Hydrology and small pelagic fish drive the spatio–temporal dynamics of springtime zooplankton assemblages over the Bay of Biscay continental shelf

Grandremy, Nina; Romagnan, Jean‐Baptiste; Dupuy, Corinne; Doray, Mathieu; Huret, Martin; Petitgas, Pierre

doi:10.1016/j.pocean.2022.102949

Cited by 8 publications

(19 citation statements)

References 80 publications

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“…There is room, however, to improve the characterization of changes in resource availability and their impact in anchovy size, including changes in prey capture efficiency (Ljungström et al., 2020), or a potential reduction in food quality (Brosset et al., 2017; Menu et al., 2023). There is evidence of changes in the structure of zooplankton communities in the Bay of Biscay, including an increase in warming tolerant copepod species (Valdés et al., 2021; see also Grandremy, Romagnan, et al., 2023). Potential changes in the size structure of plankton are another possibility worth considering (e.g., Grandremy, Bourriau, et al., 2023; Vandromme et al., 2014), given the well‐known effect of prey sizes on the growth and dynamics of small pelagics (e.g., Rykaczewski, 2019; Rykaczewski & Checkley, 2008; Thoral et al., 2021).…”

Section: Discussionmentioning

confidence: 99%

“…(2013) found a positive trend in the relative weight of anchovy stomachs from 2003 to 2010. Further, conditions in the Bay of Biscay have become more favorable for anchovy, at least in terms of the abundance of prey (see e.g., Valdés et al., 2021, for a recent review of trends in zooplankton biomass), while extensive analyses based on imaging samples reveal a stable taxonomic composition and spatial structure of the mesozooplankton community (Grandremy, Romagnan, et al., 2023). In that context, we also considered the potential impact of changes in population abundance through density‐dependence.…”

Section: Methodsmentioning

confidence: 99%

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Shrinking body size of European anchovy in the Bay of Biscay

Taboada,

Chust,

Santos Mocoroa

et al. 2023

Global Change Biology

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Decreased body size is often cited as a major response to ocean warming. Available evidence, however, questions the actual emergence of shrinking trends and the prevalence of temperature‐driven changes in size over alternative drivers. In marine fish, changes in food availability or fluctuations in abundance, including those due to size‐selective fishing, provide compelling mechanisms to explain changes in body size. Here, based on three decades of scientific survey data (1990–2021), we report a decline in the average body size—length and weight—of anchovy, Engraulis encrasicolus L., in the Bay of Biscay. Shrinking was evident in all age classes, from juveniles to adults. Allometric adjustment indicated slightly more pronounced declines in weight than in total length, which is consistent with a change toward a slender body shape. Trends in adult weight were nonlinear, with rates accelerating to an average decline of up to 25% decade−1 during the last two decades. We found a strong association between higher anchovy abundance and reduced juvenile size. The effect of density dependence was less clear later in life, and temperature became the best predictor of declines in adult size. Theoretical analyses based on a strategic model further suggested that observed patterns are consistent with a simultaneous, opposing effect of rising temperatures on accelerating early growth and decreasing adult size as predicted by the temperature‐size rule. Macroecological assessment of ecogeographical—Bergmann's and James'—rules in anchovy size suggested that the observed decline largely exceeds intraspecific variation and might be the result of selection. Limitations inherent in the observational nature of the study recommend caution and a continued assessment and exploration of alternative drivers. Additional evidence of a climate‐driven regime shift in the region suggests, however, that shrinking anchovy sizes may signal a long‐lasting change in the structure and functioning of the Bay of Biscay ecosystem.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Shrinking body size of European anchovy in the Bay of Biscay

Taboada,

Chust,

Santos Mocoroa

et al. 2023

Global Change Biology

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“…The comparison of the ZooScan and the ZooCAM highlights their interoperability on the large mesozooplankton size range, reflecting the possibility to combine zooplankton datasets originating from both instruments to expand their spatial and / or temporal coverage (e.g., Grandremy et al 2023). Following this example, efforts should be made to inter-compare and inter-calibrate other imaging systems to evaluate their interoperability and therefore the possibility to assemble existing datasets in order to spatially and/or temporally extend zooplankton ecological studies.…”

Section: The Benefits Of Comparing Zooplankton Imaging Instrumentsmentioning

confidence: 99%

The ZooScan and the ZooCAM zooplankton imaging systems are intercomparable: A benchmark on the Bay of Biscay zooplankton

Grandremy,

Dupuy,

Petitgas

et al. 2023

Limnology & Ocean Methods

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Zooplankton analysis represents a bottleneck in marine ecology studies due to the difficulty to obtain zooplankton data. The last decades have seen the intense development of zooplankton imaging systems, to increase the zooplankton data spatio‐temporal resolution as well as enabling the combination of size, taxonomy, and functional traits in aquatic ecology studies. Here, we propose a benchmark between the ZooScan, a commercially available, laboratory‐based scanner, which analyses zooplankton preserved samples, and the ZooCAM, an in‐flow imaging system designed for on‐board live zooplankton imaging. Sixty‐one zooplankton samples collected over the Bay of Biscay in environments ranging from estuarine to offshore blue waters were imaged with both instruments. Zooplankton Normalized Biovolume‐Size Spectra slopes, mean sizes, abundances, and zooplankton community biogeographical patterns were computed for each instrument and compared at the taxonomic group, the sampling stations and the Bay of Biscay scales. Both instruments produced similar zooplankton variables by stations and by taxa and described similar zooplankton community compositions and biogeographical patterns, on the large mesozooplankton size range, i.e., [0.3–3.39] mm ESD. We conclude that the ZooCAM and the ZooScan data can be combined to generate long term or spatially resolved zooplankton time series. Our study shows that benchmarking imaging instruments or techniques (1) offers a robust assessment of interoperability between instruments, mitigating possible instrumental biases, and (2) may be of great interest in the case of instrumental obsolescence or breakdown, to choose the most conservative replacement solution in a long term time series framework.

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“…Moreover, besides actual observation, modelling zooplankton remains a challenging task due to the diversity of traits, such as life forms, life cycles, body sizes, and physiological processes, exhibited by zooplankton (Mitra and Davis, 2010;Mitra et al, 2014). However, over the past 2 decades, the development of imaging and associated machine-learning semi-automatic identification tools (Irisson et al, 2022) has greatly improved the capability of scientists to analyse long (Feuilloley et al, 2022), high-frequency (Romagnan et al, 2016) or spatially resolved (Grandremy et al, 2023a) zooplankton time series as well as trait-based data (Orenstein et al, 2022). Imaging and machine learning have particularly enabled the increased development of combined size and taxonomy zooplankton ecological studies (e.g.…”

Section: Introductionmentioning

confidence: 99%

“…Combined, these datasets make up a 16-year time series of sized and taxonomically resolved zooplankton, along with context metadata allowing the calculation of quantitative data, covering the whole Bay of Biscay continental shelf from the French coast to the continental slope and from the Basque Country to southern Brittany in spring. These datasets can be used for ecological studies (Grandremy et al, 2023a), machine-learning studies and modelling studies.…”

Section: Introductionmentioning

confidence: 99%

Metazoan zooplankton in the Bay of Biscay: a 16-year record of individual sizes and abundances obtained using the ZooScan and ZooCAM imaging systems

Grandremy,

Bourriau,

Daché

et al. 2024

Earth Syst. Sci. Data

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Abstract. This paper presents two metazoan zooplankton datasets obtained by imaging samples collected on the Bay of Biscay continental shelf in spring during the PELGAS (PELagique GAScogne) integrated surveys over the 2004–2019 period. The samples were collected at night with a 200 µm mesh-size WP2 net fitted with a Hydrobios (back-run stop) mechanical flowmeter and hauled vertically from the sea floor to the surface, with the maximum depth set at 100 m when the bathymetry was deeper than this. The first dataset originates from samples collected from 2004 to 2016 and imaged on land with the ZooScan and is composed of 1 153 507 imaged and measured objects. The second dataset originates from samples collected from 2016 to 2019 and imaged onboard the R/V Thalassa with the ZooCAM and is composed of 702 111 imaged and measured objects. The imaged objects are composed of zooplankton individuals, zooplankton pieces, non-living particles and imaging artefacts ranging from 300 µm to 3.39 mm in equivalent spherical diameter which were individually imaged, measured and identified. Each imaged object is geolocated and associated with a station, a survey, a year and other metadata. Each object is described by a set of morphological and grey-level-based features (8 bit encoding, 0 = black, 255 = white), including size, that were automatically extracted from each individual image. Each object was taxonomically identified using the web-based application Ecotaxa with built-in random-forest and CNN-based semi-automatic sorting tools, which was followed by expert validation or correction. The objects were sorted into 172 taxonomic and morphological groups. Each dataset features a table combining metadata and data at individual-object granularity from which one can easily derive quantitative population and community descriptors such as abundances, mean sizes, biovolumes, biomasses and size structure. Each object's individual image is provided along with the data. These two datasets can be used in combination for ecological studies, as the two instruments are interoperable, or they can be used as training sets for ZooScan and ZooCAM users. The data presented here are available at the SEANOE dataportal: https://doi.org/10.17882/94052 (ZooScan dataset, Grandremy et al., 2023c) and https://doi.org/10.17882/94040 (ZooCAM dataset, Grandremy et al., 2023d).

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Hydrology and small pelagic fish drive the spatio–temporal dynamics of springtime zooplankton assemblages over the Bay of Biscay continental shelf

Cited by 8 publications

References 80 publications

Shrinking body size of European anchovy in the Bay of Biscay

Shrinking body size of European anchovy in the Bay of Biscay

The ZooScan and the ZooCAM zooplankton imaging systems are intercomparable: A benchmark on the Bay of Biscay zooplankton

Metazoan zooplankton in the Bay of Biscay: a 16-year record of individual sizes and abundances obtained using the ZooScan and ZooCAM imaging systems

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