Gut content metabarcoding reveals potential importance of fisheries discards consumption in marine fauna

Fisheries discards have become a source of concern for the perennation of marine resources. To reduce discards, the European Union adopted a Landing Obligation under the reform of its Common Fisheries Policy. However, food web consequences of reducing discards remain uncertain since their degree and pathway of reintegration are understudied. We used multi-marker DNA metabarcoding of gut contents and an ecological network approach to quantify marine fauna reliance on discarded fish and functional importance of discard consumers in coastal fishing grounds. We show that potential discard consumption is widespread across fish and invertebrates, but particularly important for decapods which were also pinpointed as functionally important. Potential discard consumption may represent up to 66% of all interactions involving fish prey in the reconstructed network. We highlight that discard reliance may be more important than previously assessed in some fishing areas and support functionally important taxa. While reducing discarding remains a conservation priority, it is crucial to understand discards reintegration in marine food webs to anticipate changes in the context of an ecosystem approach to fisheries management.

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DNA metabarcoding provides insights into the diverse diet of a dominant suspension feeder, the giant plumose anemone Metridium farcimen

10.1101/2020.12.07.407288 ◽

2020 ◽

Author(s):

Christopher D. Wells ◽

Gustav Paulay ◽

Bryan N. Nguyen ◽

Matthieu Leray

Keyword(s):

Taxonomic Resolution ◽

Gut Contents ◽

Prey Selectivity ◽

Gut Content ◽

Marine Food Webs ◽

Dna Metabarcoding ◽

Terrestrial Input ◽

Marine Food ◽

Mating Flights ◽

Plankton Communities

ABSTRACTBenthic suspension feeders have significant impacts on plankton communities by depleting plankton or modifying composition of the plankton through prey selectivity. Quantifying diets of planktivorous animals can be difficult because plankton are frequently microscopic, may lack diagnostic characters, and are digested at variable rates. With DNA metabarcoding, the identification of gut contents has become faster and more accurate, and the technique allows for higher taxonomic resolution-n while also identifying rare and highly degraded items that would otherwise not be detected. We used DNA metabarcoding to examine the diet of the giant plumose anemone Metridium farcimen, a large, abundant, competitively-dominant anemone on subtidal rock surfaces and floating docks in the northeast Pacific Ocean. Gut contents of 12 individuals were compared to 80- and 330-μm filtered plankton samples collected one hour prior between 0.02 and 1.5 km from the anemones. The objectives of this study were to determine if M. farcimen has a selective diet and compare our findings with traditional gut content analyses. Metridium farcimen captured a wider range of prey than previously suspected and metabarcoding found many more taxa than traditional sampling techniques. Gut contents were less diverse than 80-μm filtered plankton samples, but more diverse than 330-μm filtered plankton samples. The diet of the anemones was 52% arthropods with a surprisingly high relative abundance of an ant (10%) that has mating flights in August when this study was conducted. The gut contents of M. farcimen likely include all prey that it can detect and that cannot escape. There were no overrepresented taxa in the gut contents compared to the plankton but there were underrepresented taxa. This study highlights the usefulness of the metabarcoding method in identifying prey within the gut of planktivorous animals and the significant terrestrial input into marine food webs.

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Sifting environmental DNA metabarcoding data sets for rapid reconstruction of marine food webs

Fish and Fisheries ◽

10.1111/faf.12553 ◽

2021 ◽

Author(s):

Simone D’Alessandro ◽

Stefano Mariani

Keyword(s):

Food Webs ◽

Environmental Dna ◽

Data Sets ◽

Marine Food Webs ◽

Dna Metabarcoding ◽

Marine Food

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Feeding by Calanus glacialis in a high arctic fjord: potential seasonal importance of alternative prey

ICES Journal of Marine Science ◽

10.1093/icesjms/fsx106 ◽

2017 ◽

Vol 74 (7) ◽

pp. 1937-1946 ◽

Cited By ~ 13

Author(s):

Alison C. Cleary ◽

Janne E. Søreide ◽

Daniela Freese ◽

Barbara Niehoff ◽

Tove M. Gabrielsen

Keyword(s):

Spring Bloom ◽

High Arctic ◽

Gut Contents ◽

Larval Abundance ◽

Early Life Stages ◽

Marine Food Webs ◽

Calanus Glacialis ◽

Arctic Fjord ◽

Marine Food ◽

Generation Sequencing

Abstract The copepod species Calanus glacialis is an important component of arctic marine food webs, where it is the numerically dominant zooplankton grazer and serves as a major prey item for fish, seabirds, and other predators. These copepods are typically considered to be phytoplanktivorous, although they are also known to feed on microzooplankton, and little is known about their diet in fall and winter. To investigate their feeding, C. glacialis gut contents were analyzed over an annual cycle in a seasonally ice covered arctic fjord using next generation sequencing of 18S rDNA. During the spring bloom, diatoms, particularly Thalassiosira spp., were important contributors to the dietary sequence reads. In addition to diatoms, Chytridiomycetes, fungal parasites of diatoms, also made up a large proportion of dietary sequence reads during this productive season. This provides one of the first indications of the potential importance of the mycoloop in marine environments. Just prior to the spring bloom, chaetognath sequences dominated the prey sequence reads from C. glacialis, suggesting potential predation on eggs or other early life stages of chaetognaths by C. glacialis. Other indications of omnivorous feeding outside of the spring bloom period included sequence reads from polychaetes in summer, at the time of peak polychaete larval abundance, and from Metridia spp. (Copepoda) in winter in prey sequences from C. glacialis. Incorporating such predation into our knowledge of Calanus spp. behaviour may help refine our understanding of Calanus spp. ecology, and potential responses of C. glacialis to ongoing climate change.

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A rapid assessment of trends in the multispecies small-scale fishery of Palamós (Catalonia, Spain)

ICES Journal of Marine Science ◽

10.1093/icesjms/fsv149 ◽

2015 ◽

Vol 72 (9) ◽

pp. 2638-2649 ◽

Cited By ~ 1

Author(s):

Caterina Dimitriadis ◽

Alvar Carranza ◽

Raúl Vilela ◽

Margarida Casadevall

Keyword(s):

Rapid Assessment ◽

Ecosystem Approach ◽

Fishing Effort ◽

The State ◽

Economic Consequences ◽

Small Scale ◽

Limited Information ◽

The European Union ◽

Fisheries Policy ◽

Aichi Biodiversity Targets

Abstract Monitoring small-scale fisheries (SSFs) is challenging due to the limited information available and their underlying socioeconomic characteristics. This constitutes a serious impediment to assess the compliance level of Aichi Biodiversity Targets (ABT). The European Union has committed itself to include an Ecosystem Approach to Fisheries Management (EAFM) in its Common Fisheries Policy. EAFM depends on suites of indicators that track the pressure exercised, the state of the ecosystem, and the socio-economic consequences of management objectives. Therefore, The Living Planet Index (LPI) is proposed here for describing the performance of SSF towards the ABT. We show that the LPI can be reformulated to track trends in Fishing Effort (LPIFE), trends in Fish Populations (LPIFP), and both the state and trends related to the contribution of fisheries to broader society (LPIDEB). The implementation of the LPI in SSF applies several principles of the EAFM, including decentralization, fishers participation, and consideration of local knowledge. In this paper, we used 10-year daily data from the Cofradía at Palamós port, Catalonia - Spain. This is a multi-species SSF landing ca. 130 species, from which 10.9% are of special interest, being listed by the IUCN or in agreements by regional conventions. We observe a decreasing trend in the LPIFP, the LPIFE, and in the LPIDEB, including 36 species or groups, accounting for 90% of total landings, suggesting an overall decrease in the sustainability of this SSF. We conclude that use of the LPIFP is especially well suited to standardize the reporting of information for multispecies fisheries using a wide array of fishing strategies, and results strongly suggest the feasibility of using the LPI methodology to standardize reporting of any given agreed fisheries indicator in order enhance management towards the ABTs.

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The challenges for Croatian fisheries within current regulatory environment

Pomorstvo ◽

10.31217/p.35.1.18 ◽

2021 ◽

Vol 35 (1) ◽

pp. 170-178

Author(s):

Lidija Runko Luttenberger ◽

Ivica Ančić ◽

Axel Luttenberger

Keyword(s):

Adriatic Sea ◽

Marine Ecosystem ◽

Integrated Approach ◽

Ecosystem Approach ◽

Legal Framework ◽

The European Union ◽

Current Application ◽

Fish Stocks ◽

Fisheries Policy ◽

Blue Growth

Biodiversity as a planetary boundary and sustainability are strongly related to fish stocks and fisheries that are regulated by a number of sources of law with the aim of achieving their sustainability. The paper analyses current application, impact and effectiveness of the Common Fisheries Policy that sets the rules for fishing fleets management in the European Union and for fish stocks conservation as well as the 2020 Report on its implementation by the European Court of Auditors. It also examines the present and potential implementation and effects of Blue Growth, Marine Strategy Framework Directive, United Nations legal framework and Sustainable Development Goals on fisheries and aquaculture activities in the Adriatic Sea, a semi-enclosed and biodiversity rich sea. Improvements in implementing marine ecosystem approach and marine spatial planning are proposed in policy and regulatory framework, focusing on characteristics of the Adriatic Sea. Resilient solutions require placing more focus on characteristics of regional seas and applying site-specific tailor-made solutions and less complex but efficient governance for the seas which entail integrated approach to exploitation and preservation of the resources and their health.

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