Feeding ecology and interannual variations in diet of larval jack mackerel,Trachurus declivis (Pisces: Carangidae), from coastal waters of eastern Tasmania

Changes in the biochemical composition of the digestive gland and in the proteins of the mantle muscle of Sepia officinalis L, collected in September 1989 from the Ria de Vigo (northwest Spain), were measured during periods of 2, 4, 10 and >53 d starvation. The digestive gland lost weight faster than the rest of the body throughout the whole period of starvation. In the digestive gland, carbohydrate and protein contents did not change during starvation; however, lipid levels decreased significantly after 53 d. Phospholipid content increased during longterm starvation. The content of free fatty acids rose after 16 d. Sterols, diacylglycerylethers, triacylglycerols and carotenoids contents did not change significantly. Of the total fatty acids, 18:0, 20:2n6, 20:4n6 and the monounsaturated moieties were preferentially consumed; others, such as 22:5n3, 22:6n3 and 16:4n1, were selectively retained. In the mantle muscle, water content increased and total protein content decreased. The myofibrillar proteins decreased after 53 d starvation, whereas the sarcoplasmic fraction did not change and the stromatic proteins increased. No changes were observed in the electrophoretic patterns of sarcoplasmic and myofibrillar proteins. The digestive gland of S. officinalis does not seem to be an important reserve organ during long-term starvation, but does seem to be important during shortterm starvation.     

Rates of nitrogen fixation on coral reefs across the continental shelf of the central Great Barrier Reef

This study was undertaken in 1981 to determine whether there were major variations in potential rates of nitrogen fixation on apparently bare coralline substrate from reefs across the continental shelf of the central Great Barrier Reef. Nitrogen fixation, measured as rates of ethylene production (nmol cm^-2h^-1), was significantly lower on substrata from two inner-shelf reefs, (0.46 and 1.07) than on two middle-shelf reefs (2.10 and 2.97) and on two outer-shelf reefs (3.20 and 3.81). By contrast, algal biomass (mg cm^-2) on experimental substrate was significantly higher on inner-shelf reefs (80.8 and 59.4) than on middleshelf (27.1 and 23.8) and outer-shelf reefs (26.4 and 22.4). The rate of nitrogen fixation was positively correlated with the proportion of bare substratum and significantly higher concentrations of dissolved inorganic nitrogen were found in waters over the reefs than in water flowing onto those reefs. The abundance of algal-grazing fishes was reported previously to be significantly lower on inner-shelf reefs. It is suggested that this cross-shelf variation in the activity of algal-grazing fishes may be a determinant of the observed cross-shelf variations in potential nitrogen fixation.Contribution No. 233 from the Australian Institute of Marine Science     

No. 2 fuel oil compounds in Mytilus edulis

Mytilus edulis contaminated by a brief 2-d exposure to a slick from a No. 2 fuel oil spill in the Cape Cod Canal, Massachusetts, USA were sampled six times during an 86-d post-spill period to study the rate of release of fuel oil compounds under field conditions. Detailed measurements of compounds by high resolution glass capillary gas chromatography and quantitative glass capillary gas chromatography-mass spectrometry-computer systems analyses provided a more comprehensive examination of release rates of different types of compounds. Biological half-lives were calculated for selected compounds for the first 21 d during which the release rates were exponential. Typical half-lives were n-alkanes, 0.2–0.8 d; pristane, 1.5 d; C-2 (dimethyl or ethyl) napthalenes, 0.9 d; methyl phenanthrenes, 1.7 d. Changes in relative ratios of C-2 phenanthrenes during the release period were observed. The evidence available to date strongly supports the role of molecular weight and accompanying properties of water solubility as the main controlling factors in the rate of release of fuel oil compounds by M. edulis. However, the data for the rapid release of n-alkanes and C-2 phenanthrenes also indicate molecular type and molecular configuration as additional key factors. The data from this study are compared and contrasted to data from short term experimental studies in the laboratory, longer term studies from chronic exposure conditions, and data from two other oil spills with longer term exposure.     

Should heterogeneity be the basis for conservation? Grassland bird response to fire and grazing.

In tallgrass prairie, disturbances such as grazing and fire can generate patchiness across the landscape, contributing to a shifting mosaic that presumably enhances biodiversity. Grassland birds evolved within the context of this shifting mosaic, with some species restricted to one or two patch types created under spatially and temporally distinct disturbance regimes. Thus, management-driven reductions in heterogeneity may be partly responsible for declines in numbers of grassland birds. We experimentally altered spatial heterogeneity of vegetation structure within a tallgrass prairie by varying the spatial and temporal extent of fire and by allowing grazing animals to move freely among burned and unburned patches (patch treatment). We contrasted this disturbance regime with traditional agricultural management of the region that promotes homogeneity (traditional treatment). We monitored grassland bird abundance during the breeding seasons of 2001-2003 to determine the influence of altered spatial heterogeneity on the grassland bird community. Focal disturbances of patch burning and grazing that shifted through the landscape over several years resulted in a more heterogeneous pattern of vegetation than uniform application of fire and grazing. Greater spatial heterogeneity in vegetation provided greater variability in the grassland bird community. Some bird species occurred in greatest abundance within focally disturbed patches, while others occurred in relatively undisturbed patches in our patch treatment. Henslow's Sparrow, a declining species, occurred only within the patch treatment. Upland Sandpiper and some other species were more abundant on recently disturbed patches within the same treatment. The patch burn treatment created the entire gradient of vegetation structure required to maintain a suite of grassland bird species that differ in habitat preferences. Our study demonstrated that increasing spatial and temporal heterogeneity of disturbance in grasslands increases variability in vegetation structure that results in greater variability at higher trophic levels. Thus, management that creates a shifting mosaic using spatially and temporally discrete disturbances in grasslands can be a useful tool in conservation. In the case of North American tallgrass prairie, discrete fires that capitalize on preferential grazing behavior of large ungulates promote a shifting mosaic of habitat types that maintain biodiversity and agricultural productivity.     

Chalk and limestone quarries as wildlife habitats

Natural recolonisation by volunteer species of chalk and limestone quarries has led to the development of attractive and species-rich communities in many parts of the United Kingdom. These communities have a basic similarity in floristic composition wherever they occur, but they also show a great deal of individual variation resulting from differences in the location, history and variability of the quarry itself and in the nature of the surrounding habitats. The interest of old quarries may be enhanced by the presence of individually rare or local species and especially by their refuge status in relation to the loss of semi-natural calcareous grassland in the district. It is suggested that some sites play an important role in wildlife conservation and that this factor should be considered in any programme of land reclamation. Natural regeneration is very slow compared with the rate of land use in modern quarrying but the development of ecological techniques may make it possible to rehabilitate derelict and barren sites for amenity and conservation purposes using older quarries as models.     

The effect of inhibitors of photosynthesis on zooxanthellae in corals and other marine invertebrates

The effect of the selective photosynthesis inhibitors Monuron (CMU), Diuron (DCMU) and methyl viologen on intact algal-marine invertebrate symbiotic associations was studied. CMU or DCMU (5x10^-4M) completely inhibited photosynthesis, both in intact branches, and in suspensions of isolated zooxanthellae from the reef-building coral Pocillopora damicornis. The inhibitory effect was totally reversible in 1 to 3 h after removal of the inhibitor. Similar inhibition of photosynthesis occurred in 8 other marine coelenterates symbiotic with zooxanthellae, and in 1 marine gastropod symbiotic with functional chloroplasts. Neither CMU nor DCMU appeared to affect behavior of the various hosts, such as swimming, phototaxis, phototropism, photoreception, tentacle contraction, ciliary beating and locomotion. Methyl viologen, however, was ineffective in inhibiting photosynthesis in intact P. damicornis at low concentrations, and lethal to the tissues at high concentrations. These observations indicate that CMU and DCMU are potential useful tools for investigation of symbiotic associations. DCMU (5x10^-4M) also reversibly inhibited light-enhanced calcification in P. damicornis. This strongly suggests that light-enhanced calcification is largely photosynthesis dependent, and probably not dependent on some other photobiological effect.Contribution No. 385, Hawaii Institute of Marine Biology, University of Hawaii     

Factors controlling lead bioavailability in the Butte mining district,Montana, USA

Microprobe analyses of 38 soil and 5 mine-waste samples from Butte, Montana, demonstrated that the samples contain predominantly sulphide/sulphate and oxide/phosphates of lead (Pb)-bearing phases associated with mine waste. The sulphide/sulphate assemblage consists primarily of galena altering to anglesite and plumbojarosite, with secondary jarosite precipitating and rinding the Pb-bearing minerals. In addition, galena was encapsulated within pyrite or quartz grains. The oxide/phosphate assemblage consists of pH-neutral soils in which a plausible paragenetic sequence of PbO to Pb phosphates, PbMnO, or PbFeO is proposed, dependent on the activity of P, Mn, Fe, and Cl in the soil. In addition, Pb-bearing grains are occasionally armoured by the presence of a 1- to 3-(m rind of authigenic silicate. The low solubility of the Pb-bearing minerals resulting from encapsulation in non-Pb-bearing reaction rinds may provide an explanation for the limited Pb bioavailability observed when Butte soils were fed to rats (Freemanet al., 1992). Further evidence of the lack of absorption of lead from these soils is provided by the results of a blood-Pb study indicating very low blood-Pb levels in Butte children. The lower bioavailability of Pb from mining sites, compared to smelting and urban environments, is also due to kinetic limitations that control dissolution rates of Pb-bearing solids relative to the residence time of soil in the gastrointestinal (Gl) tract. When the test soil was fed to New Zealand White rabbits, only 9% of the total Pb was solubilised in the stomach, and therefore available for absorption. Anin vitro assay, developed to estimate maximum available Pb from soil, demonstrates that ingestion of mine-waste-bearing soil results in limited Pb dissolution, and produces results similar to thein vivo testing.     

Futurecoast: Predicting the future coastal evolution of England and Wales

Analysis of shoreline change is often based exclusively upon the littoral cell concept and modelling of hydrodynamic processes. The Futurecoast study has considered fresh approaches to assessing shoreline evolution, which have been used to provide an analysis of future long-term evolution for the entire shoreline of England and Wales. This has been based upon an improved understanding of coastal systems and their behavioural characteristics. The study has included a range of supporting studies, focussing upon maximizing use of existing information and experience. A number of additional data sets have also been produced. The integration of leading expertise from different areas of coastal research to collectively consider this information has been the foundation for the study. The key outputs from this research are: (1) Improved understanding of coastal behaviour; (2) Assessment of future shoreline evolution; (3) Supporting information and data; (4) Delivery of results on an interactive CD-ROM.     

Effect of pH on Pb biouptake by the freshwater alga<Emphasis Type="Italic"> Chlorella kesslerii</Emphasis>

The effect of pH on Pb bioaccumulation by Chlorella kesslerii was studied. Both Pb uptake fluxes and Pb bound to membrane transport sites increased with an increase in pH from 4.0–5.0, were relatively stable in the pH interval 5.0–6.5, and increased again at pH 7.0 and 8.0. Protons affected Pb adsorption to the algal surface by competing directly for surface sites, by modifying the overall algal surface charge and by modifying the chemical speciation of Pb in solution. These results indicate a failure of the free-ion activity or biotic ligand models above pH 6.5, possibly due to the bioaccumulation of hydroxo or carbonato Pb complexes.     

The effect of diesel fuel on common vetch (Vicia sativa L.) plants

When petroleum hydrocarbons contaminate soil, the carbon:nitrogen (C:N) ratio of the soil is altered. The added carbon stimulates microbial numbers but causes an imbalance in the C:N ratio which may result in immobilization of soil nitrogen by the microbial biomass, leaving none available for plant growth. As members of Leguminosae fix atmospheric nitrogen to produce their own nitrogen for growth, they may prove more successful at growing on petroleum hydrocarbon contaminated sites. During a wider study on phytoremediation of diesel fuel contaminated soil, particular attention was given to the performance of legumes versus other plant species. During harvesting of pot experiments containing leguminous plants, a recurring difference in the number and formation of root nodules present on control and contaminated Common vetch (Vicia sativa L.) plants was observed. The total number of nodules per plant was significantly reduced in contaminated plants compared to control plants but nodules on contaminated plants were more developed than corresponding nodules on control plants. Plant performance of Common vetch and Westerwold's ryegrass (Lolium multiflorum L.) was compared to illustrate any difference between the ability of legumes and grasses to grow on diesel fuel contaminated soil. Common vetch was less affected by diesel fuel and performed better in low levels of diesel fuel contaminated soil than Westerwolds ryegrass. The total amount of diesel fuel remaining after 4 months in Common vetch planted soil was slightly less than in Westerwolds ryegrass planted soil.