Marine environment microfiber contamination: Global patterns and the diversity of microparticle origins.

Microplastic and microfiber pollution has been documented in all major ocean basins. Microfibers are one of the most common microparticle pollutants along shorelines. Over 9 million tons of fibers are produced annually; 60% are synthetic and ∼25% are non-synthetic. Non-synthetic and semi-synthetic microfibers are infrequently documented and not typically included in marine environment impact analyses, resulting in underestimation of a potentially pervasive and harmful pollutant. We present the most extensive worldwide microparticle distribution dataset using 1-liter grab samples (n = 1393). Our citizen scientist driven study shows a global microparticle average of 11.8 ±â€¯24.0 particles L-1 (mean ±â€¯SD), approximately three orders of magnitude higher than global model predictions. Open ocean samples showed consistently higher densities than coastal samples, with the highest concentrations found in the polar oceans (n = 51), confirming previous empirical and theoretical studies. Particles were predominantly microfibers (91%) and 0.1-1.5 mm in length (77%), a smaller size than those captured in the majority of surface studies. Using µFT-IR we determined the material types of 113 pieces; 57% were classified as synthetic, 12% as semi-synthetic, and 31% as non-synthetic. Samples were taken globally, including from coastal environments and understudied ocean regions. Some of these sites are emerging as areas of concentrated floating plastic and anthropogenic debris, influenced by distant waste mismanagement and/or deposition of airborne particles. Incorporation of smaller-sized microfibers in oceanographic models, which has been lacking, will help us to better understand the movement and transformation of synthetic, semi-synthetic and non-synthetic microparticles in regional seas and ocean basins.

Sexual conflict: males with highest mating success convey the lowest fertilization benefits to females.

In natural populations of a coral reef fish (the bluehead wrasse, Thalassoma bifasciatum), males with the highest daily mating success produce the fewest sperm per mating, and this is reflected in significantly lower fertilization rates. The average amount released by males in pair-mating was 3.3 x 10(6) spermatozoa, resulting in a fertilization rate of 96%. Sperm released per spawn declined with increasing mating success, so that females mating with the most successful males had less than 93% of their eggs fertilized. It is unlikely that high mating-success males are physiologically incapable of increasing sperm production, because younger males with different mating strategies have absolutely larger testes and higher daily sperm output. Feeding experiments suggest that high-success males are diverting energy from gamete production to other fitness-enhancing activities such as mate guarding. Females incur the cost of low sperm release by having fewer of their eggs fertilized. There are no obvious compensatory benefits to females from mating with high-success males.

Variation in Fertilization Rate in the Tropical Reef Fish, Halichoeres bivattatus: Correlates and Implications.

Fertilization rates were estimated for natural spawns in the tropical wrasse, Halichoeres bivattatus. Fertilization rate averaged 88%, but varied with both sea conditions and with the addition of males (streakers) to pair spawns. As sea conditions became rougher, the mean fertilization rate for a day decreased. This effect was due to the two days with the roughest sea conditions and the lowest mean fertilization rates; there was no obvious trend when these two days were excluded from the analysis. On a given day, pair spawns, with a single male and female, had fertilization rates approximately 7% lower than spawns where 1-2 streakers joined the pair spawn. These results suggest that variation in fertilization rate must be considered as a potential selective force in shaping reproductive behavior in fishes with external fertilization of pelagic eggs.