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| Heath, Michael R.; Speirs, Douglas C.; Steele, John H.. |
| Climate fluctuations and human exploitation are causing global changes in nutrient enrichment of terrestrial and aquatic ecosystems and declining abundances of apex predators. The resulting trophic cascades have had profound effects on food webs, leading to significant economic and societal consequences. However, the strength of cascades-that is the extent to which a disturbance is diminished as it propagates through a food web-varies widely between ecosystems, and there is no formal theory as to why this should be so. Some food chain models reproduce cascade effects seen in nature, but to what extent is this dependent on their formulation? We show that inclusion of processes represented mathematically as density-dependent regulation of either consumer... |
| Tipo: Text |
Palavras-chave: Bottom-up; Density dependence; Food chain; Food web; Harvesting; Model; Predator-prey; Simulation; Top-down. |
| Ano: 2014 |
URL: https://archimer.ifremer.fr/doc/00171/28249/26505.pdf |
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| Saraux, Claire; Van Beveren, Elisabeth; Brosset, Pablo; Queiros, Quentin; Bourdeix, Jean-herve; Dutto, Gilbert; Gasset, Eric; Jac, Cyrielle; Bonhommeau, Sylvain; Fromentin, Jean-marc. |
| Around 2008, an ecosystem shift occurred in the Gulf of Lions, highlighted by considerable changes in biomass and fish mean weight of its two main small pelagic fish stocks (European anchovy, Engraulis encrasicolus; European sardine, Sardina pilchardus). Surprisingly these changes did not appear to be mediated by a decrease in fish recruitment rates (which remained high) or by a high fishing pressure (exploitation rates being extremely low). Here, we review the current knowledge on the population's dynamics and its potential causes. We used an integrative ecosystem approach exploring alternative hypotheses, ranging from bottom-up to top-down control, not forgetting epizootic diseases. First, the study of multiple population characteristics highlighted a... |
| Tipo: Text |
Palavras-chave: Population dynamics; Top-down; Disease; Zooplankton; Exploited species; Bottom-up. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00427/53861/54903.pdf |
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