Trophic markers and biometric measurements in Southern Ocean sea stars (1985-2017).

Sea stars (Echinodermata: Asteroidea) are a key component of Southern Ocean benthos, with 16% of the known sea star species living there. In temperate marine environments, sea stars commonly play an important role in food webs, acting as keystone species. However, trophic ecology and functional role of Southern Ocean sea stars are still poorly known, notably due to the scarcity of large-scale studies.

Effects of preservation methodology on stable isotope compositions of sea stars.

Rationale: Stable isotope analysis is used to investigate the trophic ecology of organisms and, in order to use samples from archived collections, it is important to know whether preservation methods alter the results. This study investigates the long-term effects of four preservation methods on isotopic compositions and isotopic niche parameters of sea stars.

Methods: We assessed the effects of preservation method (freezing, drying, formaldehyde, ethanol) and duration (0, 1, 3, 6, 9, 12, 24 months) on the stable isotope ratios of carbon, nitrogen and sulfur of sea star tissues.

Inter-individual differences in ontogenetic trophic shifts among three marine predators.

Ontogenetic niche shifts are widespread. However, individual differences in size at birth, morphology, sex, and personalities can cause variability in behavior. As such, inherent inter-individual differences within populations may lead to context-dependent changes in behavior with animal body size, which is of concern for understanding population dynamics and optimizing ecological monitoring.

Effect of body length, trophic position and habitat use on mercury concentrations of sharks from contrasted ecosystems in the southwestern Indian Ocean.

The non-essential metal mercury (Hg) can have deleterious effects on health of organisms, and tends to bioaccumulate with age in long-lived organisms and to biomagnify along food webs. Because elasmobranchs are fished for human consumption and their Hg levels are frequently above the maximum Hg concentration recommended for fish consumption, understanding the drivers of Hg concentration is of considerable interest. Total Hg concentrations were analysed in muscle tissues of 14 shark and 2 batoid species (n = 339 individuals) sampled across multiple habitats (coastal, open ocean and bathyal) in the southwestern Indian Ocean.

Assessing Youth Perceptions and Knowledge of Ethics at 4-H Horse Shows in Louisiana.

Due to the increased awareness of animal welfare issues and sensitized attitudes throughout society, youth animal projects provide a unique opportunity to assess and impact youth understanding and attitudes regarding animal welfare. Animal ethics training is not an uncommon requirement for participants in 4-H livestock programs. However, participants in 4-H horse projects are not universally held to the same standard.

Mother-embryo isotope (δ¹⁵N, δ¹³C) fractionation and mercury (Hg) transfer in aplacental deep-sea sharks.

Stable carbon (δ¹³C) and nitrogen (δ¹⁵N) isotopic values and total mercury (Hg) concentrations were analysed in muscle and liver of mothers and embryos of two aplacental shark species, Squalus megalops and Centrophorus moluccensis. Embryos of the two species had similar or lower isotopic values than their respective mothers, the only exception being for δ¹³C, which was higher in the liver of C. moluccensis embryos than in their mothers.

Effects of a slow-release urea product on performance, carcass characteristics, and nitrogen balance of steers fed steam-flaked corn.

Two experiments were conducted to examine the impact of source, urea (U) or Optigen II (OP), and level of dietary NPN on performance (Exp.1) and N balance (Exp. 2) of growing cattle.

Thermodynamic study in aqueous solutions of weakly soluble ionic compounds.

Any investigation for a better knowledge of precipitation/dissolution problems necessitates the availability of all the beta formation constants of the uncharged soluble species (ion-pair). Several difficulties dealing with solubility measurements are briefly reviewed, especially related to phase structure variations, time-lag or supersaturation phenomena. Thanks to some thermodynamic considerations, the evolution of the uncharged soluble species with hydration and solid phase modifications can give a new explanation about the observed dispersion in literature values for some weakly soluble ionic compounds.