Hugh B. Feeley

The potential of integrated constructed wetlands (ICWs) to enhance macroinvertebrate diversity in agricultural landscapes

Integrated Constructed Wetlands (ICWs) constitute an alternative option for the treatment of agricultural wastewater in Ireland. These surface flow systems are formed by interconnected ponds and have the capacity to fit into the landscape and provide habitat for a wide range of biota, including macroinvertebrates that have enormous potential for biodiversity enhancement. For these reasons, five ICW systems were studied. In addition, five natural ponds were investigated to account for the potential of ICW ponds to mimic natural conditions. Nine river sites were also investigated to allow for an evaluation of the catchment biodiversity contribution of the ICW systems. The present study revealed that the last ponds in the chain of these ICW systems are capable of supporting a similar number of taxa as natural ponds. Furthermore, the contribution of the last ponds to the macroinvertebrate diversity at the catchment level was high. ICWs seem to integrate their effluent management and purifying properties with that of biodiversity enhancement and landscape fit. This is the first study to investigate the potential of constructed interconnected ponds, used for wastewater treatment, to enhance biodiversity in agricultural landscapes.

A regional examination of episodic acidification response to reduced acidic deposition and the influence of plantation forests in Irish headwater streams

Episodic surface water acidification is common in many regions worldwide; the driving processes are dependent on a variety of physicochemical and climatic characteristics, and acid deposition pressures, which have changed significantly over the last two decades. This study provided a unique opportunity to re-examine the drivers of acidity in an environment of low anthropogenic input. In three geologically distinct acid-sensitive regions of Ireland during 2009-2010, 34 headwater streams were evaluated in peat-dominated catchments draining moorlands without forest, 20-50% (low) forest cover and >50% (high) forest cover. Results indicated episodic acidity/alkalinity loss in headwater streams, despite significant reductions in acid deposition. Both the differences in pH between base and storm-flow (∆pH) and the number of pH events≤5.5 were higher in forested streams. Dissolved organic carbon and inorganic aluminium concentrations were also higher in forested catchments. The primary driver of acidity was strong organic anions, which generally increased with increasing forest cover. Base-cation dilution was also prominent in west and southern regions, while surprisingly chlorine anion acidity from sea-salts had little or no influence on stream acidity. The contributions of excess non-marine sulphate (xSO(4)) and nitrate (NO(3)) to storm-water were low, with no observed increases in xSO(4) with increasing forest cover, although contributions of NO(3) were higher in forested catchments in the east. The results suggest that episodic acidification in Ireland is primarily driven by organic acids. However in peat dominant catchments, plantation forest, climate change and/or reductions in xSO(4) appear to also be having an effect on stream pH from increased DOC, with some forested streams previously unaffected by deposition now showing low pH (<5.5) during storm-flow. As quantified from this study, observed changes in stream acidification in Ireland may provide a better understanding of future chemical responses to declining acid deposition and climate change elsewhere.

The life history of Perla bipunctata Pictet, 1833 (Plecoptera: Perlidae) in the upper River Liffey, Ireland

Perla bipunctata is the most common species of Perlidae in Ireland occurring in fast flowing, clean rivers and small streams. Although a common component of freshwater biological studies, little is known about the autecology of this stonefly. Monthly kick and Surber samples were taken over a 1-year period in the upper reaches of the River Liffey (4th order) to determine the life history of larvae. Perla bipunctata has a merovoltine life cycle taking no less than three years to complete the immature stages. Life history plots suggest two periods of egg hatching, followed by two separate cohorts developing over different lengths of time. Mature larvae from both cohorts synchronise and emerge as adults over a short period in early summer. The merovoltine life cycles of long lived invertebrates like P. bipunctata emphasise the importance of such species in reflecting the ecological quality of freshwaters over a long period of time.

An evaluation of local and regional diversity of benthic macroinvertebrate communities in two small regions of Ireland and their potential as localised refugia for certain taxonomic group

The objective of this study was to evaluate the taxonomic diversity of freshwater benthic macroinvertebrate communities in two small geographical regions of Ireland and assess their potential as critical refugia for local recolonisation in the future. Areas were identifi ed from previous studies as potentially supporting a high diversity of aquatic macroinvertebrates. Six rivers in the Slieve Bloom Mountains and fi ve rivers in the Killarney region of County Kerry were sampled. Where possible, each river was sampled at intervals along its course at source, 2.5km, 5km and 10km. The local and regional taxonomic richness and β-diversity were assessed at all sites. The results showed that both regions have many healthy freshwater systems and a high occurrence of selected Irish benthic macroinvertebrate species. The local richness and diversity was found to be low, with a high heterogeneity among sites sampled. The regional richness and diversity was high, however, indicating the importance of both regions for benthic macroinvertebrate diversity in Ireland and their potential to act as local refugia in the future. The protection of these regions may be extremely important in providing refuge populations in the future from which surrounding areas can be re-populated, facilitating ecological recovery as required by the Water Framework Directive.

The influence of water quality on hyporheic invertebrate communities in agricultural catchments

Despite knowing that agricultural practices affect river ecosystems, studies on water quality and associated hyporheic invertebrate communities are rare. Yet such knowledge is essential for sustainable use of agricultural and water resources. This study, carried out in the agricultural region of south-eastern Ireland in Spring 2007, examined the effect of water pollution on hyporheic fauna. Six river sites of known water quality were assigned to two treatments, namely, clean and polluted rivers. Two hyporheic habitats, below the wetted channel (hyporheic substream) and below the exposed gravel bank (parafluvial), were sampled within each treatment. Total invertebrate densities and richness, crustacean densities and richness, and densities of Ephemeroptera, Plecoptera and Trichoptera (EPT) were significantly reduced in polluted hyporheic and parafluvial habitats. A higher recorded concentration of nitrate in the polluted hyporheic substream habitats was a significant factor in determining the invertebrate assemblages, with reductions in total and crustacean densities, and EPT richness. Similarly, invertebrate density and richness were reduced in polluted parafluvial habitats, likely being related to agricultural intensity, management practices and reduced riparian buffering. This study highlights the direct effects of agricultural practices on the invertebrate communities of hyporheic habitats and emphasises the need for holistic management and conservation measures to ensure future protection.