Premium
Changes in structure and composition of an assemblage of Hydroporus species (Coleoptera: Dytiscidae) along a pH gradient
Author(s) -
JULIANO STEVEN A.
Publication year - 1991
Publication title -
freshwater biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.297
H-Index - 156
eISSN - 1365-2427
pISSN - 0046-5070
DOI - 10.1111/j.1365-2427.1991.tb00499.x
Subject(s) - abundance (ecology) , relative species abundance , biology , dytiscidae , ecology , ditch , environmental gradient , species diversity , species richness , habitat
SUMMARY. 1. Patterns of total abundance and species relative abundances in an assemblage of predatory dytiscid beetles of the genus Hydroporus were examined along a pH gradient within a ditch in north‐cast England. 2. During spring, total abundance of adult Hydroporus was greatest at the less acidic (pH 5.6–6.2) upstream sites, whereas total abundance of larval Hydroporus was greatest at the more acidic (pH 4.5) downstream sites. Both adults and larvae were more abundant in samples from the edge than from the middle of the ditch. 3. Species number and evenness did not differ along the pH gradient. 4. Species relative abundance patterns varied along the pH gradient, with particular species dominating at different sites. However, relative abundances of species changed discontinuously along the pH gradient. 5. Comparison of species abundance patterns along this pH gradient with published patterns of presence/absence among bodies of water with different pH revealed that species relationships with pH are often not consistent. Possible sources of this inconsistency are: geographic variation in species' pH preferences; complex responses of individual species to many factors in addition to pH; or random variation among sites due to colonization and extinction history. 6. The overall results suggest that pH is not the only, or even the most important, factor influencing Hydroporus populations and assemblage organization.