bluuebunny/crossref_metadata_2025 huggingface dataset:
Downstream effects of the Gorden River Power Development, south-west Tasmania
Authors: King RD , Tyler PA
Published: November 2005

A survey of the physicochemical limnology of the Gordon River, designed to provide background environmental data for the proposed stage 2 of the Gordon River Power Development, has, ironically, revealed far-reaching consequences of the dams of stage 1, for which only rudimentary surveys were carried out. An obvious hydrological effect is the damping of seasonal flow variations so that the regulated river experiences higher summer flows and lower winter flows than under natural conditions. River levels are consequently affected and summer growth of photosynthetic algae in former shallows and riffle zones no longer occurs. Other biological effects are unknown. The effective headwaters of the river are now the hypolimnetic strata of a large stratified reservoir, Lake Gordon. Consequently, the river is fed with a relatively constant discharge of water of almost invariable temperature and chemical composition. The effects of influent tributaries downstream are now largely overridden by this constant flow. Temperatures vary little along the length of the regulated river, being above normal in winter and below normal in summer. Chemical variability has been reduced, both in respect of the lower salinity range now experienced and in the suppression of flow-dependent alternation between dominance by sodium chloride or by alkaline earth bicarbonate. An unfortunate hydrological effect is the elimination of an estuarine underflow of salt water on which the meromixis of three lakes depends. While two of them have shown little change in the short time since dam construction, a third became holomictic soon after discharge from the dam commenced. A temporary return to meromixis after a brief shutdown of the power station indicates that an appropriate operating regime, with brief summer shutdowns, could retain the affected lake in a meromictic condition of great scientific interest.
Adsorption characteristics of seston in irrigation water: implications for the use of aquatic herbicides
Authors: Bowmer KH
Published: November 2005

Adsorption of three important aquatic herbicides by seston (suspended particulate matter) in water from the Murrumbidgee Irrigation Areas of New South Wales was investigated. Seston was extremely reactive: the adsorption of terbutryn and glyphosate was generally at least an order of magnitude higher than reported in the literature for soils. although adsorption is expected to have little effect in reducing concentrations of terbutryn in practice. Adsorption of glyphosate was decreased by addition of phosphate, which may contribute to the difference in adsorbing power observed for seston from different sources. Since phosphate and glyphosate compete for adsorption sites, a high adsorption maximum for glyphosate may reflect the high capacity of seston to adsorb and transport phosphates. Although several other factors may also be involved, adsorption by seston alone was sufficient to completely inactivate diquat in irrigation drainage waters, at concentrations up to 0.5 mg 1-1. However, once the strong adsorption capacity of seston (about 8 mg g-1) was saturated. an increasing proportion of the initial concentration remained in solution, so this herbicide could be effective if sufficient were used. The general implications of adsorption on the transport, behaviour and persistence of organic compounds and pollutants in the aquatic system are also discussed.
Acute toxicity to the crab Paragrapsus quadridentatus (H. Milne Edwards), of Kuwait light crude oil, BP/AP dispersant, and an oil-dispersant mixture
Authors: Ahsanullah M , Edwards RRC , Kay DG , Negilski DS
Published: November 2005

The acute toxicity to P. quadridentatus, of Kuwait light crude oil, BP/AR dispersant and an oil-dispersant
mixture was determined. Observed 96-h LC50 values averaged 1555 mg 1-1 for oil added to water. A
statistically valid 96-h LC50 value for the dispersant was not obtained, but results indicated that a solution
containing between 1300 and 2200 mg I-1 might be expected to produce 50% mortality. A mixture of oil and
dispersant in the ratio 4 : 1 gave an observed 96-h LC50 value of 96 mg 1-1, a 16-fold increase in toxicity over
oil alone. The implications of the results are discussed.
Influence of added nutrient on the seasonal variation of algal growth potential of Mt Bold reservoir, South Australia
Authors: Ganf GG
Published: November 2005

Bioassay experiments with the natural phytoplankton assemblage showed that the major nutrient input to Mt Bold reservoir, South Australia, occurred with the onset of winter rains. Growth potential within the euphotic zone generally increased from June to November but was undetectable from December to March when the autumn overturn circulated nutrient-rich water from the hypolimnion to cause an increase in growth. Subsequently, the growth potential fell and did not rise until the onset of winter rains. Routine enrichment experiments with phosphorus, nitrogen and Na-EDTA substantially increased the growth potential above the control during periods of suspected nutrient depletion. During periods of nutrient depletion, the influence of 10 single and 45 dual nutrient additions showed that only the combined addition of nitrogen and phosphorus caused a significant increase in growth potential. To investigate further the influence of nitrogen and phosphorus on algal growth, factorial nutrient-enrichment experiments using five levels of both nitrogen and phosphorus and three of Na-EDTA at two temperatures (11 and 20�C) were conducted. The work is discussed in relation to the routine nutrient analyses done by the Engineering and Water Supply Department of South Australia.
Effect of sewage effluent on dragonflies (Odonata) of Bulimba Creek, Brisbane
Authors: Watson JAL , Arthington AH , Conrick DL
Published: November 2005

The adult dragonfly fauna and the larval fauna and abundance decrease markedly immediately downstream of the outfall from the Mimosa Sewage Treatment Plant into Bulimba Creek. The adult fauna is substantially restored farther downstream, but the larval fauna and abundance are not. Of the 36 species of Odonata observed at Bulimba Creek, the 10 abundant, essentially stream-dwelling species were most affected by the sewage effluent. Adults of only one of these stream species were found at the most contaminated site, and then only in very low numbers; those of two others were not observed downstream of the outfall. The diversities of both adult and larval dragonfly faunas give a qualitative indication of water quality. Parallels between the distribution or abundance of Odonata and the concentrations of contaminants indicate that chlorine may be the most important toxicant immediately downstream of the sewage outfall in Bulimba Creek.
Maturity and sexuality in Barramundi, Lates calcarifer (Bloch), in the Northern Territory and south-eastern Gulf of Carpentaria
Authors: Davis TLO
Published: November 2005

The histological events associated with gonad maturation in male and female L. calcarifer are described. Females are normally derived from post-spawning males. A histological description of the process of sex inversion is presented. The lengths of males at first maturity in the Northern Territory and south-eastern Gulf of Carpentaria were 600 and 550 mm, respectively. Most fish were changing sex at lengths of 900 and 850 mm, respectively in these areas. These size differences were due to a slower growth rate of barramundi in the Gulf of Carpentaria, both processes being related to age rather than to size.
Effects of length, locality and tissue type on mercury and cadium content of the commercial scallop, Pecten alba Tate, from port Phillip Bay, Victoria
Authors: Walker TI , Glover JW , Powell DGM
Published: November 2005

Concentrations of total mercury and total cadmium in P. alba were determined by atomic absorption spectroscopy. The results were greatly affected by the type of tissue analysed, the locality where the scallops were collected and, to a lesser extent, by the length of the scallops. Mean concentration of mercury was 0.02 �g g-1 wet weight (range 0.01-0.04 �g g-1 wet weight) in adductor muscle, 0.02 �g g-1 (0.01-0.03 �g g-1) in gonads, and 0.04 �g g-1 (0.01-0.11 �g g-1) in viscera. Mean concentration of cadium was 1.0 �g g-1 (0.3-1.9 �g g-1) in adductor muscle, 0.9 �g g-1 (0.5-1.4 �g g-1) in gonads, and 7.7 �g g-1 (3.7-1 5.1 �g g-1) in viscera. The concentrations of mercury tended to decrease in samples from north to south and from east to west, and concentrations in the most western region of Port Phillip Bay were intermediate in value. Although the trends for cadmium were not so well defined, concentrations in the northern region were generally higher than those in the southern region.
Aggregates of particulate matter and aufwuchs on Elodea canadensis in irrigation waters, and inactivation of diquat
Authors: Browner KH
Published: November 2005

In irrigation waters from the Murrumbidgee River and Murray River, south-eastern Australia. shoots of E. canadensis are heavily encrusted with a loosely attached complex of inorganic colloids with aufwuchs. Although 9,10-dihydro-8a,10a-diazoniaphenanthrene ion (diquat) is widely used overseas for the management of submerged weeds. it is often ineffective in Australian inland waters. Although several factors may be involved, measurements have shown that this surface complex would inactivate relatively high concentrations of diquat by adsorption. The activity of other aquatic herbicides may also be impaired.
Invertebrate fauna and ecology of temporary pools on granite outcrops in southern Western Australia
Authors: Bayly IAE
Published: November 2005

Nineteen pools distributed between nine different granite outcrops, all south of 32� s. in Western Australia,
were studied from May to July 1977. Data on depth, conductivity, pH and temperature are presented. In all,
35 invertebrate taxa, mostly identified to species, were recorded.
Anomalous stratification behaviour of Lake Gorden, headwater reservoir of the lower Gorden River, Tasmania
Authors: Steane MS , Tyler PA
Published: November 2005

Lake Gordon, a large hydro-electric reservoir in south-west Tasmania, holds water of low pH, high colour and low dissolved solids content. It stratifies each year, with consequent anoxia below the thermocline. The nett effect of the inflow pattern, combined with the deep-V morphometry of the reservoir, is to prevent holomixis. For 6 months of the year, the cold inflow of the upper Gordon River follows its old course and rolls down to the dam, intruding first as an underflow, then rising slightly to become an interflow as it warms and finds its density level. This inflow displaces older water upwards, sandwiching the former hypolimnion between the inflow and the epilimnion. The anoxic, sulfuretted water of the sandwiched stratum gradually mixes with water above and below it, leading to its ventilation and dispersion. Meanwhile; the inflowing water stagnates and anoxia develops afresh in bottom waters. This occurs at a time when the upper strata are restratifying, leading to a multiple sandwich of several strata of discrete lineage. The early history of the reservoir indicates that it was predisposed for partial meromixis of the Lake Barrington type, preconditioned by its morphometry and by a mass of flooded vegetation. That a lasting monimolimnetic pool did not form, as expected, is attributable to the annual inflow of dense, oxygenated water. The hypolimnion of Lake Gordon is now the effective headwater of, and greatest contributor to, the lower Gordon River. Because of the stratification pattern, the discharge stratum may be oxygenated or anoxic and laden with hydrogen sulfide, iron and manganese. Any undesirable effects of the latter are rapidly dissipated in a short stretch below the dam, but the relatively invariable nature of the temperature and major ion chemistry of this stratum impose an unwonted uniformity on the river, to its mouth.
Trace metals in sediments from the Yarra River
Authors: Ellaway M , Hart BT , Beckett R
Published: November 2005

The distribution and phase association of iron, manganese, cadmium, copper, lead and zinc in bottom sediments taken from the freshwater, estuarine and bay regions of the Yarra River were investigated. The fraction of the estuarine sediments smaller than 20 �m contained substantially higher concentrations of cadmium, copper, lead and zinc than did the corresponding sediment fraction from the upper river and bay regions. Sequential chemical extraction revealed that most of the variability in the trace metal concentration of these sediments was associated with changes in the reducible phase. A substantial increase in trace metal concentrations occurred in going from river to estuarine sediments. For example, the lead concentration increased approximately eightfold (43-375 �g g-1), the zinc fourfold (122-447 �g g-1) and the copper almost twofold (64-106 �g g-1). This was attributed to coagulation and sedimentation of trace-metal- enriched iron and manganese oxides in the estuarine region. The subsequent decrease in metal concentrations in the bay sediments was due to either physical dilution of the contaminated sedlment with material of lower metal concentration or remobilizatlon of the trace metals from sediments deposited in the bay.
Cadmium and other heavy metal concentrations in selected biota from Cockburn Sound, Western Australia
Authors: Talbot V , Chegwidden A
Published: November 2005

Concentrations of some heavy metals in Mytilus edulis (Cd, Cr, Cu, Fe, Mn, Pb and Zn), Ostrea angasi (Cd, Cr, Cu, Pb and Zn). Portunus pelagicus (Cd, Cu, Pb and Zn), Chaetopterus variopedatus (Cd, Cu and Zn), Posidonia spp. and their epiphytes (Cd, Cu, Fe and Zn), and Ulva lactuca (Cd, Cu, Fe. Mn, Pb and Zn) from Cockburn Sound, Western Australia, are reported. The highest concentrations of Cd; Cr and Pb in M. edulis and Cd and Zn in O. angasi were found in those animals taken from the vicinity of industrial effluent discharge points. Further, elevated concentrations of some metals were noted in the hepatopan- creas of Portunus pelagicus and in C. variopedatus and U. lactuca. Significant correlation coefficients for Cd-Cu, Cd-Fe, Cd-Zn, Cu-Fe, Cu-Zn and Fe-Zn in M. edulis indicated that elevated heavy metal levels resulted from industrial effluent discharges. Significant correlation coefficients for Cd-Zn and Cd-carapace width were found in the female crab P.pelagicus only. C. variopedatus and U. lactuca, unlike Posidonia spp. and their epiphytes, showed potential as trace metal indicators.
Population dynamics and production of Daphnia carinata (King) and Simocephalus exspinosus (Koch) in waste stabilization ponds
Authors: Mitchell BD , Williams WD
Published: November 2005

The population dynamics and production of D. carinata and S. exspinosus were investigated in two adjacent maturation-type waste stabilization ponds in South Australia. Population parameters (b', r', and d') for both species were determined from population density, brood size, and egg-development time. Length-weight relationships were determined for both species. Growth of D. carinata was investigated experimentally. Net production of both species was determined using Edmondson's population turnover- time model. Production of D. carinata was also determined using Winberg's biomass turnover model. D. carinata, the numerically dominant species, was a cold water form; high water temperatures increased mortality and reduced growth rate. Both species were food-limited at high population densities. Total annual net production of D. carinata in pond 1 during 1977 (345 g dry wt m-2): calculated using the population turnover-time model, was the highest yet recorded for any planktonic cladoceran. Annual net production of D. carinata determined using the population turnover-time model exceeded annual production determined using the biomass turnover model by 100%. Overestimation of daily production rate was highest during periods of high egg mortality. Total annual net production of D. carinata and S. exspinosus (biomass turnover model) represented a nutrient store equivalent to less than 6% of total PO4-P and total nitrogen retained in the ponds annually.
Segregation and feeding of atherinid species (Teleostei) in south-western Australian estuaries
Authors: Prince JD , Potter IC , Lenanton RCJ , Loneragan NR
Published: November 2005

Monthly samples were taken throughout the Swan-Avon estuary during 1979 and 1980 to provide information on the partitioning of space and food resources amongst the five most abundant atherinid species found in south-western Australian estuaries. The results demonstrated that Pranesus ogilbyi and Atherinosoma presbyteroides were marine species, which enter the lower estuary in considerable numbers. By contrast, Atherinosoma elongata and Allanetta mugiloides were shown to be estuarine species sensu stricto, which predominatedin the middle estuary. The fifth species, Atherinosoma wallacei, occurred in the upper estuary and more upstream regions of the river. The potential for competition between Atherinosoma species was thus reduced by their occurrence in predominantly different regions of the estuary. When they did occur together, the chance of competition was also apparently further minimized by differences in food preference, with A. elongata ingesting greater amounts of bottom fauna than either A. presbyteroides or A. wallacei. Intergeneric differences in food preferences reduced the potential for competition between A. presbyteroides and P. ogilbyi in the lower estuary and between A. elongata and Allanetta mugiloides in the middle estuary. The records of the Western Australian Museum, and data from extensive surveys, support the view that the succession formed by atherinid species from marine environments through estuaries to inland water follows a similar pattern in all south-western Australian river systems to that described for the Swan-Avon.
Alternative non-estuarine nursery habitats for some commercially and recreationally important fish species of south-western Australia
Authors: Lenanton RCJ
Published: November 2005

The distribution and relative abundance of the 0 + year classes of 16 commercially and recreationally important fish species from the inshore marine and estuarine waters of south-western Australia were investigated. The results of this study, together with data obtained from an investigation of the way in which juvenile fish used the Blackwood River estuary (Lenanton 1977), revealed that only three of these species in this region could be exclusively regarded as estuarine-dependent: two of the species entered the estuary for the entire year and the third was a seasonal migrant. The remaining 13 species all made use of at least 30% of the inshore marine environment sampled during the study, which was equivalent to the total area of nursery habitat available in the Blackwood River estuary. The main conclusion of this study is that for these species, the inshore marine environments of south-western Australia provide otherwise unavailable alternative nursery areas to those traditionally found in estuaries.
Geographical distribution of electrophoretically detected protein variation in Australian commercial fishes. I. Jack mackeral, Trachurus declivis Jenyns
Authors: Richardson BJ
Published: November 2005

Eight polymorphic loci were detected in a survey for electrophoretically detectable protein variation, carried out using liver samples from the Australian jack mackerel, T. declivis. The distribution of gene and genotype frequencies in sample sets from different areas shows that distinct subpopulations of the species occur in Western Australia and in New Zealand and that two or more geographically overlapping but genetically distinct subpopulations occur in the waters around south-eastern Australia.
Geographical distribution of electrophoretically detected protein variation in Australian commercial fishes. III. Western king prawn, Penaeus latisulcatus Kishinouye
Authors: Richardson BJ
Published: November 2005

Two polymorphic loci were detected in a survey for electrophoretically detectable protein variation carried out using the eye, muscle and hepatopancreas from the western king prawn, P. latisulcatus. The distribution of gene and genotype frequencies in sample sets from Investigator Strait and the Gulf of St Vincent were determined. No evidence of genetic isolation of the two stocks was obtained but the presence of two allopatric subpopulations, perhaps separated by time of breeding, seems possible.
Speciation of iron, copper and zinc in the Hawkesbury River
Authors: Pik AJ , Eckert JM , Williams KL
Published: November 2005

A combination of membrane filtration, ion exchange, coprecipitation and thin-film X-ray fluorescence spectrometry was used to obtain data on the chemical speciation of iron, copper and zinc in surface waters, ranging in salinity from 0 to 30Ym, of the Hawkesbury River, N.S.W. Iron, the principal trace metal, was found mainly (>90%) in the particulate form. The dissolved (filterable) iron fraction was largely non-ion- exchangeable (colloidal) in the freshwater region and ion-exchangeable in saline waters (as hydrated ions or metal complexes that dissociate on the chelating resin column). Copper and zinc, by contrast, were almost entirely filterable over the whole salinity range, copper being 50-100% in the non-ion-exchangeable fraction, and zinc, 70-100% ion-exchangeable.
Effect of some nutrient cations on uptake of cadmium by Chlorella pyrenoidosa
Authors: Gipps JF , Coller BAW
Published: November 2005

The effects of the cations calcium, iron, manganese and zinc on the uptake of cadmium by the alga C. pyrenoidosa and on the toxicity of cadmium were studied. Calcium at a level of 16 mg 1-1 reduced the short- term uptake and, in dilute cultures, the long-term uptake as well and caused a modest reduction in cadmium toxicity. Iron at a level of 1 mg I-1 greatly reduced cadmium toxicity and reduced both phases of uptake in dilute cultures. Manganese at a concentration of 0.5 mg I-1 had no consistent effect on uptake and tended to enhance cadmium toxicity. Zinc at a concentration of 3 mg I-1 reduced short-term uptake, had no consistent effect on long-term uptake, and exerted a toxic effect that was additive to that of cadmium. Factors such as coprecipitation and the physiological state of the culture were found to have an important bearing on the nature of the interaction of nutrient cations with cadmium.
Factors influencing the seasonal occurrence and abundance of the zooplankton in two waste stabilization ponds
Authors: Mitchell BD , Williams WD
Published: November 2005

Zooplankton community structure was studied in two maturation ponds at Gumeracha, South Australia. Abundance of the major zooplankters was related to physicochemical parameters and interspecific interactions. Daphnia carinata and Mesocyclops leuckarti were the numerically dominant zooplankters. Temperature was the most important factor affecting the seasonal occurrence of D. carinata, the dominant species in autumn and late winter, and M. leuckarti, the dominant species during mid-summer. Physicochemical parameters appeared to be unimportant in accounting for the occurrence and abundance of Simocephalus exspinosus, Macrothrix hirsuticornis, and Boeckella triarticulata. Although population densities of D. carinata and S. exspinosus were negatively correlated, population parameters did not indicate a marked competitive interaction. Mesocyclops leuckarti may have preyed upon the immature stages of D. carinata, although this was generally not reflected in mortality rates.
Patterns of recruitment of polychaetes to coral substrates at Lizard Island, Great Barrier Reef - an experimental approach
Authors: Hutchings P , Murray A
Published: November 2005

The spatial and temporal patterns of recruitment of seven species in six families of polychaete to coral substrates at two sites at Lizard Island, Great Barrier Reef, are described. Four species exhibit similar patterns of recruitment to both sites, and another species exhibits a similar pattern to both sites but with different intensities. The other two species recruit in different patterns to the two sites. All species exhibit peaks of recruitment, most during mid-summer. Recruitment during 1977 was significantly greater than during 1976 for five of the seven species. Factors responsible for this variation and the patchiness of successful settlement are discussed.
Macroinvertebrate assemblages in channelized and unchannelized sections of the Bunyip River, Victoria
Authors: Hortle KG , Lake PS
Published: November 2005

The macroinvertebrate fauna of channelized and unchannelized sections of the Bunyip River in southern Victoria was investigated. There were no significant differences in the physicochemical characteristics of the water between the two sections. The three sites in the channelized section were deeper and narrower than the three sites in the unchannelized section. Two of the sites in the channelized section had significantly lower mean particle size and the most stable substratum. The amount of detritus and amount of algae did not differ significantly between sites. There were no significant and consistent differences in species richness, density and standing crop of macroinvertebrates between sites. A difference in the faunal composition of the sites was clearly evident in autumn only, but differences in diversity (H') and evenness (J') between sites were not consistent. The most important factor affecting density, standing crop and species richness on the basis of principal component analysis was substratum stability, which, if decreased by channelization, is likely to reduce the abundance and species richness of resident macroinvertebrate assemblages.
Macrobenthos of the cooling watre discharge canal of the Gladstone Power Station , Queensland
Authors: Saenger P , Stephenson W , Moverley J
Published: November 2005

Quantitative sampling of the macrobenthos of the cooling water discharge canal of the Gladstone Power Station has been conducted monthly from September 1976 to July 1980 (sampling times 1-47), to provide information on (i) the effects of an initially small but increasing thermal discharge on this biota, and (ii) the likely effects that could be expected to occur in the Calliope River, which will ultimately receive a 65-m3 s-1 thermal discharge with a maximum temperature differential of 8.2� C when the power station is fully commissioned. Considerable fluctuation was found in the biotic data; however, the number of benthic organisms correlates more closely with flow rates in the canal than with any other abiotic factor, showing a positive correlation for sampling times 1-32, followed by a negative correlation for times 33-47. Times classification also indicated a major dichotomy at times 32-34. It is concluded that the changes in the benthos of the canal can be attributed primarily to changes in flow rates, which, in turn, have altered the sediment composition. This is supported by a change in the benthic fauna, with a gradual replacement of species of known sandy mud affinities by species living on or in stiff clays. With a design maximum temperature differential of 8.2� C and with lower water velocities outside the canal, the present data suggest that it is unlikely that the benthic fauna of the Calliope River, adjacent to the power station, will be markedly altered as a result of the thermal discharge; however, because of abiotic and biotic differences between thecanal and the river, the testing of this extrapolation must await the analysis of the 'post-thermal' data presently being collected.
Use of Japanese satellite GMS for following the East Australian Current
Authors: Mulhearn PJ
Published: November 2005

A series of infrared images from the Japanese geostationary meteorological satellite (GMS) for the period late July to early December 1980 was found to reveal many useful oceanographic features of the western Tasman Sea. Although the temperature signal is digitized in steps of 1.73� C, the disadvantage of this somewhat coarse thermal resolution was offset to some extent by the availability of frequent images. The positions of eddy centres could be estimated within �0.25 of an eddy diameter from September onwards, and it was possible to follow their movements over time scales of the order of a month. The hot surface 'core' of the East Australian Current off northern New South Wales was discernible intermittently on images, and composites of core positions over a month revealed complex time variations in current axes. Cloud cover is a major limitation for infrared imagery, but some oceanographic feature was discernible on 63% of images.
Cell types of the gastic mucosa of a teleost, the river blackfish, Gadopsis marmoratus
Authors: Giraud AS , Yeomans ND
Published: November 2005

The gastric mucosa of G. marmoratus was examined by electron microscopy and cytochemistry. The gastric epithelium is composed of three cell types: surface mucous cells, oxynticopeptic cells, and endocrine cells (with three subtypes identified). These cells show ultrastructural homologies with the major cell types in the gastric mucosa of classes of tetrapod vertebrates. However, one cell type present in stomachs of other vertebrates, but lacking from the blackfish stomach, is the glandular mucous cell.
Estimates of tag shedding rates for Floy FT-2 dart and FD-67 anchor tags in Barramundi, Lates calcarifer (Bloch)
Authors: Davis TLO , Reid DD
Published: November 2005

A double-tagging experiment was carried out on a temporarily landlocked population of barramundi. Shedding rates were determined for Floy FT-2 dart tags on fish with a total length over 350 mm and FD-67 anchor tags on fish shorter than 350 mm. Immediate shedding was negligible for both tag types, and the estimated instantaneous daily shedding rate was 0.00057 for FT-2 tags and 0.0018 for FD-67 tags. Results from a small number of long-term recaptures suggest that the shedding rate may decline with time, so that tag loss over long periods could be overestimated if the above shedding rates are applied.
Mixing of Burdekin River flood waters in the Great Barrier Reef
Authors: Wolanski E , Van Senden D
Published: November 2005

Wind fluctuations in the central region of the Great Barrier Reef from December 1980 to February 1981 generated low-frequency, reversing, longshore currents superimposed on the northward longshore currents initially generated both by intense direct rainfall over the continental shelf and by Burdekin River floods. The river plumes, which account for terrigenous mud distribution on the sea floor, were swept over the Great Barrier Reef. It is suggested that intense direct rainfall over the continental shelf and Burdekin River floods may create a barotropic shelf wave.
Upwelling by internal tides and kelvin waves at the continental shelf break on the Great Barrier Reef
Authors: Wolanski E , Pickard GL
Published: November 2005

A time series of 50 days duration was obtained of sea levels and winds and of temperature and currents at six depths from 27 to 104 m at 18�19'S.,147�21'E. on the continental shelf break between the Great Barrier Reef and the Coral Sea. The sea-level signal had a predominantly mixed solar and lunar semidiurnal tidal period. The currents consisted of a semidiurnal tidal component oriented primarily cross-shelf, except near the sea floor, superimposed on a low-frequency, predominantly longshore, southward component, coherent with depth, in geostrophic balance, and modulated by the longshore wind component Large fluctuations in temperature were observed, consisting of a low-frequency component, possibly generated by internal Kelvin waves, and iiucruarions of predominantiy solar semidiurnai iidai period. The latter fiiictuations are interpreted as evidence of internal tides of amplitude up to 110 m that may be generated by the interaction of the longshore currents with topographic irregularities in the shelf. It is suggested that, during any long-term studies of water properties near the shelf break, some additional monitoring of short-term temporal variations should be carried out to avoid data aliasing by internal tides. The bottom boundary layer appears to be very active in vertical mixing. Internal tides may be very important in introducing other water components, e.g. nutrients, to the outer Great Barrier Reef.
Thermal waves on the Queensland shelf
Authors: Andrews JC
Published: November 2005

Thermocline waves are found on the continental slope and shelf of Queensland. Slope waves of period near 90 days accompany upwelling and downwelling. Shelf thermal waves are created by onshore surges of shelf- break water, which is 1-4.5�C cooler than lagoon water, depending on the season. The bottom surges are investigated by means of the cross-spectra of temperatures with longshore winds, with atmospheric pressure and with mean sea level. Longshore winds are found to be the driving mechanism and significant coherence is found near periods of 4 and 8 days (summer and winter, respectively) and in a band with periods of 10-70 days, perhaps peaking near 30 days. Correlation and cross-spectral analyses of temperature at sites 100 km apart suggest that the short period thermal waves popagate equatorward wheras the long period waves, which contain most of the thermal covariance, form a standing mode. Cross-spectral analysis of the root mean square amplitude of diurnal thermal variations with the longer-period thermal waves suggests that localized tidal upwelling brings bottom water over reefs.
Estimation of dynamic heights from temperature profiles in the Tasman Sea
Authors: Pearce AF
Published: November 2005

Three methods chosen to estimate dynamic height from temperature profiles in the Tasman Sea were: (1) simple linear regression of dynamic height relative to 1300 dbar (D0/1300) on temperature at 250 m (T250); (2) simulating salinity profiles from mean temperature-salinity (T-S) relationships to use with standard- depth temperatures such as Nansen casts to 1300 m; and (3) simulating salinity profiles from mean T-S relationships to use with expendable bathythermograph profiles to 450 m; and then linear regression of D450/1300 on T450 for the dynamic height below 450 m. The approximate dynamic heights, relative to 1300 dbar, were compared with the true dynamic heights (calculated in the normal way) at the 702 stations examined. Root-mean-square differences were shown to be 7-8, 24 and 5-5 dyn cm, respectively, for the three methods.
Model for the three-dimensional structure of wind-driven and tidal circulation in Bass Strait
Authors: Fandry CB
Published: November 2005

Earlier models of the circulation in Bass Strait have been extended to include vertical structure. Time- dependent circulation fields in Bass Strait, induced by wind driving at the surface and tidal oscillations along open-sea boundaries, are computed at a number of selected depths. The original two-dimensional model is combined with an analytical solution of the Ekman equations, which at each grid point provides an expression for the time-dependent flow at any depth in terms of a convolution integral over the sea- surface slope and wind stress. This model should be applicable to winter conditions when the strait is well mixed vertically and hence the dynamical effects of density stratification negligible. The predicted wind-induced circulation fields are highly depth dependent, with equilibrium surface currents in the central Bass Strait basin flowing in a direction approximately 45� to the left of the wind. At lower levels, currents are controlled by pressure gradient forces due to the sea-surface slope and friction. Significant upwelling and downwelling motions along the Victorian and Tasmanian coastlines can be inferred from these circulation fields. In the deep water off the continental shelf, currents in the upper 100 m are dominated by the (Ekman) drift current which rotates in an anticlockwise direction with increasing depth, such that the wind drift at the surface is accompanied by a measure of return flow at depth. Tidal currents are predicted in the absence of wind stress, but include the effects of bottom topography. Considerable variation with depth is found and the distinctive features are explained in terms of the relative importance of Coriolis force, bottom friction, and water depth. Comparison with the few existing observations reveals that the present model is producing realistic results.
Semidiurnal internal tides in eastern Bass Strait
Authors: Jones ISF , Padman L
Published: November 2005

Variations in the vertical thermal structure near the shelf break in eastern Bass Strait have been observed for a 1-year period during 1980-1981. For the periods when the water column was stratified, energetic oscillations of the thermocline were frequently observed, these being well correlated with the surface tide. A peak occurred at the semidiurnal frequency in approximately half of the spectra, each constructed from 4 days of thermistor records. The amplitude of this internal tide was up to 40 m from crest to trough in February 1981. The internal tide lagged the surface tide by 0-6 h in the five records analysed for phase. This, together with the consistency of phase in longer records, supports the proposal that these internal -motions were due to forcing not far from the site of observation. It is suggested that to popographic forcing can be scaled on the parameter h-2 δh/δx, where h is water depth and x is measured perpendicular to the isobaths, and a map of this parameter shows a line of strong generation near the 100-m isobath, about 10 km from our measurement site.
Wind-driven circulation of Cockburn Sound
Authors: Steedman RK , Craig PD
Published: November 2005

The water circulation within the Cockburn Sound embayment in Western Australia is predominantly wind-driven. Observations by moored current meters showed the mean velocities to be less than 0.05 m s-1 within Cockburn Sound and 0.07 m s-1 in the adjacent open coastal waters. Maximum tidal currents were very low, with an amplitude of the order of 0.01 m s-1. The importance of the wind-forcing was evident in the time-history data collected by the wind and current meters, particularly under storm conditions when winds greater than 15 m s-1 produce currents, within the Sound, between 0.10 and 0.25 m s-1. The wind records from Fremantle were examined and recurring patterns, such as sea breeze on and winter storms, were identified and their annual frequency of occurrence was estimated. A time- dependent, vertically integrated wind-driven numerical model was used to simulate the various water circulation patterns of each wind category. The circulation Froude number was shown to be of the order of thus allowing a description in terms of the stream function. Correlation between the data collected by the moored current meters and predicted by the model ranged between 0.05 and 0.76. Profiling data showed that under near calm wind conditions (<2 m s-1), local horizontal density gradients, caused by evaporation and heating, produced currents of up to 0.1 m s-1. This inverse estuary nature of the flow appears to play a significant role in the dynamics at low wind speeds. Under these conditions there was little or no volume exchange with the open sea. By contrast, the wind-driven circulation model showed that under a sea-breeze pattern 1.4 × 107 m3 was typically exchanged diurnally, and a 2-day winter storm may exchange about 1.1 × 108 m3, which is small compared with the volume of the Soand (1.2 × 109 m3). The bathymetry is such that the Sound acts mainly as a closed system.
Tides on the Australian north-west shelf
Authors: Holloway PE
Published: November 2005

Harmonic analysis of the records from 14 current meters and three offshore tide gauges from the Australian north-west shelf and continental slope regions and a number of coastal stations shows that tidal motion is dominated by the principal lunar (M2) and principal solar (S2) constituents. The tidal velocities are essentially barotropic with flow predominantly in the cross-shelf direction at the shelf break changing to predominantly along-shelf near the coast. The elevations of the M2 and S2 constituents are amplified across the shelf off Dampier by 1 .3 times and by approximately five times along the length of the shelf, a distance of around 1000 km. Several features of the semidiurnal shelf tide are discussed with the aid of a simple analytical model. The cross-shelf bathymetry is shown to produce cross-shelf amplification of the semidiurnal tide in good agreement with the observations off Dampier. An along-shelf pressure gradient results from the change in elevation of the tide along the coast and this pressure gradient is shown to be the main driving mechanism of the along-shelf component of the M2 and S2 velocities. The gradient also influences, but to a lesser extent, the cross-shelf component of the velocity and the cross-shelf amplification of the semidiurnal tidal elevation. Results of a world ocean tidal model (Schwiderski 1979) are presented and indicate the existence of a gradient in the shelf-edge M2 tide along the shelf and this is shown to have an important effect on the shelf tide.
Distribution of protein variation in skipjack tuna (Katsumonus pelamis) from the central and south-west Pacific
Authors: Richardson BJ
Published: November 2005

Forty-two loci were electrophoretically surveyed for protein variation in the skipjack tuna. A new polymorphism in guanine deaminase was found as well as low-frequency variation in glucosephosphate isomerase and adenosine deaminase. Average heterozygosity for the species was 0 032. The gene frequencies at four variable loci for 70 sample sets, each of approximately 100 animals, collected at locations throughout the South Pacific Commission region, are given. East-west clines in allele frequencies for carboxylesterase and guanine deaminase occur across the study area. There is also within-area heterogeneity in allele frequency at these loci. Previously proposed discrete-stock models and a new isolation-by-distance model for the population structure of skipjack tuna are examined in the light of the genetic data.
Annual total mortality and population stucture of jackass morwong (Nemadactylus macropterus Bloch & Schneider) in eastren Australian waters
Authors: Smith DC
Published: November 2005

Catch curves were analysed to estimate the annual total mortality of jackass morwong landed at the port of Eden between July 1976 and June 1979. The annual total mortality of females was lower in 1978-1979 than in the previous 2 years, reflecting the expansion of the trawl fishery in New South Wales to include previously unexploited deepwater grounds. Males were fully recruited to the commercially exploited population at an earlier age than females. It is suggested that the increased mortality in older males is due to an increase in natural mortality.
Food of the squid Nototodarus gouldi in Bass Strait
Authors: O'Sullivan D , Cullen JM
Published: November 2005

A study was carried out on the food of the squid N. gouldi, based on 1277 individuals collected by Japanese vessels jigging in Bass Strait from November 1979 to April 1980. Most of the food consisted of crustaceans, fish and cephalopods, with crustaceans being more common in smaller animals and cephalopods in larger ones. The crustaceans, which included several benthic species, were more common in the diet at night than by day. Cannibalism by N. gouldi did not appear to increase appreciably after the animals were brought aboard and laid together in the collecting troughs. By frequency of occurrence, the contributions to the diet, averaged over all sizes sampled, were fish 37%, crustaceans 36%, and squid 26%; but in terms of biomass fish contributed more. From the size of the beaks of squid taken, it could be shown that the mantle length of these prey was usually not more than half that of the predator. N. gouldi feeds primarily at night, probably moving up from the bottom into the water column. Larger specimens, both male and female, were less likely to contain food in the stomach than smaller ones, and possible explanations are considered. There are some indications about the timing of spawning in 1979-1980, from records of the size and sexual maturation of the animals sampled.
Life-cycle duration, growth and spawning times of five species of atherinidae (Teleostei) found in a Western Australian estuary
Authors: Prince JD , Potter IC
Published: November 2005

Five species of atherinid were collected monthly from the estuary of the Swan-Avon river system. Length-frequency data and gonadosomic indices showed that Atherinosoma presbyteroides, A. elongata, A. wallacei and Allanetta mugiloides typically have a 1-year life cycle and generally reach maturity at total lengths of 40-85 mm. The mean length of the mature females was significantly greater than that of the mature males in each Atherinosoma species, but not in Allanetta mugiloides. The fifth species, Pranesus ogilbyi, was often represented by many individuals with far greater total lengths (100-150 mm) than were found in the other four species, a feature that reflected the presence of two year classes. Length-frequency and gonadosomic data indicated that all five atherinid species breed over protracted periods during spring and summer. Values for the gonadosomic index and the absence of local marine populations of Atherinosoma elongata, Allanetta mugiloides and Atherinosoma wallacei confirmed that the populations of these species in the Swan-Avon are estuarine or estuarine-inland water sensu stricto. Gonadosomic values for the marine species A. presbyteroides and P. ogilbyi, allied with the times of disappearance of larger individuals from the estuary, suggested that only the former of these two species may breed to any extent in the estuary. Length-frequency histograms showed that the populations of A. presbyteroides and P. ogilbyi in the Swan-Avon are more heterogeneous than those of the same species in a nearby marine embayment.
Observations on the distribution of Bankia australis calman (Mollusca : Teredinidae) in the Patonga Creek mangrove swamp, New South Wales
Authors: Rimmer MA , Battaglene SL , Dostine PL
Published: November 2005

The distribution of B. australis was found to be limited to the frontal zone of Avicennia marina despite the presence of apparently suitable wood throughout the mangrove swamp. Numbers of B. australis in dead tree stumps were found to decrease with increasing height and decreasing diameter of the stump. It is suggested that the insulating properties of the wood substratum may affect the distribution of B. australis by minimizing temperature effects during emersion.