BACKGROUND Sexual segregation in vertebrate foraging niche is often associated with sexual size dimorphism (SSD), i.e., ecological sexual dimorphism. Although foraging behavior of male and female seabirds can vary markedly, differences in isotopic (carbon, δ13C and nitrogen, δ15N) foraging niche are generally more pronounced within sexually dimorphic species and during phases when competition f...

We determined the δ15N and δ13C values of individual amino acids (AAs) isolated from chick blood of 4 penguin species that forage in different oceanic regions (from the subtropics of the Indian Ocean to Antarctica) to test if: (1) the δ15N values of phenylalanine (δNphe) revealed different foraging areas among the species; (2) the difference between glutamic acid and phenylalanine δ15N values (...

We studied the relative importance of several environmental factors for tundra plant communities in five locations across Svalbard (High Arctic) that differed in geographical location, oceanographic and climatic influence, and soil characteristics. The amount of marine-derived nitrogen in the soil supplied by seabirds was locally the most important of the studied environmental factors influenci...

The poorly known winter foraging ecology of the king penguin, a major Southern Ocean consumer, was investigated at the subantarctic Crozet Islands where the largest global population breeds. Blood δ13C and δ15N values were used as proxies of the birds' foraging habitat and diet, respectively, and circulating prolactin levels helped in determining the birds' reproductive status. Plasma prolactin...

In 2007, a study was undertaken of the long-term records of the ratios of stable isotopes of carbon (δ13C) and nitrogen (δ15N) in the skeletons of antipatharians (black corals) growing on reefs near the city of Jeddah, Saudi Arabia. Antipatharians were collected from more than 100 sites, and detailed records obtained from 31 individuals from 16 sites. Annual growth bands were identified and cou...

Stable isotope analysis in mysticete skin and baleen plates has been repeatedly used to assess diet and movement patterns. Accurate interpretation of isotope data depends on understanding isotopic incorporation rates for metabolically active tissues and growth rates for metabolically inert tissues. The aim of this research was to estimate isotopic incorporation rates in blue whale skin and bale...

Diazotrophic inputs by Trichodesmium have been shown to support production in tropical and subtropical marine environments, but the importance of Trichodesmium in the Gulf of Mexico has not been widely investigated. Here, we use stable carbon (δ13C) and nitrogen (δ15N) isotopes to determine whether diazotrophy impacts the isotope baselines of pelagic food webs in the northern Gulf of Mexico. Ph...

The cause(s) for the declines in marine mammal populations in the North Pacific and Bering Sea over the past 30 yr are unknown, despite progress in understanding the present ecology of this system. Explanations that attribute the declines to long-term decreases in marine productivity and/or short-term shifts in oceanographic conditions have been offered, but few studies have explored the issue ...

Determining the relative contributions of nitrate contamination in agricultural watersheds characterized by applications of both mineral and animal waste nitrogen to fields is important in evaluating the environmental consequences of these practices. Here, the use of nitrate–nitrogen (NO3−–N) stable isotopes to identify contaminant sources was examined in surface waters of an agricultural water...

Stable isotope analysis (SIA) is an important tool for investigation of animal dietary habits for determination of feeding niche. Ideally, fresh samples should be used for isotopic analysis, but logistics frequently demands preservation of organisms for analysis at a later time. The goal of this study was to establish the best methodology for preserving forest litter-dwelling crickets for later...