Academic literature on the topic 'New South Wales estuaries'

Estuarine acidification, caused by disturbance of acid sulfate soils (ASS), is a recurrent problem in eastern Australia. Affected waters are characterised by low pH and elevated concentrations of metals, principally aluminium and iron. The effects of acid and elevated metal concentrations associated with ASS, on adult Sydney rock oysters, have not been previously investigated. This study tested links between ASS-affected drainage, subsequent estuarine acidification and Sydney rock oyster production problems on the Hastings and Manning Rivers, mid north coast New South Wales. The primary objective of this thesis was to establish if estuarine acidification causes mortality and slow growth in individual Sydney rock oysters by exposing oysters to low pH, iron and aluminium using field and laboratory experiments. Water quality data showed that estuarine acidification was spatially extensive in the Hastings and Manning Rivers following heavy rainfall and was due to mineral acids originating from drained or excavated ASS. Estuarine acidification regularly affected areas used for Sydney rock oyster production following heavy rainfall. Field experiments showed that Sydney rock oyster mortality rates were significantly higher at sites exposed to ASS-affected waters compared to locations that were isolated from ASS-affected waters. Oyster mortality increased with the time of exposure and smaller oysters (mean weight = 5 g) experienced significantly higher mortality relative to larger oysters (mean weight = 29 g). This was caused by acid-induced shell degradation resulting in perforation of the smaller oysters??? under-developed shells. Additionally, Sydney rock oyster growth rates were dramatically reduced at sites exposed to ASS-affected waters and the overall mean condition index of oysters at ASS-affected field sites was significantly lower than the overall mean condition index of oysters at non-impacted sites. Findings from laboratory experiments showed that ASS-affected water alters oyster valve movements and significantly reduces oyster feeding rates at pH 5.5. Acidic treatments (pH 5.1) containing 7.64 mg L-1 of aluminium or ASS-affected water caused changes in the mantle and gill soft tissues following short-term exposure. Degenerative effects described in oysters in this study were also due to iron contained in ASS-affected waters. Iron precipitates accumulated on the shell, gills and mantle and were observed in the stomach, intestine, digestive tubules and rectum. This study concluded that Sydney rock oysters are unable to tolerate acidic conditions caused by ASS outflows and cannot be viably cultivated in acid-prone areas of the estuary.

Abstract Aragonite is a minor secondary mineral in many limestone caves throughout the world. It has been claimed that it is the second-most common cave mineral after calcite (Hill & Forti 1997). Aragonite occurs as a secondary mineral in the vadose zone of some caves in New South Wales. Aragonite is unstable in fresh water and usually reverts to calcite, but it is actively depositing in some NSW caves. A review of current literature on the cave aragonite problem showed that chemical inhibitors to calcite deposition assist in the precipitation of calcium carbonate as aragonite instead of calcite. Chemical inhibitors work by physically blocking the positions on the calcite crystal lattice which would have otherwise allowed calcite to develop into a larger crystal. Often an inhibitor for calcite has no effect on the aragonite crystal lattice, thus aragonite may deposit where calcite deposition is inhibited. Another association with aragonite in some NSW caves appears to be high evaporation rates allowing calcite, aragonite and vaterite to deposit. Vaterite is another unstable polymorph of calcium carbonate, which reverts to aragonite and calcite over time. Vaterite, aragonite and calcite were found together in cave sediments in areas with low humidity in Wollondilly Cave, Wombeyan. Several factors were found to be associated with the deposition of aragonite instead of calcite speleothems in NSW caves. They included the presence of ferroan dolomite, calcite-inhibitors (in particular ions of magnesium, manganese, phosphate, sulfate and heavy metals), and both air movement and humidity. Aragonite deposits in several NSW caves were examined to determine whether the material is or is not aragonite. Substrates to the aragonite were examined, as was the nature of the bedrock. The work concentrated on Contact Cave and Wiburds Lake Cave at Jenolan, Sigma Cave, Wollondilly Cave and Cow Pit at Wombeyan and Piano Cave and Deep Hole (Cave) at Walli. Comparisons are made with other caves. The study sites are all located in Palaeozoic rocks within the Lachlan Fold Belt tectonic region. Two of the sites, Jenolan and Wombeyan, are close to the western edge of the Sydney Basin. The third site, Walli, is close to a warm spring. The physical, climatic, chemical and mineralogical influences on calcium carbonate deposition in the caves were investigated. Where cave maps were unavailable, they were prepared on site as part of the study. %At Jenolan Caves, Contact Cave and Wiburds Lake Cave were examined in detail, %and other sites were compared with these. Contact Cave is located near the eastern boundary of the Late Silurian Jenolan Caves Limestone, in an area of steeply bedded and partially dolomitised limestone very close to its eastern boundary with the Jenolan volcanics. Aragonite in Contact Cave is precipitated on the ceiling as anthodites, helictites and coatings. The substrate for the aragonite is porous, altered, dolomitised limestone which is wedged apart by aragonite crystals. Aragonite deposition in Contact Cave is associated with a concentration of calcite-inhibiting ions, mainly minerals containing ions of magnesium, manganese and to a lesser extent, phosphates. Aragonite, dolomite and rhodochrosite are being actively deposited where these minerals are present. Calcite is being deposited where minerals containing magnesium ions are not present. The inhibitors appear to be mobilised by fresh water entering the cave as seepage along the steep bedding and jointing. During winter, cold dry air pooling in the lower part of the cave may concentrate minerals by evaporation and is most likely associated with the ``popcorn line'' seen in the cave. Wiburds Lake Cave is located near the western boundary of the Jenolan Caves Limestone, very close to its faulted western boundary with Ordovician cherts. Aragonite at Wiburds Lake Cave is associated with weathered pyritic dolomitised limestone, an altered, dolomitised mafic dyke in a fault shear zone, and also with bat guano minerals. Aragonite speleothems include a spathite, cavity fills, vughs, surface coatings and anthodites. Calcite occurs in small quantities at the aragonite sites. Calcite-inhibitors associated with aragonite include ions of magnesium, manganese and sulfate. Phosphate is significant in some areas. Low humidity is significant in two areas. Other sites briefly examined at Jenolan include Glass Cave, Mammoth Cave, Spider Cave and the show caves. Aragonite in Glass Cave may be associated with both weathering of dolomitised limestone (resulting in anthodites) and with bat guano (resulting in small cryptic forms). Aragonite in the show caves, and possibly in Mammoth and Spider Cave is associated with weathering of pyritic dolomitised limestone. Wombeyan Caves are developed in saccharoidal marble, metamorphosed Silurian Wombeyan Caves Limestone. Three sites were examined in detail at Wombeyan Caves: Sigma Cave, Wollondilly Cave and Cow Pit (a steep sided doline with a dark zone). Sigma Cave is close to the south east boundary of the Wombeyan marble, close to its unconformable boundary with effusive hypersthene porphyry and intrusive gabbro, and contains some unmarmorised limestone. Aragonite occurs mainly in a canyon at the southern extremity of the cave and in some other sites. In Sigma Cave, aragonite deposition is mainly associated with minerals containing calcite-inhibitors, as well as some air movement in the cave. Calcite-inhibitors at Sigma Cave include ions of magnesium, manganese, sulfate and phosphate (possibly bat origin), partly from bedrock veins and partly from breakdown of minerals in sediments sourced from mafic igneous rocks. Substrates to aragonite speleothems include corroded speleothem, bedrock, ochres, mud and clastics. There is air movement at times in the canyon, it has higher levels of CO2 than other parts of the cave and humidity is high. Air movement may assist in the rapid exchange of CO2 at speleothem surfaces. Wollondilly Cave is located in the eastern part of the Wombeyan marble. At Wollondilly Cave, anthodites and helictites were seen in an inaccessible area of the cave. Paramorphs of calcite after aragonite were found at Jacobs Ladder and the Pantheon. Aragonite at Star Chamber is associated with huntite and hydromagnesite. In The Loft, speleothem corrosion is characteristic of bat guano deposits. Aragonite, vaterite and calcite were detected in surface coatings in this area. Air movement between the two entrances of this cave has a drying effect which may serve to concentrate minerals by evaporation in some parts of the cave. The presence of vaterite and aragonite in fluffy coatings infers that vaterite may be inverting to aragonite. Calcite-inhibitors in the sediments include ions of phosphate, sulphate, magnesium and manganese. Cave sediment includes material sourced from detrital mafic rocks. Cow Pit is located near Wollondilly Cave, and cave W43 is located near the northern boundary of the Wombeyan marble. At Cow Pit, paramorphs of calcite after aragonite occur in the walls as spheroids with minor huntite. Aragonite is a minor mineral in white wall coatings and red phosphatic sediments with minor hydromagnesite and huntite. At cave W43, aragonite was detected in the base of a coralloid speleothem. Paramorphs of calcite after aragonite were observed in the same speleothem. Dolomite in the bedrock may be a source of magnesium-rich minerals at cave W43. Walli Caves are developed in the massive Belubula Limestone of the Ordovician Cliefden Caves Limestone Subgroup (Barrajin Group). At the caves, the limestone is steeply bedded and contains chert nodules with dolomite inclusions. Gypsum and barite occur in veins in the limestone. At Walli Caves, Piano Cave and Deep Hole (Deep Cave) were examined for aragonite. Gypsum occurs both as a surface coating and as fine selenite needles on chert nodules in areas with low humidity in the caves. Aragonite at Walli caves was associated with vein minerals and coatings containing calcite-inhibitors and, in some areas, low humidity. Calcite-inhibitors include sulfate (mostly as gypsum), magnesium, manganese and barium. Other caves which contain aragonite are mentioned. Although these were not major study sites, sufficient information is available on them to make a preliminary assessment as to why they may contain aragonite. These other caves include Flying Fortress Cave and the B4-5 Extension at Bungonia near Goulburn, and Wyanbene Cave south of Braidwood. Aragonite deposition at Bungonia has some similarities with that at Jenolan in that dolomitisation of the bedrock has occurred, and the bedding or jointing is steep allowing seepage of water into the cave, with possible oxidation of pyrite. Aragonite is also associated with a mafic dyke. Wyanbene cave features some bedrock dolomitisation, and also features low grade ore bodies which include several known calcite-inhibitors. Aragonite appears to be associated with both features. Finally, brief notes are made of aragonite-like speleothems at Colong Caves (between Jenolan and Wombeyan), a cave at Jaunter (west of Jenolan) and Wellington (240\,km NW of Sydney).

Glenbrook Lagoon, an 8 hectare lake receiving rainfall runoff from a residential catchment, is experiencing nutrient enrichment problems expressed as excessive aquatic plant presence. This study aims to assess the relative nutrient contribution of the total system compartments, including catchment loading, water column, aquatic plants and surface sediment. This information is utilised in the formulation of management strategies which may produce a sustainable nutrient reduction and general improvement in the system. The total nutrient content of the aquatic system was determined to be high in comparison with the present nutrient loading from the catchment. The ideal management case considers nutrient reduction of the surface sediment compartment firstly, followed by the aquatic plant community, with the water column and catchment influence as relatively low priority compartments. Various strategies for managing these are proposed. The total system benefits of the ideal management case are reductions in nutrients, aquatic plant biovolume and suspended solid loading. Unavoidable constraints placed upon the ideal management case include the excessive aquatic plant presence restricting accessability to the surface sediment for dredging. The resulting best management case requires aquatic plant eradication prior to sediment management, with the total system benefits associated with the ideal management case being retained.
Master of Science (Hons)

Over the last 60 years, grass tetany has been recognised as a significant lethal condition in sheep and cattle.Outcomes from this study include documentation of the likely precursors to grass tetany, ways to recognise these precursors, and long term practices that will enable producers to minimise livestock deaths. The benefit of this research to beef producers is that the environmental circumstances thought to be associated with outbreaks of grass tetany have been identified, along with remedial action that can be taken to prevent deaths occurring.Recommendations to industry on best practice to be adopted by leading producers to minimise outbreaks of grass tetany are made.This study provides an alternate strategy for the management of grass tetany in beef cattle, to the more clinical approaches previously recommended. It is suggested that losses from this economically important metabolic disease can be minimised if management practices of beef cattle producers in eastern Australia can incorporate a more holistic approach to farm management, which takes account of the soil/plant/animal/climate inter-relationships.
Master of Science (Hons)