Diel and seasonal movements of the critically endangered European eel

The critically endangered European eel is declining throughout its range and more information on which to base management plans is necessary. Here we present data collected by electrofishing and PIT telemetry on the habitat use and movements of eel in an English chalk stream in Dorset, southern UK. Eel were sampled quarterly for three years and movements between the main river and a side stream monitored by an in situ PIT detector. Eel abundance was highest in the side stream during summer and autumn and movement between the main river and side stream was greatest during spring, summer and autumn. Eel demonstrated nocturnal movements in/out of the side stream during spring and summer, however this diel pattern was not evident in autumn. The study demonstrates continual use of the connected floodplain by eel, underlining the importance of lateral connectivity to floodplain habitats to the species. Connectivity can be modified or lost by a number of anthropogenic activities such as hydropower and road culverts, but in many cases these can be avoided by proper and sound management. Key words: behaviour, Anguilla anguilla, movement, river connectivity, floodplain.Døgn- og sesongmessige vandringer hos den truede Europeiske ålen. Den Europeiske ålen(ål) er truet over hele dets utbredelsesområde og mer kunnskap om artens biologi og adferd er nødvendig for bedre forvaltning av arten. I denne artikkelen presenterer vi data for habitatbruk og forflytninger av ål i en kalkelv i Dorset, Sør-England basert på omfattende elektrofiske og PIT telemetri. Ål ble fanget fire ganger pr år og forflytninger mellom hovedelv og sidekanaler ble overvåket med hjelp av in situ PIT detektor i en periode på tre år. Det var høyeste forekomst av ål i sidekanalene om sommeren og høsten og det var omfattende forflytninger av ål mellom hovedelva og sidekanalene under vår, sommer og høst. Ålen hadde nattlige vandringer inn og ut av sidekanalene under vår og sommer, men denne døgn adferden var ikke tydelig om høsten når blankål startet sin utvandring mot sjøen. Studien demonstrerer ålen sin kontinuerlige bruk av flomområder og kanaler, og understreker viktigheten av å opprettholde forbindelsene fra hovedelva til disse habitatene for denne arten. Vannveier for fisk kan bli påvirket eller tapt ved en rekke antropogene aktiviteter slik som kraftutbygging og vei kulverter, men i en flere tilfeller kan dette ungåes ved god planlegging og kompetanse om fiskens adferd.publishedVersio

The influence of predation on community resilience to disease

1. Outbreaks of generalist pathogens are influenced by host community structure, including population density and species diversity. Within host communities predation can influence pathogen transmission rates, prevalence and impacts. However, the influence of predation on community resilience to outbreaks of generalist pathogens are not fully understood. 2. The role of predation on host community resilience to disease was assessed using an epidemiological multi-host Susceptible-Exposed-Infectious-Recovered (SEIR) model. Sphaerothecum destruens, an emerging fungal-like generalist pathogen, was used as a model pathogen. Six cyprinid and salmonid fishes, including an asymptomatic carrier, were selected as model hosts that are known to be impacted by S. destruens, and they were used within a model host community. 3. Pathogen release into the host community was via introduction of the asymptomatic carrier. Mortality from infection, pathogen incubation rate, and host recovery rate were set to a range of evidence-based values in each species and were varied in secondary consumers to predict top-down effects of infection on the resilience of a host community. Predation pressure within the fish community was varied to test its effects on infection prevalence and host survival in the community. 4. Model predictions suggested that predation of the asymptomatic hosts by fishes in the host community was insufficient to eliminate S. destruens. S. destruens persisted in the community due to its rapid transmission from the asymptomatic host to susceptible host fishes. Following transmission, pathogen prevalence in the community was driven by transmission within and between susceptible host fishes, indicating low host community resilience. However, introducing low densities of a highly specific piscivorous fish into the community to predate asymptomatic hosts could limit pathogen prevalence in the host community, thus increasing resilience. 5. The model predictions indicate that whilst resilience to this generalist pathogen in the host community was low, this could be increased using management interventions. The results suggest that this model has high utility for predicting community resilience to disease and thus can be applied to other generalist parasites to determine risks of disease emergence

Do non-native pumpkinseed Lepomis gibbosus affect the growth, diet and trophic niche breadth of native brown trout Salmo trutta?

Brown trout Salmo trutta Linnaeus, 1758, is a priority species for conservation and management efforts in many European countries. In its native range, interactions with non-native fishes often adversely affect somatic growth rates and population abundances. Consequences of introduced North American pumpkinseed Lepomis gibbosus (Linnaeus, 1758) for native S. trutta were examined in stream stretches with and without L. gibbosus. Data for somatic growth rates and trophic niche breadth (using stable isotope analyses) provided little evidence of L. gibbosus presence being detrimental for S. trutta. Shifts in S. trutta diet at all sites were associated with increased piscivory with increasing body length, with no evidence to suggest that interspecific resource competition with L. gibbosus structured the food web or affected trophic positions. Three years later, and following L. gibbosus removal, data revealed slight shifts in the food web at each site, but these related to shifts in resources at the bottom of the food chain rather than a response to L. gibbosus removal. Consequently, the ecological consequences of L. gibbosus for S. trutta in the study stream were minimal, with S. trutta populations responding more to natural mechanisms regulating their populations than to the presence of this non-native fish species

A Support Vector Machine Based Approach for Predicting the Risk of Freshwater Disease Emergence in England

Disease emergence, in the last decades, has had increasingly disproportionate impacts on aquatic freshwater biodiversity. Here, we developed a new model based on Support Vector Machines (SVM) for predicting the risk of freshwater fish disease emergence in England. Following a rigorous training process and simulations, the proposed SVM model was validated and reported high accuracy rates for predicting the risk of freshwater fish disease emergence in England. Our findings suggest that the disease monitoring strategy employed in England could be successful at preventing disease emergence in certain parts of England, as areas in which there were high fish introductions were not correlated with high disease emergence (which was to be expected from the literature). We further tested our model’s predictions with actual disease emergence data using Chi-Square tests and test of Mutual Information. The results identified areas that require further attention and resource allocation to curb future freshwater disease emergence successfully

Native drivers of fish life history traits are lost during the invasion process

© 2020 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd. Rapid adaptation to global change can counter vulnerability of species to population declines and extinction. Theoretically, under such circumstances both genetic variation and phenotypic plasticity can maintain population fitness, but empirical support for this is currently limited. Here, we aim to characterize the role of environmental and genetic diversity, and their prior evolutionary history (via haplogroup profiles) in shaping patterns of life history traits during biological invasion. Data were derived from both genetic and life history traits including a morphological analysis of 29 native and invasive populations of topmouth gudgeon Pseudorasbora parva coupled with climatic variables from each location. General additive models were constructed to explain distribution of somatic growth rate (SGR) data across native and invasive ranges, with model selection performed using Akaike's information criteria. Genetic and environmental drivers that structured the life history of populations in their native range were less influential in their invasive populations. For some vertebrates at least, fitness-related trait shifts do not seem to be dependent on the level of genetic diversity or haplogroup makeup of the initial introduced propagule, nor of the availability of local environmental conditions being similar to those experienced in their native range. As long as local conditions are not beyond the species physiological threshold, its local establishment and invasive potential are likely to be determined by local drivers, such as density-dependent effects linked to resource availability or to local biotic resistance

Native drivers of fish life history traits are lost during the invasion process

Rapid adaptation to global change can counter vulnerability of species to population declines and extinction. Theoretically, under such circumstances both genetic variation and phenotypic plasticity can maintain population fitness, but empirical support for this is currently limited. Here, we aim to characterize the role of environmental and genetic diversity, and their prior evolutionary history (via haplogroup profiles) in shaping patterns of life history traits during biological invasion. Data were derived from both genetic and life history traits including a morphological analysis of 29 native and invasive populations of topmouth gudgeon Pseudorasbora parva coupled with climatic variables from each location. General additive models were constructed to explain distribution of somatic growth rate (SGR) data across native and invasive ranges, with model selection performed using Akaike's information criteria. Genetic and environmental drivers that structured the life history of populations in their native range were less influential in their invasive populations. For some vertebrates at least, fitness-related trait shifts do not seem to be dependent on the level of genetic diversity or haplogroup makeup of the initial introduced propagule, nor of the availability of local environmental conditions being similar to those experienced in their native range. As long as local conditions are not beyond the species physiological threshold, its local establishment and invasive potential are likely to be determined by local drivers, such as density-dependent effects linked to resource availability or to local biotic resistance

Environmental biology and morphodynamics of the sofie Chondrostoma toxostoma (Cyprinidae), with emphasis on early development

SIGLEAvailable from British Library Document Supply Centre-DSC:DXN020113 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Allometric scaling of intraspecific space use

Allometric scaling relationships enable exploration of animal space-use patterns, yet interspecific studies cannot address many of the underlying mechanisms. We present the first intraspecific study of home range (HR) allometry relative to energetic requirements over several orders of magnitude of body mass, using as a model the predatory fish, pike Esox lucius. Analogous with interspecific studies, we show that space use increases more rapidly with mass (exponent = 1.08) than metabolic scaling theories predict. Our results support a theory that suggests increasing HR overlap with body mass explains many of these differences in allometric scaling of HR size. We conclude that, on a population scale, HR size and energetic requirement scale allometrically, but with different exponents