Reduced exploration capacity despite brain volume increase in warm-acclimated common minnow

While evidence suggests that warming may impact cognition of ectotherms, the underlying mechanisms remain poorly understood. A possible but rarely considered mechanism is that the metabolic response of ectotherms to warming is associated with changes in brain morphology and function. Here, we compared aerobic metabolism, brain volume, boldness and accuracy of maze solving of common minnows (Phoxinus phoxinus) acclimated for 8 months to either their current optimal natural (14°C) or warm (20°C) water temperature. Metabolic rates indicated increased energy expenditure in warm-acclimated fish, but also at least partial thermal compensation as warm-acclimated fish maintained high aerobic scope. Warm-acclimated fish had larger brains than cool-acclimated fish. The volume of the dorsal medulla relative to the overall brain size was larger in warm- than in cool-acclimated fish, but the proportion of other brain regions did not differ between the temperature treatments. Warm-acclimated fish did not differ in boldness but made more errors than cool-acclimated fish in exploring the maze across four trials. Inter-individual differences in the number of exploration errors were repeatable across the four trials of the maze test. Our findings suggest that in warm environments, maintaining a high aerobic scope, which is important for the performance of physically demanding tasks, can come at the cost of changes in brain morphology and impairment of the capacity to explore novel environments. This trade-off could have strong fitness implications for wild ectotherms

The negative ecological impacts of a globally introduced species decrease with time since introduction

Dataset extracted from peer-reviewed literature available by the end of the year 2016 used for a meta-analysis about temporal change of ecological impacts of non-native brown trout. For more details see the methods section of the related publication (Zavorka et al. 2018, Global Change Biology)

Data_Zavorka_et_al_2017_Func_Ecol

Data used for analyses in publication Zavorka et al. 2017 published in Functional Ecology. Data represent residuals of linear model between the measured traits and body size. For details about the models used for calculation of residuals see Supporting information Appendix 4 of the study Zavorka et al. 2017

The negative ecological impacts of a globally introduced species decrease with time since introduction

International audienc

Climate change induced deprivation of dietary essential fatty acids can reduce growth and mitochondrial efficiency of wild juvenile salmon

1. Omega-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFA) are essential micronutrients for optimal functioning of cellular metabolism and for somatic growth of all vertebrates including fishes. In addition, n-3 LC-PUFA could also play a key role in response of fishes and other ectothermic vertebrates to changing temperatures. 2. An important, but largely overlooked, consequence of climate change is the reduced availability of dietary n-3 LC-PUFA in aquatic food webs. Changes in availability of dietary n-3 LC-PUFA have recently been proposed as a major driver of novel adaptations and diversification of consumers. Yet, there is only limited knowledge about how n-3 LC-PUFA depletion in aquatic food-webs will affect the performance of wild fishes. 3. Here we combine biochemistry and physiology at the cellular level with physiological and cognitive processes at the whole-animal level to test how ecologically relevant deprivation of n-3 LC-PUFA affects performance of wild juvenile Atlantic salmon (Salmo salar). 4. We found that juvenile salmon had a limited capacity to maintain the fatty acid profile of both muscle and brain under a n-3 LC-PUFA-deficient diet. Despite these findings, brain tissues showed remarkable functional stability in mitochondrial metabolism, and we found no effect of diet on learning ability. However, we found that mitochondrial efficiency in muscles and the somatic growth were reduced under a n-3 LC-PUFA-deficient diet. Importantly, we discovered that the somatic growth of juvenile salmon within both treatments decreased with increasing rate of DHA synthesis and retention. 5. Since DHA is essential for functioning of cellular metabolism, which together with body size are traits closely related to fitness of wild fishes, we suggest that the trade-off between growth rate and accumulation of DHA could play a critical role in resilience of juvenile salmon to the ongoing rapid environmental change

Climate change induced deprivation of dietary essential fatty acids can reduce growth and mitochondrial efficiency of wild juvenile salmon

1. Omega-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFA) are essential micronutrients for optimal functioning of cellular metabolism and for somatic growth of all vertebrates including fishes. In addition, n-3 LC-PUFA could also play a key role in response of fishes and other ectothermic vertebrates to changing temperatures. 2. An important, but largely overlooked, consequence of climate change is the reduced availability of dietary n-3 LC-PUFA in aquatic food webs. Changes in availability of dietary n-3 LC-PUFA have recently been proposed as a major driver of novel adaptations and diversification of consumers. Yet, there is only limited knowledge about how n-3 LC-PUFA depletion in aquatic food-webs will affect the performance of wild fishes. 3. Here we combine biochemistry and physiology at the cellular level with physiological and cognitive processes at the whole-animal level to test how ecologically relevant deprivation of n-3 LC-PUFA affects performance of wild juvenile Atlantic salmon (Salmo salar). 4. We found that juvenile salmon had a limited capacity to maintain the fatty acid profile of both muscle and brain under a n-3 LC-PUFA-deficient diet. Despite these findings, brain tissues showed remarkable functional stability in mitochondrial metabolism, and we found no effect of diet on learning ability. However, we found that mitochondrial efficiency in muscles and the somatic growth were reduced under a n-3 LC-PUFA-deficient diet. Importantly, we discovered that the somatic growth of juvenile salmon within both treatments decreased with increasing rate of DHA synthesis and retention. 5. Since DHA is essential for functioning of cellular metabolism, which together with body size are traits closely related to fitness of wild fishes, we suggest that the trade-off between growth rate and accumulation of DHA could play a critical role in resilience of juvenile salmon to the ongoing rapid environmental change

data_Sten2014

Suporting data for the manuscript submitted to Ecolog

Guidelines for reporting methods to estimate metabolic rates by aquatic intermittent-flow respirometry

Interest in the measurement of metabolic rates is growing rapidly, because of the importance of metabolism in advancing our understanding of organismal physiology, behaviour, evolution and responses to environmental change. The study of metabolism in aquatic animals is undergoing an especially pronounced expansion, with more researchers utilising intermittent-flow respirometry as a research tool than ever before. Aquatic respirometry measures the rate of oxygen uptake as a proxy for metabolic rate, and the intermittent-flow technique has numerous strengths for use with aquatic animals, allowing metabolic rate to be repeatedly estimated on individual animals over several hours or days and during exposure to various conditions or stimuli. There are, however, no published guidelines for the reporting of methodological details when using this method. Here, we provide the first guidelines for reporting intermittent-flow respirometry methods, in the form of a checklist of criteria that we consider to be the minimum required for the interpretation, evaluation and replication of experiments using intermittent-flow respirometry. Furthermore, using a survey of the existing literature, we show that there has been incomplete and inconsistent reporting of methods for intermittent-flow respirometry over the past few decades. Use of the provided checklist of required criteria by researchers when publishing their work should increase consistency of the reporting of methods for studies that use intermittent-flow respirometry. With the steep increase in studies using intermittent-flow respirometry, now is the ideal time to standardise reporting of methods, so that – in the future – data can be properly assessed by other scientists and conservationists

Growth-enhanced salmon modify stream ecosystem functioning

Use of fast-growing domesticated and/or genetically modified strains of fish isbecoming increasingly common in aquaculture, increasing the likelihood of deliberateor accidental introductions into the wild. To date, their ecological impacts on ecosys-tems remain to be quantified. Here, using a controlled phenotype manipulation byimplanting growth hormone in juvenile Atlantic salmon (Salmo salar), we found thatgrowth-enhanced fish display changes in several phenotypic traits known to beimportant for ecosystem functioning, such as habitat use, morphology and excretionrate. Furthermore, these phenotypic changes were associated with significantimpacts on the invertebrate community and key stream ecosystem functions such asprimary production and leaf-litter decomposition. These findings provide novel evi-dence that introductions of growth-enhanced fish into the wild can affect the func-tioning of natural ecosystems and represent a form of intraspecific invasion.Consequently, environmental impact assessments of growth-enhanced organismsneed to explicitly consider ecosystem-level effects.acceptedVersio

Growth-enhanced salmon modify stream ecosystem functioning

Use of fast-growing domesticated and/or genetically modified strains of fish isbecoming increasingly common in aquaculture, increasing the likelihood of deliberateor accidental introductions into the wild. To date, their ecological impacts on ecosys-tems remain to be quantified. Here, using a controlled phenotype manipulation byimplanting growth hormone in juvenile Atlantic salmon (Salmo salar), we found thatgrowth-enhanced fish display changes in several phenotypic traits known to beimportant for ecosystem functioning, such as habitat use, morphology and excretionrate. Furthermore, these phenotypic changes were associated with significantimpacts on the invertebrate community and key stream ecosystem functions such asprimary production and leaf-litter decomposition. These findings provide novel evi-dence that introductions of growth-enhanced fish into the wild can affect the func-tioning of natural ecosystems and represent a form of intraspecific invasion.Consequently, environmental impact assessments of growth-enhanced organismsneed to explicitly consider ecosystem-level effects