Oyster reproduction affected adversely by micro-plastics

Sciencemag.org reports, 1st February 2016: Increasingly, these molluscs are exposed to tiny pieces of plastic the same size as oysters’ preferred planktonplankton Plankton is a generic term for a wide variety of the smallest yet most important organisms form that drift in our oceans. They can exist in larger forms of more than 20cm as the larval forms of jellyfish, squid, starfish, sea urchins, etc. and can be algae, bacterial or even viral down to as small as 0.2µm. They are nutrient and light dependent, and form the essential foodchain baseline for larger dependent aquatic lifeforms. Fish species rely on the density and distribution of zooplankton to coincide with first-feeding larvae for good survival of their larvae, which can otherwise starve. Man-made impacts such as dredging, dams on rivers, waste dumping, etc can severely affect zooplankton density and distribution, which can in turn strongly affect larval survival and thus breeding success and stock strength of fish species and the entire ecosystem. They also form the essential basis of CO2 take up in our seas ecosystem, hence Global Warming. meals.

More plastic from various products and industrial processes ends up in the oceans each year, and over time, this waste breaks down into smaller and smaller pieces.

In a study published online in the Proceedings of the National Academy of Sciences, researchers show that when Pacific oysters (shown) are exposed to so-called microplastics in the lab, they ingest a large proportion: 69% of the 6-micrometer particles added to the water.

These end up in the oysters’ guts and make the animals invest less energy in reproduction, either by disrupting their digestion or their hormone systems.

Female oysters exposed to microplastics made 38% fewer eggs, and males made sperm that were 23% slower. Plus, they had fewer offspring, which were themselves slower to reach maturity.

This could create difficulties for aquaculture — Pacific oysters are grown for food around the world, and other filter feeder favourites such as mussels and sea cucumbers may be similarly affected.

Source: Sciencemag.org, 1st February 2016. For further details, see www.sciencemag.org/news/2016/02/tiny-bits-plastic-ocean-are-hurting-oyster-reproduction

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