This Late Lunch Talk will be held on Zoom:
https://uio.zoom.us/j/63410749310
Meeting ID: 634 1074 9310
Size-selective fisheries generate some of the most pervasive and challenging anthropogenic perturbations faced by aquatic organisms. Yet the effects of size-selective mortality induced by fisheries on ecosystem functioning remain poorly explored. In this seminar, I will present results from an outdoor pond experiment, where we investigated the effects of two lines of medaka Oryzias latipes previously selected for large- or small-size on invertebrate abundances (i.e. zooplankton and zoobenthos) and ecosystem processes (e.g. whole-ecosystem metabolism, pelagic and benthic algae stocks). Environmental conditions (i.e. fish density and light intensity) were also manipulated to assess the importance of top-down versus bottom-up forces in shaping the effects of adaptation to size-selection on the response variables. We found that i) the effects of reduced density overwhelmed the effects of size-selection in modulating the strength of the trophic cascade, ii) small-size selected fish consumed slightly less benthic invertebrates than their large-size selected counterparts and, iii) size-selection interacted with light intensity to shape processes such as benthic primary production and fish nutrient recycling. Overall, these findings suggested that small-size selected fish displayed lower capacity to exploit benthic resources, which may ultimately affect the strength of the trophic cascade in the benthic compartment.