| Popis: |
Incidents of abrupt and persistent recruitment collapses were observed in a unique time series (since 1919) of 0-group gadoid abundance data from the Norwegian Skagerrak coast. The incidents were attributed to gradually increasing nutrient loads and in one instance to increasing temperature. Based on comprehensive testing in the field and concurrent abrupt changes in the plankton community with that of the recruitment collapses, it is concluded that the underlying mechanism is abrupt shifts in the plankton community, which is propagated to higher trophic levels by causing recruitment failure in fishes. Such shifts can be classified as bifurcations, that is, abrupt and persistent ecosystem shifts resulting from gradual environmental changes that affect several trophic levels. The indication that increasing temperature may render marine ecosystems vulnerable to bifurcations is highly worrying at the prospect of global warming. |
