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Project title

A test of different ecological response to nutrient loads of soft- and hard-water lakes.

Primary Funding Agency

Environmental Protection Agency

Co-Funding Organisation(s)

n/a

Lead Organisation

University of Dublin, Trinity College (TCD)

Lead Applicant

Kenneth Irvine

Project Abstract

Ecological stoichiometry is the study of the balance of elements in ecological interactions and processes. Recent theoretical and experimental work suggests that consideration of stoichiometric constraints on zooplankton production may substantially improve our understanding of zooplankton community composition and species interactions. This study aimed to examine the role of stoichiometry in influencing zooplankton community structure species occurrence and seasonal patterns of succession in six lakes in the west of Ireland. Stoichiometric processes were viewed in the context of the overall biotic and abiotic environment which may also potentially influence zooplankton community structure and dynamics. This research incorporated two field studies involving six sites located in the west of Ireland. These lakes were separated according to alkalinity type three high-alkalinity and three low-alkalinity lakes. Daphnia and calanoids dominated zooplankton biomass throughout the year in the high-alkalinity lakes whereas cladoceran taxa other than Daphnia such as Holopedium gibberum and Diaphanosoma brachyurum dominated at certain times of the year in the low-alkalinity lakes. Overall zooplankton community size structure also differed between the two alkalinity groups with a greater proportion of larger individuals in the high-alkalinity lakes and smaller individuals dominating the size distribution in the low-alkalinity lakes. Lough Feeagh was found to have the most distinctive taxa composition of the low-alkalinity lakes with relatively high abundances of Daphnia recorded compared with the other low-alkalinity lakes. Lough Talt was also the most distinct high-alkalinity lake and was quite similar in zooplankton community structure to the low-alkalinity lake Lough Easky. Both are upland and geographically adjacent lakes. Size distribution analyses and measures of cyclomorphosis in Daphnia were used to assess the role of both vertebrate and invertebrate predation in influencing seasonal patterns of species dominance among the lakes. There was strong evidence of fish predation in all three high-alkalinity lakes and in Lough Feeagh but was weaker in the other two low-alkalinity lakes. There was evidence of invertebrate predation in most lakes; although such evidence was weaker in Lough Carra and Lough Easky. There is therefore evidence which suggests that the physical chemical and biotic environment was fundamental in structuring the zooplankton assemblages of the six lakes of this study.

Grant Approved

�73,920.00

Research Hub

Healthy Environment

Research Theme

Impacts on Aquatic Ecosystems & Human Health (including Drinking Water)

Start Date

01/11/2002

Initial Projected Completion Date

n/a