Nutritional geometry and macronutrient variation in the diets of gannets: the challenges in marine field studies

Foraging theory proposes that the nutritional driver of food choice and foraging in carnivores is energy gain. In contrast, recent laboratory experiments have shown that several species of carnivore select prey that provides a diet with a specific balance of macronutrients, rather than the highest energy content. It remains, however, to be determined how nutritionally variable the foods of predators in the wild are, and whether they feed selectively from available prey to balance their diet. Here, we used a geometric method named the right-angled mixture triangle (RMT) for examining nutritional variability in the prey and selected diets of a group of wild carnivores and marine top predators, the gannets (Morus spp.). A prey-level diet analysis was performed on Australasian gannets (M. serrator) from two New Zealand locations, and the macronutrient composition of their chosen prey species was measured. We use RMT to extend the comparison in the compositions of foods and diets from Australasian gannets from Australia as well as Northern gannets (M. bassanus) and Cape gannets (M. capensis). We found nutritional variability at multiple scales: intra- and interspecific variability in the pelagic fish and squid prey themselves; and intra- and interspecific variability in the diets consumed by geographically disparate populations of gannets. This nutritional variability potentially presents these predatory seabirds with both opportunity to select an optimal diet, and constraint if prevented from securing an optimal diet.     

Kelvin–Helmholtz instability in the presence of variable viscosity for mudflow resuspension in estuaries

The temporal stability of a parallel shear flow of miscible fluid layers of different density and viscosity is investigated through a linear stability analysis and direct numerical simulations. The geometry and rheology of this Newtonian fluid mixing can be viewed as a simplified model of the behavior of mudflow at the bottom of estuaries for suspension studies. In this study, focus is on the stability and transition to turbulence of an initially laminar configuration. A parametric analysis is performed by varying the values of three control parameters, namely the viscosity ratio, the Richardson and Reynolds numbers, in the case of initially identical thickness of the velocity, density and viscosity profiles. The range of parameters has been chosen so as to mimic a wide variety of real configurations. This study shows that the Kelvin–Helmholtz instability is controlled by the local Reynolds and Richardson numbers of the inflection point. In addition, at moderate Reynolds number, viscosity stratification has a strong influence on the onset of instability, the latter being enhanced at high viscosity ratio, while at high Reynolds number, the influence is less pronounced. In all cases, we show that the thickness of the mixing layer (and thus resuspension) is increased by high viscosity stratification, in particular during the non-linear development of the instability and especially pairing processes. This study suggests that mud viscosity has to be taken into account for resuspension parameterizations because of its impact on the inflection point Reynolds number and the viscosity ratio, which are key parameters for shear instabilities.     

Changes in polybrominated diphenyl ether (PBDE) levels in cooked food

Food surveys for levels of toxic chemicals frequently report the levels on an uncooked basis. It is known that cooking may in some conditions decrease the amount of dioxins and related chemicals in food. Surveys of polybrominated diphenyl ether (PBDE) levels in food to date show data from uncooked food only. In this article, it was shown that broiling, with fat dripped from the foods reported here, ground beef, ground lamb, catfish, trout, and salmon, reduces the amount of PBDEs in these foods. This suggests that calculations of food intake need to take into consideration levels in the cooked food rather than in the uncooked food.     

Biochemical composition of a meso-bathyal lobster

To characterise some traits of the life strategies of Polycheles typhlops, a deep-sea small lobster usually encountered as by-catch within deep trawls in the Southern Tyrrhenian Sea (Mediterranean Sea), we analysed the biochemical composition of the caudal muscles of 49 specimens collected in March and April 2007. Differences in the biochemical composition between females and males were weak, but relevant differences in protein (>90% of the organic C) and lipid (4–6%) contents were observed between developmental stages both in females and males. These differences are likely to be related to different food items and/or to the metabolic shifts associated with their reproduction. We argue that this deep-sea lobster could cover a relevant role in the meso-pelagic food webs and attract future commercial interest.     

Bio-based films/nanopapers from lignocellulosic wastes for production of added-value micro-/nanomaterials

Environmental Science and Pollution Research - The growing demand for products with lower environmental impact and the extensive applicability of cellulose nanofibrils (CNFs) have received...     

INTEGRATING DEMOGRAPHIC AND LANDSAT (TM) DATA AT A WATERSHED SCALE1

ABSTRACT: Recurrent calls for integrated resource management urge that an understanding of human activities and populations be incorporated into natural resource research, management, and protection efforts. In this paper, we hypothesize that watersheds can be a valuable geography for organizing an inquiry into the relationship between humans and the environment, and we present a framework for conducting such efforts. The framework is grounded in the emerging field of landscape ecology and incorporates demographic theory and data. Demography has been advanced by technological capabilities associated with the 1990 Census. Employing Geographic Information System (GIS) tools, we couple Landsat Thematic Mapper (TM) land cover data with census‐derived housing density data to demonstrate the operation of our framework and its utility for better understanding human‐landscape interactions. In our investigation of the Kickapoo Watershed and two sub‐ watersheds, located in southwestern Wisconsin, we identify relationships between landscape composition and the distribution and social structure of human populations. Our findings offer insight into the interplay between people and biophysical systems.     

Genetic Introgression of Endemic Taxa by Non-natives: A Case Study with Leon Springs Pupfish and Sheepshead Minnow

Genetic studies of a pupfish (Cyprinodon bovinus) endemic to a small, spring-fed system in west Texas illustrate the potential for small introductions of non-native species to cause large-scale genetic changes through hybridization and genetic introgression. We performed a genetic survey (allozymes and RFLP analysis of mtDNA) of four samples of C. bovinus representing all wild populations of the species and a captive population maintained since 1976 at Dexter, New Mexico. The results indicate genetic introgression of the entire wild population by sheepshead minnow (C. variegatus), a coastal species with a history of introductions in west Texas. Frequencies of foreign genetic elements averaged across four diagnostic allozyme loci and mtDNA varied from 6.1 to 15.1%. The captive population appears free of foreign genetic material. Comparisons with past studies of C. bovinus indicate the present situation is largely due to a recent introduction of C. variegatus, not to an introduction in the mid-1970s; however, residual effects from the earlier introduction cannot be completely discounted. Genetic analysis indicates that the source of introduced C. variegatus in Diamond Y Draw is the nearest known population, an introduced stock in Lake Balmorhea approximately 90 km away. The results demonstrate the value of maintaining imperiled species in captivity. Captive C. bovinus provide an opportunity to restore the genetic integrity of wild populations.     

DNA fingerprints of a gorgonian coral: a method for detecting clonal structure in a vegetative species

Clonal reproduction, a common life history strategy among sessile marine invertebrates, can lead to high local abundances of one to a few genotypes in a population. Analysis of the clonal structure of such populations can provide insight into the ecological and evolutionary history of the population, but requires markers that can identify individual genets. Forensic and demographic studies have demonstrated that DNA fingerprinting can provide markers that are unique for an individual genotype. We have generated DNA fingerprints for over 70 colonies of the clonal gorgonian, Plexaura A (Plexaura sp. A) collected from June 1990 through July 1991 in the San Blas Islands, Panama. DNA fingerprints within a singic individual were identical and fingerprinting resolved multiple genotypes within and among reefs. On one reef in the San Blas Islands, Panama, 59% of the colonies sampled were of one genotype and this genotype was not found on any other sampled reefs. A previous study using tissue grafts identified 13 putative clones on these reefs, while DNA fingerprints of the same colonies differentiated 17 genotypes. The present study demonstrates the utility of DNA fingerprinting for distinguishing clones and for identifying clonal structure of marine invertebrate populations.     

Analysis of microbiological screen test data for antimicrobial residues in food animals

This study analyzes the National Residue Program (NRP) of the Food Safety and Inspection Service (FSIS), United States Department of Agriculture (USDA), data for the years 1983-1998 to determine the effectiveness of all three microbiological screen tests that were developed and used by the FSIS to control antimicrobial residues in food animals. The Swab Test On Premises (STOP) was the first screen test introduced in slaughterhouses, followed by the Calf Antibiotic Sulfonamide Test (CAST) and the Fast Antimicrobial Screen Test (FAST). The data for STOP indicates that during 1983-1998, the rate of food animal carcasses with violative levels of antimicrobial residues reduced from 2.33% to 0.45% under the monitoring plan and under the surveillance plan, the rate reduced from 55.1% to 0.56%. Similarly, the data for CAST indicates that the rate of calf carcasses with violative levels of antimicrobial residue also declined significantly during those years. Because of its higher sensitivity and shorter analytical time, the use of FAST started in 1995. By 1999, it had practically replaced the use of STOP and CAST in bovine species. The use of only one test such as FAST instead of different tests has removed confusion for testing different species of food animals and thereby has enhanced the efficiency of the NRP.