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Inferring connectivity range in submerged aquatic populations (<i>Ruppia</i> L.) along European coastal lagoons from genetic imprint and simulated dispersal trajectories
Get PDFCoastal salt- and brackish water lagoons are unique shallow habitats characterized by beds of submerged seagrasses and salt-tolerant Ruppia species. Established long-term and large-scale patterns of connectivity in lagoon systems can be strongly determined by patterns of nearshore and coastal currents next to local bird-mediated seed dispersal. Despite the importance of dispersal in landscape ecology, characterizing patterns of connectivity remains challenging in aquatic systems. Here, we aimed at inferring connectivity distances of Ruppia cirrhosa along European coastal lagoons using a population genetic imprint and modeled dispersal trajectories using an eddy-resolving numerical ocean model that includes tidal forcing. We investigated 1,303 individuals of 46 populations alongside subbasins of the Mediterranean (Balearic, Tyrrhenian, Ionian) and the Atlantic to Baltic Sea coastline over maximum distances of 563–2,684 km. Ten microsatellite loci under an autotetraploid condition revealed a mixed sexual and vegetative reproduction mode. A pairwise FST permutation test of populations revealed high levels of historical connectivity only for distance classes up to 104–280 km. Since full range analysis was not fully explanatory, we assessed connectivity in more detail at coastline and subbasin level using four approaches. Firstly, a regression over restricted geographical distances (300 km) was done though remained comparable to full range analysis. Secondly, piecewise linear regression analyses yielded much better explained variance but the obtained breakpoints were shifted toward greater geographical distances due to a flat slope of regression lines that most likely reflect genetic drift. Thirdly, classification and regression tree analyses revealed threshold values of 47–179 km. Finally, simulated ocean surface dispersal trajectories for propagules with floating periods of 1–4 weeks, were congruent with inferred distances, a spatial Bayesian admixed gene pool clustering and a barrier detection method. A kinship based spatial autocorrelation showed a contemporary within-lagoon connectivity up to 20 km. Our findings indicate that strong differentiation or admixtures shaped historical connectivity and that a pre- and post LGM genetic imprint of R. cirrhosa along the European coasts was maintained from their occurrence in primary habitats. Additionally, this study demonstrates the importance of unraveling thresholds of genetic breaks in combination with ocean dispersal modeling to infer patterns of connectivity
The Flanders Marine Institute (VLIZ) ICOS Ocean Stations. Marine Inorganic Carbon and GHGs observations in the southern part of the North Sea
Get PDFBottom trawl fishing footprints on the world’s continental shelves
Get PDFBottom trawlers land around 19 million tons of fish and invertebrates annually, almost one-quarter of wild marine landings. The extent of bottom trawling footprint (seabed area trawled at least once in a specified region and time period) is often contested but poorly described. We quantify footprints using high-resolution satellite vessel monitoring system (VMS) and logbook data on 24 continental shelves and slopes to 1,000-m depth over at least 2 years. Trawling footprint varied markedly among regions: from 50% in some European seas. Overall, 14% of the 7.8 million-km2 study area was trawled, and 86% was not trawled. Trawling activity was aggregated; the most intensively trawled areas accounting for 90% of activity comprised 77% of footprint on average. Regional swept area ratio (SAR; ratio of total swept area trawled annually to total area of region, a metric of trawling intensity) and footprint area were related, providing an approach to estimate regional trawling footprints when high-resolution spatial data are unavailable. If SAR was ≤0.1, as in 8 of 24 regions, there was >95% probability that >90% of seabed was not trawled. If SAR was 7.9, equal to the highest SAR recorded, there was >95% probability that >70% of seabed was trawled. Footprints were smaller and SAR was ≤0.25 in regions where fishing rates consistently met international sustainability benchmarks for fish stocks, implying collateral environmental benefits from sustainable fishing
Environmental impacts of offshore wind farms in the Belgian part of the North Sea: assessing and managing effect spheres of influence
Get PDFSoft sediments epibenthos and fish monitoring at the Belgian offshore wind farm area: situation 6 and 7 years after construction
Get PDFAddressing the timing and extension of phytoplankton bloom through the eastern Channel - southern North Sea continuum in spring: an automated approach
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Zeegevoel: Vissen in het Verleden: 500 jaar Vlaamse zeevisserij
Get PDFAls we vandaag denken aan de kust, dromen we weg bij het beeld van een strand, een frisse duik in de zee, een felgekleurd ijsje op de dijk. Toch is dit een vrij recente evolutie, want tot in de jaren ‘50 van de vorige eeuw bepaalde de zeevisserij het beeld van de Vlaamse kust. In de havens van Nieuwpoort, Oostende en Zeebrugge domineerden de silhouetten van vissersschepen het zeezicht. Leurende vissersvrouwen bevolkten de kades en een aanzienlijk deel van de kustbevolking was afhankelijk van de visserijsector voor hun levensonderhoud. De zee vormde toen (nog) geen bron van ontspanning, maar van voedsel, economische ontwikkeling en culturele identiteit