Identifying Metocean Drivers of Turbidity Using 18 Years of MODIS Satellite Data: Implications for Marine Ecosystems under Climate Change

Turbidity impacts the growth and productivity of marine benthic habitats due to light limitation. Daily/monthly synoptic and tidal influences often drive turbidity fluctuations, however, our understanding of what drives turbidity across seasonal/interannual timescales is often limited, thus impeding our ability to forecast climate change impacts to ecologically significant habitats. Here, we analysed long term (18-year) MODIS-aqua data to derive turbidity and the associated meteorological and oceanographic (metocean) processes in an arid tropical embayment (Exmouth Gulf in Western Australia) within the eastern Indian Ocean. We found turbidity was associated with El Niño Southern Oscillation (ENSO) cycles as well as Indian Ocean Dipole (IOD) events. Winds from the adjacent terrestrial region were also associated with turbidity and an upward trend in turbidity was evident in the body of the gulf over the 18 years. Our results identify hydrological processes that could be affected by global climate cycles undergoing change and reveal opportunities for managers to reduce impacts to ecologically important ecosystems.

Pseudotrichonotus belos new species, first record of the fish family Pseudotrichonotidae from Australia (Teleostei: Aulopiformes)

Pseudotrichonotus belos new species, described from three specimens trawled in 100–120 m offshore between Exmouth Gulf and Shark Bay, Western Australia, represents the first record of the sand-diving fish family Pseudotrichonotidae from Australian waters. It differs from its two congeners in having a more posteriorly positioned dorsal fin (predorsal length 39.6–41.2 % SL) and fewer dorsal- and anal-fin rays (31–33 and 12, respectively).

The Yannarie Solar Project: Design of a Solar Saltfield in Western Australia to Safeguard the Natural Environment

The Northwest Coast of Western Australia is the location for a number of large solar saltfields. More than 10 million tonnes of high grade solar salt is exported annually from these saltfields; predominantly servicing the chloralkali industries of Northern and Southeast Asia. Straits Resources Limited is a mining company with operations in Australia and Indonesia. It has identified the solar salt industry as an opportunity to diversify its resource portfolio and build a longer-term position within the resource sector. Access has been approved by the Government of Western Australia to a large area in the eastern Exmouth Gulf region of Western Australia suitable for a solar saltfield with an ultimate capacity as high as 10 million tonnes per annum. All new resources projects in Australia must proceed through a rigorous environmental approval process at both the Federal (Commonwealth) and State Government levels. Straits commissioned a team of saltfield design, environmental and engineering consultants to design an economically viable saltfield that minimises impacts to the environment. There has been a series of iterative changes in its design based on feedback from environmental and cultural heritage studies. This has enabled the saltfield to be specifically located within a defined footprint to avoid sensitive areas such as mangroves, tidal creeks and algal mats. Comprehensive studies have been undertaken on the local marine and terrestrial flora and fauna (including migratory bird and marine fauna), together with surveys for cultural heritage, soils, hydrology and a sweep of other parameters including hydrodynamic modelling of the marine environment. A commercial trawling fishing industry operates in the waters of Exmouth Gulf that is also the permanent home or on the migratory path of a number of significant marine fauna, including whales, turtles, and dugongs. The project, known as the Yannarie Solar Project, is progressing through the environmental approval processes of the Australian Commonwealth and Western Australian Governments. The conclusion is that the technical findings of the suite of studies that examined the environmental aspects of the engineering requirements of the saltfield provide a sound basis for project approval. Assuming that approval is given, and the current schedule maintained, construction would commence in 2008 and shipments of salt in 2011.

Nutrient exchange of extensive cyanobacterial mats in an arid subtropical wetland

Cyanobacterial mats cover extensive areas of subtropical arid coastal wetlands and are sites of active nutrient exchange. To assess spatial (low v. high in the intertidal zone) and temporal (day v. night) variability in nitrogen (N) exchange in arid Exmouth Gulf, Western Australia, we measured nutrient exchange (NOx–-N, NH4+ and soluble reactive phosphorus) during tidal inundation and N fixation of cyanobacterial mats before and during an unusual period of heavy rainfall. Additionally, we investigated the species composition within the cyanobacterial mat. We hypothesised that nutrients are released to the floodwater during tidal inundation, that N fixation is a significant path of N incorporation, that highest N fixation rates occur in the low intertidal zone at night, and that the cyanobacterial mat community composition varies across the intertidal zone. Our results showed that nutrients were removed from the floodwater during tidal inundation. N fixation accounted for 34% of N incorporation, with highest rates in the lower intertidal zone during the day. The cyanobacterial mat was dominated by Microcoleus chthonoplastes, but composition varied across the intertidal zone. The present study provided evidence of temporal and spatial variability in nutrient exchange and implied an important role of cyanobacterial mats in coastal production.