Trophodynamics of plankton communities subjected to environmental fluctuations in an inverse estuary: A case study of the Coorong; South Australia

Author: Deevesh Ashley Hemraj

Hemraj, Deevesh Ashley, 2017 Trophodynamics of plankton communities subjected to environmental fluctuations in an inverse estuary: A case study of the Coorong; South Australia, Flinders University, School of Biological Sciences

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Aquatic ecosystems contribute to the majority of earth’s surface and play a vital role in sustaining life on the earth. They are highly diverse in terms of physio-chemical properties, which in turn drive their biological properties. Yet, they are interconnected and influence the physical, chemical and biological properties of each other. Aquatic systems tend to be highly dynamic. In particular, estuaries are complex systems interconnecting coastal waters and riverines systems. The physio-chemical dynamics of estuaries are highly driven by the influences of freshwater flow from rivers and tidal input of marine water. As such, estuaries are dominated by gradients of environmental factors that fluctuate considerably. Organisms living in estuaries tend to be adapted to the variability of environmental factors. However, spatial and temporal changes remain a major influence on the populations, communities, physiologies and phenologies of estuarine dwelling organisms. Modification of natural spatial and temporal environmental variations often discrupts the natural fluctuations community structure and interactions. Such modifications often cause serious impairments to ecosystem health and functioning. The Coorong, South Australia, is a Ramsar listed inverse estuary that is highly affected by anthropogenic disruption of water flow. It is a system that has suffered extreme ecosystem function and health degradation associated to reduced freshwater input due to anthropogenic and drought influences. This research thesis uses planktonic organisms to study the health and functioning of the Coorong. Planktonic organisms are very closely linked to water quality parameters. As such, this study identified planktonic bioindicators of environmental health of the Coorong. Moreover, it examined the changes in zooplankton population structure and recruitment in relation to variations in water quality and, finally, it examined the changes in ecosystem functioning in relation to water flow in the system. Overall, this study uses innovative approaches for studying changes in plankton communities in relation to environmental fluctuations and provides important tools and information for managing the health of a degraded inverse estuary.

Keywords: Coorong, Copepod, Inverse Estuary, Plankton, Zooplankton, Foodweb, Water Quality, Ecosystem Health, Ecosystem functioning, Anthropogenic

Subject: Biological Sciences thesis

Thesis type: Doctor of Philosophy
Completed: 2017
School: School of Biological Sciences
Supervisor: Sophie Leterme