ISSN:
1573-5117
Keywords:
limnology
;
seasonality
;
aquatic invertebrates
;
zooplankton
;
zoobenthos
;
lakes
;
impoundments
;
rivers
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract The seasonality of freshwater aquatic invertebrates in Southern Hemisphere and low-latitude inland waters in Africa, Australasia and South America is reviewed. Fauna from the tropics to temperate latitudes manifests some seasonality, the amplitude of which tends to increase, albeit inconsistently, with latitude. The wide diversity of habitats considered, and deficiencies in the data preclude generalizations about patterns and magnitude of seasonal response, which principally reflect system-specific events and interactions. For example, zooplankton declined after mixing events in some stratified systems, but increased in others, food availability being implicated. Zooplankton was most abundant in summer in some stratifying systems, and in winter in others, while in most non-stratifying systems, it was most abundant around the winter solstice, and in several, declined during the rainy season. Seasonality of the zoobenthos was frequently linked to hydrological events such as fluctuations in water level which potentially influence food and habitat availability. Seasonal anaerobiosis in shallow sheltered waters and deeper hypolimnia imposes spatio-temporal restrictions on the benthic fauna. Low oxygen solubility, rapid oxygen depletion and decomposition of organic food matter at the elevated temperatures are probably significant influences. Life histories of Southern Hemisphere stream fauna appear seasonally flexible and opportunistic by contrast with the apparently synchronous cycles exhibited by north temperate representatives. Such flexibility may be selective both in respect of climatic unpredictability and equability. The influences of predation and resource availability upon seasonal dynamics remain to be explored more fully, particularly in aquatic ecosystems in warm, arid regions which lack the climatic ‘predictability’ of the cooler, humid, temperate zones.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00045932
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