Are the abiotic and biotic characteristics of aquatic mesocosms representative of in situ conditions?

• Main Authors: Andrew R. Dzialowski, Marek Rzepecki, Iwona Kostrzewska-Szlakowska, Krystyna Kalinowska, Anna Palash, Jay T. Lennon
• Format: Article
• Language: English
• Published: PAGEPress Publications 2014-05-01
• Series: Journal of Limnology
• Subjects: Mesocosms; limnocorrals; periphyton; wall effect.
• Online Access: http://www.jlimnol.it/index.php/jlimnol/article/view/721

<p class="p1">There is debate about whether results from mesocosm studies should be extrapolated to natural ecosystems. Critics argue that the <span style="font-size: 10px;">abiotic and biotic characteristics of mesocosms do not represent the </span><span class="s1" style="font-size: 10px;">i<em>n situ </em></span><span style="font-size: 10px;">conditions of the habitats in which they are designed to </span><span style="font-size: 10px;">mimic. We addressed this idea by deploying mesocosms in two lakes of varying trophic status (mesotrophic and eutrophic). Water chemistry </span><span style="font-size: 10px;">was relatively similar between the mesocosms and the respective lakes. In contrast, biological variables including most phytoplankton, </span><span style="font-size: 10px;">nanoflagellates, ciliates, and zooplankton were lower in the mesocosms than they were in the respective lakes. There was </span><span style="font-size: 10px;">also a shift in zooplankton composition such that mesocosm assemblages diverged from pelagic to littoral communities. While our </span><span style="font-size: 10px;">results show that freshwater planktonic organisms can vary considerably between mesocosms and </span><span class="s1" style="font-size: 10px;">in situ </span><span style="font-size: 10px;">habitats, we also suggest that </span><span style="font-size: 10px;">factors such as isolation from lake sediments, the lack of predators, and the temporal scale at which mesocosms are filled and sampled </span><span style="font-size: 10px;">should be considered when designing and interpreting mesocosm studies. Nevertheless, mesocosms are an important tool for developing </span><span style="font-size: 10px;">and testing general ecological hypotheses that cannot be achieved using other approaches alone.</span></p>