ABSTRACT Understanding succession of fish communities associated with artificial structures is re... more ABSTRACT Understanding succession of fish communities associated with artificial structures is required to assess the potential of these initiatives as part of fisheries enhancement strategies and determine possible impacts on the broader ecological community. Artificial reef systems constructed in three south-eastern Australian estuaries were monitored over a four-year period. Recruitment of fish to the artificial reefs was rapid, with significantly greater species richness observed on artificial reefs than on natural habitats for the majority of locations and times. The rate of community change varied between estuaries and appeared to be related to the quality and amount of existing habitat and the distance of the artificial reef from sources of recruitment. General patterns were also identified among estuaries driven by strong recruitment, followed by a rapid reduction in several mobile schooling species. By contrast, there was early and sustained recruitment of a variety of sparid species, which are of importance to recreational and commercial fisheries.
The red morwong, Cheilodactylus fuscus Castelnau (Pisces : Cheilodactylidae), is a conspicuous fi... more The red morwong, Cheilodactylus fuscus Castelnau (Pisces : Cheilodactylidae), is a conspicuous fish on the rocky reefs of the eastern Australian coast. Visual determination of the sex of individuals in the field is necessary to remove sex bias in home-range and ...
After a prolonged summer dry period, the effects of a distinctive and continuing rainfall on the ... more After a prolonged summer dry period, the effects of a distinctive and continuing rainfall on the nutrients and plankton of an urban coastal lagoon were investigated over 2 months. The lagoon filled up over 5 weeks from <10% of its maximum volume until it broke open to the sea. Nutrients (ammonia and oxidised nitrogen) significantly increased the day after initial rainfall, before returning to pre-rainfall conditions within 5 days. Phytoplankton biomass grew 10 fold within a week after initial rainfall in the 25-30 °C water and declined to near initial levels 2 weeks later. The assemblage of phytoplankton and zooplankton changed dramatically after 1 day and again by 6 days later, gradually returning to the original community by 2 weeks after the initial rainfall. Zooplankton responded within a day with a two fold increase in the adult stages of the calanoid copepod Oithona sp., followed a week later by nauplii and adult Acartia bispinosa. The influx of adult Oithona indicates resting populations that were previously under sampled by our plankton net. The plankton community returned to the initial state by 2 weeks, to being dominated by a centric diatom and A. bispinosa after 5 weeks. Dilution of the lagoon reached a maximum of 0.25 d -1, while growth rates of the phytoplankton population reached a maximum of 1 d -1, and A. bispinosa nauplii growth of 2.5 d -1. Declines in chlorophyll biomass from the maximum 10 μg l -1, at a rate of approximately 10% d -1 are consistent with the modelled uptake by zooplankton. The nutrients from runoff, growth and the influx of new zooplankton into the water column, resulted in a depleted δ13C and δ15N stable isotope signature of A. bispinosa by 2-4 ppt within 1-2 weeks, consistent with diatom growth and the terrestrial supply of depleted nutrients. δ34S of A. bispinosa was enriched by 2 ppt for 1-2 weeks after rainfall, but unlike C and N, returned to pre-rainfall levels by the end of the study period. We suggest that plankton studies in coastal lakes with variable water levels that are not tidally driven, should account for the influence of changes in water levels to help explain data variability.
ABSTRACT Understanding succession of fish communities associated with artificial structures is re... more ABSTRACT Understanding succession of fish communities associated with artificial structures is required to assess the potential of these initiatives as part of fisheries enhancement strategies and determine possible impacts on the broader ecological community. Artificial reef systems constructed in three south-eastern Australian estuaries were monitored over a four-year period. Recruitment of fish to the artificial reefs was rapid, with significantly greater species richness observed on artificial reefs than on natural habitats for the majority of locations and times. The rate of community change varied between estuaries and appeared to be related to the quality and amount of existing habitat and the distance of the artificial reef from sources of recruitment. General patterns were also identified among estuaries driven by strong recruitment, followed by a rapid reduction in several mobile schooling species. By contrast, there was early and sustained recruitment of a variety of sparid species, which are of importance to recreational and commercial fisheries.
The red morwong, Cheilodactylus fuscus Castelnau (Pisces : Cheilodactylidae), is a conspicuous fi... more The red morwong, Cheilodactylus fuscus Castelnau (Pisces : Cheilodactylidae), is a conspicuous fish on the rocky reefs of the eastern Australian coast. Visual determination of the sex of individuals in the field is necessary to remove sex bias in home-range and ...
After a prolonged summer dry period, the effects of a distinctive and continuing rainfall on the ... more After a prolonged summer dry period, the effects of a distinctive and continuing rainfall on the nutrients and plankton of an urban coastal lagoon were investigated over 2 months. The lagoon filled up over 5 weeks from <10% of its maximum volume until it broke open to the sea. Nutrients (ammonia and oxidised nitrogen) significantly increased the day after initial rainfall, before returning to pre-rainfall conditions within 5 days. Phytoplankton biomass grew 10 fold within a week after initial rainfall in the 25-30 °C water and declined to near initial levels 2 weeks later. The assemblage of phytoplankton and zooplankton changed dramatically after 1 day and again by 6 days later, gradually returning to the original community by 2 weeks after the initial rainfall. Zooplankton responded within a day with a two fold increase in the adult stages of the calanoid copepod Oithona sp., followed a week later by nauplii and adult Acartia bispinosa. The influx of adult Oithona indicates resting populations that were previously under sampled by our plankton net. The plankton community returned to the initial state by 2 weeks, to being dominated by a centric diatom and A. bispinosa after 5 weeks. Dilution of the lagoon reached a maximum of 0.25 d -1, while growth rates of the phytoplankton population reached a maximum of 1 d -1, and A. bispinosa nauplii growth of 2.5 d -1. Declines in chlorophyll biomass from the maximum 10 μg l -1, at a rate of approximately 10% d -1 are consistent with the modelled uptake by zooplankton. The nutrients from runoff, growth and the influx of new zooplankton into the water column, resulted in a depleted δ13C and δ15N stable isotope signature of A. bispinosa by 2-4 ppt within 1-2 weeks, consistent with diatom growth and the terrestrial supply of depleted nutrients. δ34S of A. bispinosa was enriched by 2 ppt for 1-2 weeks after rainfall, but unlike C and N, returned to pre-rainfall levels by the end of the study period. We suggest that plankton studies in coastal lakes with variable water levels that are not tidally driven, should account for the influence of changes in water levels to help explain data variability.
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Papers by I. Suthers