Temporal and spatial evolution of bottom-water hypoxia in the St Lawrence estuarine system

Biogeosciences, Journal Year: 2023, Volume and Issue: 20(4), P. 839 - 849

Published: Feb. 24, 2023

Abstract. Persistent hypoxic bottom waters have developed in the Lower St Lawrence Estuary (LSLE) and impacted fish benthic species distributions. Minimum dissolved oxygen concentrations decreased from ∼ 125 µmol L−1 (38 % saturation) 1930s to 65 (21 1984. remained at levels (< 62.5 µM = 2 mg or 20 between 1984 2019, but 2020, they suddenly 35 L−1. Concurrently, bottom-water temperatures LSLE increased progressively 3 ∘C nearly 7 2021. The main driver of deoxygenation warming Gulf is a change circulation pattern western North Atlantic, more specifically decrease relative contribution younger, well-oxygenated cold Labrador Current Waters Laurentian Channel, deep valley that extends continental shelf edge, through Cabot Strait, gulf head LSLE. Hence, warmer, oxygen-depleted Atlantic Central carried by Stream now make up 100 entering Channel. areal extent zone has varied since 1993 when it was first estimated 1300 km2. In 2021, reached 9400 km2, extending well into Lawrence. Severely are also found end two channels branch out namely, Esquiman Channel Anticosti

Language: Английский

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Assessing indirect biodiversity conservation benefits of fisheries closures in the Gulf of St. Lawrence, Canada

PLoS ONE, Journal Year: 2025, Volume and Issue: 20(1), P. e0316754 - e0316754

Published: Jan. 9, 2025

Marine biodiversity loss is a pressing global issue, intensified by human activities and climate change. Complementary to marine protected areas (MPAs), Other Effective Area-Based Conservation Measures (OECMs) have emerged as key tool mitigate this providing long-term protection. However, while OECMs primarily target specific taxa, they can also offer indirect conservation benefits (BCBs) wider range of taxa. In study, we assess the BCBs eleven in Gulf St. Lawrence, focusing on their role supporting life-history processes commercially important species such Atlantic halibut, Greenland redfish. We apply an integrated assessment that combines knowledge data previously unconnected provide information support OECM management. Our analysis reveals eight overlap with potential spawning habitats for these species, suggesting benefits. projected climate-driven changes bottom temperature, oxygen concentration, pH levels pose threat habitats, potentially undermining effectiveness OECMs. These findings underscore need adaptive management strategies incorporate climate-informed ecosystem indicators broaden focus beyond economically species. Such approaches are crucial ensuring continue both direct face accelerating change, thereby contributing efforts.

Language: Английский

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DNA Metabarcoding Improves the Taxonomic Resolution of Visually Determined Diet Composition of Beaked Redfish (Sebastes sp.)

Environmental DNA, Journal Year: 2025, Volume and Issue: 7(1)

Published: Jan. 1, 2025

ABSTRACT Beaked redfishes ( Sebastes fasciatus and mentella ) of the northwest Atlantic have recently reached record abundance levels in estuary northern Gulf St. Lawrence, dominated by . Knowledge their diet composition is essential to understand trophic role that these groundfish play ecosystem. The objective present study was compare performance visual examination DNA metabarcoding stomach contents same individual redfish caught Lawrence. Using a universal metazoan mitochondrial cytochrome c oxidase subunit I (COI) marker, we identified total 24 taxonomic groups, composed 22 species two genera content 185 stomachs with metabarcoding. We compared results 25 prey types, eight at genus nine level, obtained analysis (SCA). While both techniques revealed similar composition, our showed SCA perform differently for particular categories, terms detectability resolution, as well estimated relative importance weight occurrence diet. use along validates improves resolution visually determined prey, which supports concept provide useful complementary information on likely other fish species.

Language: Английский

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Ecological interactions amplify cumulative effects in marine ecosystems

Science Advances, Journal Year: 2025, Volume and Issue: 11(4)

Published: Jan. 24, 2025

Biodiversity encompasses not only species diversity but also the complex interactions that drive ecological dynamics and ecosystem functioning. Still, these critical remain overwhelmingly overlooked in environmental management. In this study, we introduce an ecosystem-based approach assesses cumulative effects of climate change human activities on St. Lawrence marine ecosystem, eastern Canada, by explicitly accounting for arising from within a multiple stressors framework. Our findings reveal previously unrecognized threats to exploited endangered fishes mammals, exposing noteworthy gaps existing management recovery strategies. By integrating less obvious yet no substantial into assessments, our provides robust tool guide more comprehensive effective conservation efforts species.

Language: Английский

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Fish use of deep-sea sponge habitats evidenced by long-term high-resolution monitoring

Research Square (Research Square), Journal Year: 2025, Volume and Issue: unknown

Published: April 23, 2025

It is critical that fish's habitat uses of benthic habitats are understood, to inform effective fisheries management and predict the impacts human activities climate change. In this study, landers were used collect long-term high-temporal resolution data gain insights into use sponge grounds by fish at Sambro Bank Conservation Area. An integrated ecosystem-based monitoring approach was used, involving collected on biology, food supply, oceanography. Fish abundance, behaviour complex benthopelagic interactions analysed over spatial extended temporal scales (i.e., 30-minute intervals from 2021–2023). A total 21 different planktivorous benthivorous taxa found utilise seafloor. We show can act as a nursery, feeding shelter for commercially important fish. In-depth analyses Redfish, urophycid hakes, Silver Hake revealed distinct diel seasonal patterns showed how food, density current speed drivers their abundance behaviour. Supported fishery trawl survey reports, ecosystem importance environmental Such information crucial developing implementing robust, evidence-based policy management.

Language: Английский

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Feeding ecology of redfish (Sebastes sp.) inferred from the integrated use of fatty acid profiles as complementary dietary tracers to stomach content analysis

Journal of Fish Biology, Journal Year: 2023, Volume and Issue: 102(5), P. 1049 - 1066

Published: Feb. 16, 2023

In the northern Gulf of St. Lawrence (nGSL), redfish (Sebastes mentella and Sebastes fasciatus combined) are at record levels abundance following strong recruitment three consecutive cohorts in 2011-2013 have become by far most abundant demersal fish region. Understanding trophic relationships is essential for effective management conservation species nGSL ecosystem. To date, description quantification diet region been restricted to conventional stomach content analysis (SCA). Using fatty acid (FA) profiles as complementary dietary tracers, authors conducted multivariate analyses on 350 livers which were collected combination with contents during a bottom-trawl scientific survey August 2017. The predator FA compared those eight different prey types identified important SCA. Results suggested similitude between SCA results, zooplankton being more related small (<20 cm) medium (20-30 (16:1n7, 20:1n?, 22:1n9 20:5n3) than large (≥30 ones, whereas shrimp seemed size classes (18:2n6 22:6n3) relative ones. Although offers glimpse only based recently consumed prey, provides mid-term view indicating pelagic consumption calanoid copepod confirming high predation pressure shrimp. This study constitutes first attempt combining assess redfish, highlights benefits qualitative tool suggests improvements future studies.

Language: Английский

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Temporal changes in the diet composition and trophic level of walleye pollock (Gadus chalcogrammus) inhabiting the middle-eastern coast of Korea

Marine Environmental Research, Journal Year: 2024, Volume and Issue: 198, P. 106493 - 106493

Published: April 11, 2024

Language: Английский

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Occurrence and behavioral rhythms of the endangered Acadian redfish (Sebastes fasciatus) in the Sambro Bank (Scotian Shelf)

Frontiers in Marine Science, Journal Year: 2023, Volume and Issue: 10

Published: April 21, 2023

The genus Sebastes is a morphologically and ecologically diverse of rockfish characterized by high longevity, late-maturity low natural mortality. On the northwest Atlantic continental shelf, Acadian redfish ( fasciatus ) most common species above 300 m depth. This has been widely exploited resulting in depletion or collapse its stocks. Management long-lived with intricate life-history characteristics challenging requires highly integrated biological oceanographic monitoring, which allow identification environmental drivers demographic behavioral trends. present study uses high-temporal resolution imaging data, acquired an autonomous lander deployed for 10-months at Sambro Bank Sponge Conservation Area (Scotian Shelf) to elucidate S. temporal dynamics trends response near-bed conditions. , mostly displayed passive locomotion static behaviors, other shelf-dwelling species. Structural complexity provided sponges positively influenced presence. Fish used avoid being dragged bottom currents. Hydrodynamics appear act as synchronizing factor conditioning swimming behavior. total counts exhibited seasonal shift rhythm’s phase likely reflecting changes lifestyle requirements. provides new insights on Nonintrusive monitoring approaches, such one this study, will be key monitor threatened populations. Especially, since it expected that experience distribution shifts higher latitudes due future climate stressors.

Language: Английский

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Insights into the circulating microbiome of Atlantic and Greenland halibut populations: the role of species-specific and environmental factors

Scientific Reports, Journal Year: 2023, Volume and Issue: 13(1)

Published: April 12, 2023

Abstract Establishing long-term microbiome-based monitoring programs is critical for managing and conserving wild fish populations in response to climate change. In most cases, these studies have been conducted on gut and, a lesser extent, skin (mucus) microbiomes. Here, we exploited the concept of liquid biopsy study circulating bacterial microbiome two Northern halibut species economic ecological importance. Amplification sequencing 16S rRNA gene were achieved using single drop blood fixed FTA cards identify core Atlantic Greenland inhabiting Gulf St. Lawrence, Canada. We provide evidence that DNA (cmDNA) driven by genetic environmental factors. More specifically, found signatures are species-specific vary according sex, size, temperature, condition factor, geographical localization. Overall, our provides novel approach detecting dysbiosis risk disease fisheries management, notably context

Language: Английский

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Deep inflow transport and dispersion in the Gulf of St. Lawrence revealed by a tracer release experiment

Communications Earth & Environment, Journal Year: 2024, Volume and Issue: 5(1)

Published: June 20, 2024

Abstract The Gulf of St. Lawrence is increasingly affected by bottom water hypoxia; however, the timescales and pathways deep transport remain unclear. Here, we present results from Deep Tracer Release eXperiment (TReX Deep), during which an inert SF 5 CF 3 tracer was released inshore Cabot Strait at 279 m depth to investigate inflow mixing rates. Dispersion also assessed via neutrally-buoyant Swish floats. Our findings indicate that moves inland 0.5 cm s −1 , with effective lateral diffusivity 2 × 10 over 1 year. Simplified 1D simulations suggest should reach estuary head in 1.7 years, bulk arriving after 4.7 years. Basin-wide vertical around −5 year; increases near basin slopes, suggesting turbulent boundary processes influence mixing. These are compared Lagrangian a regional 3D model evaluate capacity dispersion Gulf.

Language: Английский

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