Aquatic systems, including rivers, streams, and ponds are dynamic systems characterised by differing velocity patterns, sediment and nutrient loads, and thermal regimes. These physical habitat and water quality conditions change temporally (from seconds to annual fluctuations) and spatially (from habitat patches to a catchment scale). These variations produce a range of geomorphological features and habitats (i.e. depositional bars, terraces, eroding banks) that influence ecological communities. Aquatic biota, such as benthic invertebrates, fish, macrophytes, and algae have adapted to hydraulically different fluvial environments.
‘Hydroecology’ or ‘Ecohydrology’ research is at the interface between hydrological and ecological sciences, and focuses on the effects of hydrology on ecosystems or vice versa. Our hydroecological research within the RSRG has focused on how hydrological and physical habitat differences (i.e. flow, sediment and water quality) influence benthic invertebrate diversity and community composition. Identifying the influences of hydrological and physical habitat variations on aquatic biota is important for understanding the impacts of anthropogenic impacts on aquatic systems, community assemblage processes and conservation, sustaining water resources and ecosystem management. Our projects within the RSRG focus on how different hydrological and geomorphic conditions influence aquatic biota at different spatial and temporal scales.
Current Research Projects
The effect of a fine sediment pulse and differing substrate characteristics on invertebrate communities.
Dr Tory Milner and Dr Ian Maddock are currently supervising George Bunting, a river science PhD student, who is investigating the effect of a fine sediment pulse on benthic and hyporheic invertebrate communities, and how this effect is influenced by varying substrate characteristics. The studentship is fully funded by UW, and is in collaboration with Dr Iwan Jones at Queen Mary, University of London.
George’s PhD project used twelve open-air stream mesocosms to identify the effect of a fine sediment pulse on bed sediments and the dispersal pathways (i.e. surface, longitudinal and vertical) of benthic and hyporheic invertebrates. The experiment was conducted between June and October 2015 using stream mesocosms at the Freshwater Biological Association’s River Laboratory in Dorset, UK. Four blocks of mesocosms containing three aluminium linear flumes (0.33m width, 12.4m length and 0.3m in depth) are gravity-fed from the Mill Stream, a tributary of the River Frome. The use of stream mesocosms permitted us to test the influence of fine sediment on invertebrate communities, whilst allowing other factors (e.g. water quality, temperature, water depth) to be constant, which is not possible in natural rivers.
Effects of flow intermittency on invertebrate diversity and community composition in an intermittent river network.
Dr Matthew Hill, a postdoctoral researcher and lecturer in river science and freshwater ecology is examining the impacts of mid-reach drying on invertebrate diversity and community assembly processes in the River Hamps and River Manifold in Derbyshire. Matt is collaborating with Dr Tory Milner (principal investigator) and Dr Rachel Stubbington at Nottingham Trent University.
Intermittent rivers constitute more than a quarter of the total length and discharge of the global river network. Further, climate models predict that the intensity, frequency and duration of drought events will increase significantly over the next 100 years in temperate environments, increasing the occurrence and frequency of river drying. Despite this, temporary freshwaters in temperate regions have received little research attention historically. Flow cessation (drying) is a key determinant of aquatic diversity and community assemblage in flowing systems. The loss of surface flow typically causes a decline in available wetted habitat and a reduction in habitat heterogeneity and hydrological connectivity. Matt’s post doc aims to: (1) quantify the total diversity and conservation value of an intermittent river network (incorporating diversity from lotic, lentic and terrestrial phases of intermittent rivers); (2) examine the beta-diversity (nestedness/turnover) and local and regional drivers of macroinvertebrate communities among intermittent streams and; (3) examine the compositional variation in macroinvertebrate taxa between lotic and ponding stages (does intermittent stream ponding act as a refuge for lotic taxa and/or habitat for newly colonising taxa?). Understanding the impact of drying to biodiversity and community processes at the catchment scale is increasingly important given predicted changes in climate and for the effective conservation and management of these important, but understudied systems.
Pebble clusters as refugia for benthic invertebrates in mixed bedrock-alluvial streams.
Hydrological disturbances (i.e. floods and droughts) strongly influence benthic invertebrate communities. Hydraulic stresses associated with high and low flows may cause changes to benthic community structure via downstream drift, vertical movement and may increase mortality rates. However, a range of different habitat patches, such as stable stone surfaces, macrophytes, and the hyporheic zone can potentially provide refuges for invertebrates from hydraulic stress. Our research in this area examines the spatial and temporal use of pebble clusters as flow refuges for invertebrates in mixed bedrock-alluvial streams. The project is a joint collaboration between Dr Tory Milner (principal investigator), Dr Matt Hill (both UW) and Professor Paul Wood, Loughborough University.
Dr Rachael Carrie, a postdoctoral researcher and lecturer in sustainable development, has specialist knowledge of stream bio-assessment gained by working and undertaking research in the UK and Belize, Central America. Rachael’s recent research has explored context specific ecological and social methods for monitoring tropical streams in developing country contexts, with outputs including protocols for Belize’s National Biodiversity Monitoring Plan (NBMP), and the development of a checklist of macroinvertebrates for Belize, which Rachael continues to maintain. Rachael’s current research focus is an exploration of the impacts and processes of the ‘Functional Landscape Approach’: a ‘people-centred’ approach that seeks to contribute to environmentally sensitive and climate-resilient strategies for safeguarding wetland ecosystem services and improving livelihoods and well-being at the catchment-scale.
Carrie, R., Dobson, M. & Barlow, J. (in press) Challenges using extrapolated family-level macroinvertebrate metrics in moderately disturbed tropical streams: a case-study from Belize. Hydrobiologia.
Carrie, Rachael (2016) Annex 6: Freshwater Macroinvertebrate Identity, Status and Distribution and the Development of an Index of Biotic Integrity for Belize’s Wadeable Streams in the 'National Biodiversity Monitoring Program' 2016 Report. Documentation. The University of Belize Environmental Research Institute, University of Belize. (Unpublished).
Carrie, R., Dobson, M. & Barlow, J. 2015. The influence of geology and season on macroinvertebrates in Belizean streams: implications for tropical bio-assessment. Freshwater Science 34(2): 648–662.
Carrie, R. & Kay, E. 2014. Belize. pp 33-62. In Alonso-Eguía-Lis, P. et al. (Eds). Diversidad, conservación y uso de los macroinvertebrados dulceacuícolas de México, Centroamérica, Colombia, Cuba y Puerto Rico. Instituto Mexicano de Tecnología del Agua, Morelos, México.
Polhemus, D. A & Carrie R.H. 2013. A new species of Potamocoris (Heteroptera: Potamocoridae) from Belize and synonymy of the genus Coleopterocoris. Tijdschrift voor Entomologie 156, 141–149.
Carrie, R.H. 2013. A checklist of the freshwater macroinvertebrates of Belize. Figshare.
Hassall, C., Hill, M. Gledhill, D. and Biggs, J. 2016. The ecology and management of urban pondscapes. In: Francis, R. A., Millington, J. and Chadwick M. A. 2016. (eds.) Urban landscape ecology: Science, Policy and Practice, Routledge.
Hill, M. J., Sayer, C. D. and Wood, P. J. 2016. When is the best time to sample aquatic macroinvertebrates in ponds? Environmental Monitoring and Assessment 188: 1-11
Hill, M. J., Swaine, J. and Wood, P. J. 2016. Aquatic macroinvertebrate biodiversity associated with artificial agricultural drainage ditches. Hydrobiologia. 776: 249-260
Hill, M. J. and Wood, P. J. 2016. Macroinvertebrate diversity in urban and rural ponds: Implications for freshwater biodiversity conservation. Biological Conservation. 201: 50-59
Hill, M. J., Mathers, K. L. and Wood, P. J. 2016. Macroinvertebrate community composition and diversity in ephemeral and perennial ponds on unregulated floodplain meadows in the UK. Hydrobiologia.
Hill, M. J., Biggs, J., Gledhill, D., Thornhill, I., Wood, P. J. Briers, R. and Hassall, I. 2016. Urban ponds as a biodiversity resource in modified landscapes. Global Change Biology.
Mathers, K. L., Hill, M. J. and Wood, P. J. 2017. Benthic and hyporheic macroinvertebrate distribution within the heads and tails of riffles during baseflow conditions. Hydrobiologia.
Milner, V. S., Gilvear, D. J. and Thoms M. C. 2016. Characterising Riverine Landscapes; History, Application and Future Challenges. In Gilvear D, Greenwood M, Thoms MC and Wood P. (Eds) River Science: Research and Applications for the 21st Century. Wiley-Blackwell: 239-258.
Milner, V. S., Willby, N. J., Gilvear, D. J. and Perfect, C. 2015. Linkages between reach scale physical habitat and invertebrate assemblages in upland streams. Marine and Freshwater Research, 66: 438-448.
Wood, P. J. Armitage, P.D. Hill, M. Mathers, K. and Millett, J. 2016. Faunal response to fine sediment deposition in urban rivers. In: Gilvear, D. J., Greenwood, M. T., Thoms, M. C. and Wood P.J. 2016. (eds.) River Science: Research and Management for the 21st Century. John Wiley and Sons, Chichester.