Tasmanian Coastal Waters Research Articles

Mismatch of thermal optima between performance measures, life stages and species of spiny lobster

In an ocean warming hotspot off south-east Australia, many species have expanded their ranges polewards, including the eastern rock lobster, Sagmariasus verreauxi. This species is likely extending its range via larval advection into Tasmanian coastal waters, which are occupied by the more commercially important southern rock lobster, Jasus edwardsii. Here, thermal tolerances of these lobster species at two life stages were investigated to assess how they may respond to warming ocean temperatures. We found that the pattern, optimum and magnitude of thermal responses differed between performance measures, life stages and species. Sagmariasus verreauxi had a warmer optimal temperature for aerobic scope and escape speed than J. edwardsii. However, J. edwardsii had a higher magnitude of escape speed, indicating higher capacity for escape performance. There were also differences between life stages within species, with the larval stage having higher variation in optimal temperatures between measures than juveniles. This inconsistency in performance optima and magnitude indicates that single performance measures at single life stages are unlikely to accurately predict whole animal performance in terms of life-time survival and fitness. However, combined results of this study suggest that with continued ocean warming, S. verreauxi is likely to continue to extend its distribution polewards and increase in abundance in Tasmania.

Non-lethal assessment of the reproductive status of broadnose sevengill sharks (Notorynchus cepedianus) to determine the significance of habitat use in coastal areas.

Identification of the importance of habitats that are frequently used by any species is essential to a complete understanding of the species' biology and to incorporate their ecological role into conservation and management programmes. In this context, the present study investigated whether Tasmanian coastal waters have any reproductive relevance for the broadnose sevengill shark (Notorynchus cepedianus). Although this species is a large coast-associated apex predator in these areas, there is a complete gap in understanding the role that these coastal systems could play in its reproduction. Reproductive hormones were used as a non-lethal method to address the reproductive biology of this species. Females seemed to have at least a bi-annual reproductive cycle, being pregnant for ∼1 year and spending at least 1 year non-pregnant, with the ovulatory cycle separated from gestation. Mature females were found to be ovulating, in the initial stages of pregnancy, resting or starting a new vitellogenic cycle. Notorynchus cepedianus did not use these coastal habitats for mating or as a pupping ground. Although the mating season was distinguished between September to April, only 22% of males showed mating scars during the peak of the mating period and no near-term pregnant females were observed. Thus, despite these coastal waters being an important foraging ground for this species, these areas did not have any reproductive relevance. In consequence, future management and conservation planning programmes need to identify whether there are other areas in Tasmania that play a critical role for reproductive purposes in this species. Finally, although previous studies have linked reproductive hormones with external examination of the gonads to validate the use of steroids as a non-lethal tool to address reproduction, the present study used this methodology without killing any animals. This has important implications for conservation programmes of threatened and endangered species worldwide where the methodology cannot be validated.

Influence of river discharge and ocean currents on coastal optical properties

The variability in the optical properties of a coastal region influenced by river runoff and multiple ocean currents in a southern hemisphere setting has been studied. The study area, Tasmanian coastal waters, is influenced by subtropical currents such as the East Australian Current (EAC) and the Zeehan Current (ZC) mix with cooler sub-Antarctic water (SAW). Freshwater discharges from rivers around the island and their mixing with the ocean currents also influence Tasmanian coastal waters. This study was performed to understand the influence of hydrodynamic processes on coastal optical properties and underwater light propagation. Physical, biogeochemical and optical properties were measured in Tasmanian coastal water during the austral autumn of 2007. In this study we found that physical properties have a good correlation with optical properties indicating the role played by hydrodynamic processes in distribution of optically active substances, optical properties of the water mass and underwater light propagation. Analysis of in situ salinity and temperature confirmed the presence of relatively cooler ZC in the South-West region, a cooler mixture of the ZC and SAW in the South-East, warm and saline EAC waters along the East coast and relatively cooler and fresh Bass straight waters along the North coast. In Tasmanian coastal waters light absorption in the water column is controlled by Coloured Dissolved Organic Matter (CDOM) with regionally varying contributions from Non-Algal Particulate (NAP) matter and phytoplankton. Absorption due to CDOM and NAP show a conservative mixing behaviour indicating that these biogeochemical components were delivered by the river and diluted in the coastal water. Suspended particulate matter in Tasmanian coastal water are highly scattering in nature and the beam attenuation is mainly due to light scattering. Variability in probability of light backscattering was mainly due to varying availability of non-algal particulate matter in the surface waters, which is controlled by river discharges in the region. Beam attenuation was high in coastal waters that are influenced by river runoff and increasing beam attenuation had constrained the underwater light propagation in these coastal waters. In the absence of major rivers along the East coast, optical properties were mainly influenced by the EAC water mass. Optical properties of the East coast were clearly different from the rest of the Tasmanian regions. In other regions the influence of ocean currents is subtle due to strong mixing between river discharges and ocean water mass. Overall, analysis of bio-optical properties shows that optical properties are constrained by regional hydrodynamic processes. Results presented highlight importance of using hydrodynamic process specific bio-optical properties and parameterisation in modelling light propagation in coastal ecosystems that are influenced by multiple ocean currents and river discharges.

Geolocation Tracking of the Annual Migration of Adult Australasian Gannets (Morus serrator) Breeding in New Zealand

The long breeding period and high reproductive investment of seabirds make use of resource-rich foraging areas pivotal both during and between breeding seasons. We tracked adult Australasian Gannets (Morus serrator) from their New Zealand breeding colony at Cape Kidnappers to Australia during the non-breeding period to assess wintering behavior and migratory routes for this species. Data from three recovered geolocation sensor (GLS) tags showed that both a male and a female M. serrator, and a hybrid M. capensis × M. serrator migrated across the Tasman Sea to winter in Australian and Tasmanian coastal waters. Tracked birds covered distances of up to 13,000 km on their migration. These movements were consistent with historical records of band recoveries.

NOVEL UNARMORED DINOFLAGELLATES FROM THE TOXIGENIC FAMILY KARENIACEAE (GYMNODINIALES): FIVE NEW SPECIES OF KARLODINIUM AND ONE NEW TAKAYAMA FROM THE AUSTRALIAN SECTOR OF THE SOUTHERN OCEAN(1).

Six new species of unarmored dinoflagellates in the family Kareniaceae were isolated from the Australian sector of the Southern Ocean in March 2006: Takayama tuberculata de Salas sp. nov, Karlodinium antarcticum de Salas sp. nov., Karl. ballantinum de Salas sp. nov., Karl. conicum de Salas sp. nov., Karl. corrugatum de Salas sp. nov., and Karl. decipiens de Salas et Laza-Martínez sp. nov. These new taxa were characterized using light and electron microscopy and sequencing of the LSU rDNA and are well supported based either on their morphology or molecular phylogeny. Takayama tuberculata, isolated just north of the polar front (55°-57° S), is genetically close to T. tasmanica, but smaller, with a significantly reduced number of amphiesmal vesicles. Medium-sized Karl. antarcticum, also isolated from near the polar front, is characterized by its long ovoid cell outline and very long apical groove. The small Karl. ballantinum has a very short apical groove. The large Karl. conicum has a distinct conical epicone and spherical posterior nucleus. The small Karl. corrugatum, from just south of the polar front, has distinctive parallel striations on the epicone surface and a distinctively shaped and placed ventral pore. The large and widespread Karl. decipiens, distributed through Southern Ocean waters from the polar front to Tasmanian coastal waters, and coastal Spain, has a helicoidal chloroplast arrangement and a large central nucleus. This study represents the first description of species in the potentially ichthyotoxic family Kareniaceae recorded from the Southern Ocean.

Karenia umbella sp. nov. (Gymnodiniales, Dinophyceae), a new potentially ichthyotoxic dinoflagellate species from Tasmania, Australia

A new, potentially ichthyotoxic gymnodinioid dinoflagellate, Karenia umbella de Salas, Bolch & Hallegraeff, is described from Tasmanian coastal waters, Australia. It is characterized by light and electron microscopy of field samples and laboratory cultures, as well as large-subunit ribosomal DNA sequences and high-performance liquid chromatography pigment analyses of two cultured strains. The new Karenia species has a straight apical groove and contains fucoxanthin derivative carotenoid pigments, typical of the genus. Karenia umbella differs from its closest relative K. longicanalis in its larger size, longer epicone with a finger-like sulcal intrusion, asymmetrically shaped hypocone, irregularly shaped chloroplasts, and presence of six or eight radial furrows on the epicone surface. It differs from K. digitata in its significantly larger size and the shape of the epicone and hypocone. Genetically, this species is distinct from the dorsoventrally flattened Karenia species K. mikimotoi, K. brevis, and K. brevisulcata.

Scale-bearing nanoflagellates from southern Tasmanian coastal waters, Australia. I. Species of the genus Chrysochromulina (Haptophyta)

A comprehensive taxonomic survey of Chrysochromulina was undertaken in 52 samples from southern Tasmanian coastal waters. Scale morphology of both field samples and enrichment cultures was examined using transmission electron microscopy. Twenty-eight known species of Chrysochromulina were recorded. These included C. adriatica, C. alifera, C. apheles, C. brevifilum, C. chiton, C. cyathophora, C. ephippium, C. ericina, C. hirta, C. leadbeateri, C. mantoniae, C. minor, C. novae-zelandiae, C. pachycylindra, C. parkeae, C. polylepis, C. pringsheimii, C. pyramidosa, C. simplex, C. spinifera, and Chrysochromulina sp. (eyelash). There were seven new records for Australian waters: C. acantha, C. aff. brachycylindra, C. aff. camella, C. fragaria, C. mactra, C. scutellum and C. aff vexillifera. All species, except C. novae-zelandiae, had been previously reported from the northern hemisphere. A further nine undescribed species are documented. However, lack of complete cells prevented new species descriptions. Two known toxic species, Chysochromulina polylepis and C. leadbeateri, responsible for massive fish kills in Scandinavia, were found in this survey. Toxicity testing of six Chrysochromulina species isolated from Tasmanian waters (C. acantha, C. apheles, C. hirta, C. scutellum, C. simplex, Chrysochromulina sp. [eyelash]) was undertaken, using larval brine shrimp (Artemia) bioassays. None of the strains tested was found to be toxic.

Estimation of bacterioplankton activity in Tasmanian coastal waters and between Tasmania and Antarctica using stains

AME Aquatic Microbial Ecology Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials AME 37:33-45 (2004) - doi:10.3354/ame037033 Estimation of bacterioplankton activity in Tasmanian coastal waters and between Tasmania and Antarctica using stains A. T. Davidson*, P. G. Thomson, K. Westwood, R. van den Enden Australian Antarctic Division, Department of the Environment and Heritage, and Antarctic Climate and EcosystemsCooperative Research Centre, Channel Highway, Kingston, Tasmania 7050, Australia *Email: andrew.davidson@aad.gov.au ABSTRACT: Various stains have recently become available that detect bacteria with compromised cell membranes and high esterase or respiratory activity. However, the validity of these stains for determining concentrations of live, dead and active marine bacteria is the subject of debate. We used BacLightTM (Molecular Probes) to stain bacteria with intact membranes green, due to the fluorescence of SYTO®9, while ‘leaky’ bacteria that were permeable to propidium iodide (PI) stained red. Bacteria with high metabolic activity were stained using 6-carboxy fluorescein diacetate (6CFDA) or 5-cyano-2,3-ditolyl tetrazolium chloride (CTC). Total bacteria concentration was determined using 4’,6 diamidino-2-phenylindole (DAPI) and BacLightTM (SYTO®9 + PI-stained bacteria). Comparison of stains in Tasmanian coastal waters showed that total concentrations of bacteria obtained using DAPI were not significantly different from those using BacLightTM at the concentrations used in our field study. Lower concentrations of BacLightTM reduced the concentration of PI-stained bacteria but not that of those stained by SYTO®9. Concentrations of metabolically active bacteria obtained using CTC and 6CFDA were equivalent to those of viable, culturable bacteria obtained using most probable number. Bacterioplankton activity in the Southern Ocean between Tasmania and East Antarctica during austral winter 1999 and summer 2001 was investigated using these stains. SYTO®9-stained cells commonly comprised <30% of total bacteria, while the remainder stained with PI. CTC- or 6CFDA-stained bacteria comprised around half of the SYTO®9-stained bacterial concentration. Significant positive correlation was observed between concentrations of total bacteria, seawater temperature (mainly due to the correlation between temperature and concentrations of PI-stained bacteria) and in situ chlorophyll fluorescence (mainly due to the correlation between in situ chlorophyll fluorescence and concentrations of highly active bacteria). Thus, bacterioplankton in the Southern Ocean are not a homogeneous community of active cells. As bacterial metabolism determines the extent to which bacteria are involved in respiration, remineralisation and the microbial loop, our findings are of major significance for understanding pelagic carbon flow and nutrient cycling in the Southern Ocean. KEY WORDS: Antarctic · Marine · Bacteria · Activity Full article in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in AME Vol. 37, No. 1. Online publication date: November 02, 2004 Print ISSN: 0948-3055; Online ISSN: 1616-1564 Copyright © 2004 Inter-Research.

Age, growth and back-calculated birthdate distributions of larval jack mackerel, Trachurus declivis (Pisces: Carangidae), from eastern Tasmanian coastal waters

Otolith microstructure of the larvae of jack mackerel, Trachurus declivis, was examined to derive estimates of age, growth and back-calculated birthdate distributions. Larvae were collected from shelf waters of the eastern coast of Tasmania between January and March, 1989 to 1991. Daily increment formation was confirmed by successive sampling of a cohort of individuals, correlating the change in the number of increments with the sampling interval. Otoliths examined under the scanning electron microscope confirmed the otolith structure and increment counts obtained with the light microscope. Initial increments were shown to form at the time of first feeding. Estimated ages of larvae ranged from 2 to 25 days after first feeding, and larvae showed exponential growth in all three years. Interannual variations in larval growth were evident, with growth being significantly slower in 1991 (4.6% of standard length per day) than in 1989 (5.2% SL day-1) and 1990 (5.4% SL day-1). The faster growth in 1989 and 1990 may be attributable to warmer-than-normal water temperatures over the study area in these years associated with a major La Nina event. Back-calculated birthdate distributions showed that spawning occurred during summer (mid December to mid February) in all three years, with indications of semilunar spawning activity in which peaks were apparently associated with both full and new moons.

Fouling, surface bacteria and antibacterial agents of four bryozoan species found in Tasmania, Australia

Extracts from four species of bryozoans, found in Tasmanian coastal waters, have been demonstrated to exhibit selective antibacterial activity. The four species showed gradations in fouling by encrusting organisms and differential surface bacterial numbers. The two chemically defended species Amathia wilsoni and Orthoscuticella ventricosa had the most active antibacterial extracts and the lowest levels of fouling. In contrast, extracts of Cellaria pilosa and Bugularia dissimilis, which have no known secondary metabolites, had weak antibacterial properties, and colonies showed large numbers of encrusting fouling organisms. Counts of bacteria over the surfaces of the four species revealed that O. ventricosa had the lowest numbers; B. dissimilis and C. pilosa had higher numbers while A. wilsoni had the highest counts, but the most patchy distribution.

Diet of Nyctiphanes australis Sars (Crustacea: Euphansiacea)

The stomach contents of the euphausiid Nyctiphanes australis were analysed qualitatively on a monthly basis throughout a full year and for each stage of the life cycle. Dietary items occurring in decreasing order of frequency in stomachs were: inorganic matter including sponge spicules; diatoms; dino- flagellates; silicoflagellates; foraminiferans; and crustacean exuviae. Little change in the composition of the main dietary components between life stages was apparent. Minor seasonal changes in stomach contents occurred (i.e. greater prevalence of diatom resting spores and coccoliths during warmer months and greater prevalence of black particulate matter, thought to be zooplankton faecal pellets, in summer). Fluorescence of the full stomachs of adult N. australis was found to be linearly related to carapace length. Filtering rates calculated from this relationship and average levels of chlorophyll a present in south-eastern Tasmanian coastal waters suggest that N. australis could only satisfy about 25% of its carbon requirement from phytoplankton alone. Hence, it is concluded that this euphausiid needs to include detrital and animal matter in its diet.

A survey of Vibrionaceae in Tasmanian coastal waters, with special reference to bacterial species pathogenic to fish or shellfish

Samples of the water column and sediment were examined seasonally at nine sites along the east coast of Tasmania. The mean number (loglo units) of presumptive Vibrionaceae, determined on selective agar media, was 1.81 ml-1 water column and 3.95 g-1 sediment. The mean seasonal count varied slightly between sites in the water column but showed a summer peak in the sediment. Factors including sediment particle size, geographical features, or presence of animal husbandry at the site, did not strongly influence the presumptive Vibrionaceae count. Vibrionaceae formed 4.5% and 15.5% of the total heterotrophic bacterial count in the water column and sediment, respectively, but the proportion varied greatly between sites and seasons. Four hundred and fifty-two isolates were identified partially to group level according to a revised scheme based on that of West and Colwell (1984). The two groups including group 8, V. ordalii, and group 9, V. tubiashii, V. anguillarum and V. damsela, contained 30.1% and 46.7% of the isolates, respectively. The overall environmental incidence of these pathogens of fish or shellfish amongst the Vibrionaceae was V. ordalii 0.4%, V. tubiashii 1.3%, V. anguillarum 1.1 % and V. damsela 0.7%.

Sand flathead ( Platycephalus bassensis), an indicator species for mercury pollution in Tasmanian waters

A statewide survey of Tasmanian coastal waters has shown that Platycephalus bassensis, a widespread, easily-caught, non-migratory demersal finfish, is a useful indicator species for mercury pollution. Using approximately twelve fish at each of 31 locations, the mean total mercury concentration in the muscle tissue ranged from 0.03 to 1.06 mg/kg (fresh wt basis), and clearly demonstrated a site dependence for mercury uptake in this species. The correlation between mercury concentration and fish size is shown to be valid only if the effect of location is taken into account. Even then, size accounts for only about 10% of the total variability in mercury concentration.