Biology subjects

Kraan, C.

Publications and source records attributed to Kraan, C..

3 recordsLinked to original sources

bioRxiv2025

Current and future relevance of marine spatial planning for the distribution of epibenthic invertebrate and fish species in a heavily used regional sea

The SNS has recently become a European hub for installations of offshore wind farms (OWF), while extensive areas have been designated as marine protected areas (MPAs). Together with the already noticeable effects of climate warming, the region transforms from an area dominated by free ranging fisheries and shipping into an industrial landscape dominated by stationary activities. To inform decision making processes around the spatial allocation of fisheries, conservation measures and licence areas for offshore renewables in the southern North Sea, we modelled the spatial distribution of 179 epibenthic invertebrate and fish species. We identify both current and future hotspots of epibenthic and demersal fish diversity and their overlap with OWFs and MPAs. Hotspots of epibenthic and fish diversity are mostly found along the English Coast, located within an extensive network of MPA and OWF sites, which may provide opportunities for conservation and fisheries alike. In the central SNS, the MPA network could be complemented by OWF, where co-use regulations with other human uses are excluded, to protect sensitive species as well as epibenthic and demersal fish communities. Scenarios for three different time periods (until 2040, 2070 & 2100) revealed that global warming might cause an increase in the probability of occurrence for more than half of the analysed demersal fish species (n = 63). The applications in our study demonstrate the relevance of comprehensive knowledge about current, near and far future distribution patterns of species and species communities to enhance the effectiveness of marine spatial planning including spatial conservation measures.

ecology↗

bioRxiv2023

From microbial communities to regional biogeography: Unraveling patterns, determinants and the influence of bottom trawling in benthic microbiota

Microbial composition and diversity in marine sediments are shaped by environmental, biological, and anthropogenic processes that operate on different scales. However, our understanding of benthic microbial biogeography remains limited. Here, we study how benthic microbiota vary at a regional scale in the North Sea with sediment characteristics, temperature, organic matter content, shear bed stress and bottom trawling intensity, a prevalent industrial fishing practice which heavily impacts benthic ecosystems. Using 16S rDNA amplicon sequencing, we characterized benthic microbiota from the top centimeter of 349 sediment samples and used uni-and multivariate statistical models, accounting for spatial autocorrelation, to disentangle the effects of the different predictors. Fitted models demonstrate how the geographic interplay of different environmental anthropogenic drivers shapes the structure and functioning of benthic microbial communities. Sediment properties were the primary determinants, with diversity increasing with sediment permeability but at the same time increasing with mud content, highlighting different underlying processes. Alpha diversity also increased nonlinearly with total organic matter content and temperature and showed a more complex relationship with bottom shear stress but decreased with bottom trawling intensity. These trawling associated diversity changes were accompanied by shifts in functional groups related to energy metabolism. Specifically, with increasing trawling intensity, we observed a transition toward more aerobic heterotrophic and less denitrifying metabolism. Our findings provide first insights of benthic microbial biogeographic patterns on a large spatial scale and illustrate how anthropogenic activity such as bottom trawling may influence the distribution and abundances of microbes and overall benthic metabolism at macroecological scales.

ecology↗

bioRxiv2020

A genetic history of the pre-contact Caribbean

Humans settled the Caribbean ~6,000 years ago, with intensified agriculture and ceramic use marking a shift from the Archaic Age to the Ceramic Age ~2,500 years ago. To shed new light on the history of Caribbean people, we report genome-wide data from 184 individuals predating European contact from The Bahamas, Cuba, Hispaniola, Puerto Rico, Curacao, and northwestern Venezuela. A largely homogeneous ceramic-using population most likely originating in northeastern South America and related to present-day Arawak-speaking groups moved throughout the Caribbean at least 1,800 years ago, spreading ancestry that is still detected in parts of the region today. These people eventually almost entirely replaced Archaic-related lineages in Hispaniola but not in northwestern Cuba, where unadmixed Archaic-related ancestry persisted into the last millennium. We document high mobility and inter-island connectivity throughout the Ceramic Age as reflected in relatives buried ~75 kilometers apart in Hispaniola and low genetic differentiation across many Caribbean islands, albeit with subtle population structure distinguishing the Bahamian islands we studied from the rest of the Caribbean and from each other, and long-term population continuity in southeastern coastal Hispaniola differentiating this region from the rest of the island. Ceramic-associated people avoided close kin unions despite limited mate pools reflecting low effective population sizes (2Ne=1000-2000) even at sites on the large Caribbean islands. While census population sizes can be an order of magnitude larger than effective population sizes, pan-Caribbean population size estimates of hundreds of thousands are likely too large. Transitions in pottery styles show no evidence of being driven by waves of migration of new people from mainland South America; instead, they more likely reflect the spread of ideas and people within an interconnected Caribbean world.

genetics↗