Aims
In spring 2008 a sampling programme was established with the aim of monitoring two neighbouring chalk streams to assess the extent to which chalk stream communities were affected by climate. Our aims for this work are to:
- Establish a long-term high-quality replicated species-level macroinvertebrate sampling programme on chalk streams together with high-quality stream temperature logging, and access to existing water chemistry and flow data.
- Determine the extent to which inter-year differences in macroinvertebrate communities are linked to inter-year differences in climate (expressed through water temperature and flow).
- Identify and measure the significance of climate extremes events (droughts, spates, heat waves).
- Our ultimate goal is to build a predictive model that will forecast the effects of environmental change on freshwater communities.
Methods
Macroinvertebrate sampling follows the 3-minute kick/sweep and 1-minute search methodology. Kick samples are rigorously stop-watch timed so that they deliver 3 minutes of active sampling. All material is preserved on site. Samples are collected by a mixture of operators so that effects due to inter-operator variability in sampling effectiveness can be quantified and factored into subsequent analyses. Diatom samples are also collected from each site following the Dares methodology.
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| Macroinvertebrate sampling on the River Piddle in spring 2008 |
Physical variables which are known to be important descriptors of community composition are recorded on site at the time of sampling. These include stream width, water depth and substrate composition. Plant species and cover are also recorded. Each site is photographed on each sampling occasion to aid in long-term interpretation of hydro-morphological change.
RLLTM Monitoring Sites
A sampling design was chosen to provide replication within each study river, to quantify natural background variability within chalk streams, and also to provide a degree of replication between independent chalk streams so that local factors affecting a single chalk stream could be distinguished from climate driven change that would affect both streams in the same climatic region.
The study sites are located on the River Frome (at the River Laboratory, East Stoke) and on the River Piddle (at Hyde), both near Wareham in Dorset. On each of the two rivers we have five permanent monitoring sites (10 sites in all).
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| Image copyright Mapsdirect |
Image copyright Mapsdirect |
Fixed monitoring stations F1 – F5 on the River Frome (left) and P1 – P5 on the River Piddle (right).
Sampling sites are ten metres in length and are located by fixed yellow topped marker posts (one at each corner).
Other visiting researchers are asked to kindly avoid any sampling or other related in-stream field work on these RLLTM monitoring sites.
Photographs of all of the sampling sites are shown below.
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| Frome F1 |
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| Frome F2 |
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| Frome F3 |
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| Frome F4 |
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| Frome F5 |
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| Piddle P1 |
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| Piddle P2 |
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| Piddle P3 |
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| Piddle P4 |
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| Piddle P5 |
