Counting Fish and Corals

Kate Madin, Writer, Woods Hole Oceanographic Institution
Today on the Phoenix Islands expedition, scientists continued counting fish and coral. They work the reef by laying down lines of rope for a specific distance, then systematically count the fish or corals they see along the line, making notes on clip-boards they carry with them underwater.

Scientists have returned to this place seven years after a period of widespread bleaching on this reef, in order to assess the health of the reefs now. They hope to see whether an undisturbed reef system is more resilient to bleaching - and recovers faster - than reefs affected by human activity.

A group of us went ashore, to visit the island, including Greg Stone and Rob Barrel, who had both been there several times, to look for signs of the presence of rats or cats on the island. Both animals were introduced by humans, aren’t part of the natural island ecosystem, and cause great damage, so it’s important to know how many might still be there. There are large numbers of birds, such as the tern in the photo, as well as large sand and coconut crabs on the island. Tukabu, Director of the Phoenix Islands Protected Area and Tuake, Director of Research for Fisheries for Kiribati, came ashore with the rest of the landing party, and officially welcomed us to the country of Kiribati.

Nikumaroro is a coral atoll – a ring-shaped circle of coral sand and vegetation surrounding a central lagoon that opens to the sea through a channel. Scientists found abundant fish in that channel, and have also seen numerous manta rays, and many of the group took pictures of these large, plankton-feeding creatures, this one from Jim Stringer

The open, deep water surrounding a coral reef is intimately connected to the reef ecosystem, and in PIPA, the deep water is protected also. But to protect an ecosystem you have to know what’s in it. No one knows yet what animal plankton live in the open ocean around the Phoenix Islands.

So Larry Madin led four divers in a full blue-water dive today, looking for small or transparent animals (called zooplankton) that live in the open water, not near shore. Divers observed the water from the surface to about 80 feet, and collected several jelly-like transparent animals to identify back on the boat.

Tonight we leave Nikumaroro to survey other islands in PIPA, so everyone has to stow their equipment for the transit. The islands that make up the Phoenix Islands are far apart, and it may take a day of steaming to get there.