Ecosystem Health: Remediation of drinking water
Nuisance blooms of cyanobacteria and algae continue to cause problems for the Water Industry. In collaboration with Wessex Water, we are investigating underlying causes for the persistence of Microcystis spp. and other bloom forming species in supply reservoirs in the south west of England (Stal et al., (2003), Continental Shelf Research, 23: 1695-1714; Stal & Walsby (2000), European Journal of Phycology 35: 97-108). One major problem for drinking water reservoirs in this area is eutrophication. Treatment options involve phosphate stripping of external sources, sediment removal and alteration of mixing regimes to reduce growth of the cyanobacteria. Effectiveness of a microcystin removal system is also being examined. Another key problem is associated with pesticide contamination from agricultural catchments. In collaboration with the School of Geographical Sciences and Wessex Water we have two NERC-CASE funded research projects to address pesticide transport through the catchment and the impact of pesticides on biota in a drinking water reservoir in the south-west. Concurrently, the impact of pesticides on biofilms in streams, along gradients of eutrophication, forms another collaboration with the School of Geographical Sciences, with funding from the FBA and LESARS.
Ecosystem Status: Benthic Diatoms and Assessment of Ecological Status
The European Union’s Water Framework Directive requires all water bodies to achieve ‘good ecological status’ by 2015. This new legislation represents a paradigm shift in the way in which European Waterbodies are managed. A number of key ‘biological’ elements have been identified for assessment of ecological status including periphyton, of which diatoms are a key component. The attached diatom community can play a significant role in stream and lake functioning. Our understanding of the structure and functioning of benthic biofilms (Yallop et al., (2000), Microbial Ecology, 39: 116-127) and their response to pollution gradients has improved significantly over the past few decades (Yallop & Kelly (2006), Nova Hedwigia, Beiheft 130: 357-372). Collaborating with the Environment Agency, Bowburn Consultancy, University of Newcastle and University College, London, we have refined sampling methodologies (King et al., (2006), Journal of Applied Phycology, 18: 15-25) and developed tools for measuring ecological status using benthic diatoms (Kelly et al., (2008), Freshwater Biology, 53: 403-422). Ongoing refinements to the models include the response of diatoms to pH gradients and toxic metals.
Shallow Lakes and State-Switching
We are following long-term changes in autotrophic communities in a series of flooded gravel pits in the UK. Collaborating with CEH we have adapted hydroacoustic techniques to enable us to map the vegetation and examine spatial and temporal patterns of macrophyte biomass (Winfield et al., (2007), Hydrobiologia 584: 111-119). Examination of current and historical records of submerged macrophytes communities is being undertaken to examine charophyte persistence in these marl lakes. Working alongside Cotswold Water Park Society we are aiming to identify environmental factors that lead to charophyte persistence and the maintenance of a clear water state in older lakes.
Foraging strategies of waterbirds in shallow lakes: an integrated ecosystem approach
The UK supports internationally important numbers of wintering waterbirds. A study funded by Natural England in collaboration with WWT, CEH, University of Bath and the Cotswold Water Park Society has investigated how the relationship between two of these waterbird species, Tufted Duck and Pochard, is influenced by human activity on 8 lakes in the Cotswold Water Park, (O’Connell et al., (2007), Ibis 149: 65-72). In a NERC-CASE studentship (in conjunction with WWT and the University of Bath) we are investigating the distribution of wintering waterbirds across the CWP and how these relate to their food resource distribution. Data obtained from hydroacoustic surveys (see Shallow Lakes and State-Switching) has been combined with wider scale macrophyte distribution surveys to assess how macrophytes are distributed in the CWP, with particular attention paid to charophyte species. Charophytes are a preferred food resource for both Tufted Duck and Pochard and results of previous work suggests that they are influencing the distribution of these birds. These algae reproduce sexually (via oospores) and asexually (via bulbils and fragmentation). The densities of both sexual and asexual propagules have been determined in a number of lakes (supported by funding from the BSBI) to assess the reproductive potential of charophytes in different lakes, and their role as a potential direct food resource for waterbirds.