Macroinvertebrate assemblages in Pennsylvania (U.S.A.) springs

Abstract

Five distinct macroinvertebrate assemblages were identified using cluster analysis of the rank-order abundances of 13 orders in 15 freshwater springs of central Pennsylvania, U.S.A. A principal components analysis of 20 environmental factors indicated that an insect-dominated assemblage occurred in low pH, softwater sandstone springs and an amphipod-dominated assemblage was associated with medium to hardwater springs with a silt to gravel substratum. Three other assemblages were found in hardwater limestone springs: the peracaridan-hydrobiid assemblage was characterized by dense macrophyte beds and a silt to cobble substratum, the peracaridan-triclad-glossosomatid assemblage by a rubbly, gravel-cobble substratum and relatively high discharge, and the peracaridan-hydrobiid-oligochaete assemblage by a silty substratum and dense mats of green algae.Most of the common macroinvertebrate species were associated with specific physical, chemical, and (or) vegetational factors, but abundance associations between species pairs were generally lacking. We infer that assemblages are primarily determined by the match between the environmental mosaic of individual springs and the ecological requirements of the available species, rather than by strong interspecific interactions.Species-environment associations were assessed in an additional study of five closely neighboring springs in which some environmental variables of the wider study were nearly constant.

The response of chironomid assemblages to mineral richness gradient in the Western Carpathian helocrenes

“…However, in these studies water chemistry (particularly pH and associated mineral richness) was closely correlated with some other variables, the effects of which were inseparable. Only Hahn (2000) observed different macroinvertebrate assemblages at acidic rheocrenes compared to non-acidic, and Glazier & Gooch (1987) observed insectdominated assemblage in low pH springs, while amphipoddominated assemblage occurred in medium to hardwater springs.…”

“…On the other hand, an obvious assemblage response to mineral richness gradient was observed in amphipods (Glazier & Gooch 1987;Hahn 2000), which can reach a very high abundance in springs, but avoid acidic environments, where they are absent. Hahn (2000) observed a considerably lower number of taxa at acidic rheocrenes compared to non-acidic (31 vs. 53 respectively).…”

“…Therefore, it is interesting that only a very limited number of studies noticed a significant effect of basicity on spring macroinvertebrate assemblages (Glazier & Gooch 1987;Hahn 2000), though it has already been observed in several different organism groups (Horsák & Hájek 2003;Poulíčková et al 2003;Hájek et al 2006;Opravilová & Hájek 2006). The most probable reason is that the effect of water chemistry in most studies was overridden by the variance in spring types (limno-, rheo-, and helocrenes included) or by insufficient length of the gradient of mineral richness.…”

Macrozoobenthos assemblages in springs of the Penza region

“…Наиболее удачная ее классификация изло-жена в одной часто цитируемой работе [7]. Отмечая, что большинство отрядов животных представлены в их данных единственным доминирующим видом, авторы описали "трядные комплексы", выделив пять типов сообществ (насекомые; амфиподы; ракооб-разные + моллюски и др.)…”

“…Последний является одной из самых заметных составляющих структуры родниковых со-обществ. Однако обобщающих работ, посвященных макрозообентосу родников, известно немного [6][7][8]. Эти работы выполнены в разных зоогеографиче-ских регионах, свои построения авторы осуществ-ляли разными методами.…”