NRC Research Associate at NOAA

Since Dec 2017 I have been working as a research associate for EcoFOCI at the Alaska Fisheries Science Center, NOAA. My research focusses on analyzing long-term ichthyoplankton data in an effort to develop biological indicators of ecosystem changes along the US west coast from California to Alaska.

Diet tracing in ecology

Our new paper titled ”Diet tracing in ecology: method comparison and selection” just got published.

Here, we contrast diverse dietary tracing techniques, such as visual analyses of stomach or scat content, DNA identification of prey items, organic macromolecules (e.g. fatty acids), and stable isotope analyses of bulk or specific compounds, and provide recommendations for method selection, and discuss the advantages of method integration.

Link to the online version of our manuscript is available here

Thesis defence – “Assessing predator-prey interactions and energy transfer in aquatic food webs”

Thesis_pic_websiteThe last of couple of months have been busy with manuscript and thesis writing and consequently few updates on my webpage. On January 26th I successfully defended my doctoral thesis: “Assessing predator-prey interactions and energy transfer in aquatic food webs”.

For the time being I will continue working on my projects here at Stockholm University while at the same time exploring future research opportunities.

 

 

Stable isotope mixing models for estimating animal diets

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Top: Loch Lomond, Below: zooplankton diet proportions estimated using SIAR

Just got back from the Scottish Highlands and Loch Lomond, where I attended a great stable isotope mixing model course at the Centre for Ecology and the Natural Environment (SCENE) last week. The course provided a nice overview of the many possibilities of using isotope mixing models to estimate diet proportions in animals, and include introduction to SIBER, SIAR and MixSIAR.

Thanks to everyone involved, including teachers Andrew Parnell and Andrew Jackson for some great days. More information about this and future courses can be found on http://www.prstatistics.co.uk/.

New paper on zooplankton feeding ecology

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Our paper entitled ”Seasonal dynamics of zooplankton resource use revealed by carbon amino acid stable isotope values” just got published.

Here we assessed feeding patterns in zooplankton in the Baltic Sea during an entire growing season, using a combined approach of bulk (δ15N and δ13C), essential amino acid (δ13C) stable isotope values, and quantitative phytoplankton data.

Link to the online version of our manuscript is available here: http://www.int-res.com/articles/meps2015/531/m531p143.pdf

New article

Our recent article “Meta-analysis of amino acid stable nitrogen isotope ratios for estimating trophic position in marine organisms” just got published in Oecologia

Analysis of amino acid stable nitrogen isotope values (δ15N values) is a relatively new and powerful technique for estimating trophic position in diverse organisms.

One of the primary advantages of this method is that the δ15N values of some amino acids in consumers are very similar to the primary producers that synthesized them at the base of the food web (source amino acids), while the δ15N values of other amino acids (trophic amino acids) increase in 15N relative to source amino acids with each trophic step. Prediction of a species trophic position however also rely on accurate knowledge of the trophic enrichment factor (change in isotope values between consumer and diet) of each individual amino acid.

In this article, we present the first meta-analysis of δ15N amino acid values from measurements of 359 marine species covering four trophic levels.

Specifically we asked the following questions:

  1. Are trophic enrichment factors in different amino acids constant across trophic position?
  2. Does feeding ecology through variable dietary input and form of nitrogen excretion affect the value of the trophic enrichment factor ?
  3. Which trophic and source amino acid δ15N values are the most suitable for trophic position estimation?
  4. Are trophic position estimates which incorporate multiple AA δ15N values more precise than estimates using single trophic and source AA δ15N values?

Our meta-analysis clarifies the advantages and limitations of using individual δ15N AA values as tools in trophic ecology and provides a guideline for the future application of AA-CSIA to food web studies.

Link to the online version of our manuscript can be found here: http://link.springer.com/article/10.1007/s00442-015-3305-7?sa_campaign=email/event/articleAuthor/onlineFirst