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

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

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

Toxicity of arsenic species to three freshwater organisms and biotransformation of inorganic arsenic by freshwater phytoplankton (Chlorella sp. CE-35)

In the environment, arsenic (As) exists in a number of chemical species, and arsenite (AsIII) and arsenate (AsV) dominate in freshwater systems. Toxicity of As species to aquatic organisms is complicated by their interaction with chemicals in water such as phosphate that can influence the bioavailability and uptake of AsV. In the present study, the toxicities of AsIII, AsV and dimethylarsinic acid (DMA) to three freshwater organisms representing three phylogenetic groups: a phytoplankton (Chlorella sp. strain CE-35), a floating macrophyte (Lemna disperma) and a cladoceran grazer (Ceriodaphnia cf. dubia), were determined using acute and growth inhibition bioassays (EC50) at a range of total phosphate (TP) concentrations in OECD medium. The EC50 values of AsIII, AsV and DMA were 27±10, 1.15±0.04 and 19±3mg L-1 for Chlorella sp. CE-35; 0.57±0.16, 2.3±0.2 and 56±15mgL-1 for L. disperma, and 1.58±0.05, 1.72±0.01 and 5.9±0.1mgL-1 for C. cf. dubia, respectively. The results showed that AsIII was more toxic than AsV to L. disperma; however, AsV was more toxic than AsIII to Chlorella sp. CE-35. The toxicities of AsIII and AsV to C. cf. dubia were statistically similar (p>0.05). DMA was less toxic than iAs species to L. disperma and C. cf. dubia, but more toxic than AsIII to Chlorella sp. CE-35. The toxicity of AsV to Chlorella sp. CE-35 and L. disperma decreased with increasing TP concentrations in the growth medium. Phosphate concentrations did not influence the toxicity of AsIII to either organism. Chlorella sp. CE-35 showed the ability to reduce AsV to AsIII, indicating a substantial influence of phytoplankton on As biogeochemistry in freshwater aquatic systems. © 2014 Elsevier Inc

Ecotoxicological Effects of an Arsenic Remediation Method on Three Freshwater Organisms - Lemna disperma, Chlorella sp. CE-35 and Ceriodaphnia cf. dubia

© 2015 Springer International Publishing Switzerland. Chemical methods have been used for the remediation of arsenic (As)-contaminated water; however, ecological consequences of these methods have not been properly addressed. The present study evaluated the effects of the Fe-oxide-coated sand (IOCS) remediation method on As toxicity to freshwater organisms (Lemna disperma, Chlorella sp. CE-35, and Ceriodaphnia cf. dubia). The As removal efficiency by IOCS decreased substantially with time. The IOCS remediation method was less effective at suppressing the toxicity of AsV than AsIII to L. disperma but was highly effective in reducing both the AsIII and AsV toxicity to C. cf. dubia. The growth of Chlorella sp. was significantly higher (p < 0.05) in remediated and pre-remediated water than in controls (non-As-contaminated filtered Colo River water) for AsIII, while the opposite was observed for AsV, indicating that AsV is more toxic than AsIII to this microalga. Although the IOCS can efficiently remove As from contaminated water, residual As and other constituents (e.g. Fe, nitrate) in the remediated water had a significant effect on freshwater organisms

Efficiency Wages, Productivity and Simultaneity: A Meta-Regression Analysis

Efficiency wages, Productivity, Meta-regression analysis, Publication selection, Simultaneity,