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Papers by Martina Stiasny

Fish and Fisheries

Impacts of climate change on ocean productivity sustaining world fisheries are predominantly nega... more Impacts of climate change on ocean productivity sustaining world fisheries are predominantly negative but vary greatly among regions. We assessed how 39 fisheries resources—ranging from data‐poor to data‐rich stocks—in the North East Atlantic are most likely affected under the intermediate climate emission scenario RCP4.5 towards 2050. This region is one of the most productive waters in the world but subjected to pronounced climate change, especially in the northernmost part. In this climate impact assessment, we applied a hybrid solution combining expert opinions (scorings)—supported by an extensive literature review—with mechanistic approaches, considering stocks in three different large marine ecosystems, the North, Norwegian and Barents Seas. This approach enabled calculation of the directional effect as a function of climate exposure and sensitivity attributes (life‐history schedules), focusing on local stocks (conspecifics) across latitudes rather than the species in general. ...

In the coming decades, environmental change like warming and acidification will affect life in th... more In the coming decades, environmental change like warming and acidification will affect life in the ocean. While data on single stressor effects on fish are accumulating rapidly, we still know relatively little about interactive effects of multiple drivers. Of particular concern in this context are the early life stages of fish, for which direct effects of increased CO2 on growth and development have been observed. Whether these effects are further modified by elevated temperature was investigated here for the larvae of Atlantic herring (Clupea harengus), a commercially important fish species. Over a period of 32 days, larval survival, growth in size and weight, and instantaneous growth rate were assessed in a crossed experimental design of two temperatures (10°C and 12°C) with two CO2 levels (400 μatm and 900 μatm CO2) at food levels mimicking natural levels using natural prey. Elevated temperature alone led to increased swimming activity, as well as decreased survival and instantan...

Ocean acidification (OA), a direct consequence of increasing atmospheric CO2 concentration dissol... more Ocean acidification (OA), a direct consequence of increasing atmospheric CO2 concentration dissolving in ocean waters, is impacting many fish species. Little is known about the molecular mechanisms underlying the observed physiological impacts in fish. We used RNAseq to characterize the transcriptome of 3 different larval stages of Atlantic cod (Gadus morhua) exposed to simulated OA at levels (1179 µatm CO2) representing end-of-century predictions compared to controls (503 µatm CO2), which were shown to induce tissue damage and elevated mortality in G. morhua. Only few genes were differentially expressed in 6 and 13 days-post-hatching (dph) (3 and 16 genes, respectively), during a period when maximal mortality as a response to elevated pCO2 occurred. At 36 dph, 1413 genes were differentially expressed, most likely caused by developmental asynchrony between the treatment groups, with individuals under OA growing faster. A target gene analysis revealed only few genes of the universal ...

A (in press) Ocean current connectivity sets the scene for secondary spread of a marine invader a... more A (in press) Ocean current connectivity sets the scene for secondary spread of a marine invader across western Eurasia. Global Ecology and Biogeography. Note: The manuscript is included in the BIO-C3 Deliverable 2.3 report.

Ocean acidification, the decrease in seawater pH due to rising CO2 concentrations, has been shown... more Ocean acidification, the decrease in seawater pH due to rising CO2 concentrations, has been shown to lower survival in early life stages of fish and, as a consequence, the recruitment of populations including commercially important species. To date, ocean-acidification studies with fish larvae have focused on the direct physiological impacts of elevated CO2, but largely ignored the potential effects of ocean acidification on food web interactions. In an in situ mesocosm study on Atlantic herring (Clupea harengus) larvae as top predators in a pelagic food web, we account for indirect CO2 effects on larval survival mediated by changes in food availability. The community was exposed to projected end-of-the-century CO2 conditions (~760 µatm pCO2) over a period of 113 days. In contrast with laboratory studies that reported a decrease in fish survival, the survival of the herring larvae in situ was significantly enhanced by 19 ± 2%. Analysis of the plankton community dynamics suggested that the herring larvae benefitted from a CO2-stimulated increase in primary production. Such indirect effects may counteract the possible direct negative effects of ocean acidification on the survival of fish early life stages. These findings emphasize the need to assess the food web effects of ocean acidification on fish larvae before we can predict even the sign of change in fish recruitment in a high-CO2 ocean.

Throughout the twentieth and the beginning of the twenty-first century technical advancements in ... more Throughout the twentieth and the beginning of the twenty-first century technical advancements in many industries as well as the vast increase in world population have led to increasing emissions of greenhouse gases like carbon dioxide. The changes in the chemistry of the atmosphere not only result in retention of heat causing global warming, but also transfer to the oceans. The world’s oceans are not only warming, but are furthermore acidifying through the reaction of seawater with carbon dioxide, measured in pH and termed ocean acidification. The aim of this thesis was to provide greater understanding of the impact of ocean acidification on one of the most important commercial species, the Atlantic cod (Gadus morhua) and to provide a quantitative foundation to evaluate recruitment processes of this species. This thesis has quantified the effect of ocean acidification on larval survival of two Atlantic cod stocks from the Western Baltic Sea and the Barents Sea and how this translate...

Fish Physiology and Biochemistry, 2021

To date the study of ocean acidification on fish otolith formation has been mainly focused on lar... more To date the study of ocean acidification on fish otolith formation has been mainly focused on larval and juvenile stages. In the present pilot study, wild-captured adult Atlantic cod (Gadus morhua) were exposed to two different levels ofpCO2,422µatm (ambient, lowpCO2) or 1091µatm (highpCO2), for a period of 30 weeks (from mid-October to early April 2014–2015) in order to study the effects on otolith size, shape and CaCO3crystallization amongst other biological parameters. We found that otoliths from cod exposed to highpCO2were slightly smaller (− 3.4% in length; − 3.3% in perimeter), rounder (− 2.9% circularity and + 4% roundness) but heavier (+ 5%) than the lowpCO2group. Interestingly, there were different effects in males and females; for instance, male cods exposed to highpCO2exhibited significant changes in circularity (− 3%) and roundness (+ 4%) compared to the lowpCO2males, but without significant changes on otolith dimensions, while females exposed to highpCO2had smaller otol...

ICES Journal of Marine Science, 2020

The lack of any abundant recruiting year class of Norwegian spring-spawning (NSS) herring between... more The lack of any abundant recruiting year class of Norwegian spring-spawning (NSS) herring between 2005 and 2015 contributed to an approximate reduction of 40% in the spawning-stock biomass since 2009, i.e. from 7 to 4 million tonnes. Warming of the North Atlantic is suggested to contribute to this reduction in recruitment. In the past, a warm phase induced by a positive Atlantic Multidecadal Oscillation (AMO) in the North Atlantic was positively correlated to the NSS herring stock size. Recent unprecedented ocean warming in the Norwegian Sea ecosystem, besides elevated temperatures due to a positive AMO, seems to be outside optimal environmental conditions for early life history stages of NSS herring. We analysed 28 years of survey data using generalized additive models to reconstruct environmental conditions for drifting yolksac and preflexion stage larvae. Our results indicate that strong recruitment years were more likely when the larvae occurred simultaneously with a negative AM...