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  • -- Layton et al. Chemical microenvironments within macroalgal assemblages: implications for the inhibition of kelp recruitment by turf algae. Limnology & Oceanography. DOI:10.1002/lno.11138 -- Kelp forests around the world are under increasing pressure from anthropogenic stressors. A widespread consequence is that in many places, complex and highly productive kelp habitats have been replaced by structurally simple and less productive turf algae habitats. Turf algae habitats resist re-establishment of kelp via recruitment inhibition; however little is known about the specific mechanisms involved. One potential factor is the chemical environment within the turf algae and into which kelp propagules settle and develop. Using laboratory trials, we illustrate that the chemical microenvironment (O2 concentration and pH) 0.0–50 mm above the benthos within four multispecies macroalgal assemblages (including a turf-sediment assemblage and an Ecklonia radiata kelp-dominated assemblage) are characterised by elevated O2 and pH relative to the surrounding seawater. Notably however, O2 and pH were significantly higher within turf-sediment assemblages than in kelp-dominated assemblages, and at levels that have previously been demonstrated to impair the photosynthetic or physiological capacity of kelp propagules. Field observations of the experimental assemblages confirmed that recruitment of kelp was significantly lower into treatments with dense turf algae than in the kelp-dominated assemblages. We demonstrate differences between the chemical microenvironments of kelp and turf algae assemblages that correlate with differences in kelp recruitment, highlighting how degradation of kelp habitats might result in the persistence of turf algae habitats and the localised absence of kelp.

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    A 12-month program was developed and implemented in order to obtain baseline information on water quality (salinity, water temperature, dissolved oxygen, turbidity, pH, dissolved nutrients, silica), ecological condition as shown by Chlorophyll a, benthic macroinvertebrates, pathogens, and habitat extent determined from habitat mapping. Five key estuaries and coastal waters were assessed in the Southern NRM Region of Tasmania. This data includes sampling from Pitt Water / Orielton Lagoon, North West Bay, Port Cygnet, Little Swanport, Moulting Lagoon / Great Swanport.

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    We implemented a monitoring program developed by Crawford and White (2006), which was designed to assess the current condition of six key estuaries in NW Tasmania: Port Sorell, the Leven, Inglis, Black, Montagu and Arthur River estuaries. This study considered a range of water quality and ecological indictors commonly used to monitor estuaries. These included: salinity, temperature, dissolved oxygen, turbidity, pH, nutrients (nitrate + nitrite, dissolved reactive phosphorus and ammonia), silica molybdate reactive and chlorophyll a for the water column; chlorophyll a and macroinvertebrate community structure amongst the sediments.

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    Indicators of estuarine ecosystem health – temperature, salinity, turbidity, dissolved oxygen, chlorophyll a, pH, nutrients - were sampled each month for twelve months at four sites in Georges Bay and at the bridge at the river mouth by the Tasmanian Aquaculture and Fisheries Institute (TAFI), community volunteers and Break O’Day Council staff. Another indicator, macroinvertebrate fauna, was sampled by TAFI in winter and summer, and data were obtained on pathogen levels from the Tasmanian Shellfish Quality Assurance Program.

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    The National Outfall Database (NOD) project addresses the need of government and community to understand the impacts on health and the ocean environment that occur from sewerage outfalls around Australia. This dataset is part of the assessment and mapping of the marine impacts of wastewater disposal to ocean and estuarine waters in Australia. The data collected in this study is intended to be used to assist decision makers to understand risk and prioritise investment, to help the public understand water and wastewater management and make decisions when choosing recreation locations, and private operators seeking to re-use wastewater or products found within wastewater. Each outfall is divided into three levels of data; one (1) being basic information such as location, treatment, governance and size; two (2) being more detailed information taken from publicly available annual environmental monitoring reports, licence and other information; and three (3) containing highly detailed information such as daily performance data and receiving waters ecosystem assessments and studies to enable researchers and others to undertake comparative studies. The data custodian will make a data report and methodology available to provide a full explanation of this database. The National Outfall Database is an online resource available here: https://www.outfalls.info/ The database currently tracks 29 indicators across 178 monitoring sites. The data is also available for download in CSV format in the "online resources" section of this record, and will continue to be updated as new data becomes available (data currently available to 30/06/2020 - last checked 23/08/2021).