Changes in plastic ingestion by yellow-legged gulls (Larus michahellis) over the breeding season

Gulls can be particularly vulnerable to ingesting plastics when using anthropogenic food sources, with potential consequences for survival and reproductive success. Although birds are known to switch foraging habitats over the breeding season to provide higher quality food for chick provisioning, it is unclear what this means regarding the ingestion of plastics. Here, we tested whether breeding gulls decrease the amount of plastic ingested during reproduction by collecting pellets from a series of monitored nests at a large yellow-legged gull (Larus michahellis) colony in southern France. We found at least one plastic item in 83.9 % of the analyzed pellets, with the most abundant plastic type being polyethylene-based sheet plastic. As predicted, we found a slight decrease in the number of plastic items in pellets at chick hatching. These results suggest that gulls, like other birds, may adjust foraging habits to provide more digestible, less risky, food to chicks.

Competition for vitamin B1 (thiamin) structures numerous ecological interactions

Thiamin (vitamin B1) is a cofactor required for essential biochemical reactions in all living organisms, yet free thiamin is scarce in the environment. The diversity of biochemical pathways involved in the acquisition, degradation, and synthesis of thiamin indicates that organisms have evolved numerous ecological strategies for meeting this nutritional requirement. In this review we synthesize information from multiple disciplines to show how the complex biochemistry of thiamin influences ecological outcomes of interactions between organisms in environments ranging from the open ocean and the Australian outback to the gastrointestinal tract of animals. We highlight population and ecosystem responses to the availability or absence of thiamin. These include widespread mortality of fishes, birds, and mammals, as well as the thiamin-dependent regulation of ocean productivity. Overall, we portray thiamin biochemistry as the foundation for molecularly mediated ecological interactions that influence survival and abundance of a vast array of organisms.

Unexpected abundance and long-term relative stability of the brown alga Cystoseira amentacea, hitherto regarded as a threatened species, in the north-western Mediterranean Sea

Cystoseira amentacea is a Mediterranean endemic alga thriving on very shallow rocky substrates. It has been considered as a threatened species, having experienced a steady decline and is therefore protected by international conventions. The historical distribution of the species has been assessed along the French Mediterranean coast, on the basis of 467 articles and herbarium vouchers. We have produced an accurate map of its current distribution and abundance along 1832 km of coastline, through in situ surveys. C. amentacea was observed along 1125 km of shoreline, including 33% of almost continuous or continuous belt. In most of its range, there is no evidence of loss, except in 4 areas of Provence, French Riviera and Corsica. A significant relation was found between the absence or low abundance of C. amentacea and the vicinity of ports and large sewage outfalls. The status of conservation of the species should therefore be reassessed.