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IntroductionAt the cellular level, acute temperature changes alter ionic conductances, ion channel kinetics, and the activity of entire neuronal circuits. This can result in severe consequences for neural function, animal behavior and survival. In poikilothermic animals, and particularly in aquatic species whose core temperature equals the surrounding water temperature, neurons experience rather rapid and wide-ranging temperature fluctuations. Recent work on pattern generating neural circuits in the crustacean stomatogastric nervous system have demonstrated that neuronal circuits can exhibit an intrinsic robustness to temperature fluctuations. However, considering the increased warming of the oceans and recurring heatwaves due to climate change, the question arises whether this intrinsic robustness can acclimate to changing environmental conditions, and whether it differs between species and ocean habitats. MethodsWe address these questions using the pyloric pattern generating circuits in the stomatogastric nervous system of two crab species,Hemigrapsus sanguineusandCarcinus maenasthat have seen a worldwide expansion in recent decades. Results and discussionConsistent with their history as invasive species, we find that pyloric activity showed a broad temperature robustness (>30°C). Moreover, the temperature-robust range was dependent on habitat temperature in both species. Warm-acclimating animals shifted the critical temperature at which circuit activity breaks down to higher temperatures. This came at the cost of robustness against cold stimuli inH. sanguineus, but not inC. maenas. Comparing the temperature responses ofC. maenasfrom a cold latitude (the North Sea) to those from a warm latitude (Spain) demonstrated that similar shifts in robustness occurred in natural environments. Our results thus demonstrate that neuronal temperature robustness correlates with, and responds to, environmental temperature conditions, potentially preparing animals for changing ecological conditions and shifting habitats.
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Limitations of eDNA analysis for Carcinus maenas abundance estimations
Abstract BackgroundEnvironmental DNA (eDNA) is an effective tool for the detection and monitoring of presence or absence of rare and invasive species. These techniques have been extended to quantify biomass in vertebrates, particularly in fish species. However, the efficacy of eDNA techniques to quantify biomass in invertebrate species has rarely been examined. This study tested whether eDNA could be used to determine the biomass of the world-wide invasive green crab,Carcinus maenas. In a controlled laboratory study, the relationship between biomass andC. maenaseDNA concentration was examined in the context of different biotic (activity) and abiotic (temperature) parameters. ResultsWhen incubating different numbers of crabs in sterile saltwater for up to 7 days, a relationship between eDNA concentration and biomass was observed at temperatures of 6.7 ℃ and 18.7 ℃, but not at 12.8 ℃. Additionally, motor activity, aggression level, time of sampling, and features of organismal decay had significant impact on the concentration ofC. maenaseDNA collected. ConclusionsWe show that eDNA concentration did not correlate with biomass, and that biomass, temperature, organismal characteristics, and potentially many more parameters affect shedding and degradation rates for eDNA in this species, thus, impacting the recoverable eDNA concentration. Therefore, eDNA techniques are not likely to provide a reliable signal of biomass in the invasive invertebrate speciesC. maenas.
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- Award ID(s):
- 1849227
- PAR ID:
- 10362606
- Publisher / Repository:
- Springer Science + Business Media
- Date Published:
- Journal Name:
- BMC Ecology and Evolution
- Volume:
- 22
- Issue:
- 1
- ISSN:
- 2730-7182
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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