Congruence of intraspecific variability in leaf traits for two co-occurring estuarine angiosperms.

Studies seeking to identify sources of variability and trade-offs in leaf traits have done so by assembling large databases of traits, across species and time points. It is unclear to what extent interspecific patterns derived in such a manner apply to intraspecific variation, particularly at regional scales, and the extent to which interspecific patterns vary temporally. We tested the hypothesis that the leaf traits of two foundation species, the mangrove Avicennia marina and the eelgrass Zostera muelleri, would display similar patterns of intraspecific variability across gradients of latitude and estuarine condition, that match previously reported interspecific patterns, and that persist through time. We found intraspecific patterns of decreasing carbon to nitrogen ratio and mechanical elasticity, and increasing nitrogen content with latitude that were consistent between the two plant species, and with previously reported interspecific patterns for other groups of species. Specific leaf area, leaf toughness and total phenolics, by contrast, displayed species-specific patterns that varied markedly through time. Relationships between estuarine condition and leaf traits were highly variable temporally, and also displayed markedly different patterns of intraspecific variability between the two species. Our study highlights the considerable within-species variation in leaf traits that should be accounted for in regional to biome scale analyses. Although some intraspecific patterns mirrored those found across species, at global scales, the considerable variability in other leaf traits between species and through time highlights the need to better understand the drivers and constraints of this intraspecific variation.

Ingestion and defecation of marine debris by loggerhead sea turtles, Caretta caretta, from by-catches in the South-West Indian Ocean.

Marine debris, caused by anthropogenic pollution, is a major problem impacting marine wildlife worldwide. This study documents and quantifies the ingestion and defecation of debris by 74 loggerhead sea turtles, Caretta caretta, in the South-West Indian Ocean. Debris was found in 51.4% of gut or fecal samples of loggerheads by-catch from Reunion Island long liners. Anthropogenic debris was ubiquitous in our samples with plastics accounting for 96.2% of the total debris collected. No significant relationship was detected between the characteristics of ingested debris and the biometric characteristics of loggerheads. The number, weight, volume and mean length of debris were higher in gut content of deceased loggerheads than in fecal samples of live turtles, but not significantly, except for the mean length. This is the first record of debris ingestion by sea turtles in the Indian Ocean and our results highlight the magnitude of this pollution of the marine environment.