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Lorraine Maltby

Publications and source records attributed to Lorraine Maltby.

7 recordsLinked to original sources
PubMed2006

Relative toxicological importance of aqueous and dietary metal exposure to a freshwater crustacean: implications for risk assessment.

Aquatic organisms can take up toxicants from water (aqueous exposure) and from food (dietary exposure), yet current environmental regulations often fail to consider the toxic effects of dietary exposure. Such unrealistic exposure scenarios may lead to ineffective water-quality standards or discharge consents that fail to provide adequate protection of the receiving water. Both dietary and aqueous exposure routes contributed to the bioaccumulation of zinc by Gammarus pulex, and both influenced the lethal and sublethal effects of zinc exposure. However, little concordance was found between body burden and magnitude of effect on feeding rate, and the duration of the postexposure response differed between exposure routes. Feeding inhibition, resulting from water-only or simultaneous aqueous and dietary exposure, persisted after the contaminant was removed, but feeding inhibition resulting from dietary exposure alone did not. These results imply that whereas aqueous exposure resulted in either irreversible or slowly reversible physiological damage, feeding inhibition in response to dietary zinc exposure involved an avoidance response. Water-only exposure studies underestimated the effects of simultaneous exposure to contaminated food and contaminated water. Therefore, regarding compounds for which dietary exposure is important, regulatory toxicity tests should either incorporate dietary exposure routes or be subjected to an additional uncertainty factor.

Animals↗
PubMed2005

Insecticide species sensitivity distributions: importance of test species selection and relevance to aquatic ecosystems.

Single-species acute toxicity data and (micro)mesocosm data were collated for 16 insecticides. These data were used to investigate the importance of test-species selection in constructing species sensitivity distributions (SSDs) and the ability of estimated hazardous concentrations (HCs) to protect freshwater aquatic ecosystems. A log-normal model was fitted to a minimum of six data points, and the resulting distribution was used to estimate lower (95% confidence), median (50% confidence), and upper (5% confidence) 5% HC (HC5) values. Species sensitivity distributions for specific taxonomic groups (vertebrates, arthropods, nonarthropod invertebrates), habitats (saltwater, freshwater, lentic, lotic), and geographical regions (Palaearctic, Nearctic, temperate, tropical) were compared. The taxonomic composition of the species assemblage used to construct the SSD does have a significant influence on the assessment of hazard, but the habitat and geographical distribution of the species do not. Moreover, SSDs constructed using species recommended in test guidelines did not differ significantly from those constructed using nonrecommended species. Hazardous concentrations estimated using laboratory-derived acute toxicity data for freshwater arthropods (i.e., the most sensitive taxonomic group) were compared to the response of freshwater ecosystems exposed to insecticides. The sensitivity distributions of freshwater arthropods were similar for both field and laboratory exposure, and the lower HC5 (95% protection with 95% confidence) estimate was protective of adverse ecological effects in freshwater ecosystems. The corresponding median HC5 (95% protection level with 50% confidence) was generally protective of single applications of insecticide but not of continuous or multiple applications. In the latter cases, a safety factor of at least five should be applied to the median HC5.

Analysis of Variance↗
PubMed2004

Spatial and temporal variability in the structure of invertebrate assemblages in control stream mesocosms.

Outdoor stream mesocosm studies conducted between 1992 and 1996 at two facilities enabled the investigation of structural variability in invertebrate assemblages within and between studies. Temporal variability of benthic invertebrate assemblages between eight replicate streams within a study was assessed in a 28-day mesocosm study without chemical treatment. Cluster analysis, non-metric multidimensional scaling, and principal component analysis each showed the untreated assemblages as structurally distinct groups on the three sampling days. The assemblages between the eight replicate streams showed >88% Bray-Curtis similarity at any one time during the study. In addition, pre-treatment data from a series of four studies conducted at one facility were used to examine structural variability in the starting benthic invertebrate assemblages between studies. Invertebrate assemblages were structurally distinct at the start of each mesocosm study conducted in different years at the same facility and the taxa responsible for differences in the assemblages were also different each year. The implications of temporal and spatial variability in benthic invertebrate assemblages within and between mesocosm studies with regards to species sensitivity and study repeatability should be considered when results of such studies are used in risk assessment.

Animals↗
PubMed2003

Multivariate analyses of invertebrate community responses to a C12-15 AE-3S anionic surfactant in stream mesocosms.

The ecological effects of a C(12-15)AE-3S linear alkylethoxysulfate anionic surfactant on aquatic organisms were studied in stream mesocosms. Analyses of the experimental data have yielded multiple population-level no-observed effect concentrations (NOECs) but did not provide a measure of community-level response to surfactant exposure. In the present study, the invertebrate data from the mesocosm study were further examined for community-level effects using multivariate techniques. Two multivariate statistical methods were selected as representative of recommended methods and used to analyze invertebrate abundance. One method was similarity analysis using the Bray-Curtis index, and the second method was the canonical ordination technique principal response curves recently developed for analysis of mesocosm data. Both sets of techniques detected statistically significant changes in invertebrate community structure following surfactant exposure. Ordinations constructed from Bray-Curtis similarity matrices provided clearer two-dimensional representations of these changes than ordinations from redundancy analysis. Re-displaying treatment and temporal effects on community structure on separate axes as response curves provided a clearer method for interpreting community response to surfactant exposure. Both approaches detected treatment effects in low and high abundance taxa. The highest rank abundance taxa in the pretreatment streams contributed very little to the differences observed between the control and treated streams. The same set of taxa was identified as the dominant drivers for structural differences between control and treated communities despite underlying mathematical differences in these two methods. Invertebrate community-level NOECs estimated from these different multivariate methods (2.5-5.0 mg/l) were comparable and these NOECs were similar to invertebrate population NOECs determined for this surfactant.

Alkanesulfonic Acids↗
PubMed2002

Evaluation of the Gammarus pulex in situ feeding assay as a biomonitor of water quality: robustness, responsiveness, and relevance.

Biomonitoring using benthic macroinvertebrates has been used to assess water quality in Europe since the early 20th century. Most methods use community-level measurements, and the use of single-species responses has been limited, despite their potential benefits as sensitive, early warning indicators. Here we evaluate a single-species in situ assay in which the response is feeding inhibition of the freshwater amphipod Gammarus pulex. The assay was deployed in uncontaminated reference sites to quantify background variability in feeding rates and to elucidate sources of this variation. The ability of the assay to detect impacts of point-source discharges was assessed and the ecological relevance of the assay determined by comparing assay responses to aspects of community structure and functioning. Water temperature accounted for 76% of the variation in the feeding rate of animals deployed at uncontaminated sites, and summer deployments had a >90% power to detect a 30% inhibition in feeding. Inhibition of the situ feeding rate of G. pulex deployed downstream of a variety of point-source discharges ranged from 27 to 99.6%. Gammarus pulex is an important detritivore in stream communities, and a strong positive correlation existed between in situ feeding rate measured over 6 d and leaf decomposition measured over 28 d. A positive correlation also existed between in situ feeding and macroinvertebrate diversity and a biotic index. The G. pulex in situ feeding assay is a short-term sublethal biomonitor of water quality that is indicative of community- and ecosystem-level responses occurring over longer time periods. It is robust, responsive, and relevant.

Animals↗