Temporal changes in the level of infestation of Simulium ornatum Meigen (complex) (Simuliidae: Diptera) larvae by the endosymbiotic fungus Harpella melusinae Lichtwardt (Harpellales: Trichomycetes)

The fungus Harpella melusinae (Harpellales: Trichomycetes) is obligately associated with the midguts of larval Simuliidae (Diptera). The level of infestation of a population of Simulium ornatum by H. melusinae was monitored at a stream in Hampshire, England. Significant temporal changes in the level of infestation were recorded during monthly and weekly collections; a twenty-fold increase being recorded over a nine-day period. Possible mechanisms by which these changes occur are discussed.     

Recolonization following past persecution questions the importance of persistent snow cover as a range limiting factor for wolverines

Globally, climate is changing rapidly, which causes shifts in many species' distributions, stressing the need to understand their response to changing environmental conditions to inform conservation and management. Northern latitudes are expected to experience strongest changes in climate, with milder winters and decreasing snow cover. The wolverine (Gulo gulo) is a circumpolar, threatened carnivore distributed in northern tundra, boreal, and subboreal habitats. Previous studies have suggested that wolverine distribution and reproduction are constrained by a strong association with persistent spring snow cover. We assess this hypothesis by relating spatial distribution of 1589 reproductive events, a fitness-related proxy for female reproduction and survival, to snow cover over two decades. Wolverine distribution has increased and number of reproductive events increased 20 times in areas lacking spring snow cover during our study period, despite low monitoring effort where snow is sparse. Thus, the relationship between reproductive events and persistent spring snow cover weakened during this period. These findings show that wolverine reproductive success and hence distribution are less dependent on spring snow cover than expected. This has important implications for projections of future habitat availability, and thus distribution, of this threatened species. Our study also illustrates how past persecution, or other factors, that have restricted species distribution to remote areas can mask actual effects of environmental parameters, whose importance reveals when populations expand beyond previously restricted ranges. Overwhelming evidence shows that climate change is affecting many species and ecological processes, but forecasting potential consequences on a given species requires longitudinal data to revisit hypotheses and reassess the direction and magnitude of climate effects with new data. This is especially important for conservation-oriented management of species inhabiting dynamic systems where environmental factors and human activities interact, a common scenario for many species in different ecosystems around the globe.     

The feeding of the larvae of Simulium austeni Edwards and Simulium (Wilhelmia) spp.

The possibility that the feeding rates of larvae of S. austeni and S. lineatum are influenced by the nature of the food material is considered in relation to natural river conditions and laboratory feeding experiments. Diatoms appeared to be the most satisfactory food source and bacteria (Pseudomonas) the poorest. Simuliid larvae attain high assimilation efficiencies when feeding on diatoms but the proportion of river suspended solids which they assimilate is probably very low.     

Invertebrate Sampling in the Substratum of an Experimental Recirculating Stream

In order to determine the efficacy of sampling benthic invertebrates to a depth of 100 mm as compared with 200 mm, the gravel substratum of an experimental recirculating stream was sampled to both depths. Except for 6 taxa which were significantly more numerous in the shallower samplers, there was no significant difference between the densities determined from the two depths.     

Life history patterns of river invertebrates

The initiation of invertebrate distribution patterns in rivers occurs by choice of oviposition sites and is influenced by the evolved reproductive strategies of the individual species. Subsequent redistribution by migration or drifting establishes patterns which are then modified by environmental influences on growth and mortality. Continuity of life cycles is sustained by variations on a number of defined life history strategies combined with evolved behavioural responses.     

Studies on production and food consumption by the larval simuliidae (Diptera) of a chalk stream

Summary Large populations of S. ornatum and S. equinum inhabit Ranunculus plants in the Bere Stream at Bere Heath. A weekly sampling programme obtained both larvae and pupae. The results of weekly sampling indicated four annual generations of S. ornatum and three of S. equinum. Quantitative samples of larvae, obtained at least three times in each generation gave estimates of production ranging from 0.26 g to 2.75 g dry weight m-² per generation of larvae of S. equinum and 0.15 g to 1.19 g dry weight m-² per generation of larvae of S. ornatum.Retention times of food by larvae, under field conditions were in the order of twenty to thirty minutes. Following determination of the weight of the gut contents for each size class of larvae, the activity of feeding larvae was calculated to achieve complete theoretical clearance of suspended material in a distance of 0.6 km, at peak population densities in the summer months.Dept. of Applied Biology, Bath University of Technology     

Protected areas buffer the Brazilian semi‐arid biome from climate change

The Caatinga is a botanically unique semi‐arid ecosystem in northeast Brazil whose vegetation is adapted to the periodic droughts that characterize this region. However, recent extreme droughts events caused by anthropogenic climate change have challenged its ecological resilience. Here, we evaluate how deforestation and protection status affect the response of the Caatinga vegetation to drought. Specifically, we compared vegetation responses to drought in natural and deforested areas as well as inside and outside protected areas, using a time‐series of satellite‐derived Normalized Difference Vegetation Index (NDVI) and climatic data for 2008–2013. We observed a strong effect of deforestation and land protection on overall vegetation productivity and in productivity dynamics in response to precipitation. Overall, deforested areas had significantly lower NDVI and delayed greening in response to precipitation. By contrast, strictly protected areas had higher productivity and considerable resilience to low levels of precipitation, when compared to sustainable use or unprotected areas. These results highlight the importance of protected areas in protecting ecosystem processes and native vegetation in the Caatinga against the negative effects of climate change and deforestation. Given the extremely small area of the Caatinga currently under strict protection, the creation of new conservation areas must be a priority to ensure the sustainability of ecological processes and to avoid further desertification.