Buffered microclimate determines the presence of Salamandra corsica

Numerous amphibian species occupy microhabitats with buffered thermal and moisture conditions,typically under forest canopies.Here,we assessed whether the insular endemic Salamandra corsica also uses this type of habitat,which could have important implications for its conservation.We used data loggers to record the air temperature and air humidity at 4 h intervals over a period of 2 years,at 13 stations with a confirmed presence of S.corsica.These data were compared with those recorded at Corsican weather stations and those generated by a climate model(WorldClim 2).The weather station data showed significant deviations from the probe data,by an average of-1.26℃(minimum temperature),+2.61℃(maximum temperature),and-0.04%(relative humidity).Similarly,the WorldClim 2 data showed significant deviations from the probe data,by an average of-2.49°C(minimum temperature)and+1.69℃(maximum temperature).These discrepancies refl ect the use of densely vegetated and topographically complex habitats by S.corsica,which reduce temperature fluctuations.Overall,our results highlight the importance of natural vegetal cover in the conservation of populations of this endemic salamander.

Niche differentiation among facultative filter feeders: Insights from invasive Ponto-Caspian mysids

The degree of dietary specialization has a fundamental impact on the ecological function and interactions of suspension feeders.While niche differentiation by food particle size is common among obligate suspension feeders,its role is not evident in facultative ones.In this study,we aimed at providing new insights on the matter by focusing on sympatric mysid species.As mysids use different mechanisms for raptorial and filter-feeding,they represent a more adequate model system than for example,the more extensively studied copepods.We made morpholog-ical measurements on the 4 coexisting invasive Ponto-Caspian mysid species to determine the areas and mesh sizes of their filters.We also quantified their clearance rates on the microalga Cryptomonas sp.in a laboratory experiment to reveal how morphological differences manifest in their overall filtering capacity.We found relatively small but consistent differences in the primary filter area among the species,indicating that morphological constraints due to the enclosed position of the setae might limit the possibility for differentiation.The primary filter mesh sizes were small in all 4 species(0.69-2.73μm)with moderate but consistent intraspecific differences,suggesting that the benefit of being able to capture small particles might outweigh the pressure for differentiation.The observed clearance rates were in accordance with the morphological characteristics of the species,highlighting that auxiliary filters(present in one of the species,Limnomysis benedeni)are needed to increase filtering capacity considerably.Our study confirmed that food particle size can contribute to the niche differentiation of facultative filter feeders,but also indicated that they can tolerate a higher overlap than obligate ones.The observed differences were related to the habitat preferences and predatory potentials of the species,suggesting that complementarity among the different niche axes might further facilitate theircoexistence.

Selective butyric acid production from CO_(2)and its upgrade to butanol in microbial electrosynthesis cells

Microbial electrosynthesis(MES)is a promising carbon utilization technology,but the low-value products(i.e.,acetate or methane)and the high electric power demand hinder its industrial adoption.In this study,electrically efficient MES cells with a low ohmic resistance of 15.7 mU m^(2)were operated galvanostatically in fed-batch mode,alternating periods of high CO_(2)and H2 availability.This promoted acetic acid and ethanol production,ultimately triggering selective(78%on a carbon basis)butyric acid production via chain elongation.An average production rate of 14.5 g m^(-2)d^(-1)was obtained at an applied current of 1.0 or 1.5 mA cm^(-2),being Megasphaera sp.the key chain elongating player.Inoculating a second cell with the catholyte containing the enriched community resulted in butyric acid production at the same rate as the previous cell,but the lag phase was reduced by 82%.Furthermore,interrupting the CO_(2)feeding and setting a constant pH2 of 1.7e1.8 atm in the cathode compartment triggered solventogenic butanol production at a pH below 4.8.The efficient cell design resulted in average cell voltages of 2.6e2.8 V and a remarkably low electric energy requirement of 34.6 kWhel kg1 of butyric acid produced,despite coulombic efficiencies being restricted to 45%due to the cross-over of O_(2)and H2 through the membrane.In conclusion,this study revealed the optimal operating conditions to achieve energy-efficient butyric acid production from CO_(2)and suggested a strategy to further upgrade it to valuable butanol.

Using hierarchical spatial models to assess the occurrence of an island endemism: the case of Salamandra corsica

Background:Island species are vulnerable to rapid extinction,so it is important to develop accurate methods to determine their occurrence and habitat preferences.In this study,we assessed two methods for modeling the occurrence of the Corsican endemic Salamandra corsica,based on macro-ecological and fine habitat descriptors.We expected that models based on habitat descriptors would better estimate S.corsica occurrence,because its distribution could be influenced by micro-environmental gradients.The occurrence of S.corsica was modeled according to two ensembles of variables using random forests.Results:Salamandra corsica was mainly found in forested habitats,with a complex vertical structure.These habitats are associated with more stable environmental conditions.The model based on fine habitat descriptors was better able to predict occurrence,and gave no false negatives.The model based on macro-ecological variables underestimated the occurrence of the species on its ecological boundary,which is important as such locations may facilitate interpopulation connectivity.Conclusions:Implementing fine spatial resolution models requires greater investment of resources,but this is advisable for study of microendemic species,where it is important to reduce type II error(false negatives).

Size-related effects and the influence of metabolic traits and morphology on swimming performance in fish

Energy metabolism fuels swimming and other biological processes.We compared the swimming performance and energy metabolism within and across eight freshwater fish species.Using swim tunnel respirometers,we measured the standard metabolic rate(SMR)and maximum metabolic rate(MMR)and calculated the critical swimming speed(Ucrit).We accounted for body size,metabolic traits,and some morphometric ratios in an effort to understand the extent and underlying causes of variation.Body mass was largely the best predictor of swimming capacity and metabolic traits within species.Moreover,we found that predictive models using total length or SMR,in addition to body mass,signicantly in creased the explained variation of Ucrit and MMR in certain fish species.These predictive models also underlined that,once body mass has been accounted for,Ucrit can be independently affected by total length or MMR.This study exemplifies the utility of multiple regression models to assess within-species variability.At interspecific level,our results showed that variation in UcriX can partly be explained by the variation in the interrelated traits of MMR,finen ess,and muscle ratios.Among the species studied,bleak Al burn us alburnus performed best in terms of swimming performance and efficiency.By contrast,pumpkinseed Lepomis gibbosus showed very poor swimming performance,but attained lower mass-specific cost of transport(MCOT)than some rheophilic species,possibly reflecting a cost reduction strategy to compensate for hydrod yn amic disadvantages.In con elusion,this study provides insight into the key factors in fluenci ng the swimming performa nee of fish at both intra-and in terspecific levels.

Vegetation cover and occurrence of salamanders in the western Mediterranean

The Mediterranean region possesses a rich diversity of salamanders,which also exhibit a high degree of ecological diversification.It is assumed that the presence of salamanders is dependent on the level of vegetation cover in terrestrial habitats,but the strength of this association is likely to vary among species.In this study,we investigated the patterns of habitat utilization for Mediterranean salamanders based on 589 records of 33 species.We tested the hypothesis that the association between salamander presence and vegetation density varies among genera or reproductive modes(i.e.terrestrial vs aquatic).The results show that vegetation cover has similar influences on terrestrial and aquatic groups but important differences are identified for lotic and lentic aquatic species.Our findings also indicate that the aquatic lotic,terrestrial,and small-body species deviate significantly from that expected from the background range of variation.

Effect of environmental enrichment on the body shape of the pumpkinseed

How the morphology of captive-reared fish is affected by structural enrichment in their rearing tanks is not well understood.Some studies have suggested that deficiencies in rearing environments could produce inappropriate body shape in salmonids(Vehanen and Huusko 2011).Garduho-Paz et al.(2010)have found significant differences in body and head shapes of 3-spine stickleback Gasterosteus aculeatus,depending on whether fish were reared in an environment with just gravel or in an environment enriched with large stones and artificial plants.

Direct ammonium oxidation to nitrogen gas (Dirammox) in Alcaligenes strain HO-1: The electrode role

It has been recently suggested that Alcaligenes use a previously unknown pathway to convert ammonium into dinitrogen gas(Dirammox)via hydroxylamine(NH2OH).This fact alone already implies a significant decrease in the aeration requirements for the process,but the process would still be dependent on external aeration.This work studied the potential use of a polarised electrode as an electron acceptor for ammonium oxidation using the recently described Alcaligenes strain HO-1 as a model heterotrophic nitrifier.Results indicated that Alcaligenes strain HO-1 requires aeration for metabolism,a requirement that cannot be replaced for a polarised electrode alone.However,concomitant elimination of succinate and ammonium was observed when operating a previously grown Alcaligenes strain HO-1 culture in the presence of a polarised electrode and without aeration.The usage of a polarised electrode together with aeration did not increase the succinate nor the nitrogen removal rates observed with aeration alone.However,current density generation was observed along a feeding batch test representing an electron share of 3%of the ammonium removed in the presence of aeration and 16%without aeration.Additional tests suggested that hydroxylamine oxidation to dinitrogen gas could have a relevant role in the electron discharge onto the anode.Therefore,the presence of a polarised electrode supported the metabolic functions of Alcaligenes strain HO-1 on the simultaneous oxidation of succinate and ammonium.