Do functional or morphological classifications explain stream phytobenthic community assemblages?

Abstract

There are many useful metrics currently available to explain ecological variation within phytobenthic communities. However, most metrics are challenging to use (requiring specialist taxonomic skills and knowledge), limiting their widespread applicability. Furthermore, because most metrics have been developed to represent ecological responses to single pressures, no single metric in isolation can effectively describe complex changes in the state of communities responding to multiple environmental pressures. Understanding of such changes therefore requires the use of multiple metrics to account for the impacts of many environmental pressures. This study explores the potential of functional and morphological classifications to explain phytobenthic community responses to differences in nutrient concentration, current velocity, simulated high flow disturbances and invertebrate grazers. Three previously used phytobenthic classifications and a new metric developed from a phytoplankton classification were tested using two datasets from streams in the north west of England in 2010. A combination of the newly applied morphological classification (using maximum linear dimension, surface area and volume) and a functional classification (using life-forms) showed great potential for aiding the understanding of phytobenthic community responses to environmental pressures. Furthermore, it is suggested that, with further testing, this new classification, which requires less specialist knowledge, could be widely implemented and would potentially give great insight into the ecology of the entire phytobenthic community.

Keywords:

• eutrophic
• oligotrophic
• diatoms
• current velocity
• biomonitoring
• disturbance

Acknowledgements

This work forms part of a PhD project funded by the NERC Centre for Ecology and Hydrology, Lancaster University and Natural England with an additional contribution from the Hutchinson's Gilling Charity. For supervision support, thanks are due to Chris Mainstone, Prof. Phil Haygarth and Prof. Louise Heathwaite. For comments on the manuscript thanks are due to Jane Law.