Many of the processes on earth which are essential for sustaining life are driven by biological systems and it is functional diversity aswell as species richness which determines the health and sustainability of ecosystems. Ecosystem functions, from primary production to decomposition, are determined by the interactions both between organisms and between organisms and their environment. As such, there has long been an appeal in classifying species by their roles in ecological communities rather than by taxonomic groupings. However, there is often a disconnect between the criteria used to classify species into functional groups, often common morphological attributes, and the effect that the organisms within those groups have on specific ecosystem functions as the appropriateness of the classification criteria is rarely empirically tested. This thesis investigates inter- and intra-species variation in benthic invertebrates with respect to their effects on ecosystem processes (particle reworking and bioirrigation) and functions (nutrient cycling) and considers whether species can be grouped for single and multiple ecosystem functions in different environmental contexts. Overall the results show that species can be grouped by their effects on specific single ecosystem functions, but that these groups cannot be applied across multiple functions and processes. Further they show that species’ contributions to ecosystem functions change with environmental context (salinity, organic enrichment, seawater acidification and temperature), and that changes in the ecosystem processes known to mediate functions do not necessarily reflect a change in functioning. In addition intra-species variation in functional activity indicates that it may not be appropriate for all members of a population to be ascribed to the same functional group. This thesis highlights a need to test that different functional groups reflect different effects on ecosystem functioning. Further it shows that functional groups are not constant, individuals within populations are not necessarily functional equivalents, and that individuals have the capacity to change their contributions to ecosystem functions and processes. Future research needs to acknowledge and incorporate both biotic and abiotic sources of variability in species effects on ecosystem functions and processes.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:582732 |
| Date | January 2013 |
| Creators | Murray, Fiona |
| Publisher | University of Aberdeen |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=201938 |
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