Sammanfattning

Deoxygenation worldwide is increasing in aquatic systems with implications for organisms' biology, communities and ecosystems. Eastern Baltic cod has experienced a strong decline in mean body condition (i.e. weight at a specific length) over the past 20 years with effects on the fishery relying on this resource. The decrease in cod condition has been tentatively linked in the literature to increased hypoxic areas potentially affecting habitat range, but also to benthic prey and/or cod physiology directly. To date, no studies have been performed to test these mechanisms. Using otolith trace element microchemistry and hypoxia-responding metrics based on manganese (Mn) and magnesium (Mg), we investigated the relationship between fish body condition at capture and exposure to hypoxia. Cod individuals collected after 2000 with low body condition had a higher level of Mn/Mg in the last year of life, indicating higher exposure to hypoxic waters than cod with high body condition. Moreover, lifetime exposure to hypoxia was even more strongly correlated to body condition, suggesting that condition may reflect long-term hypoxia status. These results were irrespective of fish age or sex. This implies that as Baltic cod visit poor-oxygen waters, perhaps searching for benthic food, they compromise their own performance. This study specifically sheds light on the mechanisms leading to the low condition of cod and generally points to the impact of deoxygenation on ecosystems and fisheries.

Nyckelord

hypoxia; body condition; Gadus morhua; otoliths; trace element analyses

Publicerad i

Biology Letters
2019, Volym: 15, nummer: 12, artikelnummer: 20190352

SLU författare

• Limburg, Karin

  • Institutionen för akvatiska resurser (SLU Aqua), Sveriges lantbruksuniversitet
    
  • State University of New York College of Environmental Science and Forestry (SUNY-ESF)

• Casini, Michele

  • Institutionen för akvatiska resurser (SLU Aqua), Sveriges lantbruksuniversitet
    

Associerade SLU-program

Kust och hav
Klimat
Biologisk mångfald


Globala målen

Bevara och nyttja haven och de marina resurserna på ett hållbart sätt för en hållbar utveckling


UKÄ forskningsämne

Fisk- och akvakulturforskning
Vilt- och fiskeförvaltning
Ekologi


Publikationens identifierare

DOI: https://doi.org/10.1098/rsbl.2019.0352

Permanent länk till denna sida (URI)

https://res.slu.se/id/publ/103276