Marine Reserve Sustains Web of Life
The Leigh Marine Reserve (also known as Cape Rodney – Okakari Point Marine Reserve) in New Zealand was established in 1975, making it one of the oldest marine reserves in the world. It includes rocky reefs from the shoreline to depths of more than 10 meters along the North Island.
In the 1970s, much of the region’s seafloor was barren. Shallow kelp forests, which provided habitat for numerous animals, had been destroyed by grazing sea urchins. Nearly 30 years later, a scientific study found that kelp beds had recovered dramatically in the marine reserve, covering most of the seafloor. Fully fished areas outside, however, were still mostly barren.
Kelp forests now flourish inside the marine reserve because lack of fishing has allowed predatory fishes and lobsters to rebound there. The fishes and lobsters eat sea urchins, which graze on kelp. Snappers have become 8.7 times more abundant and spiny lobsters 3.7 times more abundant in the marine reserve than in the outside fished areas. An experiment testing survival of urchins (see graph below) showed that the abundant snappers and lobster predators in the marine reserve have kept the urchin population in check, allowing kelp to grow.
Outside the marine reserve, where fishing occurs, predatory snappers and lobsters are scarce, enabling urchins to increase in number quickly. Even a mass die-off of urchins did not allow kelp forests to recover outside the reserve.
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