Quantitative detection of human- and canine-associated Bacteroides genetic markers from an urban coastal lagoon.

The contamination of water catchments by nonpoint source faecal pollution is a major issue affecting the microbial quality of receiving waters and is associated with the occurrence of a range of enteric illnesses in humans. The potential sources of faecal pollution in surface waters are diverse, including urban sewage leaks, surface runoff and wildlife contamination originating from a range of hosts. The major contributing hosts require identification to allow targeted management of this public health concern. In this study, two high-performing Microbial Source Tracking (MST) assays, HF183/Bac242 and BacCan-UCDmodif, were used for their ability to detect host-specific Bacteroides 16Sr RNA markers for faecal pollution in a 12-month study on an urban coastal lagoon in Sydney, Australia. The lagoon was found to contain year-round high numbers of human and canine faecal markers, as well as faecal indicator bacteria counts, suggesting considerable human and animal faecal pollution. The high sensitivity and specificity of the HF183/Bac242 and BacCan-UCDmodif assays, together with the manageable levels of PCR inhibition and high level DNA extraction efficiency obtained from lagoon water samples make these markers candidates for inclusion in an MST 'toolbox' for investigating host origins of faecal pollution in urban surface waters.

Sediment bacterial communities associated with environmental factors in Intermittently Closed and Open Lakes and Lagoons (ICOLLs).

Intermittently Closed and Open Lakes and Lagoons (ICOLLS) are important coastal systems that are periodically separated from the ocean by a sand barrier or a berm. In urban ICOLLs, continuous inputs of organic material and nutrients into coastal lagoons are contributing to eutrophic conditions that, together with natural environmental factors have implications for the resident sediment bacterial communities. We used molecular tools to investigate the ecological communities of four ICOLLs; Narrabeen, Dee Why, Curl Curl and Manly in Sydney, Australia, which have been subjected to increasing pressure from anthropogenic activities over the last century. We used targeted gene sequencing of the prokaryotic 16S ribosomal RNA gene to describe the bacterial diversity and community structure and discuss differences with respect to environmental factors at the ICOLL scale (e.g. size, shape, normalised N loading) and site scale (e.g. water and sediment quality) within each lagoon. Due to differences in hydrological patterns, we expected that sediment bacterial communities would be more heterogenous in displacement-dominated lagoons (Curl Curl and Manly) than the mixing-dominated lagoons (Narrabeen and Dee Why). Interestingly, we did not find strong relationships between the main bacterial groups and distance from the lagoon entrance (used as a proxy for salinity and silt) in the displacement-dominated lagoons. Moreover, we found that α diversity was highest in Narrabeen and Manly lagoons despite differences in lagoon size and shape. Furthermore, while bacterial community structure was similar in Curl Curl and Dee Why, communities in Manly and Narrabeen differed along temperature/TOC and salinity/silt gradients respectively. In Manly lagoon, we found relatively more anaerobic bacteria such as Epsilonbactereota which is involved in the oxidation and reduction of sulfur compounds. Moreover, we identified several bacterial taxa (including sulfur metabolising Chlorobiaceae) related to increasing TOC that could be investigated further as potential indicators of excess enrichment.

A database of marine phytoplankton abundance, biomass and species composition in Australian waters.

There have been many individual phytoplankton datasets collected across Australia since the mid 1900s, but most are unavailable to the research community. We have searched archives, contacted researchers, and scanned the primary and grey literature to collate 3,621,847 records of marine phytoplankton species from Australian waters from 1844 to the present. Many of these are small datasets collected for local questions, but combined they provide over 170 years of data on phytoplankton communities in Australian waters. Units and taxonomy have been standardised, obviously erroneous data removed, and all metadata included. We have lodged this dataset with the Australian Ocean Data Network (http://portal.aodn.org.au/) allowing public access. The Australian Phytoplankton Database will be invaluable for global change studies, as it allows analysis of ecological indicators of climate change and eutrophication (e.g., changes in distribution; diatom:dinoflagellate ratios). In addition, the standardised conversion of abundance records to biomass provides modellers with quantifiable data to initialise and validate ecosystem models of lower marine trophic levels.

A fish kill associated with a bloom of Amphidinium carterae in a coastal lagoon in Sydney, Australia.

We report on a dense bloom (~1.80 × 105 cells mL-1) of the marine dinoflagellate species Amphidinium carterae (Genotype 2) in a shallow, small intermittently open coastal lagoon in south eastern Australia. This bloom co-occurred with the deaths of >300 individuals of three different species of fish. The opening of the lagoon to the ocean, as well as localized high nutrient levels, preceded the observations of very high cell numbers. A. carterae is usually benthic and sediment-dwelling, but temporarily became abundant throughout the water column in this shallow (<2 m) sandy habitat. Histopathological results showed that the Anguilla reinhardtii individuals examined had damage to epithelial and gill epithelial cells. An analysis of the bloom water indicated the presence of a compound with a retention time and UV spectra similar to Luteophanol A, a compound known from a strain of Amphidinium. Assays with a fish gill cell line were conducted using a purified compound from cells concentrated from the bloom, and was found to cause a loss of 87% in cell viability in 6 h. The fish deaths were likely due to the low dissolved oxygen levels in the water and/or the presence of Luteophanol A-like compounds released during the bloom.