Tasty, versatile, and rich in essential omega-3 fatty acids: salmon is one of the most popular edible fish of all. Shops sell fish caught in the wild, but their main produce is salmon from breeding farms which can pollute rivers, lakes and oceans. Just how big is the problem? Scientists are working to answer this question by examining the dissolved organic compounds which enter Chile’s rivers from salmon farms. They warn that these substances are placing huge strain on ecosystems and are changing entire biological communities. More here.