Effect of Desalination Discharge on the Abundance and Diversity of Reef Fishes

Abstract

Global growth in desalination industries has increased the need for an evidence-based understanding of associated environmental impacts. We completed a seven-year assessment of the responses of fish assemblages to hypersaline discharge from the large Sydney Desalination Plant. At 12 times before, eight times during, and four times following the cessation of discharging hypersaline brine, we sampled reef fishes at two outlet sites and two close reference sites, as well as four reference sites that were located from 2−8 km from the outlet. At each site and each time of sampling, five 50 m video transects were used to sample reef fish assemblages. Following the commencement of discharging, there was a 279% increase in the abundance of fish around the outlet, which included substantially greater abundances of pelagic and demersal fish, as well as fishes targeted by recreational and commercial fishers. Following the cessation of discharge, abundances of fishes mostly returned to levels such that there was no longer a significant effect compared to the period prior to the commencement of the desalination plant's operations. Overall, our results demonstrate that well-designed marine infrastructure and processes used to support the growing demand for potable water can also enhance local fish abundances and species richness.

Aspects of environmental impacts of seawater desalination: Cyprus as a case study

“…A potential explanation for the lack of recorded impacts may be high natural variability, which is typical of such seabed systems in combination with the rapid dilution undergone by the hypersaline brine after exiting the discharge pipe. An interesting aspect is the concentration of fish at the brine outfalls of the plants surveyed here, which is reminiscent of observations from Australia [48] and hitherto unreported for the Mediterranean. Even though only qualitative photographic surveys were conducted, they reveal the main fauna species found close to the brine discharge area and suggest overall increased fish density.…”

“…Overall, there is still a shortage of studies concerning Mediterranean marine life. Elsewhere in the world, for example, in the Red Sea, such a study has investigated brine impacts on the coral Fungia granulosa [70], whereas near Sydney, Australian scientists interestingly observed a strong increase in the abundance of fish around the outlet, which included substantially greater abundances of demersal and pelagic fish, as well as fishes targeted by recreational and commercial fishing near the recently-inaugurated desalination plant [48]. Further research should address the spatial scale of impacts, and also the underlying phy sicochemical drivers for the effects observed.…”

Sustainable desalination: Long-term monitoring of brine discharge in the marine environment

“…We cannot determine whether the effluent attracts some fish species or whether there is higher habitat diversity in the discharge area because we have no similar data from before the plant began operating. However, Kelaher et al (2020) recently reported an increase in local fish abundance and species richness related with the BD of a SWRO plant in Australia. In the present study, we also identified a decrease in fish abundance in both study areas from 2012 that could not be attributed to the discharge.…”

Energy and water without carbon: Integrated desalination and nuclear power at Diablo Canyon

“…Diffusers represent the most environmentally friendly option for brine disposal. They have been shown to have minimal impacts on local fish populations [49], and have been employed with success at other plants in sensitive ecological environments such as the Sydney Desalination Plant in Sydney, Australia [50].…”