Ecological study of the River Lambourn. Report for the period October 1973 to September 1977

The investigations described in this report were carried out to fulfill three distinct but interrelated objectives. In 1973 the Thames Conservancy were making plans for a second stage of their groundwater scheme which would take water from the chalk aquifers in the valley of the Kennet and they wanted basic information on the ecological state of this river and its upper tributaries. Little appeared to be known about limestone streams and a preliminary study of one of the streams in this area was desirable as a basis for planning more detailed studies if these were needed later. At a progress meeting held in March 1976 the problems and opportunities presented by the developing drought conditions were considered. It was concluded that the ecological effects of the exceptionally low natural flows should be studied and that it would be important to assess the ecological impact of the groundwater scheme if it was brought into operation that year. This could only be done on the Lambourn and the Winterbourne and it was decided that considerable effort should be diverted there for this purpose and that the field observations should be extended to cover any recovery period after the end of the drought. To make this possible it was agreed that the studies of invertebrates and detritus on the Kennet should be reduced considerably and that the proposed study of the limestone stream should be abandoned. The revised objectives were as follows: A detailed ecological study of several sites on the Kennet and its tributaries above Kintbury, extending over at least two years and involving observations on wate r weeds , invertebrates, fish, detritus and the trophic relationships within the river community. Quantitativ e and qualitative sampling of water weeds and invertebrates during one year at a number of sites on several chalk streams to determine whether the patterns and relationships found in the Lambourn are also found at the other sites. Observations on the Lambourn at Bagnor were to continue for most of the period to look for long-term fluctuations and to enable these sites to act as controls with which the other sites could be compared. Further detailed studies on the Lambourn and the Winterbourne to assess the impact of low flows, trial pumping and the operation of the groundwater scheme.

Composition and bulk properties of Dorset river gravels

Considerable interest has been expressed in the composition of the stream gravels, the movement of bed materials and the relationship of sediment composition, packing and siltation of void space to invertebrate ecology. In the autumn of 1982, freeze-samples of gravel were obtained in Dorset streams. Data were required on the depth of salmonid egg pocke and were part of a broader investigation of regional variation in the independent variables of salmonid fish length, gravel size, current velocity and the resultant dependent variable ~egg burial depth. The Dorset river gravels examined are bimodal. The grain size distribution may be resolved into two near-normal frequency distributions interpreted as representing a primary framework or lattice of gravel particles into which a secondary matrix population of sand particles has penetrated.

Turbidity and the suspended sediment load of the regulated River Tees

The physical effects of river regulation in the U.K. by impoundments have attracted most attention from hydrologists and engineers concerned with predicting and maintaining discharge regimes for water supply. Grimshaw & Lewin (1980) suggested two basic methods to investigate the effects of regulation on suspended sediment discharge: (i) Compare the river load before and after reservoir construction, and (ii) adopt a paired catchment approach. The former method assumes stationarity of process in the natural system. The latter method, involving selecting two adjacent catchments of similar physical attributes, one regulated and one unregulated, assumes constancy of process spatially. In this report both approaches are adopted to examine the turbidity and suspended sediment concentration regime of the regulated River Tees. Neither approach was entirely satisfactory in the present case. This report examines the discharge and turbidity record consisting of approximately 4000 paired data points, representative of an 11-year post-impoundment period, that has been examined for the River Tees at Broken Scar, Darlington. A small amount of suspended sediment concentration data was also processed: these data are representative of both the pre-impoundment and post-impoundment sediment regime.

The fish populations of the River Avon, Hampshire, downstream of Salisbury, in 1987

The objective of this study is to describe the present statu s of the coarse fish populations of the River Avon, Hampshire. The study arose from a widespread concern among anglers and riparian owners that fish numbers had decreased since the early 1970's, and from a scarcity of accurate information on population densities on which to assess this complaint. It was realised at the outset that, without such information from earlier years, the survey would not reveal the extent of any decline in the fisheries. The result s of the survey are compared with available data from other rivers , chiefly the nearby R. Frome and R. Stour. They may be used to assess any futur e changes in population densities and growth rates, and to indicate promising areas for future research. The data were collected from a quantitative survey of twelve river sections along the fifty kilometres of river between Salisbury and Sopley, and a qualitative survey of three weir pools within the same area from 14 September to 9 October, 1987.

Biological surveillance of chalk-streams

An article reviewing the methods of biological surveillance of chalk-streams developed and commonly used at that time, with a focus on their application to the River Frome catchment in Dorset. In evaluating the surveillance methods, the author looks at sampling methods (including cores and kick-sampling), the level of identification of macroinvertebrates, and temporal and spatial variations. Responses of indices to organic pollution are also discussed. A number of accompanying figures are also included.

Physiological aspects of the life cycle of the river lamprey, Lampetra fluviatilis L

The life cycle of the river lamprey, L. fluviatilis, is reviewed. The larval lamprey, or ammocoete, is a blind, filter-feeding animal, which normally lies concealed in the silt deposits of streams and rivers. After a period of 3-5 years in fresh water the ammocoete undergoes a metamorphosis in the summer months into a sexually immature, non-feeding stage known as the macrophthalia, which is active. This stage migrates downstream in late winter. It adopts a parasitic existence, in intertidal areas. After 18 months it returns to spawn in fresh water, after a final freshwater stage lasting up to 9 months. The river lamprey dies within a few days after the spawning period of 3-4 weeks, and none survive to spawn the following year.

The impact of Cow Green Reservoir on invertebrate populations in the River Tees

Cow Green is a new reservoir situated in Pennine moorland. It has an area of 312 ha, a capacity of 40 . 9 x 10 SUP-6 m SUP-3 and a maximum depth of 22 . 8 m. The function of the reservoir is to regulate flow in the River Tees to provide industrial Teesside with sufficient water during the dry spells. Invertebrate studies were carried out in the Tees to monitor changes resulting from the construction of the reservoir both in the flooded basin and below the dam. The overall effect of the reservoir on the Tees has been to increase the numbers and biomass of certain taxa, but generally not at the expense of previous fauna. Some of the positive effects, ie. increase in number and biomass, and maintenance of faunal diversity, may in part be attributable to the presence of the rapids and waterfall. Turbulence resulting from this rapid flow over heterogeneous bottom is sufficient to prevent clogging of interstitial spaces by silt and to maintain the variety of ecological niches necessary for a diverse fauna.

Long-term natural acidification of upland sites in Cumbria: Evidence from post-glacial lake sediments

Studies by the Freshwater Biological Association over the last 25 years have supplied data relevant to the levels of acidity in local soils and water before the onset of industrial pollution and current interest in acid rain. This article reviews published analysis from cores of lake sediments, in or near the catchment of the River Duddon. Electron spin resonance spectra of humic acids and iodine values confirm evidence from pollen analysis for a history of progressive acidification of the source material of lake sediments since before 5000 radiocarbon years, in upland catchments of the Lake District. Processes involved included: removal of basic ions from soils by rainfall, the effects of which were intensified by removal by man of deciduous forest; acidification of soils and waters by decomposition products of Calluna and further acidification of waters by Sphagnum species which colonized habitats where drainage became impeded by paludification processes.

Nitrates in surface waters, inputs and seasonality: Phase 2

Changes in management practices and agricultural productivity over the past twenty years have lead to nitrate pollution and eutrophication of lakes and rivers. Information on nitrate concentrations and discharge has been collected on the River Frome at East Stoke since 1965, using the same analytical nitrate method so that the results are comparable. These records of weekly spot values of nitrate concentration and daily mean discharges have been analysed for trends and seasonal patterns in both concentration and nitrate loadings. In this extension of our nitrate contract, a new automated method of intensive sampling has been used to monitor short-term variability and to assess how well similar routine (weekly) sampling schemes can represent the true nitrate record.

Discharge and turbidity of the regulated River Tees. Variance spectrum analysis

High suspended sediment loads may be deleterious to adult salmonids and invertebrates in gravel-bedded streams. Further, the accumulation of fine material in the interstices of the gravel may have an adverse impact on the recruitment of the young stages of salmonids. It is important therefore not only to quantify the rates and degrees of silting but also to identify sediment sources and to determine both, the frequency of sediment inputs to the system and the duration of high sediment concentrations. This report explores the application of variance spectrum analysis to the isolation of sediment periodicities. For the particular river chosen for examination the method demonstrated the essentially undisturbed nature of the catchment. The regulated river chosen for examination is the River Tees in Northern England. Variance spectrum analysis was applied to a series of over 4000 paired daily turbidity and discharge readings.

Nitrates in surface water, inputs and seasonality

Because of the widespread concern over increasing nitrate concentrations in river water , the Freshwater Biological Association has undertaken a study to investigate seasonality, nitrate concentrations and loads in the River Frome catchment in relation to land use and compare the results for 1984/86 with data obtained in 1970/71. Information on land use changes and fertiliser applications were obtained both from MAFF and individual farmers. The study concludes that input of nitrogen from rainfall to the River Frome catchment had not significantly changed between 1970/71 and 1984/86.

Description of sampling stations, methods of benthic sampling and biological water quality assessment; with some consideration of the influence of sample variation on the assessment values obtained

The first bilateral study of methods of biological sampling and biological methods of water quality assessment took place during June 1977 on selected sampling sites in the catchment of the River Trent (UK). The study was arranged in accordance with the protocol established by the joint working group responsible for the Anglo-Soviet Environmental Agreement. The main purpose of the bilateral study in Nottingham was for some of the methods of sampling and biological assessment used by UK biologists to be demonstrated to their Soviet counterparts and for the Soviet biologists to have the opportunity to test these methods at first hand in order to judge the potential of any of these methods for use within the Soviet Union. This paper is concerned with the nine river stations in the Trent catchment.

Joint Anglo-Soviet biological surveillance exercise on River Dnieper

As one part of an on-going programme concerned with environmental protection as provided for under the terms of a UK/USSR Joint Environmental Protection Agreement signed in London, 21 May 1974, a seminar — ”The elaboration of the scientific basis for monitoring the quality of surface water by hydrobiological indices” was held at Valdai in Russia 12—14 July, 1976. As a continuation of this theme it was agreed that delegations of hydrobiologists from each side should carry out reciprocal visits to carry out comparative field tests on selected systems of biological surveillance in use in the respective countries. In May 1978 a team of British hydrobiologists visited the USSR, under the auspices of the Department of Environment, to carry out joint exercises on the River Dnieper and some tributaries. This paper reports the results of selected methods used by the British side when applied to the conditions found in the River Dnieper.

Scientific investigations into the eutrophication of the Norfolk Broads

The word ”Broads” is used to describe a series of relatively shallow lakes resulting from the flooding of medieval peat diggings. Broadland is essentially freshwater, but because the rivers have such low gradients the lower reaches are brackish. The influence of tide is particularly apparent on the River Yare; in Norwich 40 km from the sea there is a vertical movement of half a metre at spring tide. This study examines the problems that the broadlands are facing. The problems are basically the progressive loss of aquatic plants, in particular the macro- phytes, animal life, outbreaks of avian botulism, occasional fish kills due to a toxin produced by the blue-green alga Prymesium parvum and the emergence of very heavy algal blooms. The main factor for the deteriation of the Broaslands is the eutrophication resulting from enhanced nutrient inputs, in particular of nitrates and phosphates, from a variety of sources. The most important of these are sewage effluents, agricultural drainage, which includes fertilisers and nutrient rich effluents from piggeries and dairy un

Ecological indicators of water quality in small rivers

At the present time hydrobiological indicators are widely used for the control of surface water quality. Results of the applying of methods suggested at the 1st Soviet-American seminar (1975), development of improved methods and estimation of their usefulness for various conditions are presented in this report. Among the criteria permitting an estimation of the degree and character of changes in water quality and their connection with the functioning of river ecosystems in general, the biological tests of natural waters appears to be the most universal one and is being carried out in two main directions — ecological and physiological. This study summarises approaches in both directions.