Larval dispersal and juvenile survival are crucial in determining variation in recruitment, stock size and adult distribution of commercially important fish. This study investigates the dispersal of early-life stages of common sole (Solea solea L.) in the southern North Sea, both empirically and through modeling. Age at different life-history events of juvenile flatfish sampled along the coasts of Belgium, the Netherlands and the United Kingdom in 2013, 2014 and 2016, was determined through the counting of daily growth rings in the otoliths. Juveniles captured between August and October were estimated to be on average 140 days old with an average pelagic larval duration of 34 days. The hatching period was estimated between early April and mid-May followed by arrival and settlement in the nurseries between May and mid-June. Growth rates were higher off the Belgian coast than in the other nursery areas, especially in 2013, possibly due to a post-settlement differentiation. Empirical pelagic larval duration and settlement distributions were compared with the LARVAE&CO larval dispersal model, which combines local hydrodynamics in the North Sea with sole larval behavior. Yearly predicted and observed settlement matched partially, but the model estimated a longer pelagic phase. The observations fitted even better with the modelled average (1995–2015) distribution curves. Aberrant results for the small juvenile sole sampled along the UK coast in March 2016, led to the hypothesis of a winter disruption in the deposition of daily growth rings, potentially related to starvation and lower food availability. The similarities between measured and modelled distribution curves cross-validated both types of estimations and accredited daily ageing of juveniles as a useful method to calibrate biophysical models and to understand early-life history of fish, both important tools in support of efficient fisheries management strategies.
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RBINS Staff Publications 2020
Between 2015 and 2022, over 200 wells were sampled in four catchment areas of Benin, using both Cvetkov plankton nets (funnel 200 μm mesh size, 150 μm below valve) and baited traps. As artificial wells serve as ecotones (interfaces between surface and groundwater ecosystems), the ostracod fauna is mostly represented by two families; Cyprididae (mainly epigeic) and Candonidae (hypogeic). Here, we describe a new subfamily of Candonidae from the wells in Benin, the Benincandoninae subfam. nov. Hotèkpo & Martens, represented by one genus, Benincandona gen. nov. Hotèkpo & Martens. we found 35 species belonging to this evolutionary radiation, of which we describe five new species: Benincandona martini gen. et spec. nov. Hotèkpo & Martens, B. ibikounlei gen. et spec. nov. Hotèkpo & Martens, B. sakitii gen. et spec. nov. Hotèkpo & Martens, B. cebios gen. et spec. nov. Hotèkpo & Martens and B. trapezoides gen. et spec. nov. Hotèkpo & Martens. The new subfamily and genus are characterised by a unique combination of characters, such as a seven-segmented antennula and a caudal ramus with a fully developed ramus, a single apical (anterior) claw and three short setae. Species within the genus can be distinguished by their carapace and hemipenis morphology, together with some limb characteristics. whereas extensive subterranean candonid radiations have previously been reported from Europe, North and Central America and Northwest Australia (Pilbara), this is the first time such a vast radiation of subterranean candonids is reported from (west) Africa.
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RBINS Staff Publications 2024
