knowledge Lead to Misperceptions? Disentangling the Factors Modulating Public Knowledge About and Perceptions Toward Sharks

Afonso AS, Roque P, Fidelis L, Veras L, Conde A, Maranhão P, Leandro S, Hazin FHV. Does Lack of Knowledge Lead to Misperceptions? Disentangling the Factors Modulating Public Knowledge About and Perceptions Toward Sharks. Frontiers in Marine Science [Internet]. 2020 ;7. Available from: https://www.frontiersin.org/articles/10.3389/fmars.2020.00663/full?utm_source=F-AAE&utm_medium=EMLF&utm_campaign=MRK_1406443_45_Marine_20200818_arts_A
Freely available?: 
Yes
Summary available?: 
No
Type: Journal Article

Identifying sources of variability in public perceptions and attitudes toward sharks can assist managers and conservationists with developing effective strategies to raise awareness and support for the conservation of threatened shark species. This study examined the effect of several demographic, economic and socioenvironmental factors on the quality of knowledge about and perceptions toward sharks in two contrasting scenarios from northeastern Brazil: a shark hazardous coastal region and a marine protected insular area. Ordered logistic regression models were built using Likert data collected with a self-administered questionnaire survey (N = 1094). A clear relationship between education, knowledge and perceptions was found, with low education level and knowledge of sharks resulting in more negative perceptions toward these species. Prejudice toward sharks stemmed as a potentially limiting factor because the positive effects of other variables such as affinity for nature and specific knowledge about sharks were superseded by the effects of negative prejudice. Other practical factors such as age, economic level, and gender, also influenced respondent’s knowledge and perceptions and could provide a guidance for optimizing socioenvironmental gains relative to public engagement efforts. Results also suggested that populations inhabiting regions with high shark bite incidence likely require distinct outreach methods because some factors underlying knowledge and perception dynamics exhibited structural differences in their effects when compared to the trends observed in a marine protected area. Altogether, public perceptions and attitudes toward sharks could be feasibly enhanced with educational development and nature experiencing strategies. Moreover, disseminating shark-specific knowledge across the society might catalyze support for the conservation of these species in a cost-effective way. This study provides a potentially useful socioenvironmental framework to deal with the human dimensions of shark management and to strengthen conservation policies aimed at promoting societal compliance with pro-environmental values, which is crucial to endow shark populations with effective protection from anthropogenic threats.

Disparities in Spawning Times Between in situ and ex situ Pillar Corals

Neely KL, Lewis CL, Macaulay KA. Disparities in Spawning Times Between in situ and ex situ Pillar Corals. Frontiers in Marine Science [Internet]. 2020 ;7. Available from: https://www.frontiersin.org/articles/10.3389/fmars.2020.00643/full?utm_source=F-AAE&utm_medium=EMLF&utm_campaign=MRK_1406443_45_Marine_20200818_arts_A
Freely available?: 
Yes
Summary available?: 
No
Type: Journal Article

Contrasts in spawning time between in situ and ex situ colonies of the pillar coral Dendrogyra cylindrus were assessed by comparing 8 years of in situ spawning observations with 3 years of observations on ex situ corals held in outdoor flow-through tanks. In situ colonies exhibited a 3-day spawning window, with peak spawning occurring three nights after the full moon and 90 (males) – 96 (females) min after sunset. The ex situ spawning window extended across 7 days, with a peak on nights 4–5 after the full moon; females continued to spawn through night 8. Ex situ spawning occurred ∼50 min later than in situ spawning, and the spawning window for ex situ females was significantly greater than for in situ colonies. Fragments held ex situ for as few as 10 days experienced delayed spawning times, but corals held for greater than one lunar year exhibited significantly later spawning than those held less than one lunar year. Early and late full moons resulted in earlier male spawn time and asynchronous gamete release between males and females. Comparing spawn times throughout the Caribbean identified distance from lighted shorelines as a strong correlate with spawn time in minutes after sunset; proximity to artificial light resulted in delayed spawn times. We propose that artificial lights are red-shifting the twilight spectrum and affecting corals’ perception of lighting cues that trigger spawning. Coral colonies held at outdoor ex situ facilities, which are subject to even higher levels of artificial light, exhibit even further asynchrony in spawning time as well as spawning night. The effects of widespread and increasing light pollution on spawning synchrony may represent a potential stressor that could inhibit natural reef recovery.

Beyond Reef Restoration: Next-Generation Techniques for Coral Gardening, Landscaping, and Outreach

Schmidt-Roach S, Duarte CM, Hauser CAE, Aranda M. Beyond Reef Restoration: Next-Generation Techniques for Coral Gardening, Landscaping, and Outreach. Frontiers in Marine Science [Internet]. 2020 ;7. Available from: https://www.frontiersin.org/articles/10.3389/fmars.2020.00672/full?utm_source=F-AAE&utm_medium=EMLF&utm_campaign=MRK_1406443_45_Marine_20200818_arts_A
Freely available?: 
Yes
Summary available?: 
No
Type: Journal Article

Anthropogenic disturbances have led to the degradation of coral reef systems globally, calling for proactive and progressive local strategies to manage individual ecosystems. Although restoration strategies such as assisted evolution have recently been proposed to enhance the performance of coral reef populations in response to current and future stressors, scalability of these concepts and implementation in habitat or ecosystem-wide management remains a major limitation for logistical and financial reasons. We propose to implement these restoration efforts into an ecotourism approach that embeds land-based coral gardening efforts as architectural landscape elements to enhance and beautify coastal development sites, providing additional value and rationale for ecotourism stakeholders to invest. Our approach extends and complements existing concepts integrating coral reef restoration in ecotourism projects by creating a participatory platform that can be experienced by the public, while effectively integrating numerous restoration techniques, and providing opportunities for long-term restoration and monitoring studies. In this context, we discuss options for pre-selection of corals and systematic, large-scale monitoring of coral genotype performance targeting higher resilience to future stressors. To reduce operating costs during out-planting, we suggest to create coral seeding hubs, clusters of closely transplanted conspecifics, to quickly and efficiently restore/enhance active reproduction. We discuss our land-based coral gardening approach in the context of positive impacts beyond reef restoration. By restoring and strengthening resilience of local populations, we believe this strategy will contribute to a net positive conservation impact, create a culture on restoration and enhance and secure blue economical investments that rely on healthy marine systems.

An Interview-Based Approach to Assess Angler Practices and Sea Turtle Captures on Mississippi Fishing Piers

Cook M, Dunch VS, Coleman AT. An Interview-Based Approach to Assess Angler Practices and Sea Turtle Captures on Mississippi Fishing Piers. Frontiers in Marine Science [Internet]. 2020 ;7. Available from: https://www.frontiersin.org/articles/10.3389/fmars.2020.00655/full?utm_source=F-AAE&utm_medium=EMLF&utm_campaign=MRK_1406443_45_Marine_20200818_arts_A
Freely available?: 
Yes
Summary available?: 
No
Type: Journal Article

During 2010–2015, the Mississippi Sea Turtle Stranding and Salvage Network (STSSN) documented 1,073 sea turtles, primarily juvenile Kemp’s ridleys (Lepidochelys kempii), incidentally caught by recreational anglers. Due to increases in interactions, an angler interview survey was conducted during 2013 at six Mississippi fishing piers. Anglers were interviewed about fishing practices and sea turtle interactions. Interviewers conducted outreach and distributed Rehabilitation Hotline business cards. Angler participation was 86%, and over 60% used J-hooks and were not targeting specific species, which was similar to data collected from incidental captures reported to the STSSN. Over 58% of anglers used dead shrimp followed by cut up fish for bait. This greatly differs from STSSN reported captured sea turtles where 60% were caught on cut up fish and only 6% on dead shrimp. Over 18% of participants captured at least one sea turtle in the last 12 months. Anglers stated that nearly half of the sea turtles were taken for rehabilitation, 41% were released by the angler and 10% broke the line and swam away. Only 60% of anglers reported the capture because many were unaware they should report it. During and after the survey period, there was an increase in reported incidental captures, possibly indicating outreach is an effective means of increasing awareness and reporting. Recently, NOAA Fisheries developed a survey that can be used nationally to conduct similar research. We recommend conducting angler surveys every few years unless there is a noticeable change in incidental capture trends or angler practices.

Quantifying the Impact of Climate Change on Marine Diazotrophy: Insights From Earth System Models

Wrightson L, Tagliabue A. Quantifying the Impact of Climate Change on Marine Diazotrophy: Insights From Earth System Models. Frontiers in Marine Science [Internet]. 2020 ;7. Available from: https://www.frontiersin.org/articles/10.3389/fmars.2020.00635/full?utm_source=F-AAE&utm_medium=EMLF&utm_campaign=MRK_1406443_45_Marine_20200818_arts_A
Freely available?: 
Yes
Summary available?: 
No
Type: Journal Article

Nitrogen fixation is a major source of new nitrogen to the ocean, supporting biological productivity in the large nitrogen-limited tropical oceans. In Earth System Models, the response of nitrogen fixation to climate change acts in concert with projected changes to physical nitrogen supply to regulate the response of primary productivity in nitrogen-limited regions. We examine the response of diazotrophy from nine Earth System Models and find large variability in the magnitude and spatial pattern of nitrogen fixation in both contemporary periods and future projections. Although Earth System Models tend to agree that nitrogen fixation will decrease over the next century, strong regional variations exist, especially in the tropical Pacific which may counteract the response of the Atlantic and Indian oceans. As the climate driven trend of nitrogen fixation emerges by mid-century in the RCP8.5 scenario, on regional scales it may modulate the broad climate trends in productivity that emerge later in the century. The generally poor skill and lack of agreement amongst Earth System Models indicates that the climate response of nitrogen fixation is a key uncertainty in projections of future ocean primary production in the tropical oceans. Overall, we find that the future evolution of nitrogen fixation plays an important role in shaping future trends in net primary production in the tropics, but the poor skill of models highlights significant uncertainty, especially considering the role of multiple concurrent drivers.

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