Ecology and management of water plants in lowland streams

A review article which discusses the ecology and management of common water plants in lowland streams, with an introduction containing a review of previous studies on the subject. The article covers the significance of seasonal growth, the significance of stand structure (particularly in relation to hydraulic resistence), an assessment of current river management, improvements to plant management techniques (in relation to cutting), and alternatives to the traditional techniques of river plant management. There are a number of accompanying figures.

Bacterial production of nitrate in aquatic systems: progress report. Nitrate-loss processes in raw water

This short interim progress report builds on previous progress reports which have described the quantification of the process both within and between lakes of different degrees of eutrophication. These data indicated that slight changes in methodology, particularly when investigating sediment deposits, could grossly affect the measured activity. The aim of the present research was an attempt to rationalize these differences. If this could be achieved it would enable meaningful interpretation of published data obtained using different methods and therefore enlarge the available database. In addition some observations have been made on the production of nitrite by Grasmere profundal sediment slurries sampled during the circulation period.

Acid precipitation and its effects on aquatic systems in the English Lake District

There is no evidence of an increase in the acidity (lower pH or alkalinity) of water-bodies in the Lake District over the last 50 years. Brown trout occur in acid streams and upland tarns where pH is 4.5-5.2 throughout the year. Their occurrence in such waters in Britain and Ireland has been known for most of this century and there is no previous evidence of harmful effects on salmonid fisheries, though numbers of fish are naturally low. However, many benthic invertebrates that are common in hill-streams where pH is above 5.7 do not occur in more acid streams. This phenomenon occurs in the headwaters of several western rivers in Cumbria. It is not a recent response to "acid rain". Harmful effects of pH are undoubtedly more pronounced in waters that are poor in other dissolved ions. Low concentrations of sodium, potassium, calcium and chloride are especially important and may limit the distributions of some aquatic animals even where pH is above 5.7. The concentration of sulphate ions is usually relatively high but this is not important to the fauna; concentrations are at least two times higher in productive alkaline water-bodies than they are in unproductive acid waters.

Joint research project on the aquatic ecotoxicity of organo-aluminium: Chemical reactions. First interim report

The overall goal of the joint research project is to relate the chemical reactions involved in the formation of organo-aluminium complexes under acid conditions to their toxic effects on the physiology of aquatic organisms. Finally, this research is intended to predict toxic effects arising from acidity and aluminium under varying environmental conditions. This interim report examines the chemical modelling of ion-binding by humic substances where a computer model has been developed and is being tested using field data, and conditions required for the precipitation of aluminium in surface waters.

'The highly nervous system of the English Lakes': aquatic ecosystem sensitivity to external changes, as demonstrated by diatoms.

The author reviews the stratigraphic diatom profile of Cumbrian lakes since the last glaciation. Knowledge of both present and previous interglacials suggests that a natural cycle of change is imposed on all lakes. The nature of inwashed material is dependant on climatic and natural soilcycles and this affects the water quality and sensitive aquatic biota. Anthropogenic effects are superimposed upon this with forest clearance and pollution. Whilst some Cumbrian diatom profiles extend over the entire post glacial, others cover only detailed sections relating to particular problems. Causes and effect of recent changes in lakes can be studied using indicator species but palaeocology contributes greatly to understanding of long term changes.

Analysis and adsorption of phosalone on aquatic sediment

Phosalone is a non systematic, wide spectrum organophosphate pesticide which was discovered in 1961 in the laboratories of the Societe des Usines Chimique Rhone-Poulenc in France. It has been approved for commercial use since 1964 in France, in Australia since 1966, in the United Kingdom in 1967 and in many other countries including Japan, Egypt, USSR and the USA. This study provides a full literature review on all aspects of phosalone including its physical, biological and chemical characteristics, and analytical methods of analysis with particular reference to soils/sediments. Furthermore, it aims to develop a method for the determintion of phosalone in aquatic sediments and to determine the adsorption of phosalone onto kaolinite.

A bibliography of works for the identification of freshwater invertebrates in the British Isles

This bibliography covers the literature up to the end of 1978. The criteria used in the selection of references were that they should aid identification of invertebrates directly; thus, works solely concerned with the taxonomy of a particular group are in general omitted unless they contain a key. Some check-lists are however included where they give current nomenclature. The references are arranged alphabetically within each group and deal mainly with macro-invertebrates but include available keys to some microscopic invertebrates. Internal parasites and hymenopterous parasitoids are omitted. For insects the life stages to which the key applies are given where this is not clear in the reference. A number of keys to non-aquatic stages have been included in the hope that they may prove useful in certain circumstances. In addition, under a general head, latest check-lists are referred to together with bibliographies of algal keys and a guide for the identification of British water plants.

An annotated bibliography of aquatic sediment traps and trapping methods

This annotated bibliography is intended to give as reasonably complete a review of the existing literature as possible, and to offer some practical guidance in the selection and operation of sediment traps in future monitoring programmes.

Metallothionein as an indicator of water quality: assessment of the bioavailability of cadmium, copper, mercury and zinc in aquatic animals at the cellular level

The study of metallothioneins (MTs) has greatly improved our understanding of body burdens, metal storage and detoxification in aquatic organisms subjected to contamination by the toxic heavy metals, Cd, Cu, Hg and Zn. These studies have shown that in certain organisms MT status can be used to assess impact of these metals at the cellular level and, whilst validation is currently limited to a few examples, this stress response may be linked to higher levels of organisation, thus indicating its potential for environmental quality assessment. Molluscs, such as Mytilus spp., and several commonly occurring teleost species, are the most promising of the indicator species tested. Natural variability of MT levels caused by the organism's size, condition, age, position in the sexual cycle, temperature and various stressors, can lead to difficulties in interpretation of field data as a definitive response-indicator of metal contamination unless a critical appraisal of these variables is available. From laboratory and field studies these data are almost complete for teleost fish. Whilst for molluscs much of this information is lacking, when suitable controls are utilised and MT measurements are combined with observations of metal partitioning, current studies indicate that they are nevertheless a powerful tool in the interpretation of impact, and may prove useful in water quality assessment.

Molecular biomarkers and toxic consequences of impact by organic pollution in aquatic organisms

Organic contaminants are readily bioaccumulated by aquatic organisms. Exposure to and toxic effects of contaminants can be measured in terms of the biochemical responses of the organisms (i.e. molecular biomarkers). The hepatic biotransformation enzyme cytochrome P4501A (CYP1A) in vertebrates is specifically induced by organic contaminants such as aromatic hydrocarbons, PCBs and dioxins, and is involved in chemical carcinogenesis via catalysis of the covalent binding of organic contaminants to DNA (DNA-adducts). Hepatic CYP1A induction has been used extensively and successfully as a biomarker of organic contaminant exposure in fish. Fewer but equally encouraging studies in fish have used hepatic bulky, hydrophobic DNA-adducts as biomarkers of organic contaminant damage. Much less is known of the situation in marine invertebrates, but a CYPlA-like enzyme with limited inducibility and some potential for biomarker application is indicated. Stimulation of reactive oxygen species (ROS) production is another potential mechanism of organic contaminant-mediated DNA and other damage in aquatic organisms. A combination of antioxidant (enzymes, scavengers) and pro-oxidant (oxidised DNA bases, lipid peroxidation) measurements may have potential as a biomarker of organic contaminant exposure (particularly those chemicals which do not induce CYP1A) and/or oxidative stress, but more studies are required. Both CYP1A- and ROS-mediated toxicity are indicated to result in higher order deleterious effects, including cancer and other aspects of animal fitness.