Lake Illawarra Research Articles

Consequences of artificially opening coastal lagoons on their fish assemblages

The consequences of artificially opening lagoon entrances on the fish assemblages of coastal lagoons in south-eastern Australia were investigated. Impacts of lagoon opening were assessed by comparing changes in the fish assemblages of Werri and Shellharbour Lagoons, both of which intermittently opened to the sea with that of Lake Illawarra, a third coastal lagoon which remained closed during the study period. Numbers of fish species and individuals did not differ significantly after lagoon openings at Werri Lagoon and Shellharbour Lagoon. However, higher numbers of species and individuals were found in Lake Illawarra before the other lagoons had opened. Abundances of some economically significant species (namelyMugil cephalus, Myxus elongatus andLiza argentea) significantly increased after openings, mainly due to small juveniles ( 70 mm FL) in Lake Illawarra. Furthermore, their abundance in Lake Illawarra declined during successive months, coinciding with declining salinity. Abundances of resident species (such asPseudomugil olorum andAfurcagobius tamarensis) remained largely unchanged after openings. Although it was clear that marine-spawning species must benefit from lagoon openings, the number and composition of species able to move into lagoons from adjacent waters may be dependent upon the frequency, duration and time of year that the entrance is connected to the sea. The present study thus provides data which may be useful for fisheries management in intermittently open lagoons. However, these results should not be cited as reason to artificially open lagoon entrances as further detailed studies of other aspects of lagoon biota, such as their invertebrate and avian faunas, are also needed to provide sufficient basis for broader management frameworks.

Investigation of a cluster of leukaemia in the Illawarra region of New South Wales, 1989-1996.

To investigate a cluster of leukaemia among young people and assess the plausibility of a disease-exposure relationship. Descriptive analysis of population-based leukaemia incidence data, review of evidence related to the causation of leukaemia, assessment of environmental exposures to known leukaemogens, and resulting risks of leukaemia. Illawarra region of New South Wales, Australia, focusing on suburbs between the Port Kembla industrial complex and Lake Illawarra (the Warrawong area). Standardised incidence ratios (SIRs) for leukaemia; current measured and past estimated ambient air benzene concentrations; and expected leukaemia cases attributable to estimates of ambient air benzene concentrations. In 1989-1996, 12 leukaemia cases among Warrawong residents aged less than 50 years were observed, more than the 3.49 cases expected from the rate in the rest of the Illawarra region (SIR, 343.8; 99% CI, 141.6-691.7). These people lived in suburbs immediately to the south-southwest of a coke byproducts plant (a major industrial source of benzene, one of the few known leukaemogens). The greatest excess was among 15-24-year-olds (SIR, 1085.6; 99% CI, 234.1-3072.4). In 1996, ambient air concentrations of benzene averaged less than 1 part per billion (ppb). Since 1970, ambient air concentrations of benzene were estimated to have averaged up to 3 ppb, about one-thousandth of the level at which leukaemia risk has been identified in occupational epidemiological studies. Using the risk assessment model developed by the US Environmental Protection Agency, we estimate that past benzene levels in the Warrawong area could have resulted in 0.4 additional cases of leukaemia in 1989-1996. The excess occurrence of leukaemia in the Warrawong area in 1989-1996 is highly unusual. Current environmental benzene exposure and the reconstructed past environmental benzene exposure level are too low to explain the large excess of leukaemia. The cause of the cluster is uncertain.

Current and Historical Occurrence of Platypuses, Ornithorhynchus anatinus, around Sydney.

No formal survey of platypus (Ornithorhynchus anatinus) distribution around the greater Sydney area has previously been carried out. However, using 126 records of 0. anatinus from various sources (Pre-1900 (7), 1900-69 (43), 1970-89 (57), 1990-96 (19)), an assessment of the current and historical occurrence of the species in this area has been made. The species has been observed regularly since European settlement in the upper reaches of the Nepean River and its tributaries above the sites of the current Sydney water storages. Apparently once common in the Nepean River between the current water storages and the Warragamba River junction, the species is now seldom observed in this section of the river. It was previously more common in the lower reaches of the Nepean and upper Hawkesbury Rivers and platypuses are still occasionally recorded in this part of the river system. The species also still occurs upstream of the Lake Yarrunga storage in the Kangaroo River. It is currently found in streams of the Lake Illawarra catchment and the south coast, as far south as Berry, and in the Wollondilly and Coxs Rivers upstream of Lake Burragorang. Platypuses are no longer reported from the streams flowing through the Wollongong metropolitan area. Some recent records exist for the Sydney metropolitan area, but most are from national parks. The river systems around Sydney, Wollongong and their satellite settlements have been severely degraded by a range of human activities since early European settlement. At present it is not possible to attribute changes in 0. anatinus distribution to any single human activity over that period.

Anthropogenic marker evidence for accelerated sedimentation in Lake Illawarra, New South Wales, Australia

The chronology of near-surface sediments in Lake Illawarra has been investigated using radiocarbon dating and anthropogenically derived substances including trace metals, ash, and137Cs. Sediments at depths about 1 m below the water-sediment interface ranged in age from Modern to 786 calendar years bp on the basis of radiocarbon dating ofNotospisula trigonella valves. Multiple marker (for example ash-trace metals) depth-concentration sediment profiles yielded estimates of sedimentation rate ranging from 3 to 5 mm yr−1 at Griffins Bay to more than 16 mm yr−1 at Macquarie Rivulet. Sedimentation rates of approximately 10 mm yr−1 appeared to be typical of the western and southwestern portions of the lagoon. Rates of sediment accretion, prior to catchment clearing, urbanization, and industrialization have been estimated at less than 1 mm yr−1, thus indicating a general tenfold increase in sediment accumulation adjacent to the western foreshore caused by catchment development. Accelerated sedimentation in shallow coastal lagoons constitutes significant environmental impacts including shoaling, degradation of seagrass beds, and increased turbidity with consequent loss of aesthetic appeal. Management policy should be directed at attempts to reduce the amount of sediment input by the construction of strategically placed sediment retention ponds. Siltation within the shallow embayments of Lake Illawarra could be ameliorated by a carefully planned program of dredging.

Ostracod fauna associated with sublittoral kelp forest vegetation at Windang Island, New South Wales, Australia

Sublittoral kelp forests, such as those occupying the wave-dominated shallow marine rocky substrata around Windang Island, New South Wales, provide an important habitat for ostracods. This is reflected in the diverse biocoenotic assemblage (69 species, including one new genus and three new species) and populations of juveniles recorded from this area. The thanatocoenotic assemblage contributes a further 37 ostracod species. The total assemblage is more diverse than, and has only 17 species in common with, the previously documented intertidal biocoenotic assemblages around Windang Island. The distribution of the more abundant ostracod species reflects the energy levels within the environment, with a greater proportion of smooth-shelled forms occurring in the higher-energy zones at shallow depths. Most of the thanatocoenose population represents species moved up from the deeper shelf or into the region from the adjacent tidal channel into Lake Illawarra, rather than species from the intertidal region around Windang Island.

Ash distribution and metal contents of Lake Illawarra bottom sediments

The distribution of anthropogenically derived ash and metal contents of Lake Illawarra bottom sediments have shown that elevated concentrations of trace metals, particularly Zn, are linked to ash concentrations. The highest concentrations of total metals (up to 10 times the locally defined background) were recorded from Griffins Bay, adjacent to the Port Kembla industrial complex. Other sites investigated exhibited only slight trace metal enrichment in near-surface sediments, typically 1.4 to 2 times the background. Analytical data from inductively coupled plasma mass spectrometry (ICPMS) indicate that the ratio of EDTA-extractable ratio:total metal present in the sediment generally decreases in the order Pb, Zn and Cu. Lake sedimentation rates, calculated on the basis of metal and ash depth profiles, were found to lie in the range 6.9 to 16 mm year-1 and represent the most serious long-term environmental problem in the Illawarra region.

Accumulation and regulation of heavy metals by the intertidal snail Polinices sordidus

The gastropod Polinices sordidus was collected from an uncontaminated area in Quibray Bay, New South Wales, Australia, in 1990. The snails were exposed for 2 wk to polluted sediments collected from Port Kembla Harbour, Blackwattle Bay, Lake Illawarra, Lake Macquarie in New South Wales, Australia, and the Derwent River in Tasmania, Australia. Metal accumulation and regulation by this species were evaluated. Metal concentrations in snail tissues and total, EDTA and HCl-extractable metals in the sediments were compared. Copper concentrations were extremely varied in snails exposed to the same sediment. This was not the case for other matals tested. No accumulation of copper was found in snails exposed to different sediments. There was no zinc accumulation from sediments containing less then 10 mg Zn/g. P. sordidus could accumulate lead, manganese and iron from some of the sediments. Manganese concentrations in the snail tissues correlated with total, HCl-extractable and, more significantly, EDTA-extractable Mn in the sediments. P. sordidus was not considered to be a good bioindicator of copper and zinc contaimination in sediments; however, this species could be used as an indicator of lead and manganese contamination.

Impact of Catchment Urbanisation on Lake Macquarie (Australia)

Increasing urbanisation of coastal areas is leading to impacts on coastal lakes which decrease their amenity for recreation and tourism. Runoff and wastewater discharge cause siltation, impact seagrass beds and change the characteristics of open waters, affecting boating, swimming, fishing and the aesthetic quality of the locale. Management of urban development and wastewater disposal is required to minimise sedimentation and nutrient enrichment. This could include development restrictions, runoff controls and a strategy for wastewater treatment and discharge. The catchment of Lake Macquarie, a marine coastal lake, has been progressively urbanised since 1945. Urbanisation, through increased stormwater runoff and point source discharges, has caused a major impact on the lake in terms of sedimentation and nutrient enrichment. Losses of lake area and navigable waters have occurred. Accompanying problems include changes in the distribution of seagrass beds and nuisance growths of benthic algae. Since the 1950's, dry weather nutrient concentrations have increased and mean water clarity has decreased. Severe problems, as observed in other New South Wales coastal lakes, for example benthic algae in Lake Illawarra and Tuggerah Lakes, have not yet developed. Because of the lead time taken to implement policies and controls, trends should be identified and policies developed now so as to avoid nutrient buildup and development of sustained problems.

Ostracoda in Lake Illawarra: Environmental factors, assemblages and systematics.

Major controls of the distribution pattern and abundance of living ostracod populations in Lake Illawarra, a coastal lagoon south of Wollongong, New South Wales, are salinity and the benthic flora. The biocenotic ostracod assemblage from the intertidal zone around Windang Island is a typical, diverse, upper sublittoral, open ocean fauna. The lake entrance channel, which is a transport corridor for marine sediments into the lagoon, has a restricted ostracod biocenose (14 species) but contains an additional 72 species in the diverse thanatocenose resulting from the mixing of estuarine and marine species. Within the lagoon, the benthic flora influences the ostracod distribution pattern with the most diverse assemblage (13 species) occurring in areas covered by seagrasses. Seagrass distribution is, in turn, controlled by water depth, circulation, turbidity and substrate. Estuarine ostracods associated with the seagrass beds can tolerate florally induced fluctuations in pH from 7 to 10 and in dissolved oxygen from 1 mg l-1 to 14 mg l-1. In the deeper parts of the lagoon with a predominantly mud substrate, the ostracod assemblage is dominated by Osticythere reticulata. Most samples retrieved from the most polluted part of the lagoon contained no ostracods. A total of 90 ostracod species and subspecies belonging to 50 genera has been identified; nine species: Cytheralison cosmetics, Callistocythere janiceburrowsae, Callistocythere windangensis, Neocytherideis anneclarkeae, Actinocythereis robustus, Bradleya rectangulata, Procythereis jonesi, Hemicytherura windangensis and Cytheropteron wrighti; and one subspecies, Callistocythere dorsotuberculata paucicostata, are described as new to science.

Corrigenda - Ostracoda in Lake Illawarra: Environmental factors, assemblages and systematics

Corrigenda - Ostracoda in Lake Illawarra: Environmental factors, assemblages and systematics

The West Dapto flood of February 1984: rainfall characteristics and channel changes

Summary This paper describes the distribution, magnitude and areal pattern of recurrence intervals for a very severe rainstorm centred over the West Dapto area of Wollongong in February 1984. It also examines the impact of this storm on the channel geometry of streams draining the Illawarra escarpment. The storm was the largest 24 hour rainfall ever recorded in temperate Australia, and was very likely in excess of the 200 year event for the Dapto area. However, the localised nature of such storms in the region suggests that Wollongong can expect a major flood (in excess of the 100 year event) somewhere within the city every 25–50 years. Similarly, because the catchment of Lake Illawarra is usually larger than the areal distribution of these very high‐intensity storm centres, the frequency of severe flooding in the lake is bound to be greater than the frequency of any individual storm event. The most pronounced channel erosion (up to a fourfold increase in channel size) resulting from the 1984 storm occurr...

Species Diversity of Waterbirds on Lake Illawarra, Coomaditchy Lagoon and the Cordeaux Storage Dams, New South Wales

(1982). Species Diversity of Waterbirds on Lake Illawarra, Coomaditchy Lagoon and the Cordeaux Storage Dams, New South Wales. Emu - Austral Ornithology: Vol. 82, No. 2, pp. 106-108.

Water polution studies on Lake Illawarra. I. Salinity variations and estimation of residence time

Surface and bottom water salinities were determined at 10 monitoring stations over a 2-year period. Mean salinity is controlled primarily by rainfall and varied from 12.8 to 31.3%, during the monitoring period. The rate of flushing of Lake Illawarra by tidal action and by freshwater entry was estimated from salinity variations and by mathematical modelling; for dry periods a flushing time (for reduction by a factor of e) of about 60 days was calculated for a conservative substance introduced into the lake. Mean tidal volume was 1 % of the lake volume. Vertical mixing by wave action is complete within 2-4 weeks. Although the major creeks are on the western side of the lake, no significant east-west salinity gradient was found. Lake Illawarra is characterized by the small ratio of catchment to lake area and the short distance from the very elevated watershed to the lake shores, resulting in rapid response to rainfall. The volume of direct precipitation was estimated to be comparable with creek input.

Water polutions on Lake Illawarra. II. Thermal behaviour

Temperature variations in surface and bottom water at 10 monitoring stations in Lake Illawarra were determined over the period 28 January 1972 to 31 May 1974. Except for the bay near Tallawarra Power Station, no permanent vertical temperature gradients were found. A statistically significant correlation was found between water temperature and distance from the power station, but no such relationship could be established for tidal heat flow either alone or acting together with the thermal discharge from the power station. Mean water temperature for Lake Illawarra fluctuated in the range 11.6-25.6� C, compared with 15.7-24.0�C for the sea adjacent to Wollongong Harbour. Seasonal maxima and minima in lake water temperature occur 3 weeks earlier than those of the sea.

Water pollution studies on Lake Illawarra. III. Distribution of heavy metals in sediments

Samples of recent sediments from 18 sites in Lake Illawarra showed marked enrichment of copper, zinc, cadmium and lead. The highest concentrations were found in Griffins Bay in the north-east corner of the lake, which is closest to the Port Kembla industrial complex. Maximum enrichments for copper, zinc and lead are respectively 4, 34 and 11 times the background concentrations found in deep cores. By comparison of vertical profiles of heavy metal concentration with historical data on the growth of metal smelting industries in the Illawarra region, the recent sedimentation rate has been estimated as 2.5-3 mm/year. A depth of 40-50 cm below the surface of the sediment marks the beginning of human influence on the lake.

Statistics and Data Analysis in Geology. John C. Davis

Previous articleNext article No AccessReviewsStatistics and Data Analysis in Geology. John C. Davis Gerard V. MiddletonGerard V. Middleton Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by The Journal of Geology Volume 83, Number 1Jan., 1975 Article DOIhttps://doi.org/10.1086/628074 Views: 4Total views on this site Citations: 1Citations are reported from Crossref Copyright 1975 University of ChicagoPDF download Crossref reports the following articles citing this article:Junjie Deng, Qiangsheng Yao, Brian G. Jones, Kerrylee Rogers, Colin D. Woodroffe, Jan Harff A methodological framework for reconstructing historical delta front morphology: case study at Macquarie rivulet delta within Lake Illawarra, Australia, Journal of Coastal Conservation 23, no.44 (May 2019): 717–726.https://doi.org/10.1007/s11852-019-00699-7

Geographic variation in the snail Velacumantus (Gastropoda : Potamididae)

A morph-frequency cline and a size cline are described for the snail Velacumantus australis. The frequency of a white-banded form decreases clinally with latitude South. Living populations from Queensland and northern New South Wales have frequencies between 7 and 18% whereas all populations from southern New South Wales and eastern Victoria, except those from Lake Illawarra, have frequencies between 2 and 5%. The frequency in Port Phillip Bay is less than 0.1%. The frequency in a sample from Swan River, Western Australia, was 9.1% about the same as in samples from localities of the same latitude on the eastern coast of Australia. The frequency in most fossil samples was similar to that in nearby living populations. The mean length of populations from the eastern states increases clinally with increase in latitude South, although there are some irregular fluctuations between adjacent populations which are probably influenced by population density.