The ecology of Bassenthwaite Lake (English Lake District)

Bassenthwaite Lake is, in many ways, different from the other major lakes in the English Lake District: it is the most northerly, the shallowest, has the largest catchment and the shortest mean retention time. There is also considerable temporal variation in lake level. This article summarises the limnological features of Bassenthwaite Lake, the catchment and physical characteristics before describing the water chemistry, phytoplankton, macrophytes, zooplankton, invertebrates, fish, mammal and invertebrate population. The authors then describe the ecological pressures faced by Bassenthwaite Lake such as nutrients, sediments and introduced species.

A seven year study of the life cycle of the Mayfly Ephemera danica

Ephemera danica Müller, 1764 (Ephemeroptera) is one of the largest mayflies found in the British Isles with some females reaching over 30 mm. It is a common and widespread species found in rivers, lakes and streams throughout Europe and is particularly abundant in many of the lowland rivers of the British Isles. The larvae are burrowers – mainly found where silt accumulates below macrophytes. This article gives a general overview of research work on the factors affecting the life cycle of Ephemera danica over a seven year period (1995–2002) on two rivers, the River Test at Leckford in Hampshire and the North Wey at Tilford in Surrey.

Simulations of phytoplankton dynamics in El Gergal Reservoir, Southern Spain (PROTECH)

The Mediterranean region is characterised by a variable climate with most of the rain falling during the winter and frequent summer droughts. Such warm, dry periods are ideal for the growth of large algal blooms that often consist of potentially toxic Cyanobacteria. This makes the management of water for human use particularly challenging in such a climate and it is important to understand how such blooms can be avoided or at least be reduced in size. PROTECH (Phytoplankton RespOnses To Environmental CHange) is a model that simulates the dynamics of different species of phytoplankton populations in lakes and reservoirs. Its distinct advantage over similar models is its ability to simulate the relative composition of the algal flora, allowing both quantitative and qualitative conclusions to be drawn e.g. whether Cyanobacteria could be a potential problem. PROTECH has been applied primarily to lakes and reservoirs in northern Europe. Recently, however, the model has been applied to water bodies in lower latitudes, including Australia to a water supply reservoir in the south of Spain, El Gergal. El Gergal is the last in a chain of reservoirs that supply water to the city of Seville. It was brought into service in April 1979 and has a maximum storage volume of 35 000 000 m3. This article summarises the application of PROTECH in order to simulate the following problems: • the effect of a large influx of Ceratium biomass into El Gergal from another reservoir • the effect of using alternative water sources instead of the Guadalquivir River (used occasionally to raise water levels in El Gergal) • the effect of installing tertiary sewage treatment on the Cala River • the effect of simulated drought conditions on phytoplankton in the reservoir.

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.

Some aspects of the ecology of the limnoplankton, with special reference to the phytoplankton. [Translation from: Svensk Botanisk Tidskrift 13(2) 129-163, 1919.]

This paper tries to develop more generally some fundamental bases for the ecological study of freshwater plankton. A special attention is given to the phytoplankton associations which can be separated out and made into groups according to their dependence upon changing environments. Plankton formations in different types of water bodies (ponds, lakes and rivers) are studied.

Predation and selection in copepod populations of Alpine waters [Translation from: Bollettino di Zoologia 21 541-545, 1954]

Zooplankton was studied in four alpine lakes in Switzerland, France and Italy. The presence the presence of the invertebrate predator Heterocope in three lakes was stated. It is then discussed why in three of these four lakes, the copepod Arctodiaptomus denticornis is present in the absence of Arctodiaptomus bacillifer, and vice versa respectively in the second and first parts of the lacustrine summer.

The problem of the co-existence of Arctodiaptomus bacillifer (Koelb.), Acanthodiaptomus denticornis (Wierz.) and Heterocope saliens Lill [Translation from: Memorie dell'Istituto Italiano di Idrobiologia Dott.Marco de Marchi 8 81-94, 1954]

In freshwater environments of modest size and without notable ecological structure, there is usually present only one diaptomid species. When two or more diaptomid species are present in the same habitat, generally their body dimensions are distinctly different. There are only four examples of co-existence of Arctodiaptomus bacillifer (Koelb.) and Acanthodiaptomus denticornis (Wierz.) situated at higher altitudes alpine lakes. The article discusses the results of sampling in the summer of 1953 and the problem of the co-existence of Arctodiaptomus bacillifer, Acanthodiaptomus denticornis and Heterocope saliens.

The influence of constant temperature on the embryonic growth of Asellus aquaticus L. (Crustacea) [Translation from: Vestsi Akademii Navuk Belorusskoi SSR, Seriya Biyal. 1979(1) 128-130]

It is known that an adequately large amount of work has been devoted to investigations on the influence of temperature on the growth period of aquatic invertebrates. However, the action of the given factors on the basic biological characteristics of embryonic growth in crustaceans is virtually unknown. An experimental study of the effectiveness of the transformation of matter and energy during the period of embryogenesis in the isopod Asellus aquaticus L. under different constant temperatures was carried out. Specimens were collected in the quarry lakes of the Kurasovshchin zone (city-Minsk). The authors developed a quantitative analysis of the basic energetic properties of animals during one of the physiological stages at different constant temperatures, which allows one to determine the temperature range in which the expenditure of energy, at a given instance during embryonic growth, is minimised. For A. aquaticus this range is represented by the limits 10-22°C, during which the least expenditure of energy is observed between 14.5 and 18.8°C.

Respiration and the efficiency of energy during embryonic development of Asellus aquaticus L. (Crustacea) [Translation from: Vestsi Akademii Navuk Belorusskoi SSR, Seriya Biyal. 1978(5) 112-114, 1978]

Experimental studies were carried out on the transformation of matter and energy during embryonic development of the isopod Crustacea Asellus aquaticus L. under two constant temperatures. Material for the experiments was collected in the quarry lakes of the Kurasovshchin-zone (city-Minsk) at 9°C in April and at 18°C in June, 1977. The rate of consumption of oxygen per specimen by eggs and embryos of Asellus aquaticus was observed and dynamics of the basic biological characteristics during embryonic development studied.

The role of infusoria and bacteria as food for Cyclopoida in Rybinsk Reservoir [Translation from: Trudy Instituta Biologii Vnutrennykh Vodnany 22(25), 37-42, 1971]

Despite the fact that it is a long time sinc e the methods of collection and quantitative estimatio n of protozoa were worked out data on the abundance of these animals in freshwaters are not very numerous. Nevertheless, Infusoria and Rhizopoda at high densities are widespread in the water and sediments of lakes and reservoirs. In order to find ou t the importance of infusoria as a food source for cyclopoids we carried out experimental investigations using C14. For this three species of cyclopoids, widely distributed in open regions of Rybinsk reservoir were selected: Cyclops vicinus, Mesocyclops oithonoides and Kesocyclops leuckarti. The data presented give evidence that the species investigated are able as predators to consume infusorian plankton arid bacteria in the form of flocs or small clumps of detritus.

The life capacity of copepod's eggs passed through the gut of Ladoga lake Coregonus [Translation from: Zool.Journal.Moscow 29-5, 476-477, 1950]

This short paper summarises findings of experiments that were carried out using copepod eggs taken from guts of Coregonus which breeds in various Ural lakes. The study showed that copepod eggs can pass through the gut of Coregonus unharmed.

The efficiency of plankton in the utilization of the sun radiation [Translation from: Briroda, 12, 29-35, 1948]

The efficiency of utilisation of the sun's radiation by natural communities has not been properly demonstrated with what so far has been obtained of reliable values, and it represents a great interest in many respects. A systematic study of the biotic balance of lakes was done in the course of a succession of summers starting in 1932, extensive material was obtained, which permitted to compute a value fear the utilisation of the sun's radiation by plankton in lakes, and to compare this with corresponding values for marine plankton and terrestrial vegetation.

Alligator Diet in Relation to Alligator Mortality on Lake Griffin, FL

Alligator mississippiensis (American Alligators) demonstrated low hatchrate success and increased adult mortality on Lake Griffin, FL, between 1998 and 2003. Dying Lake Griffin alligators with symptoms of poor motor coordination were reported to show specific neurological impairment and brain lesions. Similar lesions were documented in salmonines that consumed clupeids with high thiaminase levels. Therefore, we investigated the diet of Lake Griffin alligators and compared it with alligator diets from two lakes that exhibited relatively low levels of unexplained alligator mortality to see if consumption of Dorosoma cepedianum (gizzard shad) could be correlated with patterns of mortality. Shad in both lakes Griffin and Apopka had high levels of thiaminase and Lake Apopka alligators were consuming greater amounts of shad relative to Lake Griffin without showing mortality rates similar to Lake Griffin alligators. Therefore, a relationship between shad consumption alone and alligator mortality is not supported.

Changes in the phytoplankton

An article discussing changes observed in phytoplankton of the Lake District. An overview is given of previous phytoplankton studies undertaken in the area, detailing some changes found in various waterbodies. Water quality changes in Lake Windermere are mentioned, including the gradual increase of dissolved organic matter (DOM), believed to be caused by the increase of sewage to the lake. The lakes in the Alps are given as an example of a similar anthropogenic pollution scenario. The treatment of a Lake District tarn with bone meal is described. The article goes on to discuss the composition of plankton throughout the year under a variety of climatic conditions. A figure shows seasonal variation in the consistuents of phytoplankton in Windermere (north basin).

Changes in physical and chemical variables

An article reviewing the work undertaken looking at the seasonal variation of chemical conditions in water at various depths in lakes. The laboratory tests undertaken for the research is outlined, as well as details of the sampling locations and the staff involved with the work. One figure shows the seasonal variation in the amounts of dissolved substances in the surface water of Windermere during 1936. Another figure shows seasonal varation inthe dry weight of phyto- and zooplankton in Windermere. Seasonal changes are discussed further and a table is included showing chemical conditions in winter and summer for Windermere.