Discriminating Canadian Arctic beluga management stocks using dentine oxygen and carbon isotopes

In the eastern Canadian Arctic, belugas Delphinapterus leucas exhibit genetic and ecological differentiation across their distribution that forms the basis of management stocks for traditional Inuit hunts. Using oxygen and stable carbon isotope ratios in dentine phosphate (δ18OP) and structural carbonate (δ13CSC), respectively, we evaluated the spatial structure of 3 of these beluga stocks: Western Hudson Bay (WHB, n = 30), Cumberland Sound (CS, n = 44), and Eastern High Arctic-Baffin Bay (EHA-BB, n = 29). Pairwise comparisons revealed significant differences in δ18OP and Suess-adjusted δ13CSC among all stocks, with the exception of similar δ18OP between the WHB and CS stocks. A linear discriminant analysis (LDA) model fit to 60% of the data set (training data) successfully classified 84% of the remaining belugas (test data) to their respective stocks based on hunt location. Isotopic overlap among stocks could reflect (1) homogeneous baseline stable isotope (SI) composition between geographically adjacent stocks, (2) some degree of marginal geographic overlap in ranges or individual movements among stocks, perhaps during late spring, or (3) confounding dietary influences that increased within-stock SI variation. Some misclassifications consistent with individual movements among stocks were supported by limited genetic data, with a small number of belugas hunted from the CS stock exhibiting both isotopic and genetic similarity to WHB belugas. Geographic stock differentiation inferred from oxygen and carbon isotope proxies largely corroborates current eastern Canadian Arctic beluga stock definitions, which is relevant not only for management purposes but also for monitoring changing beluga distributions in response to ongoing climate-driven changes in Arctic marine ecosystems

Pseudostalked barnacles Xenobalanus globicipitis attached to killer whales Orcinus orca in South African waters

Several records describe pseudostalked barnacles Xenobalanus globicipitis attached to killer whales Orcinus orca, yet little is known of this association in Southern African waters. Here we describe Xenobalanus prevalence on killer whales in South African waters and assemble previous records. Killer whales were photographed opportunistically between July and September 2013. Sex and age class were determined, and if Xenobalanus were present, attachment site and colony size noted. A prevalence of 50% was recorded, with barnacles most commonly observed on the dorsal fin and tail flukes. The high prevalence of Xenobalanus on killer whales in South African waters and lack thereof on killer whales at Marion Island implies that these are separate populations, and thus we suggest Xenobalanus prevalence is an additional means to distinguish between these populations.National Research Foundation (NRF) Thuthuka programme, the South African Department of Science and Technology through the NRF, the Mohamed bin Zayed Species Conservation Fund (project number: 10251290) and the International Whaling Commission’s Southern Ocean Research Partnership.http://link.springer.com/journal/125262016-12-31hb201

CO2 Degassing from Volcanic Lakes

Measurements of CO2 flux emitted at the surface of volcanic lakes have been performed using the so-called floating accumulation chamber method. Two statistical methods are used to process data: the graphical statistical and stochastic simulation methods. The results of graphical statistical approach allow the quantification of two degassing processes acting at the lake surface: one corresponding to CO2 fluxes resulting from rising bubbles and the second corresponding to equilibrium diffusion of dissolved CO2 at the water-air surface. The sequential Gaussian simulation method has been used for mapping the CO2 flux and estimating the total CO2 emission rate at the surface of volcanic lakes. The study of two volcanic lakes is presented in this chapter: Kelud, Indonesia and El Chichón, Mexico. Before a lava dome appeared in the middle of Kelud Lake on the 4th November 2007, the lake contained near neutral waters with a pH of 6. The total CO2 emission rate estimated by stochastic simulation ranged from 105 t day−1 for 2001 to 35 t day−1 for 2006. In early July 2007, the total flux for the lake area was estimated at 307 t day−1, showing that CO2 flux monitoring at the surface of volcanic lakes is a powerful tool in the improvement of early warning systems of volcanic eruptions. A significant change in CO2 flux was not detected for El Chichón lake during the period of survey (2007-2008) but the mapping of the CO2 flux on the lake area highlighted lineaments reflecting structures controlled by the main local and regional tectonic patterns.SCOPUS: ch.binfo:eu-repo/semantics/publishe

The somatotropic axis in short children born small for gestational age: relation to insulin resistance.

To determine whether hyperinsulinemia and reduced insulin sensitivity in individuals born small for gestational age (SGA) could be related to persisting abnormalities of the GH/IGF-I axis, we assessed overnight GH secretory profiles and measured fasting glucose, insulin, intact and 32,33 split proinsulin, and IGF-I levels in 16 short SGA children (age range 2.3-8.0 y) and in controls. Insulin sensitivity was calculated using the homeostasis model. Compared with short normal-birthweight controls (n = 7, age range 2.3-5.0 y), short SGA children had higher fasting insulin levels (means: 26.8 vs 20.6 pmol/L, p = 0.02), lower insulin sensitivity [means: 204 vs 284 %homeostasis model assessment (HOMA), p = 0.01], and higher beta cell function (112 vs 89 %HOMA, p = 0.04). SGA children also had lower levels of IGFBP-1 (87.0 vs 133.8, p = 0.04), but similar IGF-I levels (IGF-I SDS: -1.1 vs -1.7, p = 0.4). Compared with normal-height controls (n = 15, age range 5.6-12.1 y), SGA children had higher overnight GH secretion (GH maximum: 55.9 vs 39.6 mU/L, p = 0.01; mean: 13.1 vs 8.9, p = 0.004; minimum: 1.2 vs 0.6, p = 0.02). Interestingly, among SGA children, fasting insulin levels and insulin sensitivity were significantly related to overnight GH secretion (insulin sensitivity vs maximum GH: r = -0.68, p = 0.01; vs GH pulse amplitude r = -0.71, p = 0.007). The only hormone level significantly related to current height velocity was C-peptide (r = 0.75, p = 0.008). In conclusion, elevated fasting insulin levels and reduced insulin sensitivity in short SGA children was related to elevated levels of overnight GH secretion. We hypothesize that resistance to the somatotropic actions of GH and IGF-I in short SGA children may contribute directly to reduced insulin sensitivity