Port Stephens Fisheries Institute

Taylors Beach, Australia

Port Stephens Fisheries Institute

Taylors Beach, Australia
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Gribben P.E.,University of Technology, Sydney | Byers J.E.,University of Wollongong | Byers J.E.,University of Georgia | Wright J.T.,University of Tasmania | Glasby T.M.,Port Stephens Fisheries Institute
Oikos | Year: 2013

Habitat-forming invasive species have complex impacts on native communities. Positive above ground and negative below ground impacts are reported, suggesting that habitat-forming invasive species may affect community components differently. Furthermore, such effects may vary depending on the density of the invader. We determined the responses of community components to different densities of the invasive green alga Caulerpa taxifolia in southeastern Australia. Initially we investigated differences in soft-sediment faunal communities (above and below ground) across a biomass gradient at two invaded sites. Caulerpa taxifolia biomass was positively associated with the composition and abundance of the epifaunal community, but negatively correlated with the abundance of infauna. To examine the response of common community members in more detail, we caged two species of mollusk (the infaunal bivalve, Anadara trapezia and the epifaunal gastropod, Batillaria australis) across the same biomass gradient to determine lethal and sublethal effects of C. taxifolia biomass on individuals. Survivorship of A. trapezia was low when C. taxifolia was above 300 g m-2. Negative sublethal effects were also density-dependent with A. trapezia tissue weight being lowest above this same C. taxifolia biomass. The proportion of B. australis surviving was unaffected by C. taxifolia biomass. However, the total number of live B. australis recovered in cages increased as C. taxifolia biomass increased, providing further evidence of positive density dependent effects (in line with the survey data) of C. taxifolia on epifauna. Finally, we removed C. taxifolia from plots of differing C. taxifolia biomass and followed community change for 5 months. Community change following C. taxifolia removal was also density dependent as recovery 5 months post-removal depended on the initial biomass of C. taxifolia, suggesting a lag in the recovery of communities due to residual environmental effects post-removal (i.e. hysteresis). We have shown that the effects of a habitat-forming invasive species are biomass dependent and also affect community components differently, suggesting that, globally, the impact of these types of invaders may be context dependent. © 2012 The Authors. Oikos © 2012 Nordic Society Oikos.

Boys C.A.,Port Stephens Fisheries Institute | Williams R.J.,Australian Department of Primary Industries and Fisheries
Ecological Engineering | Year: 2012

Fish and decapod crustacean assemblages were sampled from two manipulated creeks in which tidal flow had been increased through culvert removal. Assemblages were compared to those of two control creeks where culverts remained and two reference creeks without culverts. The presence of culverts reduced the richness and abundance of estuarine-marine dwelling species. Successional changes over a 16 year period (2 years prior to culvert removal and 14 years after) showed an immediate response at one manipulated creek but many years to attain reference condition. The other manipulated creek showed a completely different trajectory: oscillation between control and reference status with no clear intermediary condition. We concur with other investigators that short-term studies may give only a partial indication of response to rehabilitation efforts in coastal wetlands and longer-term studies (5-10 years) are recommended. There is some evidence that over longer-time frames, the presence of distinct groups of fish and/or decapods may indicate stages in the maturation of a rehabilitated wetland. © 2012 Elsevier B.V.

Epizootic ulcerative syndrome (EUS) is a fish disease of international significance and reportable to the Office International des Epizootics. In June 2010, bony herring Nematalosa erebi, golden perch Macquaria ambigua, Murray cod Maccullochella peelii and spangled perch Leiopotherapon unicolor with severe ulcers were sampled from the Murray-Darling River System (MDRS) between Bourke and Brewarrina, New South Wales Australia. Histopathology and polymerase chain reaction identified the fungus-like oomycete Aphanomyces invadans, the causative agent of EUS. Apart from one previous record in N. erebi, EUS has been recorded in the wild only from coastal drainages in Australia. This study is the first published account of A. invadans in the wild fish populations of the MDRS, and is the first confirmed record of EUS in M. ambigua, M. peelii and L. unicolor. Ulcerated carp Cyprinus carpio collected at the time of the same epizootic were not found to be infected by EUS, supporting previous accounts of resistance against the disease by this species. The lack of previous clinical evidence, the large number of new hosts (n = 3), the geographic extent (200 km) of this epizootic, the severity of ulceration and apparent high pathogenicity suggest a relatively recent invasion by A. invadans. The epizootic and associated environmental factors are documented and discussed within the context of possible vectors for its entry into the MDRS and recommendations regarding continued surveillance, research and biosecurity are made.

Parker L.M.,University of Western Sydney | Ross P.M.,University of Western Sydney | O'Connor W.A.,Port Stephens Fisheries Institute
Marine Biology | Year: 2010

This study compared the synergistic effects of elevated pCO2 and temperature on the early life history stages of two ecologically and economically important oysters: the Sydney rock oyster, Saccostrea glomerata and the Pacific oyster, Crassostrea gigas. Gametes, embryos, larvae and spat were exposed to four pCO2 (375, 600, 750, 1,000 μatm) and four temperature (18, 22, 26, 30°C) levels. At elevated pCO2 and suboptimal temperatures, there was a reduction in the fertilization success of gametes, a reduction in the development of embryos and size of larvae and spat and an increase in abnormal morphology of larvae. These effects varied between species and fertilization treatments with S. glomerata having greater sensitivity than C. gigas. In the absence of adaptation, C. gigas may become the more dominant species along the south-eastern coast of Australia, recruiting into estuaries currently dominated by the native S. glomerata. © 2010 Springer-Verlag.

Dafforn K.A.,University of New South Wales | Glasby T.M.,Port Stephens Fisheries Institute | Johnston E.L.,University of New South Wales
PLoS ONE | Year: 2012

Natural systems are increasingly being modified by the addition of artificial habitats which may facilitate invasion. Where invaders are able to disperse from artificial habitats, their impact may spread to surrounding natural communities and therefore it is important to investigate potential factors that reduce or enhance invasibility. We surveyed the distribution of non-indigenous and native invertebrates and algae between artificial habitats and natural reefs in a marine subtidal system. We also deployed sandstone plates as experimental 'reefs' and manipulated the orientation, starting assemblage and degree of shading. Invertebrates (non-indigenous and native) appeared to be responding to similar environmental factors (e.g. orientation) and occupied most space on artificial structures and to a lesser extent reef walls. Non-indigenous invertebrates are less successful than native invertebrates on horizontal reefs despite functional similarities. Manipulative experiments revealed that even when non-indigenous invertebrates invade vertical "reefs", they are unlikely to gain a foothold and never exceed covers of native invertebrates (regardless of space availability). Community ecology suggests that invertebrates will dominate reef walls and algae horizontal reefs due to functional differences, however our surveys revealed that native algae dominate both vertical and horizontal reefs in shallow estuarine systems. Few non-indigenous algae were sampled in the study, however where invasive algal species are present in a system, they may present a threat to reef communities. Our findings suggest that non-indigenous species are less successful at occupying space on reef compared to artificial structures, and manipulations of biotic and abiotic conditions (primarily orientation and to a lesser extent biotic resistance) on experimental "reefs" explained a large portion of this variation, however they could not fully explain the magnitude of differences. © 2012 Dafforn et al.

Otway N.M.,Port Stephens Fisheries Institute
Veterinary Clinical Pathology | Year: 2015

Background: Sharks are top-order predators in ocean food chains and the star attractions in aquaria worldwide. Unfortunately, blood biochemistry reference intervals (RI) have been determined for few species. Objective: The study aims to establish serum biochemical RI for free-living Sand Tiger sharks (Carcharias taurus) off eastern Australia. Methods: Thirty-seven sharks were captured and their sex, length, weight, reproductive maturity, and health status were recorded. After blood collection, serum analytes were quantified using standard analytical and statistical methods. Reference intervals, means, medians, and 90% confidence intervals were generated. Physiologic data from live and necropsied sharks were used to enhance the study results. Results: Thirty healthy sharks were included in the study. Albumin could not be detected. With the exception of ALP activity, values were unaffected by sex, length, weight, age, and life-history stage. The means (RI) were: sodium 258 (249-267) mmol/L, potassium 5.0 (4.3-5.7) mmol/L, chloride 242 (227-257) mmol/L, inorganic phosphate 1.8 (1.7-2.0) mmol/L, total calcium 3.9 (3.3-4.4) mmol/L, magnesium 1.9 (1.6-2.2) mmol/L, glucose 2.7 (2.2-3.2) mmol/L, urea 377 (360-394) mmol/L, ALP 20 (8-31) U/L, ALT 3 U/L (no RI), AST 29 (13-45) U/L, CK 42 (5-79) U/L, total protein 30 (24-36) g/L, triglyceride 0.3 (0.1-0.6) mmol/L, cholesterol 1.4 (0.9-2.1) mmol/L, creatinine 32 μmol/L (no RI), total bilirubin 1.5 μmol/L (no RI), and osmolarity 1082 (1027-1136) mmol/L. Conclusions: These preliminary RI will assist with the clinical evaluation and treatment of captive and free-living Sand Tiger sharks worldwide. Studies with more animals will increase the precision of upper and lower reference limits. © 2015 American Society for Veterinary Clinical Pathology.

Parker L.M.,University of Western Sydney | Ross P.M.,University of Western Sydney | O'Connor W.A.,Port Stephens Fisheries Institute
Marine Biology | Year: 2011

Acidifying oceans are predicted to fundamentally alter marine ecosystems. Over the next century, acute studies suggest that the impacts of climate change on marine organisms and ecosystems may be catastrophic. To date, however, little is known about whether the response of marine organisms varies within a species and whether this provides a potential "adaptive capacity". Here, we show that selectively bred lines of the ecologically and economically important estuarine mollusc, the Sydney rock oyster Saccostrea glomerata, are more resilient to ocean acidification than the wild populations. When reared at elevated pCO2, we found a 25% reduction in shell growth of the selectively bred population of the Sydney rock oyster, Saccostrea glomerata, compared to a 64% reduction in shell growth of wild populations. This study shows that there are significantly different sensitivities to ocean acidification even within the same species, providing preliminary evidence that selective breeding may be a solution for important aquaculture industries to overcome the future effects of ocean acidification. © 2010 Springer-Verlag.

Otway N.M.,Port Stephens Fisheries Institute | Ellis M.T.,Port Stephens Fisheries Institute
Marine and Freshwater Research | Year: 2011

Knowledge of migratory movements and depth/temperature-related use of coastal waters by sharks can lead to more sustainable fisheries and assist in managing the long-term conservation of those species now considered threatened. Pop-up archival satellite tags (PATs) provide an alternative to conventional tagging for documenting migratory movements. This study focussed on the migratory movements of Carcharias taurus, a critically endangered shark found along the east coast of Australia. From October 2003 to July 2008, 15 C. taurus individuals were tagged with PATs with varying deployments (60-150 days) and acoustic tags linked to an acoustic monitoring system providing accurate geo-location. Distances moved by C. taurus individuals ranged from 5 to 1550km and varied according to sex and season. Migrations north and south were punctuated en route by occupation of sites for varying periods of time. The deepest depth recorded was 232m off South West Rocks on the New South Wales mid-north coast. On average, C. taurus males and females spent at least 71% of their time in waters <40m and 95% of their time in waters 17-24°C. By mainly occupying inshore waters, C. taurus is exposed to potentially adverse fishing-related interactions that may be difficult to mitigate. © CSIRO 2011.

Dove M.C.,Port Stephens Fisheries Institute | O'Connor W.A.,Port Stephens Fisheries Institute
Aquaculture | Year: 2012

Since 1990, Industry and Investment New South Wales' (NSW) Sydney rock oyster (SRO) breeding programme has successfully used selective breeding to improve oyster growth rates. But, some oyster growers have observed that selected oysters condition at a different rate and to a different extent compared to naturally caught oysters grown under similar conditions. The condition index, sex, gametogenic stage and gonad area of fifth generation SROs selectively bred for fast growth were investigated by collecting monthly samples at a northern, mid and southern site in NSW between June 2005 and July 2006. Non-selected oysters farmed under the same conditions were also sampled at the same time. Overall, selected and non-selected oysters developed and spawned at each site synchronously, however, selectively bred oysters, in most instances, had a lower condition index, different meat conditioning cycle and reduced gonad area than their non-selected counterparts. Although selective breeding for fast growth hasn't changed reproductive timing, the variation in meat condition is consistent with oyster grower's observations and has encouraged further research to better understand the environmental responses of selected oysters and improve reproductive condition in SRO through breeding. © 2011.

Glasby T.M.,Port Stephens Fisheries Institute
Biological Invasions | Year: 2013

Seagrass habitats are being lost throughout the world and the invasive alga C. taxifolia has often been implicated in seagrass declines. Although C. taxifolia can impact a variety of species, evidence for its effects on seagrasses is largely correlative. This study combined observational studies and manipulative experiments done over many years to test hypotheses about effects of C. taxifolia on two Australian seagrasses, namely Posidonia australis and Zosteracapricorni. Results indicated that C. taxifolia is not having adverse impacts on the coverage of these seagrasses in the sites studied. Rather, C. taxifolia appears to be an opportunist, persisting longer and its coverage being greater in previously non-vegetated sediments than amongst seagrasses. C. taxifolia co-existed with P. australis and did not cause reductions in the cover of the seagrass. Outcomes of experimental manipulations of C. taxifolia amongst Z. capriconi were less clear due to losses of Z. capriconi in all plots, regardless of the presence of C. taxifolia. It was possible that C. taxifolia may have enhanced the decline in canopy cover of Z. capricorni, but the presence of alga did not alter the final fate of Z. capricorni. There was also no evidence that long-term areal coverage of P. australis or Z. capriconi has been affected by the introduction of C. taxifolia in the embayments studied. A review of literature on effects of species of Caulerpa on seagrasses provided limited experimental evidence for negative impacts of this genus on seagrass abundance. © 2012 Springer Science+Business Media Dordrecht.

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