Abstract
Biodiversity in terms of species richness and the role of diversity in marine ecosystems have been much discussed recently. However, biodiversity below the species level (of primary importance in the interaction of climate and biota) is only scarcely documented for marine holoplanktonic species. The question arises how much and on which spatial scales genetic variation is present within an unexploited pelagic coastal marine zooplankton species and how important is it for survival in the event of environmental changes (global change, chemicals, habitat degradation) The genetic population structure in a neritic carnivorous hermaphroditic plankton species (Sagitta setosa J. Müller, 1847 (Chaetognatha) will be studied to determine the amount of gene flow within its northern range. Of this species meristic differences which could be either genetic or ecophenotipic are known. The results will be compared with the results of similar studies carried out in Theme 1 of the PRIORITEIT programme on exploited species (see projects 1 and 2) to determine whether jurisdictional fragmentation and differential management affects genetic structure and whether there is an mismatch of scales (project 4). Another aspect of our studies will be an evaluation of the health of the neritic ecosystem. If reduced heterozygosity is found in an unexploited species our study will provide baseline data to evaluate environmental stress. Also the infection parasite frequency and genetic diversity of different populations will be compared to investigate whether there is a negative correlation. This would mean that population with reduced genetic diversity are more susceptible to parasites.
Netherlands