Ecological-network models link diversity, structure and function in the plankton food-web

Abstract

A planktonic food-web model including sixty-three functional nodes (representing auto- mixo- and heterotrophs) was developed to integrate most trophic diversity present in the plankton. The model was implemented in two variants - which we named ‘green’ and ‘blue’ - characterized by opposite amounts of phytoplankton biomass and representing, respectively, bloom and non-bloom states of the system. Taxonomically disaggregated food-webs described herein allowed to shed light on how components of the plankton community changed their trophic behavior in the two different conditions, and modified the overall functioning of the plankton food web. The green and blue food-webs showed distinct organizations in terms of trophic roles of the nodes and carbon fluxes between them. Such re-organization stemmed from switches in selective grazing by both metazoan and protozoan consumers. Switches in food-web structure resulted in relatively small differences in the efficiency of material transfer towards higher trophic levels. For instance, from green to blue states, a seven-fold decrease in phytoplankton biomass translated into only a two-fold decrease in potential planktivorous fish biomass. By linking diversity, structure and function in the plankton food-web, we discuss the role of internal mechanisms, relying on species-specific functionalities, in driving the ‘adaptive’ responses of plankton communities to perturbations.

Seasonal and Interannual Changes in Ciliate and Dinoflagellate Species Assemblages in the Arctic Ocean (Amundsen Gulf, Beaufort Sea, Canada)

“…Under these new conditions ciliates and dinoflagellates that are better able exploit smaller prey would be selected for. Our results support recent mesocosm and modeling experiments that suggest that under future conditions, the microzooplankton and microbial loop will become more prominent as efficient intermediates between bacteria-picoplankton and the classical food webs (Skjoldborg et al, 2003;O'Connor et al, 2009;Montagnes et al, 2010;Lewandowska et al, 2014;D'Alelio et al, 2016).…”

Mammoth grazers on the ocean's minuteness: a review of selective feeding using mucous meshes

“…Although mucus-based feeding mechanisms have independently evolved in multiple animal classes, this review is restricted to 'large planktonic microphages' [8] (pelagic tunicates and thecosome pteropods) because of their important, yet understudied, roles as benthic-pelagic links and key species in the planktonic food web [4,8,9]. All of these animals use mucous filters with large surface areas to maximize particle capture rates (figure 1a).…”

“…If and how grazers select particles from this mixed assemblage influences food web structure and carbon flux [3,4]. Some of the more abundant marine grazers use mucous meshes to capture prey-a process considered to have minimal potential for dietary selection [5][6][7].…”

Present and future of aquatic sciences: The perspective of AIOL scientific community for a priority roadmap over the next five years

“…They also host invaluable biodiversity that shapes complex ecosystems and play a fundamental role in planetary biogeochemical cycles (e.g. Boero et al, 2007;Howarth et al, 2011;Gamfeldt et al, 2015;D'Alelio et al, 2016). Altogether, marine ecosystems are exposed to a plethora of threats (Crain et al 2008).…”