A mass spectrometric study of some trifluorophosphine-substituted transition metal carbonyls

Call number: LD2668 .T4 1968 K738Master of Scienc

Effects of chlorpyrifos on macroinvertebrate communities in coastal stream mesocosms

This study measured the effects of a single pulse of chlorpyrifos at nominal concentrations of 1 and 10 μg/l on the macroinvertebrate community structure of a coastal stream mesocosm system. Analysis of data using Principal Response Curves (PRC) and Monte Carlo tests showed significant changes in the treated stream mesocosms relative to that of the controls. These changes in the macroinvertebrate assemblages occurred within 6 h, and persisted for at least 124 days after dosing. Significant community-level effects were detected at the lowest concentration on days 2 and 16 post-dosing, giving a no-observed effect concentration (NOECcommunity) of 1.2 μg/l (measured). The mayflies Atalophlebia sp. and Koorrnonga sp., Chironomidae and Acarina were all sensitive to chlorpyrifos and decreased in abundance in treated mesocosms after dosing. The fauna of these coastal stream mesocosms showed similar sensitivity to chlorpyrifos with that of other reported studies, but there was no evidence of recovery after 124 days. © 2007 Springer Science+Business Media, LLC

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Population ecology of the Sydney rock oyster saccostrea commercialis and the pacific oyster crassostrea gigas in a New South Wales estuary

University of Technology Sydney. Faculty of Science.The Sydney rock oyster Saccostrea commercialis is a dominant sessile organism of intertidal rocky shore and mangrove communities of Port Stephens, New South Wales. This study describes patterns of distribution and abundance of S. commercialis in these habitats, as well as those of the recently introduced Pacific oyster Crassostrea gigas. Observations drawn from these mensurative studies were used to formulate and test hypotheses concerning the importance of some ecological processes in structuring intertidal oyster communities. A preliminary survey in the spring of 1990 revealed for the first time the presence of C. gigas among S. commercialis rocky shore and mangrove communities in the inner port of Port Stephens. However, few C. gigas were present in the definitive surveys performed 1-2 years later, demonstrating a failure of the 1990 recruits to survive. For the purposes of characterising the intertidal oyster communities, rocky shore and mangrove communities were divided into low, mid and upper intertidal zones. In both communities, the density of S. commercialis increased with intertidal height to above the mid tide level, although a comparison of sites within Port Stephens demonstrated that oyster densities were significantly different within each intertidal zone. The maximum density in the low and mid zone rocky shore plots was approximately 600m-2. The size class structure of both communities was unimodal, with juvenile oysters poorly represented. This low density of juvenile oysters was despite an apparently abundant supply of S. commercialis larvae. Oysters were found to occur in abundance on mangrove pneumatophores, with the degree of aggregation and size of oyster clumps decreasing with intertidal height. Space was not limited, as most pneumatophores were unoccupied by oysters. Recruitment onto experimental patches on a rocky shore and mangrove pneumatophore community was assessed over 1 year, and were examined biweekly during peak settlement times. Three to four episodes of recruitment were observed, with the first two suffering complete mortality over the summer period (December through March). Successful recruitment of S. Commercialis occurred in autumn, although initial mortalities were high across all intertidal zones. The density of recruits decreased with increasing intertidal height in both communities. The presence of adult conspecifics or shells of conspecifics significantly enhanced the density of S. commercialis recruits onto model pneumatophores, but this was not always apparent on rocky shore plots. However, densities of recruits did not differ between treatments over time. The upper limit of intertidal distribution in mangroves and on the rocky shore sites was similar. Recruitment of C. gigas was observed in July, but were few in number. Thermal tolerances of larvae, 1 month-post settlement spat and adults of both S. commercialis and C. gigas were determined to assess the role of thermal stress in structuring oyster communities. The thermal tolerances of the larvae of the two species were similar. Oysters were more resistant to elevated temperatures with age, although C. gigas was less tolerant than S. commercialis over short exposures of elevated temperatures. The body temperatures of insolated model oysters were observed in some instances to exceed the thermal tolerances of spat, but not adults. Shading by mangroves reduced oyster body temperatures by up to 13.5 degrees C, to below that where mortality may be expected in spat. The lower relative thermal tolerance of spat may explain the failure of recruits to survive the summer, and the low density of oysters in the upper intertidal zone. The effect of intra and inter-specific density on survival, size, and shape was tested at low, mid, and upper intertidal zones at 3 sites within Port Stephens. In the upper intertidal zone, high mortalities and reduced growth rates prevented any competitive interactions with both species. However in the low and mid intertidal zones, the presence of both high and low densities of C. gigas induced significant mortalities, reductions in size, and changes in shape in S. commercialis. This experiment demonstrated the potential competitive pressure faced by S. commerciaUs if density of C. gigas recruitment was to increase

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INST: L_08

Effects of tidal elevation and substrate type on settlement and postsettlement mortality of the Sydney rock oyster, Saccostrea glomerata, in a mangrove forest and on a rocky shore

Patterns of settlement and postsettlement mortality determine the distribution and abundance of sessile marine organisms. In mangrove forests and on rocky shores of eastern Australia, the Sydney rock oyster, Saccostrea glomerata, displays a pattern of declining abundance with increasing tidal elevation that might be related to or independent of the tidal elevation gradient in the substrate (bare, dead conspecifics, live conspecifics) available for attachment. We conducted parallel manipulative experiments on a rocky shore and in a mangrove forest to assess (1) the relative importance of tidal elevation and substrate type (bare, live oysters, or dead oysters) in determining the spatial distribution of new (<1 mm) S. glomerata recruits and (2) the contribution of settlement and postsettlement processes in setting patterns of spatial variation in established oyster populations. Patches of habitat with either live oysters, dead oysters, or no conspecifics were established at 3 tidal elevations at each site, and natural settlement and postsettlement mortality were monitored through time. At each site, and regardless of the substrate provided, we detected a similar pattern of fewer new S. glomerata recruits and greater postsettlement mortality on the high intertidal shore rather than the mid or low intertidal shore. Substrate type, by contrast, influenced the abundance of new recruits, but not subsequent postsettlement mortality. Consequently, over a period of months, direct effects of tidal elevation rather than effects of substrate type determined spatial patterns of oyster recruitment on the rocky shore and in the mangrove. Consequently, we documented that on a rocky shore and in a mangrove forest, settlement and early postsettlement mortality vary similarly across tidal elevation gradients and substrate types to determine the distribution of S. glomerata.8 page(s

Comparison of the fate and toxicity of chlorpyrifos-Laboratory versus a coastal mesocosm system

The widespread use of chlorpyrifos for pest control in urban and rural environments poses a risk of contamination to aquatic environments via runoff, spray drift or spillage. The aim of this study was to assess the fate of chlorpyrifos and its toxicity to common freshwater invertebrates in the laboratory and in stream mesocosms. Chlorpyrifos was rapidly lost from the test systems but the rates of loss varied considerably, such that losses in the mesocosms could not be reliably predicted from the static laboratory studies. This was likely due to the mass transport of chlorpyrifos from the mesocosm via stream flow. Chlorpyrifos was acutely toxic to all invertebrates tested with the cladoceran species (laboratory 48 h LC50 values 0.07-0.10 μg L-1) being most sensitive. Despite the differences in the dynamics of chlorpyrifos in the laboratory and mesocosm systems, the sensitivities of the mayfly Atalophlebia australis and the cladoceran Simocephalus vetulus were similar in the 2 systems. © 2007 Elsevier Inc. All rights reserved

Comparative sensitivity of the cnidarian Exaiptasia pallida and a standard toxicity test suite: testing whole effluents intended for ocean disposal

The sea anemone Exaiptasia pallida (formally Aiptasia pulchella) has been identified as a valuable test species for tropical marine ecotoxicology. Here, the sensitivities of newly developed endpoints for E. pallida to two unidentified whole effluents were compared to a standard suite of temperate toxicity test species and endpoints that are commonly used in toxicological risk assessments for tropical marine environments. For whole effluent 1 (WE1), a 96-h lethal concentration 50 % (LC50) of 40 (95 % confidence intervals, 30–54) % v/v and a 12-day LC50 of 12 (9–15) % v/v were estimated for E. pallida, exhibiting a significantly higher sensitivity than standard sub-lethal endpoints in Allorchestes compressa (96-h effective concentration 50 % (EC50) of \u3e100 % v/v for immobilisation) and Hormosira banksii (72-h EC50 of \u3e100 % v/v for germination), and a similar sensitivity to Mytilus edulis galloprovincialis larval development with a 48-h LC50 of 29 (28–30) %v/v. Sub-lethal effects of whole effluent 2 (WE2) on E. pallida pedal lacerate development resulted in an 8-day EC50 of 7 (3–11) % v/v, demonstrating comparable sensitivity of this endpoint to standardised sub-lethal endpoints in H. banksii (72-h EC50 of 11 (10–11) % v/v for germination), M. edulis galloprovincialis (48-h EC50 for larval development of 12 (9–14) % v/v) and Heliocidaris tuberculata (1-h EC50 of 13 (12–14) % v/v for fertilisation; 72-h EC50 of 26 (25–27) % v/v for larval development) and a significantly higher sensitivity than A. compressa immobilisation (96-h EC50 of \u3e100 % v/v). The sensitivity of E. pallida compared to a standard test species suite highlights the value in standardising the newly developed toxicity test methods for inclusion in routine toxicological risk assessment of complex whole effluents. Importantly, this species provides an additional taxonomic group to the test species that are currently available for tropical marine ecotoxicology and, being a cnidarian, may represent important tropical marine environments including coral reefs