Temporal dynamics of aquatic communities and implications for pond conservation

Conservation through the protection of particular habitats is predicated on the assumption that the conservation value of those habitats is stable. We test this assumption for ponds by investigating temporal variation in macroinvertebrate and macrophyte communities over a 10-year period in northwest England. We surveyed 51 ponds in northern England in 1995/6 and again in 2006, identifying all macrophytes (167 species) and all macroinvertebrates (221 species, excluding Diptera) to species. The alpha-diversity, beta-diversity and conservation value of these ponds were compared between surveys. We find that invertebrate species richness increased from an average of 29. 5 species to 39. 8 species between surveys. Invertebrate gamma-diversity also increased between the two surveys from 181 species to 201 species. However, this increase in diversity was accompanied by a decrease in beta-diversity. Plant alpha-, beta and gamma-diversity remained approximately constant between the two periods. However, increased proportions of grass species and a complete loss of charophytes suggests that the communities are undergoing succession. Conservation value was not correlated between sampling periods in either plants or invertebrates. This was confirmed by comparing ponds that had been disturbed with those that had no history of disturbance to demonstrate that levels of correlation between surveys were approximately equal in each group of ponds. This study has three important conservation implications: (i) a pond with high diversity or high conservation value may not remain that way and so it is unwise to base pond conservation measures upon protecting currently-speciose habitats; (ii) maximising pond gamma-diversity requires a combination of late and early succession ponds, especially for invertebrates; and (iii) invertebrate and plant communities in ponds may require different management strategies if succession occurs at varying rates in the two groups

Developing measures for valuing changes in biodiversity : final report

This document reports the findings from the DEFRA funded research project 'Developing measures for valuing changes in biodiversity'. The aim of the research was to develop an appropriate framework that will enable cost-effective and robust valuations of the total economic value of changes to biodiversity in the UK countryside. The research involved a review of ecological and economic literature on the valuation of biodiversity changes. The information gathered from this review, along with the findings from a series of public focus groups and an expert review of valuation methodologies, were used to develop a suite of valuation instruments that were used to measure the economic value of different aspects of biodiversity. Contingent valuation and choice experiment studies were administered to households in Cambridgeshire and Northumberland, while valuation workshops were conducted in Northumberland only. The data from these studies were also used to test for benefits transfer

Spiders in the agricultural landscape

Spiders in agroecosystems play a role in natural pest suppression and contribute to biodiversity. In this thesis I have investigated if and when spiders recolonise cereal fields in spring when they have the potential to suppress establishing pest aphid populations. Furthermore, the influence of different environmental factors on spiders has been investigated to understand how it might be possible to provide suitable conditions for enhancement of their populations. Linyphiid spiders recolonised fields after being negatively affected by sowing in spring, while lycosid spiders were unaffected. Conversely, lycosids showed a recolonisation in winter cereals after overwintering, but not linyphiids. But linyphiid migratory patterns also differed over time, because they were positively influenced by landscape heterogeneity in the beginning of spring but not at the end. Diversity of lycosid and linyphiid spiders was positively influenced by perennial crops and forest in the surrounding landscape. Field margins were found to be a key habitat for the diversity of both spider families. Lycosid abundance was affected on the habitat scale and linyphiid abundance on the larger landscape scale, which can be explained by the families' different modes of dispersal. Farming systems, conventional or organic, contained different compositions of lycosid and linyphiid species. The dominant lycosid and linyphiid species were more abundant at organic sites. Body condition of Pardosa (Lycosidae) turned out to be superior in landscapes dominated by large fields with annual crops, irrespective of farming system, perhaps because of less competition for available resources. This thesis provides evidence that spiders are present in crop fields early in spring when they have the opportunity to suppress establishing aphid pests. Different spider species were associated with different farming systems, but the abundances of the most common species were enhanced by organic management. A diverse landscape with easy access to perennial crops and field margins will augment both number of species and individuals of spiders

A new measure of conservation value combining rarity and ecological diversity: a case study with light trap collected caddisflies (Insecta: Trichoptera)

The objective of the present study was to analyse the conservation importance of streams, rivers and lakes for maintaining caddistly assemblages of Hungarian localities. Light traps ensured comparable catches of caddisflies from different aquatic habitats. A total of 245,363 individuals belonging to 152 species collected from 23 localities over the flight period were included in the analysis. Conservation value of caddistly assemblages was evaluated on the basis of a newly developed Rarity and Ecological Diversity (RED)-index expressing ecological diversity and the average rarity of caddistlies in Hungarian localities. The results showed that streams were the most suitable habitats for maintaining rare caddisfly species in diverse assemblages, while rivers had the lowest conservation importance

Freshwater Macroinvertebrates

The purpose of this resource is to sample, identify, and count macroinvertebrates at a Hydrology Site. Students collect, sort, identify, and count macroinvertebrates from habitats at their site. Educational levels: Middle school, High school, Intermediate elementary, Primary elementary

Choosing the best of both worlds

The great crested newt (Triturus cristatus) is dependent on two environments for its survival: the aquatic habitat necessary for breeding and development, and the terrestrial habitat required for post-breeding and juvenile activities. For a population to be able to survive in a landscape, both habitat types must be present within migration distance from each other. The overall aim of this thesis is to find and describe prerequisites of environments and landscapes that make them sufficient as habitats for the great crested newt. The purpose is also to present the results in a conservation perspective and to discuss them in relation to practical examples. In five separate studies, performed in Örebro County, south-central Sweden, the aquatic and terrestrial habitats of the species were examined. The first study examined aquatic plants in a variety of ponds and landscapes, to determine if the diversity of plant species was higher in ponds where great crested newts were present. I found that ponds with newts had a significantly higher mean number of plant species than ponds without the species. The second study focused on the question if there are chemical and physical characteristics that determine occurrence of great crested newts. The results showed that temperature and nutrient levels (nitrogen and phosphorus) were important in distinguishing between ponds with and without newts, whereas other physical variables were less important. My results also suggest that the great crested newt selects ponds with low nutrient levels for breeding, while the species may also be present in ponds with higher nutrient levels. The third study used radio-telemetry in an attempt to determine how the great crested newt moved in its terrestrial habitat and which micro-habitats it used while the focal point of study four was the landscape and if landscape composition may predict use of ponds as aquatic habitats. Combined, studies three and four suggest that management of the species should to a greater extent include terrestrial habitat, with special attention given to older, deciduous-rich forest within approximately 200 m of breeding ponds. The aim of the last study was to describe and evaluate a project concerning translocation of a great crested newt population. I point out the necessity of long-term monitoring to distinguish any possible success with respect to site sustainability and population size

Fish assemblages associated with natural and anthropogenically-modified habitats in a marine embayment: Comparison of baited videos and opera-house traps

Marine embayments and estuaries play an important role in the ecology and life history of many fish species. Cockburn Sound is one of a relative paucity of marine embayments on the west coast of Australia. Its sheltered waters and close proximity to a capital city have resulted in anthropogenic intrusion and extensive seascape modification. This study aimed to compare the sampling efficiencies of baited videos and fish traps in determining the relative abundance and diversity of temperate demersal fish species associated with naturally occurring (seagrass, limestone outcrops and soft sediment) and modified (rockwall and dredge channel) habitats in Cockburn Sound. Baited videos sampled a greater range of species in higher total and mean abundances than fish traps. This larger amount of data collected by baited videos allowed for greater discrimination of fish assemblages between habitats. The markedly higher diversity and abundances of fish associated with seagrass and limestone outcrops, and the fact that these habitats are very limited within Cockburn Sound, suggests they play an important role in the fish ecology of this embayment. Fish assemblages associated with modified habitats comprised a subset of species in lower abundances when compared to natural habitats with similar physical characteristics. This suggests modified habitats may not have provided the necessary resource requirements (e.g. shelter and/or diet) for some species, resulting in alterations to the natural trophic structure and interspecific interactions. Baited videos provided a more efficient and non-extractive method for comparing fish assemblages and habitat associations of smaller bodied species and juveniles in a turbid environment