Self-Organizing Maps in Revealing Variation in Non-obligatory Riverine Fish in Long-term Data |
| |
Authors: | Andrzej Kruk |
| |
Institution: | (1) Department of Ecology and Vertebrate Zoology, University of Łódź, 12/16 Banacha Str., 90-237 Łódź, Poland |
| |
Abstract: | Sensitiveness to the overall influence of the river channel regulation, impoundment and pollution was studied for 12 non-obligatory
riverine (NOR) fish species in the Warta River, Poland, over the period of 1963–1998. Their total abundance has not considerably
changed unlike the structure of their aggregation, which was revealed by a self-organizing map (SOM, Kohonen unsupervised
artificial neural network) almost perfectly separating 1960s samples from 1990s ones. The greatest changes in proportion were
recorded for the dominant roach Rutilus rutilus (from 28.6 to 60.0%), perch Perca fluviatilis (1.9 to 9.5%), pike Esox lucius (2.9 to 4.9%), and the former codominant bleak Alburbus alburnus (22.9 to 1.8%). They resulted from highly significant (p < 0.001), reaching even one order of magnitude, differences in the abundance of these species. Such remarkable alternations
in dominant NOR ichthyofauna obviously influenced the whole fish assemblage structure, which was best illustrated by a clear
vertical gradient over SOM in Simpson and Shannon indices. Thus, NOR species, both studied together and separately, can supply
valuable information on the fish assemblage dynamics and should not be neglected in temporal analyses, often focused only
on vulnerable obligatory riverine, migratory and/or endemic species. |
| |
Keywords: | fish assemblages roach perch pike bleak habitat destruction river regulation water pollution |
本文献已被 SpringerLink 等数据库收录! |
|