Change in Fish Community Structure in the Barents Sea

Abstract

Change in oceanographic conditions causes structural alterations in marine fish communities, but this effect may go undetected as most monitoring programs until recently mainly have focused on oceanography and commercial species rather than on whole ecosystems. In this paper, the objective is to describe the spatial and temporal changes in the Barents Sea fish community in the period 1992–2004 while taking into consideration the observed abundance and biodiversity patterns for all 82 observed fish species. We found that the spatial structure of the Barents Sea fish community was determined by abiotic factors such as temperature and depth. The observed species clustered into a deep assemblage, a warm water southern assemblage, both associated with Atlantic water, and a cold water north-eastern assemblage associated with mixed water. The latitude of the cold water NE and warm water S assemblages varied from year to year, but no obvious northward migration was observed over time. In the period 1996–1999 we observed a significant reduction in total fish biomass, abundance, mean fish weight, and a change in community structure including an increase in the pelagic/demersal ratio. This change in community structure is probably due to extremely cold conditions in 1996 impacting on a fish community exposed to historically high fishing rates. After 1999 the fish community variables such as biomass, abundance, mean weight, P/D ratio as well as community composition did not return to levels of the early 90s, although fishing pressure and climatic conditions returned to earlier levels.

Food‐web structure varies along environmental gradients in a high‐latitude marine ecosystem

“…These gradients in hydrography are linked to productivity, where the warmer and nutrientrich Atlantic waters of the southwest are more productive than the colder and ice-covered Arctic waters in the northeast (Reigstad et al 2011). The resulting spatial variability in environmental conditions has strong structuring effects on fish and benthic communities (Johannesen et al 2012, Aschan et al 2013, Degen et al 2016, leading to different food-web structures (Kortsch et al 2015). Owing to these distinct subdivisions in species composition, the Barents Sea is a suitable ecosystem to investigate spatial variation in trophic interactions, i.e.…”

The Effects of Sub-Regional Climate Velocity on the Distribution and Spatial Extent of Marine Species Assemblages

“…The assessment and prediction of climate change effects on biota is a major area of research [ 1 – 7 ]. Most studies examine the climate-related responses of individual species and illustrate variable patterns in species distribution shifts in response to drivers such as changing temperature [ 8 – 12 ] and fishing pressure [ 5 , 13 – 16 ]. However, interactions between species and aggregate community-level responses may have important implications for ecosystem functioning [ 17 ].…”

Bioenergetics of Brown Bullhead in a Changing Climate

“…This study examined only one species, yet these species do not operate in an environment free of interactions with other species. Interspecific competition, predation, and other factors play a key role in maintaining community structure (Glasser 1979;Robertson 1996;Aschan et al 2013). Therefore future studies should begin to consider multiple species and community level reactions to climate change (Poulard and Blanchard 2005;Breeggemann et al 2015;MacDonald et al 2015).…”