Respiration and nitrogen metabolism of Atlantic halibut eggs (Hippoglossus hippoglossus)

Naturally spawned and fertilized eggs of Atlantic halibut,Hippoglossus hippoglossus L., were analysed for protein, free amino acids (FAA), ammonium ions and energy content. The chemical composition was found to be size-dependent but varied little during egg development. Ammonium ions did, however, accumulate during the late embryonic stage, and the trend in FAA content was downward during the same period. Rates of O₂ uptake and NH₃ excretion followed exponential patterns. A total of 1µmol O₂ was consumed and 120 nmol NH₃ excreted between the time intervals of fertilization and 1 d post hatch. Derived O:N ratios indicated that the dominant portion of the energy metabolism was lipid- or carbohydrate-based during the mid-development period but switched to FAA as hatch was approached.Correspondence should be addressed to: Zoological Laboratory, University of Bergen, Allégt. 41, N-5007 Bergen, Norway     

Inorganic element uptake by barley from soil supplemented with flue-gas desulphurisation waste and fly-ash

Fresh snow and streamwater samples were collected on a daily basis throughout the winter and spring periods of 1984 and 1985 at a remote, upland catchment located within the Cairngorm Mountains, Scotland. Laboratory based partial-melt experiments undertaken on the snow samples demonstrated that both fractionation and preferential elution of trace-elements occur during melting, with the concentrations being 1.3 to 5.4 times greater than in the first 10 percent meltwater fractions than in the bulk snow (Abrahamset al., in press). At the onset of snowpack melting, the ions may be mobilised and redistributed within the snow profile, concentrating at depths from where they may be quickly removed during the early spring run-offf. The raised major- (Ca, Mg, Na, Cl, NO3 and SO4) and trace-element (Al, Cd, Cu, Fe, Mn and Pb) concentrations recorded in the streamwaters during the acid-flush episodes at the time of the first major periods of snow-melt, reflect both the meltwater composition and the influence of the catchment soils (Abrahamset al., submitted for publication). Differences in streamwater chemistry during the two periods of snow-melt which were studies can probably be related to the fact that snow-melt occurs under a variety of circumstances with significant variations in the sequence of precipitation, melt-events, temperature and snowcover occurring from year to year, even in the same catchment. The high concentrations of Al (up to 330 g L^–1) in the sireamwaters at the time of snow-melt, probably reflect leaching of this element from the soil. These elevated concentrations, in combination with other streamwater parameters, may prove toxic to aquatic life-forms at this time of year.     

Inorganic element uptake by barley from soil supplemented with flue gas desulphurization waste and fly ash

To evaluate the influence of waste products from coal- and oil-fired power plants on the inorganic element content of plants, barley was grown in pots each with 22 kg of sandy loam supplied with increasing amounts of six waste products. The plants were harvested at maturity and analysed for a number of inorganic elements. The salinity of the soil was the limiting factor for the amount added in terms of plant growth. Concerning the quality of the plants as fodder, addition of the waste to the soil at levels of about 0.5% by weight increased the Se concentration of the barley from a level deficient for animals to that approaching sufficiency for animals. The increase in Cd from the flue gas desulphurization (FGD) products was deemed undesirable, even though the concentrations following this single addition were far from toxic. All other increases in element concentrations were without any biological significance.Environmental Geochemistry and Health, 1988,10(1), 21–25     

Windblown dust contributes to high PM2.5 concentrations

The revised National Ambient Air Quality Standards for PM include fine particulate standards based upon mass measurements of PM2.5. It is possible in arid and semi-arid regions to observe significant coarse mode intrusion in the PM2.5 measurement. In this work, continuous PM10, PM2.5, and PM1.0 were measured during several windblown dust events in Spokane, WA. PM2.5 constituted approximately 30% of the PM10 during the dust event days, compared with approximately 48% on the non-dusty days preceding the dust events. Both PM10 and PM2.5 were enhanced during the dust events. However, PM1.0 was not enhanced during dust storms that originated within the state of Washington. During a dust storm that originated in Asia and impacted Spokane, PM1.0 was also enhanced, although the Asian dust reached Washington during a period of stagnation and poor dispersion, so that local sources were also contributing to high particulate levels. The "intermodal" region of PM, defined as particles ranging in aerodynamic size from 1.0 to 2.5 microns, was found to represent a significant fraction of PM2.5 (approximately 51%) during windblown dust events, compared with 28% during the non-dusty days before the dust events.     

A stochastic model for estimating sustainable limits to wildlife mortality in a changing world

Human-caused mortality of wildlife is a pervasive threat to biodiversity. Assessing the population-level impact of fisheries bycatch and other human-caused mortality of wildlife has typically relied upon deterministic methods. However, population declines are often accelerated by stochastic factors that are not accounted for in such conventional methods. Building on the widely applied potential biological removal (PBR) equation, we devised a new population modeling approach for estimating sustainable limits to human-caused mortality and applied it in a case study of bottlenose dolphins affected by capture in an Australian demersal otter trawl fishery. Our approach, termed sustainable anthropogenic mortality in stochastic environments (SAMSE), incorporates environmental and demographic stochasticity, including the dependency of offspring on their mothers. The SAMSE limit is the maximum number of individuals that can be removed without causing negative stochastic population growth. We calculated a PBR of 16.2 dolphins per year based on the best abundance estimate available. In contrast, the SAMSE model indicated that only 2.3–8.0 dolphins could be removed annually without causing a population decline in a stochastic environment. These results suggest that reported bycatch rates are unsustainable in the long term, unless reproductive rates are consistently higher than average. The difference between the deterministic PBR calculation and the SAMSE limits showed that deterministic approaches may underestimate the true impact of human-caused mortality of wildlife. This highlights the importance of integrating stochasticity when evaluating the impact of bycatch or other human-caused mortality on wildlife, such as hunting, lethal control measures, and wind turbine collisions. Although population viability analysis (PVA) has been used to evaluate the impact of human-caused mortality, SAMSE represents a novel PVA framework that incorporates stochasticity for estimating acceptable levels of human-caused mortality. It offers a broadly applicable, stochastic addition to the demographic toolbox to evaluate the impact of human-caused mortality on wildlife.     

Habitat and landscape characteristics underlying anuran community structure along an urban-rural gradient

Urbanization has been cited as an important factor in worldwide amphibian declines, and although recent work has illustrated the important influence of broad-scale ecological patterns and processes on amphibian populations, little is known about the factors structuring amphibian communities in urban landscapes. We therefore examined amphibian community responses to wetland habitat availability and landscape characteristics along an urban-rural gradient in central Iowa, USA, a region experiencing rapid suburban growth. We conducted call surveys at 61 wetlands to estimate anuran calling activity, and quantified wetland habitat structure and landscape context. We used canonical correspondence analysis (CCA) to examine patterns in anuran community structure and identify the most important variables associated with those patterns. Urban density at the landscape scale had a significant negative influence on overall anuran abundance and diversity. While every species exhibited a decrease in abundance with increasing urban density, this pattern was especially pronounced for species requiring post-breeding upland habitats. Anurans most affected by urbanization were those associated with short hydroperiods, early breeding activity, and substantial upland habitat use. We suggest that broad-scale landscape fragmentation is an important factor underlying anuran community structure in this region, possibly due to limitations on the accessibility of otherwise suitable habitat in fragmented urban landscapes. This study underscores the importance of a regional approach to amphibian conservation in urban and urbanizing areas; in fragmented landscapes, a network of interconnected wetland and upland habitats may be more likely to support a successful, diverse anuran community than will isolated sites.     

Physiological energetics of developing embryos and yolk-sac larvae of Atlantic cod (Gadus morhua). II. Lipid metabolism and enthalpy balance

This paper presents quantitative data for the changes in the contents of total lipids, lipid classes and their associated fatty acids, together with the changes in caloric contents of developing eggs and yolk-sac larvae of Atlantic cod (Gadus morhua L.). During development between Day 0 to 28 post fertilisation, 32% of catabolic metabolism was fuelled by lipids. On a mass-specific basis, polar lipids (mainly phosphatidyl choline) contributed 60%, and neutral lipids (mainly triacyl-glycerol) contributed 40% to this catabolic component, with each class supplying similar amounts of fatty acids as fuel. The fatty acids supplied by phosphatidyl choline were catabolised non-selectively (i.e. in proportion to their presence in the egg), with about half of them being polyunsaturated. However, of the fatty acids esterified in triacylglycerol, the larvae showed an apparent oxidation preference for monoenes over polyunsaturates or saturates. Routine rates of oxygen consumption and ammonia production were related to the caloric contents of the eggs and larvae in order to derive an enthalpy balance equation (of the form P=C+R+E) for an Atlantic cod larva during its period of endogenous nutrition. For the interval of Day 0 to 25 post fertilisation (the period of yolk dependence), integration of the physiological and caloric data revealed that Atlantic cod larvae conserved 53% of yolk enthalpy (C) for growth (P), 42% was dissipated due to metabolism (R) while only 5% was lost via excretion (E).     

Calorespirometry of developing embryos and yolk-sac larvae of turbot (Scophthalmus maximus)

The rates of oxygen consumption and heat dissipation were simultaneously measured and related to contents of glucose, glycogen and lactate in order to determine whether anaerobic processes contributed significantly to the energy metabolism of developing turbot embryos and larvae. The results suggest that metabolism is fully aerobic between Days 0 and 12 post fertilisation. The data further suggest that glycogen is the sole metabolic fuel during the first 18 to 19 h post fertilisation. After the commencement of epiboly, carbohydrates play an insignificant role in the energy metabolism of the developing embryo and yolk-sac larva.