Farm ponds in New South Wales, Australia: relationship between macrophyte and phytoplankton abundances

Abstract

The physical, chemical and biological characteristics of 65 farm ponds in the Northern Tablelands and Central Western Slopes regions of New South Wales, Australia, were similar to those recorded for Australian ponds in other studies. The strongest single relationship between physico-chemical characteristics and biological characteristics was for high abundance of phytoplankton, low abundance of macrophytes, high turbidity, and high nutrient concentrations in ponds on granitic soil. Variation among the ponds was such that no other relationship was significant. Five groups of ponds were discerned on the basis of their biological and physico-chemical characteristics. One group could be classed as reasonably ‘pristine’, with high water clarity and high abundance of macrophytes; another group presented highly eutrophic, phytoplankton-dominated conditions. Ponds in these two groups can be described as being in ‘alternative stable states’. A third group had been modified with the intention of improving the appearance or utility of the ponds. The last two groups identified in this analysis had no specific parallels in the literature. Abundance of macrophytes was related to good water quality, and encouragement of increased abundance of submerged plants in farm ponds could result in improved water quality.

Alternative stable states in the aquatic vegetation of shallow urban lakes. I. Effects of plant harvesting and low-level nutrient enrichment

“…Casanova et al (1997) also have reported the co-occurrence of high macrophyte and phytoplankton biomass in a number of farm dams in New South Wales, Australia. It is possible that the nutrient-enriched mesocosms in Victoria Park Lake were in a transitional phase, on the way to ultimate dominance by phytoplankton; however, this would seem unlikely, given that no deleterious effects of nutrient enrichment were detected on any aspect of the performance of the submerged angiosperms.…”

Ecological regime shifts in salinised wetland systems. II. Factors affecting the dominance of benthic microbial communities

“…High nutrient conditions often lead to high biogenic turbidities (phytoplankton dominance) (e.g. Casanova et al, 1997). This suggests that at intermediate salinities, wetlands subject to episodic rainfall with moderate to high nutrient levels, may be prone to phytoplankton blooms (Fig.…”

Does toxic Microcystis aeruginosa affect aquatic plant establishment?

“…Results of a survey of farm dams in New South Wales indicate that aquatic plant communities are less diverse and abundant where Ž . cyanobacterial blooms occur Casanova et al, 1997 . This phenomenon is well supported by Northern Hemisphere studies in which the decline in submerged plant abundance has been attributed to shading of sub-Ž merged plants by algae in the water column Phillips et . al., 1978;Moss, 1991;Moss et al, 1996 .…”

“…Ž . cm Casanova et al, 1997 . A shade control 20% , assumed to produce similar light attenuation to the turbidity in the cultures, and a culture solution control were added to the low density experiment to control for Ž .…”