Biology subjects

Goulon, C.

Publications and source records attributed to Goulon, C..

4 recordsLinked to original sources

bioRxiv2025

Early-life temperature drives recruitment success in Eurasian perch (Perca fluviatilis) populations

Interannual fluctuations in the abundance of young-of-the-year (YOY) European perch (Perca fluviatilis) were studied in two large French peri-alpine lakes using a 12-year dataset of late summer hydroacoustic surveys. Previous research based on sampling over only a few years in localized areas or experimental systems has already highlighted the importance of temperature. However, these studies often considered only monthly or seasonal averages. In our study, we sought to understand the factors behind the significant annual fluctuations in perch stock and analysed 12 years of data at the ecosystem level. We used traditional thermal indices based on average values, as well as novel indices reflecting daily temperature fluctuations, which were derived from 36 years of in situ perch spawning data. Embryonic thermal conditions alone accounted for between 44% and 88% of the variation in YOY density across the lakes. An increase in temperature during the embryonic phase was beneficial, whereas significant daily variations had the opposite effect. In contrast, trophic factors and the adult stock did not exhibit consistent trends. Our study confirms previous findings using ecosystem-scale analyses, long-term data, and novel thermal indices, validating in natura the central role of spring thermal regimes in shaping recruitment and improving our understanding of recruitment variability under climate change.

ecology↗

bioRxiv2025

Environmental DNA (eDNA) sampling strategies influence estimates of freshwater fish eDNA concentrations.

Quantifying in-situ environmental DNA (eDNA) concentrations is increasingly used to infer fish abundance and biomass in freshwater ecosystems. While various sampling strategies (i.e. the combination of sample collection, eDNA preservation and extraction protocols) have been proposed to collect eDNA, little efforts have been undertaken to evaluate how these different strategies affect taxon-specific eDNA recovery and the subsequent estimates of in-situ eDNA concentrations. In this study, we compared a point (i.e. eDNA collection from relatively small and spatially separated water samples filtered using low capacity filter units) and a spatially integrated sampling strategy (i.e. eDNA collected from spatially integrated larger water volumes filtered using high capacity filter units) in two natural lakes. Through quantitative analyses of total DNA, total fish eDNA and species-specific eDNA, we assessed the performance of both strategies to infer in-situ eDNA concentrations. Our results showed that the integrated strategy led to a reduced recovery of fish eDNA and a subsequent underestimation of in-situ eDNA concentrations compared to the point sampling strategy. While the exact mechanisms underlying this pattern require further investigation, our findings highlight the importance of carefully selecting sampling strategies according to study objectives.

genetics↗

bioRxiv2022

A quantitative eDNA-based method to monitor fish spawning in lakes: application to European perch and whitefish

There is an urgent need to evaluate the effects of anthropogenic pressures and climatic change on fish populations dynamics. When monitored in lakes, the spawning of fish is generally assessed using traditional, mostly destructive or damaging, methods as gillnetting and collection of fertilized eggs. Over the last decade, environmental DNA (eDNA) based methods have been widely developed for the detection of aquatic species, offering a non-invasive alternative method to conventional biomonitoring tools. In particular, the emergence of new methods as the droplet digital PCR (ddPCR) offer the possibility to quantify an absolute eDNA signal in a very sensitive way and at a low cost. Here, we developed and implemented a quantitative eDNA method to monitor the spawning activity of two fish species, European perch and whitefish. ddPCR protocols were formalized based on existing and newly designed COI primers, and were applied during four spawning periods in lake Geneva. The results demonstrate the efficiency of eDNA coupled with ddPCR to identify the timing and duration of the spawning periods, as well as the peak of the spawning activity for the targeted species. In addition, the use of a control species (i.e., quantification of the eDNA signal of a fish that does not reproduce during the monitoring period) was shown to be relevant to clearly discriminate fluctuations of the eDNA signal associated to the spawning activity from the baseline eDNA signal. For future implementation, we recommend using an integrative sampling strategy (e.g., pooled samples for a give station) to smooth the local variability of the eDNA signal. These results show that we reached an operational level to use these non-invasive eDNA methods to monitor the spawning periods of these two fish species in large lakes.

ecology↗

bioRxiv2021

Influence of warming temperatures on coregonine embryogenesis within and among species

The greatest known global response of lakes to climate change has been an increase in water temperatures. The responses of many lake fishes to warming water temperatures are projected to be inadequate to counter the speed and magnitude of climate change. We experimentally evaluated the responses of embryos from a group of cold, stenothermic fishes (Salmonidae Coregoninae) to increased incubation temperatures. Study groups included cisco (Coregonus artedi) from lakes Superior and Ontario (USA), and vendace (C. albula) and European whitefish (C. lavaretus) from Lake Southern Konnevesi (Finland). Embryos from artificial crossings were incubated at water temperatures of 2.0, 4.5, 7.0, and 9.0{degrees}C, and their responses were quantified for developmental and morphological traits. Embryo survival, incubation period, and length-at- hatch were inversely related to incubation temperature whereas yolk-sac volume increased with incubation temperature within study groups. However, varying magnitudes of responses among study groups suggested differential levels of developmental plasticity to climate change. Differential levels of parental effects indicate genetic diversity may enable all study groups to adapt to cope with some degree of changing environmental conditions. Our results suggest that the coregonines sampled within and among systems may have a wide range of embryo responses to warming incubation conditions.

ecology↗