New study on nutritional composition of zooplankton

Here we investigate the nutritional value of resources for pelagic fishes of the upper San Francisco Estuary to understand whether recent fish declines are liked to shifts in zooplankton nutritional conditions due to the establishment of invasive species. Using stable isotopes, elemental stoichiometry and fatty acid analyses for all dominant invasive and native zooplankton taxa and seston, we characterized the plankton community structure in the estuary and demonstrated taxon-specific differences in their nutritional value. We found temporal increase in the community-level DHA, n3 to n6 fatty acid ratio, decrease in the community-level EPA and PUFA in the brackish water region, but no change in the bulk PUFA proportions in the freshwater region of the estuary. These changes were caused mainly by declines of native cladocerans that are rich in EPA and by an increase in the dominance of invasive taxa with high DHA concentrations, similar to that of native taxa. Although we showed temporal shifts in individual fatty acid classes, the proportion of the essential fatty acids remained relatively high, suggesting that nutritional prey availability for fish remained unchanged with the shift in species composition. The study in published in:

Kratina P, Winder M (2015) Biotic invasions can alter nutritional composition of zooplankton communities. OIKOS. DOI: 10.1111/oik.02240

Science Communcation Training for PhD students

We are excited to announce that we will be holding a course on Science Communication Training for PhD students this coming spring 23-27 March 2015.

A brief description of the course is below and you can find more information on the course website http://scicommstockholmuni.wordpress.com/

The goal of this course is to provide basic training in communicating science to non-scientific audiences. We will explore motivations and goals of science communication. You will develop a communication portfolio consisting of a message box, elevator pitch, public speed talk, and press release focused on your research. While developing your portfolio, you will learn techniques for successful communication including how to avoid jargon, developing analogies, using narrative techniques, and public speaking skills. In addition, we will engage with communication specialists, members of the media, and scientist communicators to explore the challenges and expectations from all participants in the science communication process. Students from all scientific disciplines are welcome to apply.

New paper on the effect of species invasion on plankton interaction networks

Kratina, P., R. Mac Nally, W. J. Kimmerer, J. R. Thomson, and M. Winder. 2014. Human-induced biotic invasions and changes in plankton interaction networks. Journal of Applied Ecology. Doi: 10.1111/1365-2664.12266.

This study reports on how zooplankton species invasion affected multitrophic interaction network in the upper San Francisco Estuary over the last four decades.

We used multivariate autoregressive models with detailed time-series data from largely freshwater and brackish regions of the upper San Francisco Estuary to assess the topology, direction and strength of trophic interactions following major invasions and establishment of non-native zooplankton in the early 1990s. We found changes in the networks of biotic interactions in both regions after the major zooplankton invasions. Our results imply an increased pressure on native herbivores; intensi-fied negative interactions between herbivores and omnivores; and stronger bottom-up influence of juvenile copepods but weaker influence of phytoplankton as a resource for higher trophic levels following the invasions. We identified salinity intrusion as a primary pressure but showed relatively stronger importance of biotic interactions for understanding the dynamics of entire communities. Our findings highlight the dynamic nature of biotic interactions and provide evidence of how simultaneous invasions of exotic species may alter interaction networks in diverse natural ecosystems over large spatial and temporal scales.

SF estuary

New PhD student: Konrad Karlsson

We have a new PhD student in our group – Konrad Karlsson. Welcome!

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Konrad’s PhD project will focus on investigating the adaptive capacity of zooplankton to environmental change. His thesis is connected to the interdisciplinary BONUS project BIO-C3, which focuses on causes, consequences and management implications of biodiversity change in the Baltic Sea. Understanding the capacity for biological adaptation is critical to predict effects of climate change. Konrad’s thesis is expected to enhance the current knowledge on environmental tolerances and preferences of various Baltic Sea species.