Measuring swimming performance of small fishes contributes to a better understanding of how environmental factors affect individual organisms and potentially populations dynamics (e.g., through variable dispersal and connectivity). Here, we automated multi-lane swimming chambers to reduce operator interference and optimize swimming performance measurements of early life stages of fishes. Testing different experimental protocols, we found species-specific sensitivities in offspring from two tropical fishes.
In this study we found that micropredation by a single parasite (gnathiid isopod) significantly decreased escape performance and swimming behaviour of coral reef fish juveniles. However, stress hormone (cortisol) levels doubled. These findings suggest that micropredation may affect the overall fitness of juvenile fish hosts, which may result in large scale changes in the number of fish succesfully recruiting to adult populations on coral reefs.
Here we investigated whether the decreasing annual productivity (i.e. larval abundances) of Baltic Sea herring over the last decade is linked to warmer springs exceeding the physiological optimum of early life stages. Linking physiological thermal tolerance and recruitment indexes from the field, we found that warming is at least partially responsible for the steady decline in recruitment.
In this study, we showed that critical thermal maxima differ across species and life stages in tropical fishes. Furthermore, body mass and experimental heating rate had a strong influence on the measured thermal tolerance. This suggests that these factors need to be accounted for when estimating and comparing heat tolerance across early ontogeny in tropical fishes.
Salinity adds energetic costs for ion regulation in fishes. We tested whether shiner perch are affected by changes in salinity, and found that most metrics related to swimming performance and oxygen consumption of shiner perch were unaffected. This suggests that shiner perch are well-adapted to the fluctuating salinity in their coastal habitat.
We parameterized an individual-based model for Atlantic herring larvae with data on swimming activity, nutritional and somatic condition, and standard metabolic rate under contrasting feeding environments. Larvae survived longer in the model, when they downregulated their standard metabolic rate.
Management and conservation advice can benefit from physiological findings, as these support a mechanistic understanding of changes that are observed on organism- or even population-levels. We highlight examples for coral reef fishes, and advocate better collaboration and knowledge exchange between physiologists and decision-makers.
Swimming ability is crucial for larval fish survival. We measured growth, development and ontogenetic changes in critical swimming speed of Atlantic herring larvae at three temperatures, and found it to be negatively correlated to body length-at-age, suggesting a trade-off between growth rate and locomotor activity.
The stability of marine fish populations is, next to natural or fishing mortality, based on the annual recruitment of the young-of-the-year. The variability in the number of these recruited fish is determined by effects of several abiotic and biotic …
Climate change will reduce the salinity in the Baltic Sea to levels that marine fish species may not be able to tolerate. We acutely exposed Atlantic herring larvae from different Baltic Sea populations to low salinities, and modelled the survival threshold now, and for salinity projections at the end of the 21st century. Climate-driven freshening will make some Baltic habitats unsuitable for larvae.