11/13/18

According to the study, rats have decimated seabird populations across 90 percent of the world's island archipelagos. Professor Nick Graham of Lancaster University in Britain says at a recent visit at the Chagos archipelago in the Indian Ocean,

there were stark differences between the islands populated with rats compared to the ones that were rude and free. Where there's rats, the sky's empty, the island's very quiet.

You go to an island with no rats, the sky's full of sea birds, it's very noisy and it smells. It's very pungent. You can smell the guano or the bird poo in the air.

The scientists found guano which is sometimes used as fertilizer to be crucial to the functioning of tropical ecosystems. The seabirds, they're flying great distances away from the islands,

and they're feeding in what we call the pelagic ecosystem, so the deep areas of the ocean. And then there they're flying back to the islands to roost and to breed,

and that's when they're depositing these rich nutrients that they've captured in the open ocean back onto the islands. Now when those nutrients go onto the coral reef

which was showing that it's boosting the productivity and the functioning of those reefs, rats eat bird eggs, chicks and even adult birds.

Rat-free Islands saw significantly more sea bird life and had nitrogen in the soil which made its way into the sea benefiting filter-feeding sponges, turf algae and fish.

Fish, unique in coral reefs and that they provide important processes or functions that help reefs be healthy and to bounce back from disturbances.

These are things like clearing away algae following disturbances, so new corals can settle and grow back on the reef.