How many color metrics do we need? Evaluating how different color-scoring procedures explain carotenoid pigment content in avian bare-part and plumage ornaments

For a variety of technical and conceptual reasons, biologists have come to use several different methods to quantify the colors of animals. However, the relative abilities of these different color-scoring procedures to capture variation in the actual color-generating mechanisms—pigment or structural composition of the integument—have never been tested systematically. Here, we examined which commonly employed color metrics predict carotenoid content of ornaments in three avian species (house finch Carpodacus mexicanus, mallard duck Anas platyrhynchos, and zebra finch Taeniopygia guttata). We used spectrophotometry to measure reflectance spectra from beak and feather tissue, calculated numerous color metrics (e.g., hue, chroma, brightness, principal components, and tetrahedral color space position) from these spectra, and determined carotenoid content at the site of color measurement with high-performance liquid chromatography. We found that several principal component, tristimulus, and avian visual model metrics significantly correlated with carotenoid content of house finch feathers and duck beaks. Carotenoid content of mallard beaks was most closely correlated with brightness and saturation metrics, whereas in house finch feathers, carotenoid concentration was best captured by hue and saturation metrics. According to tristimulus scores and visual models, we found that the ultraviolet portion of the spectrum was not an essential predictor of variation in carotenoid content. Also, visual model chromatic contrasts generally were not significant predictors of carotenoid content, although some achromatic contrasts and tetrahedral color space vector parameters were. Our results indicate that numerous methods, especially tristimulus scores, are suitable for capturing pigment-based color variation in two carotenoid-containing ornaments, and we discuss the merits and shortcomings of these different approaches. In contrast, there were no significant relationships between any color metrics and the carotenoid content of zebra finch beaks, suggesting that other color-generating mechanisms besides carotenoids may contribute to color variability in this species.     

Adsorption of the quinolone antibiotic nalidixic acid onto anion-exchange and neutral polymers

Pharmaceutical products are being found in surface and ground waters around the world. While the consequences to human health are unknown, it is suspected that these contaminants adversely alter aquatic ecosystems. This study presents adsorption results for one pharmaceutical product, nalidixic acid (NA), on neutral and anion-exchange polymers at three pH values. The adsorption of NA below and above its pKa of approximately 6 on polymers with different matrices, forms, and degrees of polarity were evaluated. By comparing the Freundlich constants KF and n, the results show that the neutral form of NA adsorbs to a greater extent on neutral polymers, and that the anionic form of NA adsorbs more to anion-exchange polymers. Also, results of the adsorption experiments suggest that aromatic ring interactions between NA and the surface of both neutral and anion-exchange polymers are important in the adsorption process. These results have important implications for the treatment of pharmaceutical-contaminated water, as many pharmaceutical contaminants are ionizable and have aromatic rings in their structure. This study illustrates the importance of pH and sorbate and sorbent structure in considering polymer sorption for treatment of pharmaceutical-contaminated aqueous systems.     

Effects of El Niño on distribution and reproductive performance of Black Brant

Climate in low-latitude wintering areas may influence temperate and high-latitude breeding populations of birds, but demonstrations of such relationships have been rare because of difficulties in linking wintering with breeding populations. We used long-term aerial surveys in Mexican wintering areas and breeding areas in Alaska, USA, to assess numbers of Black Brant (Branta bernicla nigricans; hereafter brant) on their principal wintering and breeding area in El Ni?o and non-El Ni?o years. We used Pollock's robust design to directly estimate probability of breeding and apparent annual survival of individually marked brant at the Tutakoke River (TR) colony, Alaska, in each year between 1988 and 2001. Fewer brant wintered in Mexico during every El Ni?o event since 1965. Fewer brant were observed on the principal breeding area following each El Ni?o since surveys began in 1985. Probability of breeding was negatively related to January sea surface temperature along the subtropical coast of North America during the preceding winter. Between 23% (five-year-olds or older) and 30% (three-year-olds) fewer brant nested in 1998 following the strong El Ni?o event in the winter of 1997-1998 than in non-El Ni?o years. This finding is consistent with life history theory, which predicts that longer-lived species preserve adult survival at the expense of reproduction. Oceanographic conditions off Baja California, apparently by their effect on Zostera marina (eelgrass), strongly influence winter distribution of brant geese and their reproduction (but not survival), which in turn affects ecosystem dynamics in Alaska.     

Effects of knowledge,personal attribution and perception of ecosystem health on depreciative behaviors in the intertidal zone of Pacific Rim National Park and Reserve

Human activities levy a biological cost on ecosystems as resources are accessed and utilized at rates which are often incompatible with inherent ecosystem processes and structures. The recreational impact of humans upon intertidal zones and particularly fucoid algal assemblages is one major threat facing coastal ecosystems. The effect of human values, knowledge and perception in effecting biologically costly behaviors has rarely been examined. We hypothesize that with respect to intertidal zones: (1) Personal attribution and perception of ecosystem resiliency are more important than knowledge in determining the extent of depreciative behaviors individuals engage in, and; (2) Individuals who are uncertain about ecosystem resiliency will behave in a manner consistent with the 'precautionary principle'. We measured the depreciative behavior, and the attitudes and perceptions to ecosystem resilience, of visitors to Wick Headland in Pacific Rim National Park, British Columbia. Attitudes, knowledge, perceptions, and personal attribution were measured using questionnaire survey and structured interviews undertaken in situ. Depreciative behaviors of visitors were discreetly observed and correlated to the questionnaire survey and interview responses. We show that visitors who recorded greater knowledge of intertidal ecology engaged in more depreciative behaviors than visitors recording less knowledge. Visitors who perceived high ecosystem resilience in the intertidal zone engaged in significantly more behaviors eliciting biological cost than those who perceived low ecosystem resilience. Visitors who recorded uncertainty regarding ecosystem resilience engaged in significantly more depreciative behaviors than those who perceived low ecosystem resilience but slightly fewer depreciative behaviors than those who perceived high ecosystem resilience. Personal attribution was inversely correlated to the mean number of depreciative behaviors. We discuss the relevance of these results to the management of intertidal zones and marine protected areas, to multiple use management, the management of visitor impact, and natural resource use.