Understanding the effects of cross-system fluxes is fundamental in ecosystem ecology andbiological conservation. Source-sink dynamics and spillover processes may link adjacent ecosystems by movement of organisms across system boundaries. However, effects of temporal variability in these cross-system fluxes on a whole marine ecosystem structure have not yet been presented. Here we show, using 35 y of multitrophic data series from the Baltic Sea, that transitory spillover of the top-predator cod from its main distribution area produces cascading effects in the whole food web of an adjacent and semi-isolated ecosystem. At varying population size, cod expand/contract their distribution range and invade/retreat from the neighboring Gulf of Riga, thereby affecting the local prey population of herring and, indirectly, zooplankton and phytoplanktonviatop-downcontrol.TheGulfofRigacanbeconsideredforcod a “truesink” habitat, whereinthe absence ofimmigration fromthe sourceareasofthecentralBalticSeathecodpopulationgoesextinct due to the absence of suitable spawning grounds. Our results add a metaecosystem perspective to the ongoing intense scientific debateonthekeyroleoftoppredatorsinstructuringnaturalsystems. The integration of regional and local processes is central to predict species and ecosystem responses to future climate changes and ongoing anthropogenic disturbances.
Predator transitory spillover indices trophic cascades in ecological sinks
Casini M
;
2012
Abstract
Understanding the effects of cross-system fluxes is fundamental in ecosystem ecology andbiological conservation. Source-sink dynamics and spillover processes may link adjacent ecosystems by movement of organisms across system boundaries. However, effects of temporal variability in these cross-system fluxes on a whole marine ecosystem structure have not yet been presented. Here we show, using 35 y of multitrophic data series from the Baltic Sea, that transitory spillover of the top-predator cod from its main distribution area produces cascading effects in the whole food web of an adjacent and semi-isolated ecosystem. At varying population size, cod expand/contract their distribution range and invade/retreat from the neighboring Gulf of Riga, thereby affecting the local prey population of herring and, indirectly, zooplankton and phytoplanktonviatop-downcontrol.TheGulfofRigacanbeconsideredforcod a “truesink” habitat, whereinthe absence ofimmigration fromthe sourceareasofthecentralBalticSeathecodpopulationgoesextinct due to the absence of suitable spawning grounds. Our results add a metaecosystem perspective to the ongoing intense scientific debateonthekeyroleoftoppredatorsinstructuringnaturalsystems. The integration of regional and local processes is central to predict species and ecosystem responses to future climate changes and ongoing anthropogenic disturbances.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
