Freshwater Fauna

Freshwater Fauna


the aggregate of animals that inhabit rivers, lakes, subterranean waters, and other freshwaters. Freshwater fauna includes various protozoans, turbellarians, gastro-trichs, rotifers, nematodes, nematomorphans, oligochaetes, leeches, gastropod and bivalve mollusks, crustaceans, ticks, mites, aquatic insects, and fishes and the aquatic spider (Ar-gyroneta aquatica). Many groups characteristic of marine fauna, such as echinoderms, cephalopod mollusks, and radiolarians, are absent among freshwater fauna or are represented by only a few species (sponges, coelenterates, polychaetes, bryozoans).

Freshwater animals include those that are primarily aquatic and those that are secondarily aquatic. All inhabitants of fresh-waters, that is, waters with a salinity no higher than 0.1 percent, are homeosmotic. This means that they are capable of maintaining an osmotic pressure of cellular, tissue, and cavity fluids that is higher than that of fresh water. Only a few freshwater animals can tolerate salination. Owing to sharp seasonal variations in freshwater conditions, many of the animals have developed adaptations for surviving unfavorable periods in a resting state. For example, the gemmules of sponges, the statoblasts of bryozoans, and the eggs of many crustaceans can survive prolonged desiccation and freezing. Some freshwater animals can live in warm waters with temperatures up to 40° to 50°C. The freshwater fauna of the tropics is the richest and most diverse.

Freshwater fauna probably originated from primarily aquatic marine animals that settled in freshwater lagoons and river mouths, mainly in tropical zones. Fossils of freshwater fauna dating as far back as the Devonian have been found. However, freshwater animals apparently existed in earlier periods of the earth’s history. Fossils of secondarily aquatic freshwater animals (pulmonates and insects) are known from the Jurassic.


Zhizn’presnykh vod SSSR, vols. 1–3. Moscow-Leningrad, 1940–50.
Lipin, A. N. Presnye vody i ikh zhizn’, 3rd ed. Moscow, 1950.
Konstantinov, A. S. Obshchaia gidrobiologiia, 2nd ed. Moscow, 1972.


References in periodicals archive ?
The local Oligochaeta fauna is exclusively a freshwater fauna, without any connection with the fauna of the brackish-water Caspian Sea.
This last work features the lake with water birds, flesh-water fish on its edge, and nets being set in the shoal alkaline waters to capture and study the freshwater fauna.
Kirikulaht, a lagoon closely connected with the bay of Reigi laht, revealed a diverse freshwater fauna dominated by chironomid and ephemeropteran larvae, nematodes, and planktonic cladocerans.
Water pollution has long impacted the freshwater fauna of east Texas (Shira 1913; Howells 1997).
Our studies have shown the freshwater fauna of the wheatbelt is comparatively salt-tolerant and that substantial changes in community composition will be seen only when salinity exceeds 10000 milligrams per litre,' Halse says.
Halse believes this phenomenon is due to the naturally saline conditions in Western Australia, which have led to an evolution of salinity tolerance among freshwater fauna.
Although most losses in the continent's freshwater fauna can be attributed to a variety of factors acting together, physical habitat alteration is implicated in 93 percent of the declines, according to an AFS study.
The spread of non-indigenous species and the decline in autochthonous species lead to the homogenization of the freshwater fauna in terms of systematic units; however, the functional consequences are poorly documented (Devin et al.
A recent paper in the journal Conservation Biology projects the future extinction rate to be 4 percent per decade for North American freshwater fauna, suggesting that North America's temperate freshwater ecosystems are being depleted as rapidly as tropical forests.
The age of this whale is interesting, as it coincides with what's known as The Great American Interchange, where various land and freshwater faunas migrated between North and South America.