Place of publishing:
Subject and Keywords:
The article conitains a discussion of literature dealing with the effect of temperature and concentration and kind of food, on seasonal and habitat variations (both between habitats and within one habitat) of zooplankton (crustaceans and rotifers belonging to plankton filtrators and sedimentators). Such variations relate both to the size and growth rate of individuals, and to length of development, length of life, reproduction rate and fertility. The results of a large number of field observations and laboratory experiments shows beyond doubt that there is a distinct correlation between variations in temperature and concentration and kind of food and differences, both seasonal parameters. Among the main factors determing variation in growth rate, reproduction, fertility and development of zooplankton, attention is drawn chiefly to the temperature factor, and less often to the food factor, a distinct tendency being observed here to carrying out experimental work in a laborartory at a constant temperature and referring the results obtained to natural conditions. As a result the effect exercised by the temperature gradient on development, growth and fertility of zooplankton is not taken into consideration. ; The situation is similar in relation to the food factor. The majority of studies on the effect of kind and concentration of food on the development, growth and production of zooplankton are laboratory observations, in which monocultures of algae and bacteria are used as food. This is an easily accessible food on account of the food particles and is fairly homogenous in respect of energy value, but rarely dominates under natural conditions. In a natural habitat the plankton consumer has many kinds of food available (bacteria, nannoplankton, detritus, soluble organic matter), very heterogeneous in respect of nutritive value and accessibility. What is more, the food concentrations used in this kind of experiment are usually many times greater than those encountered in a natural habitat. As a result considerable differences occur in the utilization and assimilation of food between individuals ,cultured in a laboratory and individuals in a natural habitat, which in turn has an important influence on development rate, growth and production of plankton organism. In consequence interpretation of the food-consumer relation under natural conditions, the question of the limiting role of food in a natural habitat, its accessibility, food preferences and the influence of food development and production of zooplankton is still far from constituting a final explanation and further intensive research is required.
Language of abstract:
Projects co-financed by:
Operational Program Digital Poland, 2014-2020, Measure 2.3: Digital accessibility and usefulness of public sector information; funds from the European Regional Development Fund and national co-financing from the state budget.