Re-thinking the “ecological envelope” of Eastern Baltic cod (Gadus morhua): conditions for productivity, reproduction, and feeding over time

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Svedäng , H , Savchuk , O P , Villnäs , A , Norkko , A , Gustafsson , B , Wikström , S A & Humborg , C 2022 , ' Re-thinking the “ecological envelope” of Eastern Baltic cod (Gadus morhua): conditions for productivity, reproduction, and feeding over time ' , ICES Journal of Marine Science , vol. 79 , no. 3 , pp. 689-708 . https://doi.org/10.1093/icesjms/fsac017

Title: Re-thinking the “ecological envelope” of Eastern Baltic cod (Gadus morhua): conditions for productivity, reproduction, and feeding over time
Author: Svedäng, Henrik; Savchuk, Oleg P; Villnäs, Anna; Norkko, Alf; Gustafsson, Bo; Wikström, Sofia A.; Humborg, Christoph
Contributor organization: Tvärminne Zoological Station
Tvärminne Benthic Ecology Team
Marine Ecosystems Research Group
Biological stations
Date: 2022-04
Language: eng
Number of pages: 20
Belongs to series: ICES Journal of Marine Science
ISSN: 1054-3139
DOI: https://doi.org/10.1093/icesjms/fsac017
URI: http://hdl.handle.net/10138/343675
Abstract: Hypoxia is presently seen as the principal driver behind the decline of the former dominating Eastern Baltic cod stock (EBC; Gadus morhua). It has been proposed that both worsening conditions for reproduction and lower individual growth, condition, and survival are linked to hypoxia. Here, we elucidate the ecological envelope of EBC in terms of salinity stratification, oxygen content, and benthic animal biomasses, and how it has affected EBC productivity over time. The spawning conditions started deteriorating in the Gotland Deep in the 1950s due to oxygen depletion. In contrast, in the Bornholm Basin, hydrographic conditions have remained unchanged over the last 60 years. Indeed, the current extent of both well-oxygenated areas and the frequency of hypoxia events do not differ substantially from periods with high EBC productivity in the 1970s–1980s. Furthermore, oxygenated and therefore potentially suitable feeding areas are abundant in all parts of the Baltic Sea, and our novel analysis provides no evidence of a reduction in benthic food sources for EBC over the last 30 years. We find that while reproduction failure is intricately linked to hydrographic dynamics, a relationship between the spread of hypoxia and the decline in EBC productivity during the last decades cannot be substantiated.
Subject: ATLANTIC COD
BODY-SIZE
DEMERSAL FISH
DYNAMICS
Eastern Baltic cod
HYPOXIA
LONG-TERM CHANGES
OXYGEN
REGIME SHIFTS
SEA
VARIABILITY
benthic biomass
hypoxia
productivity
reproduction volume
spatial scales
1181 Ecology, evolutionary biology
Peer reviewed: Yes
Rights: cc_by
Usage restriction: openAccess
Self-archived version: publishedVersion


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