Intact navigation skills after bilateral loss of striate cortex.

A patient with bilateral damage to primary visual (striated) cortex has provided the opportunity to assess just what visual capacities are possible in the absence of geniculo-striate pathways. Patient TN suffered two strokes in succession, lesioning each visual cortex in turn and causing clinical blindness over his whole visual field. Functional and anatomical brain imaging assessments showed that TN completely lacks any functional visual cortex. We report here that, among other retained abilities, he can successfully navigate down the extent of a long corridor in which various barriers were placed. A video recording shows him skillfully avoiding and turning around the blockages. This demonstrates that extra-striate pathways in humans can sustain sophisticated visuo-spatial skills in the absence of perceptual awareness, akin to what has been previously reported in monkeys. It remains to be determined which of the several extra-striate pathways account for TN's intact navigation skills. © 2008 Elsevier Ltd. All rights reserved

The Influence of Diet on Mercury Intake by Little Tern Chicks

We assessed mercury levels in the feathers of little tern (Sternula albifrons) chicks from hatching to fledging and in their prey captured by adults in three main foraging habitats: lagoon, salinas, and adjacent sea. These data were used to model mercury concentration in chick feathers through food ingestion, in order to explore the effects that changes in diet would have on the mercury burden of chicks as they aged. The mercury concentration in feathers of chicks raised in sandy beaches was higher than in those raised in salinas. Lagoon prey had a significantly higher mercury concentration (0.18 ± 0.09 µg g-1 dry weight [d.w.]) than prey from salinas and the adjacent sea (both 0.06 ± 0.03 µg g-1 d.w.). In relation to prey species group, mercury content was significantly higher for bottom fish (0.17 ± 0.10 µg g-1 d.w.) than for pelagic (0.08 ± 0.06 µg g-1 d.w.), euryhaline fish (0.04 ± 0.02 µg g-1 d.w.), and crustacea (0.08 ± 0.03 µg g-1 d.w.). To understand the importance of mercury content of each prey group, we ran several theoretical scenarios assuming that chicks were fed on only one species at a time. Considering a diet restricted to lagoon (mostly benthic) prey, A- and B-chicks may encounter health problems with an excess of mercury. On the contrary, a diet restricted to marine (mostly pelagic) prey would decrease the mercury concentration in chick feathers; the fast growth rate and the related mercury dilution effect in little tern chicks seem to decrease mercury levels in their feathers. Our study supports the fact that marine pelagic prey are important for estuarine seabirds because they provide a food resource with lower contamination levels. This model may have a wider application in similar seabird species and coastal environments

Oil Vulnerability Index, Impact on Arctic Bird Populations (Proposing a Method for Calculating an Oil Vulnerability Index for the Arctic Seabirds)

In recent decades, political and commercial interest in the Arctic’s resources has increased dramatically. With the projected increase in shipping activity and hydrocarbon extraction, there is an increased risk to marine habitats and organisms. This comes with concomitant threats to the fragile Arctic environment especially from oil, whether from shipping accidents, pipeline leaks, or sub-surface well blowouts. Seabirds are among the most threatened group of birds, and the main threats to these species at-sea are commercial fishing and pollution. Seabirds are vulnerable to oil pollution, which can result in mass mortality events. Species are affected to a differing extent, therefore it is important to objectively predict which species are most at risk from oil spills and where. Assessing the vulnerability of seabirds to oil is achieved through establishing an index for the sensitivity of seabirds to oil – Oil Vulnerability Index (OVI). This incorporates spatial information on the distribution and density of birds as well as on species specific behaviours and other life history characteristics. This chapter focuses on the threat of oil to seabirds, especially in the Arctic, and how an OVI can be used to highlight which species are most at risk and where within the Arctic region.© Springer Nature Switzerland AG 2020. The attached file is the final accepted manuscript version