Laboratory-made artificial marine snow: a biological model of the real thing

Cylindrical tanks of unfiltered seawater were rotated on a roller table until the particles in the seawater formed aggregates resembling marine snow. During the summer of 1987 comparisons were made between marine snow in field samples from two coastal sites on seven separate dates, and aggregates formed in the laboratory in seawater samples taken on the same dates. Aggregates in field and laboratory samples were photographed and their dimensions were determined. Particulate composition of the aggregates was characterized by the abundance of diatoms, benthic diatoms, diatom frustules, mineral grains, fecal pellets, and fungal spores. Laboratory-prepared aggregates had a significantly greater short axis, and significantly larger calculated volume than field aggregates. Particulate compositions of field aggregates were paralleled by similar changes in the laboratory product. Dry weights of known numbers of aggregates collected on three dates indicated no significant differences in calculated densities or porosities of marine snow formed in the field and in the laboratory. We suggest that this method of forming marine snow in the laboratory may provide researchers with a useful experimental tool.     

Movement and feeding activity of red sea urchins (Strongylocentrotus franciscanus) adjacent to a kelp forest

Movement and feeding were studied in a population of red sea urchins, Strongylocentrotus franciscanus (Agassiz, 1863), found within and immediately seaward of a kelp forest offshore from Santa Cruz, California, USA. Mean sea urchin movements varied from 7.5 cm/day inside the kelp forest to over 50 cm/day at 15 and 100 m outside the kelp forest. The percentage of sea urchins feeding decreased from 66% inside the kelp forest to 16 and 15% at 15 and 100 m outside the kelp forest. These data indicate that movement by these sea urchins is a response to a low food supply.     

Survival and growth of the Norway lobster Nephrops norvegicus in relation to light-induced eye damage

 The long-term survival and growth of Norway lobsters, Nephrops norvegicus (L.), were examined in relation to light-induced retina breakdown. The incidence of eye damage was first assessed in tagged N. norvegicus released in Loch Torridon, on the west coast of Scotland between 1978 and 1983. Of 34 recaptures examined, all but four showed evidence of eye damage, varying in extent from 1 to 63% of the retina. Additional tagged N. norvegicus were released in Loch Torridon in 1984 and 1985 in order to compare recapture and growth rates in lobsters with and without eye damage. Three groups of N. norvegicus were released; normal sighted, partially sighted (median retina damage = 68%) and fully blinded (retina damage = 100%). From 1217 lobsters released, 235 were recovered by September 1992, when the experiment was concluded. The final proportions of N. norvegicus recaptured were found to be independent of eye-damage condition, and there was no evidence that growth rate was affected by eye damage. Combining all categories of releases, the overall proportion of females recaptured (0.244) was significantly greater than the proportion of males (0.145), suggesting better long-term survival in females than in males. At the time of release, ∼80% of the females were carrying recently spawned eggs. Although the proportion of berried females in the recaptures was slightly reduced in the two eye-damaged groups compared with the normal sighted group, the difference was not statistically significant. It is concluded that light-induced eye damage in N. norvegicus is irreversible, but such damage does not seem to influence their long-term survival, growth or reproduction. Received: 21 October 1998 / Accepted: 26 October 1999     

Phytotoxicity and phytoremediation of 2,6-dinitrotoluene using a model plant, Arabidopsis thaliana

Biochemical and genetic studies of xenobiotic metabolism in the model plant Arabidopsis have significant potential in providing information for phytoremediation. This paper presents the toxicity of 2,6-dinitrotoluene (2,6-DNT) to Arabidopsis under axenic conditions, the fate and transformation of 2,6-DNT after uptake by the plant, and the effect of a putative glutathione S-transferase (GST), which is highly induced by 2,4,6-trinitrotoluene (TNT) in the previous study, on the detoxification of 2,6-DNT. 2,6-DNT had toxic effects on the growth of Arabidopsis based on whole seedling as well as root growth assays. Using [U- 14C]2,6-DNT, the recovery was over 87% and less than 2% accounted for the mineralization of 2,6-DNT in axenic liquid cultures during the 14d of exposure. About half (48.3%) of the intracellular radioactivity was located in the root tissues in non-sterile hydroponic cultures. 2-Amino-6-nitrotoluene (2A6NT) and two unknown metabolites were produced as transformation products of 2,6-DNT in the liquid media. The metabolites were further characterized by proton NMR spectra and the UV-chromatograms when the plant was fed with either 2,6-DNT or 2A6NT. In addition, polar unknown metabolites were detected at short retention times from radiochromatograms of plant tissue extracts. The GST gene of the wild-type of Arabidopsis in response to 2,6-DNT was induced by 4.7-fold. However, the uptake rates and the tolerance at different concentrations of 2,6-DNT and TNT were not significantly different between the wild-type and the gst mutant indicating that induction of the GST gene is not related to the detoxification of 2,6-DNT.     

Assessment of the impact of landfill on groundwater quality: A case study of the Pirana site in western India

In present study focus has been given on estimating quality and toxicity of waste with respect to heavy metals and its impact on groundwater quality, using statistical and empirical relationships between different hydrochemical data, so that easy monitoring may be possible which in turn help the sustainable management of landfill site and municipal solid waste. Samples of solid waste, leachate and groundwater were analyzed to evaluate the impact of leachates on groundwater through the comparison of their hydrochemical nature. Results suggest the existence of an empirical relationship between some specific indicator parameters like heavy metals of all three above mentioned sample type. Further, K/Mg ratio also indicates three groundwater samples heavily impacted from leachate contamination. A good number of samples are also showing higher values for and Pb than that of World Health Organization (WHO) drinking water regulation. Predominance of Fe and Zn in both groundwater and solid waste samples may be due to metal plating industries in the area. Factor analysis is used as a tool to explain observed relation between numerous variables in term of simpler relation, which may help to deduce the strength of relation. Positive loading of most of the factors for heavy metal clearly shows landfill impact on ground water quality especially along the hydraulic gradient. Cluster analysis, further substantiates the impact of landfill. Two major groups of samples obtained from cluster analysis suggest that one group comprises samples that are severely under the influence of landfill and contaminated leachates along the groundwater flow direction while other assorted with samples without having such influence.     

Bioethics of fish production: Energy and the environment

Aquatic ecosystems are vital to the structure and function of all environments on earth. Worldwide, approximately 95 million metric tons of fishery products are harvested from marine and freshwater habitats. A major problem in fisheries around the world is the bioethics of overfishing. A wide range of management techniques exists for fishery, managers and policy-makers to improve fishery production in the future. The best approach to limit overfishing is to have an effective, federally regulated fishery, based on environmental standards and fishery carrying capacity. Soon, overfishing is more likely to cause fish scarcity than fossil fuel shortages and high energy prices for fish harvesting. However, oil and other fuel shortages are projected to influence future fishery policies and the productive capacity of the fishery industry. Overall, small-scale fishing systems are more energy efficient than large-scale systems. Aquaculture is not the solution to wild fishery production. The energy input/output ratio of aquacultural fish is much higher than that of the harvest of wild populations. In addition, the energy ratios for aquaculture systems are higher than those for most livestock systems.     

Cross-sectional biomonitoring study of pesticide exposures in Queensland,Australia, using pooled urine samples

A range of pesticides are available in Australia for use in agricultural and domestic settings to control pests, including organophosphate and pyrethroid insecticides, herbicides, and insect repellents, such as N,N-diethyl-meta-toluamide (DEET). The aim of this study was to provide a cost-effective preliminary assessment of background exposure to a range of pesticides among a convenience sample of Australian residents. De-identified urine specimens stratified by age and sex were obtained from a community-based pathology laboratory and pooled (n = 24 pools of 100 specimens). Concentrations of urinary pesticide biomarkers were quantified using solid-phase extraction coupled with isotope dilution high-performance liquid chromatography–tandem mass spectrometry. Geometric mean biomarker concentrations ranged from <0.1 to 36.8 ng/mL for organophosphate insecticides, <0.1 to 5.5 ng/mL for pyrethroid insecticides, and <0.1 to 8.51 ng/mL for all other biomarkers with the exception of the DEET metabolite 3-diethylcarbamoyl benzoic acid (4.23 to 850 ng/mL). We observed no association between age and concentration for most biomarkers measured but noted a “U-shaped” trend for five organophosphate metabolites, with the highest concentrations observed in the youngest and oldest age strata, perhaps related to age-specific differences in behavior or physiology. The fact that concentrations of specific and non-specific metabolites of the organophosphate insecticide chlorpyrifos were higher than reported in USA and Canada may relate to differences in registered applications among countries. Additional biomonitoring programs of the general population and focusing on vulnerable populations would improve the exposure assessment and the monitoring of temporal exposure trends as usage patterns of pesticide products in Australia change over time.     

Topographically generated fronts,very nearshore oceanography,and the distribution of chlorophyll,detritus, and selected diatom and dinoflagellate taxa

At four sites (Sunset Bay, Miller's Cove, and Shore Acres 43° 20.13 N; 124° 22.40 W, Nellies Cove 42° 44.75 N; 124° 29.75 W) along the Oregon coast, USA, relationships between fronts associated with shore-parallel foam lines and the distributions of chlorophyll, selected phytoplankters, and detritus were investigated. Sampling dates at the study sites were as follows: Sunset Bay, 1 August 1997, 25 June 1999 and 20 July 1999; Miller's Cove, 24 August 2000; Shore Acres, 19 July 1999 and 16 August 2000; Nellies Cove 17 August 2000 and 31 August 2000. Conductivity, temperature and depth data were used to describe the water masses on either side of the fronts, and vertical plankton tows with a 53-m mesh net were used to describe the distribution of selected phytoplankters and detritus. At the cove sites during upwelling, fronts marked the presence of warm water within the bay and cooler water offshore. Chlorophyll a (Chl a) and phytoplankton concentrations were generally lower within the coves than seaward while detritus concentrations were higher. From 3 July 2000 to 15 September 2000, a period when upwelling winds from the north prevail, a time series of samples was collected at Sunset Bay. The front was only present during periods of upwelling favorable winds. During these periods there were significantly higher concentrations of Chl a, Pseudo-nitzschia spp., and Protoperidinium spp. seaward of the front than landward. During downwelling winds the front was absent and there were no significant differences in the concentrations inside and outside the mouth of the bay. At Shore Acres, an exposed, relatively straight stretch of shoreline, the shore-parallel front appears to be formed by boundary mixing. Chl a and phytoplankton from the coastal ocean spread well shoreward of the boundary-mixing front. When present, the front at the mouth of the coves and bay indicated the presence of water masses with distinct physical and biological characteristics, but not at Shore Acres. Alongshore differences in the very nearshore oceanography, by altering the availability of continental shelf phytoplankton production, may affect both the growth rates of intertidal benthic suspension feeders and community structure.Electronic Supplementary Material Supplementary material is available in the online version of this article at .Communicated by J.P. Grassle, New Brunswick     

Enhanced degradation of carbofuran in Pacific Northwest soils

Persistence of 14C-carbonyl carbofuran was measured in Pacific Northwest soils that had received 1-14 applications of the insecticide for root weevil control on perennial crops. Insecticide decay curves were obtained in nonautoclaved soil and several autoclaved soil samples from previously-treated fields and in nonautoclaved soils from paired control sites not previously treated with carbofuran. The insecticide usually degraded faster in soil from previously-treated fields than in soil from corresponding control fields. Among 26 previously-treated fields, the pseudo half-life (time for 50% loss) of carbofuran was less than one wk in 11 soils, 1-3 wks in 8 soils and greater than 4 wks in the remaining soils. Among the nontreated control fields the pseudo half-life was greater than 2 wks in all cases and greater than 15 wks in 5 of the soils. The carbofuran decay curve always possessed an initial lag phase where soil mixing enhanced insecticide decline. Carbofuran degraded very slowly in autoclaved soil samples. The half-life of carbofuran exceeded 16 wk in all autoclaved soils tested and in most instances 85-90% of the original dosage remained when the tests were terminated 112 days after treatment. These results provided evidence that many of the soils which received applications of carbofuran over the past several years have developed a capacity to degrade carbofuran very rapidly.