DOI: 10.5061/dryad.tf641
title: Data from: Thermal limits in native and alien freshwater peracarid Crustacea: the role of habitat use and oxygen limitation

description: 1. In order to predict which species can successfully cope with global
 warming and how other environmental stressors modulate their vulnerability
 to climate related environmental factors, an understanding of the
 ecophysiology underpinning thermal limits is essential for both
 conservation biology a nd invasion biology. 2. Heat tolerance and the
 extent to which heat tolerance differed with oxygen availability were
 examined for four native and four alien freshwater peracarid crustacean
 species, with differences in habitat use across species. Three hypotheses
 were tested: 1) Heat and lack of oxygen synergistically reduce survival of
 species; 2) Patterns in heat tolerance and the modulation thereof by
 oxygen differs between alien and native species, and between species with
 different habitat use; 3) small animals can better tolerate heat than
 large animals and this difference is more pronounced under hypoxia. 3. To
 assess heat tolerances under different oxygen levels, animal survival was
 monitored in experimental chambers in which the water temperature was
 ramped up (0.25 ˚C min-1). Heat tolerance (CTmax) was scored as the
 cessation of all pleopod movement, and heating trials were performed under
 hypoxia (5kPa Oxygen), normoxia (20 kPa) and hyperoxia (60 kPa). 4. Heat
 tolerance differed across species as did the extent by which heat
 tolerance was affected by oxygen conditions. Heat tolerant species, e.g.,
 Asellus aquaticus and Crangonyx pseudogracilis, showed little response to
 oxygen conditions in their CTmax, whereas the CTmax of heat sensitive
 species, e.g., Dikerogammarus villosus and Gammarus fossarum, was more
 plastic, being increased by hyperoxia and reduced by hypoxia. 5. In
 contrast to other studies on crustaceans, alien species were not more heat
 tolerant than native species. Instead, differences in heat tolerance were
 best explained by habitat use, with species from standing waters being
 heat tolerant and species from running waters being heat sensitive. In
 addition, larger animals displayed lower CTmax, but only under hypoxia. An
 analysis of data available in the literature on metabolic responses of the
 study species to temperature and oxygen conditions suggests that oxygen
 conformers and species whose oxygen demand rapidly increases with
 temperature (low activation energy) may be more heat sensitive. 6. The
 alien species D. villosus appeared most susceptible to hypoxia and heat
 stress. This may explain why this species is very successful in colonizing
 new areas in littoral zones with rocky substrate which are well aerated
 due to continuous wave action generated by passing ships or prevailing
 winds. This species is less capable of spreading to other waters which are
 poorly oxygenated and where C. pseudogracilis is the more likely dominant
 alien species.
description: Dataset on Heat
 toleranceThis dataset gives heat
 tolerance values measured for 8 different species, measured at hypoxia
 (5kPa), normoxia (20 kPa) and hyperoxia (60kPa). The 8 species comprise 4
 exotic and 4 native species and they further differ in their preferred
 habitat (standing waters, running waters or
 indifferent).FE_datfile_TTolerance.csvR-scripts for analysing heat tolerance dataR-script contains code to analyse and plot the data on heat tolerance and is programmed in RFE_R-script_Ttolerance.RDataset on activation energy (Ea)This dataset compiles published data on respiration rates for 6 different species, measured at different temperatures to calculate its thermal dependency, expressed as Activation Energy (Ea). Literature sources are given in full in the accompanying paper.FE_datafile_Ea.csvR-scripts for analyzing activation energy (Ea)R-script contains code to analyse and plot the data on activation Energy and is programmed in RFE_R-script_Ea.RDataset on respiratory responses to hypoxiaThis dataset compiles published data on respiration rates for 4 different species, measured at different levels of oxygen. Literature sources are given in full in the accompanying paper.FE_datafile_Pcrit.csvR-scripts for analysing respiratory responses to hypoxiaR-script contains code to analyse and plot the data on respiratory responses to hypoxia and is programmed in RFE_R-script_Pcrit.R