Bioenergetics, Exercise, and Fatty Acids of Fish

The bioenergetic aspects of pentachlorophenol poisoning andexercise in fish are discussed. When cichlids are exposed to0.2 ppm of pentachlorophenol, the intake of food was increasedand energy losses were also increased. Growth was decreased.The cost of specific dynamic action was higher and the costof exercise was increased above the cost of similar exercisein nonpoisoned controls. In salmon swimming to exhaustion at52 cm/sec fatty acids 18:1, 16:0, and 16:1, and at 59 cm/secfatty acids 22:6, 18:2, and 20:4 suffered the greatest depletion.At 52 and 59 cm/sec, respectively, average exhaustion timeswere 1141 and 398 minutes; the equivalents of distance traveledwere 26.0 and 12.7 miles; the loss in lipids, 54 and 10 mg;and the average weight losses, 830 and 480 mg per salmon. Totalcaloric losses calculated from the data on lipid and weightlosses were approximately 1118 and 566 calories. Calculatedfrom the data of Brett (1964) on O₂ consumption, caloric losseswere estimated at only 344 and 188 calories. The differencebetween observed values and values calculated from the dataof Brett may lie in the duration and severity of the exercise.Brett collected his data on O₂ consumption on the basis of atmost two hours at high velocity. Possibly when maximum effortis involved each succeeding mile and each succeeding hour ismore difficult and more costly to the salmon.     

A metabolic model for the determination of shell composition in the bivalve mollusc, Mytilus edulis

Rosenberg. G. D. & Hughes, W. W. 1991 01 15: A metabolic model for the determination of shell composition in the bivalve mollusc, Mytilus edulis. Lethaia, Vol. 24. pp. 83–96. Oslo. ISSN 0024–1164. This research describes compositional variations within the shell of the extant mussel Mytilur edulis and proposes that they are produced by metabolic gradients within the shell-secreting mantle. Because we have previously proposed that the same metabolic gradients are responsible for variations in shell form (curvature), we establish here a model for molluscan shell growth integrating. for the first time. shell form and composition with mantle metabolism. The electron microprobe was used to measure the distribution of Mg. S, and Ca in the outer calcitic shell layer of sectioned. polished, and either A1- or C-coated shell. Mg/Ca and S/Ca ratios in the outer shell are respectively 1.25 and 1.40 times higher along slow-growing, commissure-umbo axes of high shell curvature and high metabolic activity than along rapidly growing axes of low curvature and low metabolic activity. The ratios within the inner surface of the calcitic shell layer decline most rapidly along commissure-umbo axes where mantle metabolic activity also declines rapidly. We reject the null hypothesis, generally at high levels of significance (1-tests. F-tests. regression analyses, and discriminant analysis. with p 4 0.01) that there is no difference in either Mg or S concentration in sections of the calcitic shell layer that differ in shell curvature and mantle metabolic activity. We conclude that calcium (mineral)-rich portions of shells are energctically less costly to produce than matrix or minor element-rich portions. in agreement with the proposal that natural selection favors mineral-rich shells because they are more efficient to produce than matrix-rich shells. Among-specimen differences are also highly significant (mixed model ANOVA). This confirms our assertion that paleontologists need to describe variations in skeletal composition among populations and throughout ontogeny as systematically as classical taxonomists describe morphology. if ever the environmental and the genetic influences on skeletal composition are to be distinguished. Bivalves. biomineralization, shell composition. magnesium, sulfur, calcium, metabolism, growth. Mytillus edulis     

Use of Volatile Organic Components in Scat to Identify Canid Species

Abstract: Identification of wildlife species from indirect evidence can be an important part of wildlife management, and conventional methods can be expensive or have high error rates. We used chemical characterization of the volatile organic constituents (VOCs) in scat as a method to identify 5 species of North American canids from multiple individuals. We sampled vapors of scats in the headspace over a sample using solid-phase microextraction and determined VOC content using gas chromatography with a flame ionization detector. We used linear discriminant analysis to develop models for differentiating species with bootstrapping to estimate accuracy. Our method correctly classified 82.4% (bootstrapped 95% CI = 68.8–93.8%) of scat samples. Red fox (Vulpes vulpes) scat was most frequently misclassified (25.0% of scats misclassified); red fox was also the most common destination for misclassified samples. Our findings are the first reported identification of animal species using VOCs in vapor emissions from scat and suggest that identification of wildlife species may be plausible through chemical characterization of vapor emissions of scat. (JOURNAL OF WILDLIFE MANAGEMENT 72(3):792–797; 2008)     

Why are Aedes mosquitoes rare colonisers of Nepenthes pitcher plants?

1. Nepenthes pitcher plants produce fluid‐containing animal traps that are colonised by a variety of specialised arthropods, especially dipterans. However, container‐breeding vector mosquitoes, such as Aedes albopictus Skuse have rarely been recorded from pitchers. Increasing overlap in the geographical ranges of Nepenthes and Ae. albopictus in urban parts of Southeast Asia owing to urbanisation highlights a growing need to investigate the potential role of pitchers as larval habitats for vector mosquitoes. 2. The ability of Ae. albopictus larvae to survive in three common lowland Nepenthes in Peninsular Malaysia that are most likely to co‐occur with Ae. albopictus [viz., Nepenthes ampullaria Jack, Nepenthes gracilis Korth., and Nepenthes mirabilis (Lour.) Druce] was investigated. 3. The larval survival rates of Ae. albopictus in pitcher fluids of the three Nepenthes species were determined, then the effects of low pH, larvicidal agents (such as microbes, predators, and chemical compounds) through manipulative experiments were investigated. 4. It was found that pitchers represent a hostile environment to Ae. albopictus, but that the principal cause of larval mortality varies among Nepenthes species (i.e. low fluid pH in N. gracilis, predation by Toxorhynchites acaudatus Leicester larvae in N. ampullaria, and microbial activity in N. mirabilis). It was concluded that Nepenthes pitchers are generally not suitable larval habitats for Ae. albopictus. However, the pitcher environment of N. ampullaria is worthy of further study, as pitchers that lack predators are nevertheless rarely colonised by Ae. albopictus, indicating that other aspects of the host pitcher environment inhibit oviposition or larval survivorship.     

The systematics of the Phelsuma madagascariensis species group of day geckos (Reptilia: Gekkonidae) in the Seychelles

Conventional taxonomy of the Seychelles populations of the Phelsuma madagascariensis species group has failed to illustrate the principal patterns of phenetic variation between island populations. The taxonomic history of the populations is discussed critically, and a revised nomenclature is suggested from the results of a recent comprehensive study of the forms using multivariate morphometrics. Three phenetic groups from the granitic islands are referred to as Phelsuma sundbergi sundbergi from the north western islands; P. s. ladiguensis from the north eastern islands; and P. s. longinsulae from the southern islands. Phelsuma abbotti populations from Aldabra and Assumption are considered subspecifically distinct, and not conspecific with the granitic island forms. The other coralline island populations are closely allied to the races from the granitic islands and probably represent recent colonization or introductions by man.     

Giving‐up densities and ideal pre‐emptive patch use in a predatory benthic stream fish

1. We used observational and experimental field studies together with an individual‐based simulation model to demonstrate that behaviours of mottled sculpin (Cottus bairdi) were broadly consistent with the expectations of Giving‐Up Density theory and an Ideal Pre‐emptive Distribution habitat selection model. 2. Specifically we found that: (i) adult mottled sculpin established territories within patches characterised by significantly higher prey densities and prey renewal rates than patches occupied by juveniles or randomly selected patches; (ii) patches abandoned by adult sculpin possessed significantly lower prey densities than newly occupied patches, although this was not true for juveniles; (iii) the observed giving‐up density (GUD) for adult sculpin (i.e. average prey density in patches recently abandoned) increased linearly with increasing fish size up to the average prey density measured in randomly selected patches (i.e. 350 prey items per 0.1 m²) and decreased with increasing sculpin density and (iv) juveniles rapidly shifted their distribution towards the highest quality patches following removal of competitively dominant adult sculpin. 3. These results provide the first evidence of the applicability of GUD theory to a stream‐dwelling organism, and they elucidate the underlying factors influencing juvenile and adult sculpin habitat selection and movement behaviours. Furthermore, optimal patch use, ideal pre‐emptive habitat selection and juvenile ‘floating’ provide behavioural mechanisms linking environmental heterogeneity in the stream benthos to density‐dependent regulation of mottled sculpin populations in this system.     

Winter climate change implications for decomposition in northeastern forests: comparisons of sugar maple litter with herbivore fecal inputs

Forests in northeastern North America are influenced by varying climatic and biotic factors; however, there is concern that rapid changes in these factors may lead to important changes in ecosystem processes such as decomposition. Climate change (especially warming) is predicted to increase rates of decomposition in northern latitudes. Warming in winter may result in complex effects including decreased levels of snow cover and an increased incidence of soil freezing that will effect decomposition. Along with these changes in climate, moose densities have also been increasing in this region, likely affecting nutrient dynamics. We measured decomposition and N release from ¹⁵N‐labeled sugar maple leaf litter and moose feces over 20 months in reference and snow removal treatment (to induce soil freezing) plots in two separate experiments at the Hubbard Brook Experimental Forest in New Hampshire, USA. Snow removal/soil freezing decreased decomposition of maple litter, but stimulated N transfer to soil and microbial biomass. Feces decomposed more rapidly than maple litter, and feces N moved into the mineral soil more than N derived from litter, likely due to the lower C : N ratio of feces. Feces decomposition was not affected by the snow removal treatment. Total microbial biomass (measured as microbial N and C) was not significantly affected by the treatments in either the litter or feces plots. These results suggest that increases in soil freezing and/or large herbivore populations, increase the transfer rate of N from plant detritus or digested plants into the mineral soil. Such changes suggest that altering the spatial and temporal patterns of soil freezing and moose density have important implications for ecosystem N cycling.     

Freeze avoidance: a dehydrating moss gathers no ice

Using cryo‐SEM with EDX fundamental structural and mechanical properties of the moss Ceratodon purpureus (Hedw.) Brid. were studied in relation to tolerance of freezing temperatures. In contrast to more complex plants, no ice accumulated within the moss during the freezing event. External ice induced desiccation with the response being a function of cell type; water‐filled hydroid cells cavitated and were embolized at ?4 °C while parenchyma cells of the inner cortex exhibited cytorrhysis, decreasing to ～20% of their original volume at a nadir temperature of ?20 °C. Chlorophyll fluorescence showed that these winter acclimated mosses displayed no evidence of damage after thawing from ?20 °C while GCMS showed that sugar concentrations were not sufficient to confer this level of freezing tolerance. In addition, differential scanning calorimetry showed internal ice nucleation occurred in hydrated moss at ～?12 °C while desiccated moss showed no evidence of freezing with lowering of nadir temperature to ?20 °C. Therefore the rapid dehydration of the moss provides an elegantly simple solution to the problem of freezing; remove that which freezes.     

Polymorphic microsatellite markers,isolated using a simple enrichment procedure,in the threatened smooth snake (Coronella austriaca)

The smooth snake, Coronella austriaca, is particularly rare within the UK and little is known about the genetic variability within the species. Here we report the isolation of 16 polymorphic microsatellite markers in the smooth snake, using a simple enrichment procedure. Despite screening individuals from a potentially isolated population, levels of polymorphism were high. These microsatellite markers will prove very useful in investigating population parameters, which will lead to effective conservation and management plans for this rare species.