Meta-Analysis of Cod–shrimp Interactions Reveals Top-Down Control in Oceanic Food Webs

Abstract

Here we present a meta‐analytic approach to analyzing population interactions across the North Atlantic Ocean. We assembled all available biomass time series for a well‐documented predator–prey couple, Atlantic cod (Gadus morhua) and northern shrimp (Pandalus borealis), to test whether the temporal dynamics of these populations are consistent with the “top‐down” or the “bottom‐up” hypothesis. Eight out of nine regions showed inverse correlations of cod and shrimp biomass supporting the “top‐down” view. Exceptions occurred only close to the southern range limits of both species. Random‐effects meta‐analysis showed that shrimp biomass was strongly negatively related to cod biomass, but not to ocean temperature in the North Atlantic Ocean. In contrast, cod biomass was positively related to ocean temperature. The strength of the cod–shrimp relationship, however, declined with increasing mean temperature. These results show that changes in predator populations can have strong effects on prey populations in oceanic food webs, and that the strength of these interactions may be sensitive to changes in mean ocean temperature. This means that the effects of overfishing in the ocean cascade down to lower trophic levels, as has been shown previously for lakes and coastal seas. In order to further investigate these processes, we establish a methodological framework to analyze species interactions from time series data. Corresponding Editor: O. J. Schmitz.

Nutrient regime shift in the western North Atlantic indicated by compound-specific δ 15 N of deep-sea gorgonian corals

“…The lack of any trend in trophic level or POM diagenetic state indicates that the local plankton community along the upper continental slope was unaffected or perhaps more resilient to the "trophic cascade" thought to have occurred elsewhere on the Eastern Scotian Shelf and Labrador Sea in response to overexploitation of Atlantic cod and other groundfish species (40,41). On the other hand, whereas nitrate concentration may be impacted by internal processes, nitrate source is externally forced; our results from the Scotian/Maine upper continental slope indicate that increasing nitrate levels were associated with externally driven shifts in nitrate source partitioning.…”

Human transformations of the Wadden Sea ecosystem through time: a synthesis

“…4). The decrease in top-down control commonly leads to an increase of former prey species and competitors (Daan 1980;Worm and Myers 2003), a trend that is often compensated for by increasing and shifting human exploitation to those species that are lower and lower in the food web (Pauly et al 1998). Also, the loss of large predators results in the loss of long-term storage and export of organic matter.…”

Predation and habitat modification synergistically interact to control bivalve recruitment on intertidal mudflats

“…Contrastingly, the invasive American razor clam, originally an inhabitant of the lower surf-zone, but now strongly increasing in the Wadden Sea, may actually be facilitated as this species profits from unstable sediments (Armonies, 2001). Apart from deteriorated substrate conditions, predation pressure by crustaceans is increasing in many coastal areas, often due to overfishing of top-predators resulting in mesopredator release (Worm and Myers, 2003). In the Dutch Wadden Sea, shrimp numbers are over twice as high compared to other European coastal waters (Tulp et al, 2012), peaking in summer at over 100 individuals/m 2 on intertidal flats (van der Veer et al, 1998).…”

“…One potentially important biotic factor is increased predation by crustaceans (e.g., shrimp, crab) on bivalve spat. Outbreaks of crustaceans can, for instance, occur due to climate change (Philippart et al, 2003) or overfishing of predatory fish that feed on crustaceans -so-called mesopredator release (Worm and Myers, 2003). Second, declines of reef-forming species like mussels and oysters may reduce inter-and intraspecific facilitation mechanisms, further hampering bivalve recovery (Brinkman et al, 2002;Schulte et al, 2009;Troost, 2010;Donadi et al, 2013).…”