Ocean Acidification Effects on Atlantic Cod Larval Survival and Recruitment to the Fished Population.

Rüdiger Voss,Felix H Mittermayer,Atle Mortensen,Catriona Clemmesen,Martina H Stiasny,Velmurugu Puvanendran,Thorsten B H Reusch,Fredrik Jutfelt,Michael Sswat,Melissa Chierici

doi:10.1371/journal.pone.0155448

Abstract

How fisheries will be impacted by climate change is far from understood. While some fish populations may be able to escape global warming via range shifts, they cannot escape ocean acidification (OA), an inevitable consequence of the dissolution of anthropogenic carbon dioxide (CO2) emissions in marine waters. How ocean acidification affects population dynamics of commercially important fish species is critical for adapting management practices of exploited fish populations. Ocean acidification has been shown to impair fish larvae’s sensory abilities, affect the morphology of otoliths, cause tissue damage and cause behavioural changes. Here, we obtain first experimental mortality estimates for Atlantic cod larvae under OA and incorporate these effects into recruitment models. End-of-century levels of ocean acidification (~1100 μatm according to the IPCC RCP 8.5) resulted in a doubling of daily mortality rates compared to present-day CO2 concentrations during the first 25 days post hatching (dph), a critical phase for population recruitment. These results were consistent under different feeding regimes, stocking densities and in two cod populations (Western Baltic and Barents Sea stock). When mortality data were included into Ricker-type stock-recruitment models, recruitment was reduced to an average of 8 and 24% of current recruitment for the two populations, respectively. Our results highlight the importance of including vulnerable early life stages when addressing effects of climate change on fish stocks.

Highlights

At increased CO2 concentrations the daily mortality rates had approximately doubled in both experiments, from 7 to 13% in the Barents Sea stock (Fig 1a) and from 9.2 to 20.4% in the Western Baltic Sea stock (Fig 1b) (Western Baltic experiment, T-test, t = -3.749, df = 2.41, p = 0.024; Barents Sea experiment Two-way ANOVA F = 8.434, df = 1, p = 0.023)
Cod larvae appear to be negatively affected by ocean acidification even when ad libitum prey densities should ensure that energy is available for potential acidbase regulation mechanisms
Under realistic scenarios of end-of-century ocean acidification, early larval survival of cod was significantly reduced in two separate experiments with two different Atlantic cod stocks

Summary

Introduction

In which the survival of cod larvae was quantified in direct response to increased pCO2 levels as predicted for the end of the century. Eggs and larvae from the Western Baltic cod stock, caught in the Øresund, and from the Arcto-Norwegian Barents Sea cod stock were kept under control (~400–500 μatm) and high CO2 (~1100 μatm) concentrations in two separate experiments until 25 and 22 days post-hatching (dph) respectively and survival was monitored closely.

Results

Conclusion