5ο Πανελλήνιο Î£Ï Î½Î­Î´ÏÎ¹Î¿ Οικολογίας «Οικολογικές διεργασίες στο ...

Ελληνική Οικολογική Εταιρεία - Ελληνική Ζωολογική Εταιρεία - Ελληνική Βοτανική Εταιρεία5 ο Πανελλήνιο Συνέδριο Οικολογίας - «Οικολογικές διεργασίες στο χώρο και το χρόνο»Πάτρα 7 - 10 Οκτωβρίου 2010Marine zooplankton ecology in the high Arctic: challenging environment, challengingbiologyClaudia Halsband-LenkPlymouth Marine Laboratory, Plymouth, UK. E-mail: clau1@pml.ac.ukIn marine ecosystems minute zooplankton represent a crucial link between primary production,mostly represented by growth of photosynthetic unicellular microalgae, and secondaryconsumers, such as fish, sea birds and mammals. Knowledge about zooplankton ecology andbiogeography is therefore essential for an understanding of marine food webs, their functioningand resilience in the face of environmental pressures, such as global climate change andanthropogenic pressures.At high latitudes pelagic diversity is generally decreased, with a relatively small number ofhighly abundant species. This applies for example to krill, Euphausia superba, in the SouthernOcean. In the Arctic the copepod genus Calanus plays an equivalent role, but a number ofsmaller copepods are also of importance in the coastal areas and fjord systems due to theircontributions to abundance, biomass and secondary production. They also play an importantrole as omnivores in the microbial loop and may be favoured by regime shifts brought about byclimate change. One of them is the copepod Pseudocalanus, an important grazer ofphytoplankton and in turn a food source for higher trophic levels in arctic food webs. In contrastto its cousin Calanus, however, few studies address its ecological significance, not only due tosmaller size, but also because species identification is challenging. Hence, knowledge of thebiogeography of Pseudocalanus populations, their inter-specific interactions and differentialresponses to environmental change is paramount. Unfortunately, the genus lacks significantinter-specific divergence in morphological, meristic, and morphometrical traits, while mostPseudocalanus co-occur with one or more congener(s). A reliable method of speciesidentification is thus warranted.We studied two species, P. minutus and P. acuspes, known to inhabit the waters around theSvalbard archipelago, situated between the Barents Sea and the Arctic Ocean. Both species cooccurredin Rijpfjorden, Austfjorden, Billefjorden, Van Mijenfjorden, Hornsund and Storfjordenbased on morphological IDs. Bimodal size distributions of P. acuspes in many locations indicatepopulations of different origin, different degrees of isolation, or hybridization. Themorphological identification generally matched species-specific polymerase chain reaction(PCR), but a number of analyses failed and for some locations results were ambiguous. Thepresence of additional unidentified Pseudocalanus species was therefore considered andadditional PCR analyses performed. Indeed, additional molecular information confirmed thepresence of a third - yet unexpected - species, raising new questions about population dynamicsand large-scale pan-arctic transport mechanisms of zooplankton.5