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Detection and characterisation of microplastics and microfibres in fishmeal and soybean meal
Get PDFAquaculture is an increasingly important source of nutrition for global food security, which is reliant on animal and plant-based feeds. Anthropogenic particles, including microplastics and semi-synthetic cellulosic fibres, are
prolific marine pollutants that are readily consumed by marine organisms, including small pelagic fish commonly
used in fishmeal. Conversely, there is no indication plants can accumulate anthropogenic microparticles. We
explore whether aquaculture feed presents a route of contamination for farmed fish. Commercially-sourced
aquaculture feedstocks, including fishmeals and soybean meal, were processed (KOH digestion and ZnCl2 density separation) and anthropogenic particles characterised using microscopy and spectroscopic methods. Both fishmeal and soybean meals contained anthropogenic particles, with concentrations ranging 1070–2000 particles kg− 1. The prevalence of anthropogenic particles in plant-based feeds indicates that the majority of contamination occurs post-harvest. Based on our findings, farmed Atlantic salmon may be exposed to a minimum of 1788–3013 anthropogenic particles from aquaculture feed across their commercial lifespan
Nitrogen driven niche differentiation in bacterioplankton communities of northeast coastal Bay of Bengal
Get PDFThe Bay of Bengal receives nitrogen inputs from multiple sources and the potential role of nitrogenmetabolizing
microbial communities in the surface water is not well understood. The nitrogen budget
estimate shows a deficit of 4.7±2.4 TgNyr-1, suggesting a significant role of dissolved organic
nitrogen remineralization in fuelling ecosystem processes. Unravelling the process of remineralization
leading to increasing concentrations of dissolved inorganic nitrogen (DIN) in coastal ecosystems such
as in mangroves require a better understanding of the composition of functional resident
bacterioplankton communities. Bacterioplankton communities were elucidated from eight stations
along different estuaries spanning west to east of northeast coastal Bay of Bengal to understand the
influence of DIN on shaping these communities. The eight stations were differentiated into ‘low’ and
‘high’ DIN stations based on DIN concentration, with five stations with High DIN concentration
(>45 μM) and three stations with Low DIN concentration (<40μM). The V3–V4 region of 16S rRNA
was amplified and sequenced to elucidate resident bacterioplankton community structure from
environmental DNA. Proteobacteria, Bacteroidetes, and Firmicutes were the dominant bacterioplankton
phyla across all stations. Nitrogen-fixing groups such as Nitrospirae, Lentisphaerae,
Chloroflexi, and Planctomycetes make up about1%of the bacterioplankton communities.
Abundances of Spirochaetes and Tenericutes showed a positive correlation with DIN. Pseudomonadales,
Alteromonadales, and Desulfovibrionales were found to distinctly vary in abundance between
Low and High DIN stations. Predicted metagenomic profiles from taxonomically derived community
structures indicated bacterial nitrate-nitrite reductase to be negatively correlated with prevalent DIN
concentration in High DIN stations but positively correlated in Low DIN stations. This trend was also
consistent for genes encoding for nitrate/nitrite response regulators and transporter proteins. This
indicates the need to delineate functional bacterioplankton community structures to better understand their role in influencing rates and fluxes of nitrogen within mangroves
Climate-smart spatial planning assessment in support of conservation and blue growth in Da Nang city’s marine environment.
Get PDFThis study assessed ocean climate modelling datasets to establish what sensitivities to
climate change could be identified for species of commercial and conservation value in the
waters of Da Nang City, Vietnam, and what actions could be taken to support their adaptation
to these pressures. Commissioned via the UK Research Councils Official Development
Assistance national Capability funded project ‘Addressing Challenges of Coastal
Communities through Ocean Research for Developing Economies’ (ACCORD), and co-developed with the Da Nang Da Nang Department of Natural Resources and Environment with
the support of PEMSEA, our main ambition was to highlight what spatial management
activities could be undertaken in the waters off the city to support climate change adaptation in
its resources. We identified substantial sensitivities of species of commercial and conservation
value across the whole bay and its offshore waters to climate change under increasing global
greenhouse emissions. For species that occupy the water column (as opposed t the seabed), this
sensitivity appeared to be concentrated in the southern part of the bay. Importantly, fishing
pressure exacerbated the pressure of climate change on pelagic target species, highlighting the
challenges of delivering food security and a growing blue economy imposed by a changing
climate. Additionally, lowered emissions, in line with the Paris Agreement, would deliver clear
benefits to all types of species assessed, supporting a more sustainable path for the exploration
of Da Nang’s marine resources and it’s blue economy. Recommendations are made about how
the Coastal Use Zoning Plan for Da Nang City could be adapted to support climate change
adaptation in these species and habitats, and well as the broader sustainability of these
ecosystems
Identifying conservation priorities for gorgonian forests in Italian coastal waters with multiple methods including citizen science and social media content analysis
Get PDFAim
Gorgonian forests are among the most complex of subtidal habitats in the Mediterranean Sea, supporting high biodiversity and providing diverse ecosystem services. Despite their iconic status, the geographical distribution and condition of gorgonian species is poorly known. Using multiple online data sources, our primary aims were to compile, map and analyse observations of gorgonian forests in Italian coastal waters to assess the biological complexity of gorgonian forests, evaluate impacts and vulnerable species, and identify areas of special interest inside and outside of marine protected areas (MPAs) to help prioritize conservation strategies and actions.
Location
Italy. Mediterranean Sea.
Methods
Using a multi-source data integration approach, we collected and integrated data from scientific publications, the World Wide Web including social media platforms, citizen science projects and SCUBA diver questionnaires into a unified spatial framework. This method provided up-to-date information on the geographical distribution, abundance, and health of major habitat-forming gorgonian species in Italian coastal waters.
Results
Higher abundance and complexity of gorgonian species occurred outside MPAs. Areas of Special Interest (n = 167) were identified (80 inside and 87 outside MPAs). Three locations supported all seven focal species: Capo Caccia MPA, Portofino MPA and Catania (unprotected). The purple gorgonian (Paramuricea clavata), the most abundant and geographically widespread species with highest forest complexity, was affected by multiple stressors including thermal stress, disease and fishing.
Main conclusions
The multi-source approach was a rapid and cost-effective tool to gather, analyse and map disparate data on gorgonian forests spanning 27 years of underwater observations both inside and outside of MPAs. The unique perspective given by this approach demonstrates the suboptimal protection of several habitat-forming gorgonian species. The approach has great potential for wider application and offers a more inclusive participatory model for crowdsourcing and repurposing under-utilized observations while also increasing ocean literacy
Characterising retrieval uncertainty of chlorophyll-a algorithms in oligotrophic and mesotrophic lakes and reservoirs
Get PDFCarbon capture and storage is a key mitigation strategy proposed for keeping the global temperature rise below
1.5 ◦C. Offshore storage can provide up to 13% of the global CO2 reduction required to achieve the Intergovernmental Panel on Climate Change goals. The public must be assured that potential leakages from storage reservoirs can be detected and that therefore the CO2 is safely contained. We conducted a controlled release of 675 kg CO2 within sediments at 120 m water depth, to simulate a leak and test novel detection, quantification and attribution approaches. We show that even at a very low release rate (6 kg day− 1
), CO2 can be detected within sediments and in the water column. Alongside detection we show the fluxes of both dissolved and gaseous CO2 can be quantified. The CO2 source was verified using natural and added tracers. The experiment demonstrates that existing technologies and techniques can detect, attribute and quantify any escape of CO2 from subseabed reservoirs as required for public assurance, regulatory oversight and emissions trading schemes
Supporting academic freedom as a human right: challenges and solutions in academic publishing
Get PDFThis article explores academic freedom as it relates to scholarly publishing. While most discussions of academic freedom as a human right focus on threats to individuals’ personal safety and careers, we open this out to include the ‘soft repression’ that it is possible to encounter during the publication process, and its potential impact on the scholarly record. An overview is given of some of the ethical issues encountered by editors and publishers working with authors experiencing academic, intellectual, or political repression – for example, the manifestation of these issues in authorship, metadata, transparency and reproducibility, research ethics, and competing interests. We go on to formulate suggestions on managing such conflicts while upholding academic freedoms and the integrity of the scholarly record
Carbon and Lipid Contents of the Copepod Calanus finmarchicus Entering Diapause in the Fram Strait and Their Contribution to the Boreal and Arctic Lipid Pump
No full textThe boreal copepod Calanus finmarchicus sequesters substantial amounts of carbon (C) in the deep layers of the North Atlantic Ocean through their contribution to the “lipid pump.” This pump is driven by these zooplankton descending from the surface layers to spend prolonged periods at depth during which time they metabolise substantial lipid reserves and a fraction suffer mortality. C. finmarchicus is principally a boreal species but is expatriated by currents flowing northwards into Arctic regions such as the Fram Strait, where it is now able to complete its life cycle. We considered how this expansion to its distributional range adds to the estimated magnitude of the lipid pump. Field sampling in the Fram Strait found C. finmarchicus abundance to be spatially variable with high values, equivalent to those reported for core distributional areas further south, found mainly in the eastern region. Lipid reserve levels were sufficient for many individuals to survive the overwintering period and reproduce the following spring. In accordance with abundance patterns, lipid pump magnitude was greater in the Eastern Fram Strait (2.04 g C m−2 year−1) compared to the Western Fram Strait (0.33 g C m−2 year−1). At least for the eastern region, these rates are similar to those reported for this species elsewhere (average of 4.35 g C m−2 year−1). When extrapolated to the wider spatial area of the Fram Strait, the lipid pump generated by this species in this ocean sector amounts to 0.3 Mt C year−1. Although constituting a modest proportion of the total C. finmarchicus lipid pump of 19.3 Mt C year−1, it indicates that the continued northwards expansion of this species will act to increase the size of its lipid pump, which may counteract that lost through the northwards retreat of its Arctic congeners, Calanus glacialis and Calanus hyperboreus
Circles in the sea: annual courtship “torus” behaviour of basking sharks Cetorhinus maximus identified in the eastern North Atlantic Ocean
Get PDFGroups of basking sharks engaged in circling behaviour are rarely observed, and their function remains enigmatic in the absence of detailed observations. Here, underwater and aerial video recordings of multiple circling groups of basking sharks during late summer (August and September 2016–2021) in the eastern North Atlantic Ocean showed groups numbering between 6 and 23 non-feeding individuals of both sexes. Sharks swam slowly in a rotating “torus” (diameter range: 17–39 m), with individuals layered vertically from the surface to a maximum depth of 16 m. Within a torus, sharks engaged in close-following, echelon, close-flank approach or parallel-swimming behaviours. Measured shark total body lengths were 5.4–9.5 m (mean LT: 7.3 m ± 0.9 s.d.; median: 7.2 m, n = 27), overlapping known lengths of sexually mature males and females. Males possessed large claspers with abrasions that were also observed on female pectoral fins. Female body colouration was paler than that of males, similar to colour changes observed during courtship and mating in other shark species. Individuals associated with most other members rapidly (within minutes), indicating toroidal behaviours facilitate multiple interactions. Sharks interacted through fin–fin and fin–body contacts, rolling to expose the ventral surfaces to following sharks, and breaching behaviour. Toruses formed in late summer when feeding aggregations in zooplankton-rich thermal fronts switched to non-feeding following and circling behaviours. Collectively, the observations explain a courtship function for toruses. This study highlights northeast Atlantic coastal waters as a critical habitat supporting courtship reproductive behaviour of endangered basking sharks, the first such habitat identified for this species globally
Regulation of the Respiration Quotient Across Ocean Basins
Get PDFA key uncertainty for predicting future ocean oxygen levels is the response and feedback of organic matter respiration demand. One poorly constrained component of the respiration demand is the oxygen-to-carbon remineralization ratio—the respiration quotient. Currently, multiple biological hypotheses can explain variation in the respiration quotient of organic matter produced in the surface ocean. To test these hypotheses, we directly quantified the particulate respiration quotient in 715 samples along a meridional section of the Atlantic Ocean and compared to previous Pacific Ocean observations. We demonstrate significant
regional shifts in the respiration quotient and a two-basin average of 1.16. Possible diel oscillations were also
observed in the respiration quotient. Basin and regional variation in the respiration quotient were positively
linked to temperature, N versus P stress, and plankton size structure. These observations suggest a complex
regulation of the respiration quotient with important implications for the regional coupling of carbon and
oxygen cycling