bluuebunny/crossref_metadata_2025 huggingface dataset:
Monitoring Larval Fluxes through the Surf Zones of Australian Coral Reefs
Authors: Doherty P , McIlwain J
Published: November 2005

The first successful trials with stationary 'crest' nets to monitor the nocturnal fluxes of larval fish crossing reef margins in both eastern and western Australia are described. Lengthy deployments were possible on Ningaloo Reef, north-western Australia, because that system is topographically suitable: i.e. a fringing barrier reef where surf produces a constant flow into a coastal lagoon. Sampling on 85 nights between October 1994 and March 1995 revealed a rich larval fish fauna (56474 individuals) dominated by pelagic juveniles nearing settlement stage. Variations in the daily catches of replicate nets (200 m apart) were highly correlated, showing the suitability of this technique for monitoring larval supply. Another trial (five nights) was made at One Tree Reef, southern Great Barrier Reef. On nocturnal flood tides, when rising water first spilled into the lagoon, triplicate nets caught many presettlement fish (47797 individuals) in this flow. The behaviour of some taxa clearly assisted their transport through the surf. Despite the successful short-term deployments at One Tree, there may be limited potential to deploy this gear elsewhere on the Great Barrier Reef because of unsuitable flow regimes.
Colonization of Reef Fishes at Moorea Island, French Polynesia: Temporal and Spatial Variation of the Larval Flux
Authors: Dufour V , Riclet E , Lo-Yat A
Published: November 2005

Colonization by settlement-stage fishes of the lagoon at Moorea Island, French Polynesia, was studied with nets fixed at five sites on the outer reef crest around the island. The study occurred between 30 January and 29 March 1995 when an estimated 1.8 million settlement-stage fishes were collected in 164 samples, which contained 65 families and several new records for the biogeographical region. The results here concern only the largest taxa (length >1.5 cm), representing 46 families of reef fishes. Patterns of larval colonization varied strongly among families, although all displayed lunar cycles. The serranid Epinephelus merra occurred sporadically in catches but in very high abundances (1000 to 4000 individuals per sample). In contrast, some acanthurids such as Acanthurus triostegus were collected in most samples but catches never exceeded 100 individuals per sample. This methodology allows the colonization to be monitored and provides the first estimates of larval density at settlement. Future applications could include estimation of mortality rates during this critical phase of the life history.
Two-phase Recruitment of Apogonids (Pisces) on the Great Barrier Reef
Authors: Finn MD , Kingsford MJ
Published: November 2005

Settlement and recruitment of the apogonids Apogon doederleini (Jordan & Snyder) and Cheilodipterus quinquelineatus (Cuvier) to continuous reef were examined at One Tree Island, southern Great Barrier Reef. Many settled to patch reefs in sand habitat. Moreover, peaks in settlement (over five to six days) corresponded to peak catches of potential settlers in ichthyoplankton nets at the reef crest. Few newly settled (<20 mm standard length) apogonids were found on continuous reef where juveniles and adults were abundant. A similar pattern was found on the reef slope outside the lagoon, but total abundance of both species was low in this environment. Results of tagging with tetracycline, diel censuses of patch reefs, and examination of gut contents indicated that fish of all size classes moved from daytime sites and foraged at night. Recruitment to continuous reef appears, particularly in A. doederleini, to take place in two phases: potential settlers enter the lagoon at night and settle into sand rubble habitats; fish feed at night and their night-time excursions increase with the size of the fish until they move to continuous reef as Phase 2. The monitoring of continuous reef would not have detected patterns of settlement to One Tree Island.
Laval and Juvenile Fishes in the Surf Zone Adjacent to the St Lucia Estuary Mouth, KwaZulu-Natal, South Africa
Authors: Harris SA , Cyrus DP
Published: November 2005

Composition, seasonality and developmental stages of larval and juvenile fish in the surf zone adjacent to the St Lucia Estuary mouth, KwaZulu-Natal, were investigated. Samples were collected monthly, from February 1992 to January 1993, at six stations along the beach north of the estuary mouth. A 24-h study was also undertaken in the surf zone when the estuary mouth was closed. In the 12-month study a total of 2931 larvae, representing 88 taxa and 47 families, was collected. The most abundant families were the Sparidae, Haemulidae, Ambassidae, Tripterygiidae and Chanidae, together comprising 64.2% of the total catch. The most abundant species were Pomadasys olivaceum, Ambassis sp. and Rhabdosargus holubi. In the 24-h study a total of 13731 larvae, representing 43 taxa and 22 families, was collected and was dominated by Ambassis sp., Croilia mossambica and Chanos chanos.
Temperature and turbidity were the most important environmental variables related to fish densities of estuary-associated species. Temporal changes in fish densities were most significant for daylnight catches, with densities being significantly higher at night than during the day. Fish species associated with estuaries peaked in abundance in mid autumn and late winter. Spatial trends in fish densities indicated significantly higher densities of estuary-associated species at Stations 2 and 3, with densities decreasing thereafter away from the estuary mouth. Larval stages were predominantly postflexion for all months sampled. The total catch was dominated by marine spawner species, with 36% of all taxa having some degree of estuarine association. Species with some degree of estuarine association dominated the catch in terms of density during both the 12-month study (60%) and the 24-h study (83%). Results from this study indicate that the surf zone adjacent to the St Lucia Estuary functions as a transit route and a nursery habitat for certain estuary- and non-estuary-associated fish species.
SAR observations of internal wave wakes from sea mounts
Authors: Cresswell G , Zhou C , Tildesley PC , Nilsson CS
Published: November 2005

The synthetic aperture radar on the European Space Agency Remote Sensing Satellite ERS-1 detected undular and V-shaped features on the ocean surface above the continental slope and shelf off eastern Australia near 31�S. These are suggested to be expressions of transverse and oblique internal waves caused by the influence of seamounts and canyons on an energetic East Australian Current (EAC). The phase speed of the 1-km-wavelength internal waves was calculated from an assumed ocean density structure to be a little over 1 m s-1 -close to the expected speed of the EAC. This meant that transverse waves could become 'anchored' behind canyons and ridges aligned across the EAC flow. Single-peak seamounts appeared to produce oblique waves with half angles generally around 45�, but sometimes less. Some of the seamounts causing the internal waves may have been as deep as 600 m.
Comparison of the Semtner and Chervin eddy-resolving global ocean model with LUCIE and satellite observations in the Leeuwin Current region
Authors: Reason CJC , Pearce AF
Published: November 2005

Output from the Semtner and Chervin eddy-resolving global ocean general circulation model is compared with observations from the Leeuwin Current Interdisciplinary Experiment (LUCIE) and satellite data for the coastal waters of Western Australia. The model output is a snapshot over the domain 9-43�S, 90-120�E for a day in mid July 1987, which is during the season that the Leeuwin Current is expected to be well established along the western and southern coasts of Western Australia. Maximum Leeuwin Current velocities in the model are of the order of 60 cm s-1 and are found in the southern part of the current on the western coast and around into the Great Australian Bight. At depths below about 200 m, and centred near 400 m, there is an equatorward-flowing undercurrent with maximum velocity of order 25 cm s-1. Comparison of temperature and salinity cross-sections with LUCIE observations reveals that the model output for this day exhibits many realistic features. In particular, the model fields display a number of prominent meanders and eddies on the Leeuwin Current as well as further offshore. Consistent with observations, mesoscale features associated with the Leeuwin Current are concentrated between 25�S and the Cape Mentelle region; the flow in the northern part of the Leeuwin Current and the North West Shelf may be too weak to induce eddy-generating instabilities. Prominent in the model output are two large meanders on the Leeuwin Current between 25�S and 29�S and two anticyclonic eddies further downstream; features similar to these are evident in satellite data during winter 1987.
Dynamics of the Swan River Estuary: The seasonal variability
Authors: Stephens R , Imberger J
Published: November 2005

The Swan River is a south-westem Australian estuary that undergoes a distinct seasonal stratification cycle. Motivated by the increasing nutrient loading of the estuarine system, an intensive investigation into the hydrodynamics was performed with the aim of understanding the physical processes responsible for transport within the estuary. The seasonal variability of the stratification was documented with regular conductivity-temperature-depth-dissolved oxygen transects that were used to piece together an overview of the dynamics. The estuarine dynamics were classified into a gravitational overflow produced by the winter rains, a salt wedge condition governed by both discharge and topographic constraints, tidal dynamics that influence the degree of flushing, and the roles of two sills that control fluid exchange between the estuary and the ocean and control the propagation of the salt wedge and the gravitational overflow.
Drying-induced stimulation of ammonium release and nitrification in reflooded lake sediment
Authors: Qui S , McComb AJ
Published: November 2005

Air drying of intact sediment cores from a shallow freshwater wetland caused the release of a substantial amount of ammonium following reflooding. The increased ammonium concentration stimulated nitrification at a rate 10 times higher than in the original waterlogged sediments under aerated conditions. Under non-aerated conditions, nitrate concentrations decreased more rapidly in reflooded systems than in the waterlogged systems. Ammonium and nitrite had accumulated in the original waterlogged systems, but this was rare in reflooded dried cores because of the depletion of bioavailable organic carbon. These results suggest that drawdown and drying of wetlands can accelerate mineralization of the organic matter in sediment, and can temporarily increase ammonium and nitrate concentrations in the water column during reinundation. Drying and reflooding of wetland sediments may eventually increase N loss through promotion of denitrification.
Normal development and embryonic gene activity of the ascidian Herdmania momus
Authors: Degnan BM , Rohde PR , Lavin MF
Published: November 2005

Embryonic and post-larval development of the tropical solitary ascidian Herdmania momus is shown to be similar to that of extensively studied ascidian model systems. H. momus development is rapid and temperature-dependent, with hatching occurring 8.5 h after fertilization at 28�C. An increase in total embryonic gene transcription is detected at the 110-cell stage or the onset of gastrulation. Treatment of early embryos with actinomycin D inhibits transcription and curtails morphogenetic cell movement in the early gastrula without immediately inhibiting cell division. The prevalence of homeobox-containing transcripts increases around the 110-cell stage and later in development. Isolated H. momus homeobox genes, expressed at the tailbud stage, have greatest sequence identity to members of Hox, otd/Otx, eve/Evx and cad/Cdx homeobox classes. Evidence from H. momus and other ascidians suggests that urochordates possess most of the homeobox genes of the chordate HOX cluster.
Age validation, growth and mortality rates of the tropical snappers (Pisces: Lutjanidae) Lutjanus adetii (Castelnau, 1873) and L. quinquelineatus (Bloch, 1790) from the central Great Barrier Reef, Australia
Authors: Newman SJ , Williams DM , Russ GR
Published: November 2005

The age and growth of Lutjanus adetii and L. quinquelineatus from the central Great Barrier Reef were determined from studies of annuli in sectioned otoliths (sagittae). The period of annulus formation was validated by oxytetracycline labelling of externally tagged fishes. For L. adetii, validation was obtained from tagged fishes that were recaptured after a minimum of 12 months at liberty, the first time this has been achieved for a Lutjanus species. A single opaque and translucent zone was formed once a year, with the opaque band (annulus) being formed during the winter months. Otolith weight was strongly correlated with age for both species. There was significant differential growth between the sexes in length-at-age and weight-at-age for both species, with males growing larger than females. The oldest individuals found were a male L. adetii of 24 years of age and a female L. quinquelineatus of 31 years of age. The shape of the growth curves were steep for the first few years and then became asymptotic. The annual instantaneous rate of natural mortality (M) was 0.235 for L. adetii and 0.154 for L. quinquelineatus, representing an annual survivorship of 79% and 86%, respectively. The protracted longevity and low natural mortality rates imply that both L. adetii and L. quinquelineatus are vulnerable to overfishing despite their small size.
Review of information on diurnal vertical migration in the bignose shark (Carcharhinus altimus)
Authors: Anderson RC , Stevens JD
Published: November 2005

The bignose shark (Carcharhinus altimus) has been described in the literature as a deep-benthic species. Evidence is presented that C. altimus is a diurnal vertical migrator. It occurs near the bottom in about 90-500 m by day. At night, at least some individuals move into shallower water or up into the pelagic zone.
Validity of using translucent zones of otoliths to age the pilchard Sardinops sagax neopilchardus from Albany, Western Australia
Authors: Fletcher WJ , Blight SJ
Published: November 2005

Otoliths (sagittae) of the pilchard (Sardinops sagax neopilchardus) from the Albany region of Western Australia were examined on a monthly basis during 1989 to 1991. When read consecutively, with the month of capture known, a clear annual cycle of an increase in marginal increments to October followed by a decline was recorded. This pattern was, however, severely distorted when samples were re-examined after having been jumbled and the month of capture concealed. Younger age groups (≤3) showed evidence of multiple rings being formed annually, but not in all years or individuals, and this was not evident in older individuals (≥4). Agreement between readings was low (43-53%), especially between different readers. Resultant growth curves showed that males grow to a smaller size (L∞ =164, K = 0.805, Φ = 1.03) than females (L∞ = 174, K = 0.584, Φ= 0.95). Agreement between counts of annuli and ages estimated by using otolith weight and length was only 54% for all individuals, but increased to 76% for individuals assigned the same age by different readers. Given the poorer predictions of future catch rates from the relative number of 2-year-olds in the commercial catch using annuli (implying lower accuracy) and increased complexity in preparation, otolith weights will be the method adopted for future ageing.
Sea snake by-catch of prawn trawlers on the northern Australian continental shelf
Authors: Ward TM
Published: November 2005

This paper describes and compares the sea snakes caught by vessels that target tiger prawns and endeavour prawns or that target the banana prawns Penaeus merguiensis and P. indicus. In 1989-90, 5203 sea snakes (14 species; 7 unidentified specimens) were purchased from fishers who trawled between Koolan Island and Cape York and participated in a dedicated carcass-tagging and data-collection programme. Hydrophines (11 species) represented 86.7% of the total catch. Aipysurines (3 species) represented 15.0% of specimens from vessels that targeted tiger prawns or endeavour prawns, but only 1.1% of specimens from vessels that targeted the banana prawns P. merguiensis and P. indicus. Prawn trawlers that operated between Koolan Island and Cape York during 1990 caught approximately 81 080 (� 13 670) sea snakes. Vessels that targeted tiger/endeavour prawns, P. merguiensis and P. indicus caught approximately 69260 (� 8750), 7200 (� 3250) and 4620 (� 1120) sea snakes respectively. The results emphasize the advantages of interactions between fishers and scientists and the need to assess separately the impacts of the three fisheries that constitute the northern prawn fishery.
Seasonal occurrence, distribution and movements of the whale shark, Rhincodon typus, at Ningaloo Reef, Western Australia
Authors: Taylor JG
Published: November 2005

Aerial surveys between 1989 and 1992 demonstrated that large numbers of whale sharks appear on Ningaloo Reef in north-western Australia during autumn, shortly after the coral has undergone mass spawning. This movement into the reef waters would allow whale sharks to capitalize on the increased production of zooplankton brought about as a result of this mass spawning of corals and other marine organisms. Sharks occupied mainly the relatively turbid waters on the reef front, where a northerly current prevailed, rather than the offshore, warmer waters of the southerly flowing Leeuwin Current. The sharks moved in to the reef front from offshore but, once inshore, the majority swam parallel to the reef. The maximum density in any sector of the reef at any one time was four sharks per km, recorded in May 1992. The longer the time since sharks first appeared on the reef, the greater was their tendency to aggregate in a particular region of the reef. Evidence is presented that indicates that whale shark numbers at the northern end of Ningaloo Reef declined during the latter half of the 1980s; this decline may be related to the massive destruction of coral by the gastropod mollusc Drupella cornus during this period.
Major cyanobacterial bloom in the Barwon-Darling River, Australia, in 1991, and underlying limnological conditions
Authors: Bowling LC , Baker PD
Published: November 2005

The occurrence of a severe cyanobacterial bloom is described. This bloom affected almost 1000 km of the Barwon-Darling River, New South Wales, Australia, in November and December 1991 and was dominated by Anabaena circinalis Rabenhorst. This cyanobacterium was present in concentrations of around half a million cells per millilitre at some localities during its peak in mid November. Moderate to very high toxicity was demonstrated by mouse bioassay at many localities during this time. The bloom was attributed to very low flow conditions and high nutrient concentrations, especially of total phosphorus. However, warm water temperatures, elevated pH, reduced turbidity, and improved water transparency would also have been contributing factors. Very high ammonia concentrations were also observed during the bloom. The bloom declined during December and was eventually flushed from the river by increased flows following heavy catchment rainfall between mid December and early January.
Pelagic primary production in the Coral and southern Solomon Seas
Authors: Furnas MJ , Mitchell AW
Published: November 2005

Phytoplankton primary production was measured around the periphery of the Coral Sea during October 1985 and in the boundary current systems bordering the northern Australian Great Barrier Reef (GBR) and Papuan Barrier Reef (PBR) during October 1985 and June-July 1988. Under strong wind conditions (mean winds 8-12 m s-1), the north-western Papuan Barrier Reef region was characterized by a shallow surface mixed layer, shallow nutriclines (25-75 m) and shallow subsurface chlorophyll maxima. Under low wind stress conditions (mean winds <5 m s-1), the southern and western Coral Sea were also characterized by a shallow surface mixed layer and stable underlying density profiles but deep (>I00 m) nutriclines and deep (60-125 m) subsurface chlorophyll and primary production maxima. Regardless of location, most primary production occurred above the 20% mid-day isolume surface. Phytoplankton standing crop and primary production in all regions were dominated by picoplankton (<2 μm size fraction). Very high primary production rates (1-3 g C m-2 day-1) were measured at a number of stations adjacent to the western margin of the PBR and within the central basin of the Louisiade Archipelago. Evidence for upwelling along the western margin of the PBR was observed under both north-easterly (normal to the reef axis) and south-easterly (parallel to the reef axis) wind regimes; however, surface outcropping of upwelled water did not occur. Oceanic primary production in the Coral Sea is estimated to be between 100 and 200 g C m-2 year-1. Primary production in and around the Louisiade Archipelago appears to be on the order of 200-300 g C m-2 year-1. Near-surface chlorophyll standing crop was generally better correlated with near-surface primary production than was total chlorophyll with total areal primary production.
Differences in morphology and reproduction of the barnacles Elminius covertus and Hexaminius spp. from mangrove forests in the Sydney region of New South Wales
Authors: Ross PM
Published: November 2005

E. covertus is found on bark and leaves of the grey mangrove Avicennia marina, H. foliorum is found on leaves and H. popeiana is found on bark. 7655 barnacles were collected from two sites at Woolooware Bay from winter 1987 to summer 1989. Reproductive and external features in E. covertus differed depending on the substratum on which it lived; reproductive output was greater on leaves than on bark. The genus Hexaminius has been classified elsewhere as two species on the basis of external features and reproductive differences of adults, larval development and larval setation; however, the adults were living on different substrata. A detailed study of larval and juvenile stages of Hexaminius in the field showed no differences in external features until juveniles were one month old and no differences in the time taken to rear cyprid larvae. This suggests that Hexaminius should not continue to be divided into two species.
Litter production and accumulation in stressed mangrove communities in the Embley River estuary, north-eastern Gulf of Carpentaria, Australia
Authors: Conacher CA , O'Brien C , Horrocks JL , Kenyon RK
Published: November 2005

From March 1993 to March 1994, the three main mangrove communities in the Embley River Estuary (12�37'S, 141�52'E) were studied: Rhizophora forest in the main river channel and in a small creek, and Ceriops forest and Avicennia forest in a small creek. In November 1993, all A. marina trees in the main river channel lost their leaves, and some understorey species in Avicennia forests in tributaries died; this is attributed to environmental stress. This defoliation and death continued for at least a year.
The Rhizophora forests were moderately to highly productive of litter, were the tallest, and had the greatest canopy cover and the greatest surface area of ground structures or potential refugia for juvenile finfish and crustaceans; all the litter was quickly transported by the tides to other parts of the estuary. The Ceriops and Avicennia forests produced less litter and were probably under water stress and salinity stress during the dry season; litter accumulated on the forest floor for much of the year, but from November to March was carried away by the higher tides and rainfall. Hence, in the wet season, pulses of litter are exported to the estuary, potentially forming temporary habitats in the estuary for juvenile finfish and crustaceans.
Determination of the age of brown and rainbow trout in a range of New Zealand lakes
Authors: Graynoth E
Published: November 2005

Brown trout (Salmo trutta) and rainbow trout (Oncorhynchus mykiss) from eight New Zealand lakes were aged by length-frequency analysis and by examining otoliths, pectoral fin rays and scales. Bimonthly changes in the length frequency of age classes were used to age fish for their first 2 or 3 years of life. Growth rates were highest in spring and summer, when a single wide opaque band was laid down on otoliths and fin rays, followed by a narrow transparent band in winter. Age estimates from otoliths agreed with 94-97% of those from length-frequency methods and with the ages of 21 tagged fish. Otoliths were used to age fish up to 11 years old and were more accurate than fin rays and scales. Although fin rays could be used to age juvenile fish from Lake Coleridge, where there was 78-80% agreement between otolith and fin ray ages, they were of little value for older fish in Lake Alexandrina (28% agreement). Rainbow trout scales from all lakes were difficult to read because of indistinct annuli and the presence of false checks. Mature trout were also difficult to age owing to scale absorption and a cessation of scale growth. The degree of agreement between otolith and scale ages ranged from 83-84% for trout in Lake Coleridge to 32-38% for older rainbow trout in other lakes. This study supports the findings of other researchers that trout scales can provide inaccurate estimates of the age of trout in New Zealand and Australia. It is suggested that otolith examination, supported by length-frequency analysis of juvenile trout, be used to age trout from New Zealand lakes. In many cases, examination of otoliths will be cheaper and quicker than the release and later recapture of fin-clipped or tagged juvenile trout.
Seagrass depth range and water quality in southern Moreton Bay, Queensland, Australia
Authors: Abal EG , Dennison WC
Published: November 2005

Correlations between water quality parameters and seagrass depth penetration were developed for use as a biological indicator of integrated light availability and long-term trends in water quality. A year-long water quality monitoring programme in Moreton Bay was coupled with a series of seagrass depth transects. A strong gradient between the western (landward) and eastern (seaward) portions of Moreton Bay was observed in both water quality and seagrass depth range. Higher concentrations of chlorophyll a, total suspended solids, dissolved and total nutrients, and light attenuation coefficients in the water column and correspondingly shallower depth limits of the seagrass Zostera capricorni were observed in the western portions of the bay. Relatively high correlation coefficient values (r2 > 0.8) were observed between light attenuation coefficient, total suspended solids, chlorophyll a, total Kjeldahl nitrogen and Zostera capricorni depth range. Low correlation coefficient values (r2 < 0.8) between seagrass depth range and dissolved inorganic nutrients were observed. Seagrasses had disappeared over a five-year period near the mouth of the Logan River, a turbid river with increased land use in its watershed. At a site 9 km from the river mouth, a significant decrease in seagrass depth range corresponded to higher light attenuation, chlorophyll a, total suspended solids and total nitrogen content relative to a site 21 km from the river mouth. Seagrass depth penetration thus appears to be a sensitive bio-indicator of some water quality parameters, with application for water quality management.
Nearshore fish community of the Port River-Barker Inlet Estuary, South Australia. I. Effect of thermal effluent on the fish community structure, and distribution and growth of economically important fish species
Authors: Jones GK , Baker JL , Edyvane K , Wright GJ
Published: November 2005

The nearshore fish community of the Port River-Barker Inlet Estuary was sampled between January 1986 and May 1987 using a beach seine to determine the effect of thermal effluent on the community structure and nursery function of the estuary. A total of 41 species was found in the estuary, with decreasing numbers of species with decreasing distance from the thermal outfall. Cluster analyses and multi-dimensional scaling ordination separated the thermally polluted sites from the non-affected sites. During the summer/auturnn period, thermal effluent only affected water temperature and the species compositions in the inner estuary, and the estuary-opportunistic species Aldrichetta forsteri, Arripis georgiana, A. truttacea and Hyporhamphus melanochir avoided the area at this time. During winter/spring months, thermal effluent acted in the opposite way, with A. forsteri attracted to the warmer waters of the inner estuary. The extended growth season for this species and significantly higher growth rates promoting premature movement out of the inner estuary for S. punctata were additional direct effects. These latter effects may alter the population structures of these species by increasing their vulnerability to heavy localized fishing intensity, aggregation of natural predators and point-source pollution. The species composition of the fish fauna of the estuary may also be indirectly affected by the thermal pollution-mediated seagrass loss in the inner estuary and a method is described to test this hypothesis.
Use of the daily egg production method to estimate the stock size of Western Australian sardines (Sardinops sagax)
Authors: Fletcher WJ , Lo NCH , Hayes EA , Tregonning RJ , Blight SJ
Published: November 2005

The daily egg production method was used to estimate the spawning biomass of the sardine Sardinops sagax in the Albany region of Western Australia. Plankton surveys covering 10000 - 14000 km² were completed in July of 1991 and 1992 in three to five days using up to three boats. Adult sardines were obtained from the local purse-seine fleet. The spawning area was similar in both years at approximately 3800 km² (1100 nmile²), but the number of eggs collected was larger in 1991 with egg production values of 6.5 per 0.05 m2 day-1 compared with 3.9 per 0.05 m2 day-1 in 1992. The average batch fecundity values were similar (approximately 11000 eggs female-1) as were the proportions spawning (0.13 in 1991; 0.09 in 1992). The calculated biomass estimates were 23 121 t (CV = 0.51) and 16 121 t (CV = 0.44) in 1991 and 1992 respectively.
Grazer-epilithon interactions in an Australian upland stream
Authors: Jordan J , Lake PS
Published: November 2005

Effects of macroinvertebrate grazers on the distribution of their food resource, epilithon, were examined in a south-eastern Australian stream. The hypothesis that grazers would significantly alter the development of epilithon was tested experimentally: macroinvertebrates were excluded from some experimental substrata and allowed to colonize others. Epilithic chlorophyll a concentration, organic matter content and total diatom density were used to monitor the effects of the grazer assemblage over 35 days.
As predicted, epilithon density was higher on bricks with exclusion barriers than on bricks open to colonization by grazers. Similarly, diatom densities were significantly higher on bricks from the grazer-exclusion treatment. Patterns in the development of epilithon over time point to the importance of prevailing abiotic conditions in determining the outcome of macroinvertebrate grazing. Differences in total epilithon biomass, algal biomass and diatom density between treatments clearly indicate the independent importance of macroinvertebrate grazing to the microdistribution of epilithon in upland streams.
Effects of golden perch (Macquaria ambigua (Richardson)) larvae, fry and fingerlings on zooplankton communities in larval-rearing ponds: An enclosure study
Authors: Arumugam PT , Geddes MC
Published: November 2005

In the absence of fish, the plankton community in enclosures in a larval-rearing pond showed a marked successional pattern from rotifers and Moina to copepod and then Daphnia-calanoid dominance. The impact of growing larvae and fry, with densities of 40-118 m-2 at harvest, on zooplankton was conspicuous only after Day 22 when Daphnia became rare and calanoid numbers were suppressed. Predation by fry caused reductions in the size of Moina, cyclopoids and calanoids found. An increase in Daphnia size, 'gigantism', occurred because of limitations in the mouth gape of the fry. Low densities of fingerlings (0.65 g wet weight and stocked at 1 and 2 m-2) had little effect on zooplankton succession, whereas high density (15 fingerlings m-2) caused a shift to a zooplankton community dominated by small cladocerans, rotifers and cyclopoids. High fingerling density also caused a reduction in the size of the microcrustaceans found. The size and density of fish determined their impact on zooplankton composition and succession, demonstrating that similar starting times and consistency in fish density are necessary in obtaining 'sensible' statistical inferences in field fish-zooplankton experiments.
Small spate disturbance and the complexity of habitat architecture in Mountain River, Tasmania
Authors: Robson BJ
Published: November 2005

Densities of benthic invertebrates were counted over several weeks before and after a small winter spate (15.5 times base flow) in two riffle types of contrasting architectural complexity in Mountain River, Tasmania. Complex benthic architecture reduced the impact of this spate on invertebrate densities over the short term (seven days). Longer-term recovery (several weeks) was unaffected by riffle architecture, with one of the riffles recovering much more slowly than the others. Refuges from small spates in Mountain River may exist in mid channel in complex boulder-cobble riffles. Within its temporal context, the effects of the spate on the study sites were of a similar magnitude to other unexplained population fluctuations.
Fishes of a shallow tropical mangrove estuary, Gazi, Kenya
Authors: Kimani EN , Mwatha GK , Wakwabi EO , Ntiba JM , Okoth BK
Published: November 2005

The composition and abundance of teleosts in an estuarine mangrove bay, sampled with a beach seine-net, are described. Site 1, at the mouth of a small river, was fringed by mangroves and had a silty substratum; Site 2 was also mangrove-fringed but had a sandy substratum and seagrass patches; Site 3 had a muddy sand substratum and also supported seagrasses. In total, 128 teleost species belonging to 50 families were identified in samples collected over 12 months. Gerreidae, Atherinidae and Clupeidae accounted for 78.5% of the total number of fish. Juveniles were found for 63% of the species. Of the fish species found, 44% were species associated with coral reefs. The mean numbers of species were similar at all sites, despite the differences in substratum type. Ecological diversity indices were higher, and fish density and biomass were lower, in the mangrove-fringed silt site than in the seagrass sites. Mean number of species was highest in February and June. Most families of commercial fish sought by fishers in the area were represented in the samples.
Observer-based survey of by-catch from prawn trawling in Botany Bay and Port Jackson, New South Wales
Authors: Liggins GW , Kennelly SJ , Broadhurst MK
Published: November 2005

Catches and by-catches were surveyed in the commercial prawn trawl fleets of Botany Bay and Port Jackson, two estuaries in the Sydney metropolitan area (NSW, Australia). Catches were surveyed in all tows during replicate fishing trips in each month during the 1990-91 and 1991-92 prawn trawl seasons in each estuary. Significant species-specific variabilities in abundances were detected between estuaries, between years, and between early and late in the fishing season. The mean annual ratio of by-catch to catch of prawns (by weight) was 2.5 : 1 for Botany Bay and 1.8 : 1 for Port Jackson. A mean annual by-catch (� 1 s.e.) of 142 � 14 t was taken from the Botany Bay fishery and 38 � 3 t from Port Jackson. These by-catches included large numbers of small recreationally and commercially important finfish: a mean annual by-catch of 1.52 �0.20 million fish from Botany Bay and 219� 23 thousand fish from Port Jackson. Despite uncertainties about the impacts of such by-catches on interacting commercial and recreational fisheries, it is recommended that strategies for the reduction of such by-catches be considered.
Genetic structure of the western rock lobster, Panulirus cygnus, with the benefit of hindsight
Authors: Thompson AP , Hanley JR , Johnson MS
Published: November 2005

Allozyme variation was used to investigate the genetic structure of the western rock lobster, Panulirus cygnus, along the coast of Western Australia. The study involved genetic surveys in 1980 and 1994. The first survey showed strong suggestions of latitudinal variation at two polymorphic loci, EST and GPI, but these suggestions were statistically suspect. With the benefit of hindsight gained from 1980, the 1994 survey was designed to examine more directly the suggestion of latitudinal genetic subdivision in this species. No evidence of genetic subdivision was found at either the EST or the GPI locus. In addition, the average FST value over nine polymorphic loci was a very low 0.0002. The evidence is consistent with current interpretations that P. cygnus is a single, panmictic population. In contrast with this spatial genetic homogeneity, however, there were significant changes in allelic frequencies at the GPI locus between 1980 and 1994, indicating genetic differences among cohorts.
Patterns in sponge (Porifera) assemblages on temperate coastal reefs off Sydney, Australia
Authors: Roberts DE , Davis AR
Published: November 2005

Pattern and process in deep-water macrobenthic assemblages have largely been inferred from the study of such assemblages on shaded artificial structures in relatively shallow water. This paper examines patterns in the diversity and abundance of sponges to a depth of 50 m on coastal reefs off Sydney, Australia. Photo-quadrats were used to provide estimates of the species richness and percentage cover of sponges on three reefs. Sponge morphotype (i.e. encrusting or massive) was also recorded. Within-reef variation was examined by nesting three sites within each reef at each of three depths; replicate photo-quadrats (0.45 m², n = 5) were taken at each site. In addition, a remotely operated vehicle was used to collect voucher specimens. Over 50 species of sponge were identified, many of which have never been described. In general, sponge richness increased with depth, as did the number of erect or massive forms. In contrast, cover decreased with depth, particularly for encrusting sponges. Univariate and multivariate analyses revealed considerable small-scale spatial and temporal variation in sponge distribution and abundance. A significant positive relationship between richness and cover was also apparent. In general, there were greater temporal changes in the patterns of abundance for the shallow reef assemblages at 20 m, relative to those at 30 m and 50 m.
Aqueous chemistry of major ions and trace metals in the Clutha River, New Zealand
Authors: Kim JP , Reid MR , Cunninghame RG , Hunter KA
Published: November 2005

Concentrations of the major ions Na+, K+, Mg2+, Ca2+, HCO32-, SO42- and Cl-, of silicate, and of both total and dissolved trace metals Zn, Cu, Pb and Cd were determined at sites along the Clutha River. The major ions exhibited differing behaviour both spatially and temporally. A large proportion of Cl- and Na+ throughout the catchment could be attributed to atmospheric input of sea salt. Contributions from this source for the rest of the major elements were minimal, except perhaps near the mouth of the river (K+, Mg2+). The water composition was dominated by the weathering of carbonate rather than of silicate minerals. Increases in the concentrations of Mg and Na + K indicate the weathering of Mg, K and Na from rock, minerals and clays within the catchment. The concentrations of major ions and Si were relatively low compared with other rivers in New Zealand and elsewhere. Concentrations of dissolved Zn, Cu, Pb and Cd all increased consistently with distance down river, and between 40% and 100%, for a given metal, was found in the dissolved fraction. High correlation among the dissolved trace metals, with essentially constant Cu : Zn : Pb : Cd ratios of 755 : 716 : 223 : 1 (molar basis), indicates that the same weathering process or source may be occurring throughout the catchment.
Phenolic compounds in the nearshore waters of Sydney, Australia
Authors: Jennings JG , de Nys R , Charlton TS , Duncan MW , Steinberg PD
Published: November 2005

Ten pollutant phenols extracted from an oil refinery discharge, urban storm water and sewage effluent were analysed by gas chromatography-mass spectrometry. Recoveries varied from 43% to 97%, with a detection limit of 0.5 μg L-1. Concentrations ranged from below the detection limit up to 114.0μg L-1, the highest being in sewage effluent. The most common were phenol and cresol.
The effects of similar concentrations were determined in bioaccumulation experiments using the mussel Mytilus edulis and fish Trachurus novaezelandiae. Recoveries of phenols from tissues were 10-40%, with a detection limit of 0.5 ng g-1. 2,4-dimethylphenol, 2,4-dichlorophenol, 4-chloro, 3-methylphenol, 2,4,6-trichlorophenol and pentachlorophenol were accumulated, with bioconcentration factors ranging from 2.51 � 0.51 for dimethylphenol to 283.8 � 5.58 for pentachlorophenol; when placed in clean sea water, both species depurated all accumulated phenols to concentrations below detection within 24 h. Neither phenol nor cresol were accumulated.
Phenol and o-cresol inhibited the germination of Ulva lactuca gametes at concentrations above 1 mg L-1 (100 times the concentrations detected in the water samples).
Muscle and liver tissue from fish and invertebrates collected from the oil refinery discharge site in Botany Bay and control localities contained no detectable phenols.
Rigid and flexible separator panels in trawls that reduce the by-catch of small fish in the Clarence River prawn-trawl fishery, Australia
Authors: Broadhurst MK , Kennelly SJ
Published: November 2005

Two experiments were done in the Clarence River prawn-trawl fishery that compared catches and by-catches from conventional trawls with those from modified trawls containing rigid and flexible separator panels. The modifications included (1) a soft separator panel, the 'blubber-chute' (used commercially by fishers to exclude jellyfish), (2) the standard Nordm�re grid, containing a guiding panel, and (3) a modified Nordm�re grid that had no guiding panel but included a flexible cover of mesh lying semi-attached over the escape exit. In the first experiment, simultaneous paired comparisons among these designs and their controls showed that although all three modified trawls significantly reduced the by-catch of small fish by between 75% and 90%, the standard Nordm�re grid was the only design that did not significantly reduce catches of prawns. In the second experiment, which compared this standard grid with the control during a period of flooding when the by-catch of non-target species was quite high, the standard grid significantly reduced the by-catch of juvenile bream (Acanthopagrus australis) (by 67%) with no significant reduction in catches of prawns. The potential for the Nordm�re grid to alleviate deleterious effects of prawn trawling in estuaries is discussed.
Effect of sewage effluents on germination of three marine brown algal macrophytes
Authors: Burridge TR , Portelli T , Ashton P
Published: November 2005

Inhibition of germination of zygotes of the fucoid macroalgae Hormosira banksii and Phyllospora comosa and zoospores of the laminarian Macrocystis angustifolia was used as an end-point to assess the toxicity of three sewage effluents of differing quality. For each species, between-assay variation was low and results of tests with the reference toxicant 2,4-dichlorophenoxyacetic acid suggested that results are reproducible, especially in R. comosa. Each species showed a greater sensitivity to primary-treated effluent than to secondary-treated effluent, and higher variability in response to the primary effluent. High variation in response for each species when exposed to the primary effluent (compared with that for the secondary effluent) is presumably indicative of variation in quality of the primary effluent. The capacity to reproduce these assays, the sensitivity of species employed, and the ecological relevance of germination as a toxicological end-point suggest that germination tests of this nature may be useful in biological testing of effluent quality at discharge sites in south-eastern Australia.
Grazing by a river zooplankton community: Importance of microzooplankton
Authors: Kobayashi T , Gibbs P , Dixon PI , Shiel RJ
Published: November 2005

Grazing rates by a zooplankton community were measured in situ by a radiotracer cell method at depths of 1 m and 4 m at the upper tidal freshwater portion of a regulated river over a year. The objectives were to evaluate the likely grazing impact on the river phytoplankton community and to produce predictive models by regressing the measured grazing rates against zooplankton biomass, temperature and food concentrations (represented by chlorophyll a). Grazing attained rates (overall average 0.2 day-1, range 0.01-0.59 day-1, expressed as instantaneous mortality rates of algal cells) comparable to those reported for lentic zooplankton communities. The measured community grazing rates were predictable largely as a function of total biomass or rotifer biomass and surface temperature for 1 m depth, and as a function of total biomass or juvenile copepod biomass and surface temperature for 4 m depth, with all-positive regression coefficients in the models. Owing to the predominance of microzooplankton in the river, the impact of zooplankton community grazing appears likely to be linked to a small-size fraction of the phytoplankton community all year. Management strategies for river water quality may need to take account of possible functional demarcation of grazing by river zooplankton.
First record of the Australian longfinned eel, Anguilla reinhardtii, in New Zealand
Authors: Jellyman DJ , Chisnall BL , Dijkstra LH , Boubee JAT
Published: November 2005

Anguilla reinhardtii has been identified by vertebral counts and DNA markers, from a sample of 27 individuals (364-790 mm), within eight consecutive year classes caught by commercial eel fishers in the Waikato River, North Island, New Zealand. There is anecdotal evidence that A. reinhardtii has been present in small numbers in New Zealand for at least 25 years, although its incidence in commercial catches is thought to be increasing. The present known distribution covers approximately 500 km of latitude along the top half of the west coast of the North Island.