Temperature, organic matter and the sustainability of aquatic systems

Changes in sustainability of aquatic ecosystems are likely to be brought about by the global warming that has been widely predicted. In this article, the effects of water temperature on water-bodies (lakes, oceans and rivers) are reviewed followed by the effects of temperature on aquatic organisms. Almost all aquatic organisms require exogenous heat before they can metabolise efficiently. An organism that is adapted to warm temperatures will have a higher rate of metabolism of food organisms and this increases feeding rate. In addition, an increase in temperature raises the metabolism of food organisms, so food quality can be altered. Where populations have a different tolerance to temperature the result is habitat partitioning. One effect of prolonged high temperature is that it causes water to evaporate readily. In the marine littoral this is not an important problem as tides will replenish water in pools. Small rain pools are found in many tropical countries during the rainy season and these become incompletely dried at intervals. The biota of such pools must have resistant stages within the life cycle that enable them to cope with periods of drying. The most important potential effects of global warming include (i) the alteration of existing coastlines, (ii) the development of more deserts on some land masses, (iii) higher productivity producing higher crop production but a greater threat of algal blooms and (iv) the processing of organic matter at surface microlayers.

The distribution of aquatic bugs (Hemiptera-Heteroptera) in Scotland

Data on the distribution of aquatic bugs in Scotland was compiled with a widely-used biological recording software called RECORDER supplemented by a mapping program (DMAP) and a program that linked the two. Status lists are given with a brief account of the distribution of each species. Common and widespread species are listed in group one, including Velia caprai and Gerris lacustris, with less common species in group two such as Hydrometra stagnorum and Microvelia reticulata. Rare, uncommon or under-recorded species are also listed. These include Hebrus ruficeps, Gerris najas and Cymatia coleoptrata.

Testable models of aquatic systems: A NERC special topic for integrating experiments and modelling

A major part of the support for fundamental research on aquatic ecosystems continues to be provided by the Natural Environment Research Council (NERC). Funds are released for ”thematic” studies in a selected special topic or programme. ”Testable Models of Aquatic Ecosystems” was a Special Topic of the NERC, initiated in 1995, the aim of which was to promote ecological modelling by making new links between experimental aquatic biologists and state-of-the-art modellers. The Topic covered both marine and freshwater systems. This paper summarises projects on aspects of the responses of individual organisms to the effects of environmental variability, on the assembly, permanence and resilience of communities, and on aspects of spatial models. The authors conclude that the NERC Special Topic has been highly successful in promoting the development and application of models, most particularly through the interplay between experimental ecologists and formal modellers.

Heated aquatic microcosms for climate change experiments

Ponds and shallow lakes are likely to be strongly affected by climate change, and by increase in environmental temperature in particular. Hydrological regimes and nutrient cycling may be altered, plant and animal communities may undergo changes in both composition and dynamics, and long-term and difficult to reverse switches between alternative stable equilibria may occur. A thorough understanding of the potential effects of increased temperature on ponds and shallow lakes is desirable because these ecosystems are of immense importance throughout the world as sources of drinking water, and for their amenity and conservation value. This understanding can only come through experimental studies in which the effects of different temperature regimes are compared. This paper reports design details and operating characteristics of a recently constructed experimental facility consisting of 48 aquatic microcosms which mimic the pond and shallow lake environment. Thirty-two of the microcosms can be heated and regulated to simulate climate change scenarios, including those predicted for the UK. The authors also summarise the current and future experimental uses of the microcosms.

Angling and species richness of aquatic macrophytes in ponds

Ponds are unjustly neglected habitats. This paper aims to raise awareness of the potential interaction between angling and the macrophyte vegetation of ponds. The work described by the author followed on from a study of 57 ponds in East Yorkshire, northeast England, by Linton & Goulder (2000). They found that the species richness of aquatic vascular plants (macrophytes) is greater in ponds that are used for angling and suggest that to some extent there are more species because disturbance by anglers leads to greater habitat diversity. This article describes how the hypothesis was tested by comparing species richness at fished sites with that at non-fished sites around the margins of ponds in two localities in East Yorkshire. The localities were investigated during August-September 1999.

Falling through the cracks: are European directives and international conventions the panacea for freshwater nature conservation?

There are many ways of practising freshwater nature conservation: from strict legislative protection of individual species considered rare or threatened to protecting whole lakes or long stretches of rivers; from practical conservation management at a local scale to integrated catchment management at the river basin scale; and from the encouragement of better habitat management through codes of good practice to statutory control of pollution or abstraction. Whatever the mechanism, an essential pre-requisite is a way of choosing where to put the effort, especially when resources for nature conservation are severely limited. The aim of this article is to review the contribution from four specific international measures to the task of assigning priorities for conservation. The 1990s saw the introduction of two European directives (the Habitats Directive (HD) and the Water Framework Directive (WFD)) and one international convention (the Biodiversity Convention (CBD)) each with the potential for influencing, to a greater or lesser extent, the conservation of freshwater habitats and species. This article also discusses a much older convention – the Ramsar Convention – adopted in 1971 specifically to help tackle the conservation and management of wetlands and aquatic ecosystems. Although the authors have focused mainly on the UK, the subject is relevant to other parts of Europe and beyond. The article explores the degree to which these measures help in identifying the most important fresh waters for conservation, and asks whether or not they present the right conservation message to a wide audience.

Production of the chironomids of the Uchinsk Reservoir. [Translation of: Methods for the estimation of production of aquatic animals. (Handbook and papers) (ed. G. G. Vinberg) p226-239. Minsk, Vysheishaya Shkola, 1968]

The method of E.V. Borutski was used for determining the production of chironomids, that is, the dynamics of the number and biomass of the larvae were analysed, their death, a calculation of emergence and the number of deposited egg layings was carried out. In addition to the method of Borutski, the authors also calculated the seasonal dynamics of the number of larvae of the younger age stages in the microbenthos.

Generation time and utilization of energy by aquatic bacteria. [Translation from: Trudy Instituta Biologii Vnutrennykh Vodnany 11(14), 198-202, 1966.]

Recent research has shown that the biomass of bacteria in lakes and other water-bodies can attain significant values. The huge production of bacteria is brought about by their great rate of reproduction. In a series of cases their biomass exceeds the biomass of phytoplankton. Therefore in a study of the biological productivity of water bodies it is necessary to calculate the biomass and production not only of the phyto- and zooplankton, but also of bacteria.The authors uses different methods and formulae to to compare the time of one generation of the bacteria.

The transport of aquatic animals by birds. [Translation from: Binnengewaesser 18, 156-159, 1950.]

A great deal has been written on the part which birds play in the dispersal of freshwater fauna. This article summarises literature on the dispersal of aquatic animals by birds and aquatic insects.

Chemical composition of Iraq water resources (abbreviated translation) [Translation from: Vodnye Resursy 1975(4,) 173-185]

This abbreviated translation summarises the chemical composition of Iraq water resources. Among the described water bodies are the River Euphrates, Shatt al Arab River and a number of standing waters.

Extent and biomass of the aquatic chariphytes and mosses in Lake Sevan [Translation from: Rasprostranenie i biomassa kharovykh vodoroslei i mkha v os. Sevan, 1951]

This study focusses on the plants in the open parts of the lake - mostly aquatic charophytes and mosses, in what are called in Lake Sevan (Armenia), the ”zones of chara and moss”. Distribution and other ecological conditions are reviewed. Quantity of chara in the littoral zone of lake Sevan is provided

A survey of aquatic invertebrates of the Somerset Levels, August 13-14, 1981

Since 1975 the wildlife interest of the Somerset Levels and Moors have been assessed. Detailed information has been obtained on the conservation interest of meadows, breeding and wintering bird populations and the botany of aquatic habitats (rhynes). Little work to date has been carried out on the terrestrial and aquatic invertebrate fauna. The prime aim of this survey was to sample a wide variety of rhynes in order to obtain information on the nature and distribution of aquatic invertebrates.

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.