Ontogenetic exposure to light influences seabird vulnerability to light pollution.

Light pollution critically affects fledglings of burrow-nesting seabirds, leading to massive mortality events. The successful management of this pollutant depends upon a comprehensive understanding of the factors influencing visual sensitivity and corresponding behaviours towards light. Factors shaping the development of the visual system could account for variation in seabirds' vulnerability to light pollution. We investigated how Cory's shearwater chicks respond to selected contrasting artificial light stimuli. Chicks were subjected to blue and red light treatments, and repeatedly tested throughout the nestling period. We analysed behavioural responses (number, timing and orientation of reactions) to determine how age, exposure to experimental light stimuli and spectra influenced the onset of visually guided behaviours, thus inferring drivers of vulnerability to light pollution. Repetitive exposure to light significantly increased the number of reactions, and chicks predominantly displayed light avoidance behaviour. We did not find differences in the number of reactions, timing and orientation between blue and red light treatments. The responses did not differ across different age groups. These results provide empirical evidence for the contribution of the light available in the rearing environment to seabird visual development. They support the hypothesis that differential exposure to light during the growth period influences responses to artificial light, and that the state of visual development at fledging could be a main driver of the age bias observed during seabird fallout events. It is thus important to evaluate lighting schemes in both urban and natural areas, and determine the as yet unknown consequences that may be affecting the populations.

Beaches of the Azores archipelago as transitory repositories for small plastic fragments floating in the North-East Atlantic.

Plastic pollution is among the most pervasive stressors currently influencing the marine environment and affecting even the most remote areas. To date, there are still fundamental gaps in our understanding of the major pathways and fate of plastic debris in the oceans. Here we show that oceanic insular environments are important transitory repositories of small plastic items floating in the open ocean. Monthly monitoring of seven beaches over a three-year period demonstrate that beaches of the Azores islands with particular characteristics can capture significant quantities of fragments between 2 and 5 mm in length. The beach with the highest plastic loading rates was found to occasionally accumulate densities exceeding 15,000 fragments m-2 on part of the backshore. However, a large portion of these fragments can be rapidly washed back into the marine environment. Detailed characterization of those plastic items revealed the typology and size distribution to be similar throughout the seven beaches and through the 33 months surveyed, suggesting a same and unique source. Our results show that these oceanic islands of the North-East Atlantic are under pressure of high quantities of fragmented plastic debris that probably entered the ocean many years ago.

Spatio-temporal variability of beached macro-litter on remote islands of the North Atlantic.

Marine litter has been identified as one of the major environmental problems that oceans are currently facing. Worldwide efforts are being made to reduce the input of litter into the oceans, and projects aimed at monitoring their quantities are key to evaluate their success. This study, provide baseline information on the quantities of marine litter found on 42 beaches spread throughout the nine islands of the Azores archipelago, North Atlantic Ocean. A total of 31,439 items were collected throughout the archipelago with an average density of 0.62 ±â€¯0.15 macro-litter items m-2. Of this litter 87% were plastic and its majority (67%) plastic fragments. Six beaches were further monitored every three months for two years. Substrate type and wind exposure were important factors for explaining patterns of litter deposition. Our results highlight that marine litter have the tendency to accumulate in remote islands of the North Atlantic Ocean.