Saving Precious Corals

by Julie Zeidner Russo

Their beauty is marvelous. Far beneath the ocean, precious corals in shocking pink, gold, alabaster, and black dot the ancient seamounts of Hawaii. When brushed by a predator, gold corals defense is to shoot bioluminescent sparks into the water creating a deepsea fireworks display. Otherwise, the corals look stately clustering on vertical limestone walls like miniature versions of the oak forests warranted protection by our national parks.

This perfection--paradoxically grand and delicate like the Japanese-manicured bonsai tree--must be captured. Prized as jewelry and other ornaments, a single ten-year old red coral can sell for $200 per lb. The precious coral industry in Hawaii, which has been inactive for the past 20 years, is about to start up again. The industry is already valued at more than $25 million at the retail level, according to marine ecologist R.A. Grigg.

Tangle nets dragged across the bottom of the ocean, which yank up branches of coral and tear apart their seabeds, are still used in many parts of the world where regulations are not in place to protect corals. Concern over the boom-bust cycle of precious coral fisheries in Taiwan, Japan, and the Mediterranean, prompted resource managers in Hawaii to set aside a refuge at the WesPac Bed in the Northwest Hawaiian Islands. Permits are required to fish for coral in the main Hawaiian Islands, and the coral, which can only be taken by the robotic arms of a submarine or ROV (Remotely Operated Vehicle), must be of reproductive maturity.

The purpose of the WesPac reserve--the only one of its kind established in the Hawaiian Islands or the northwest Emperor Seamount Chains--is to provide a reproductive reserve for the replenishment of corals beds. The refuge is also designed as a baseline study area for evaluating the effects of over-exploitation on other coral beds. But until recently, very little was known about the life history of corals, how they varied, or whether a sole refuge in Hawaii would serve its purpose. Any effort to protect precious corals would depend on reliable information about the fishery.

 

That's where oceanographers Amy Baco, George Roderick, and Craig Smith enter. In the first genetic study of precious corals in the Hawaiian Islands, the researchers will solve some of the mysteries associated with these distinct stocks in research that could help pave the way for effective management and protection of corals. Baco is a PhD candidate and Smith, an oceanography professor, at the University of Hawaii at Manoa. Roderick is an assistant researcher at the Center for Conservation Research and Training. The research is funded by the National Undersea Research Program (NURP)and the National Sea Grant College Program.

The arm of the Pisces V maneuvered the delicate task of breaking off small pieces of 283 individual corals.

"The precious corals fishery represents a huge potential income resource that needs to be managed properly or it's going to crash," Baco said. "Following a boom-bust cycle, it takes a long time (if ever) for the fishery to recover, whereas if you manage it properly there's a steady supply of resources."

Before the fishery can be managed properly researchers must first figure out how deep water corals live, reproduce, and vary. "Knowledge of stock structure, and the related issue of maintenance of genetic diversity, are often neglected with dire consequences for the exploited species," Roderick said. What genetic differences account for the spectacular range of coral colors and shapes? How closely are the corals related from one submerged island, and if so, what are the consequences of fishing out a population? Are precious corals in the WesPac "Refugium" sufficient for replenishing commercial beds of corals throughout the Hawaiian Islands?

Precious corals in the Hawaiian islands take advantage of historic volcanic activities and erosion, growing on the slopes of sunken islands where they can best feed on particles floating by. These "dwarf forest" coral beds at depths of 350 to 500 m., attract a tremendous diversity of life. At least 90 different species of gorgonians are found in the Hawaiian islands, Baco said.

Several recent genetic studies of shallow water corals in the Mediterranean have shown evidence for genetic isolation of populations in both hard and soft corals, Baco said. This means that a fished out population in one area would deprive another area close by of the genetic diversity it needs to remain healthy. While the precious corals of Hawaii are closely related to the ones in the Mediterranean, it is not known whether they exhibit similar reproductive strategies. "If significant genetic structure exists in populations of precious corals," Baco said, "this would suggest that elimination (through overharvesting) of a bed of precious corals would result in loss of overall genetic diversity within a species."

 

Genetic differences account for the spectacular range of coral colors and shapes.

On a map, precious corals look like a tiny constellation orbiting the main Hawaiian islands. Researchers theorize that gold, red and pink coral there have dispersed and multiplied across the submerged islands in a stepping stone pattern. "The issue comes down to how far these corals are able to disperse and how closely the coral populations on different islands are related," Baco said. "If gold corals need stepping stones, then if you fished out one of these beds along the way, it might be too great a distance for some of these corals to disperse, resulting in isolation of coral populations and reduced genetic diversity."

Six dives in the Pisces V submersible to the precious corals beds of Makapuu and other sites were performed by Baco last summer. The lights of the Pisces V illuminated the brilliantly colored corals. Its arms maneuvered the delicate task of breaking off the small pieces of 283 individual corals. With the coral's tissue, Baco and research assistants will be able to analyze DNA makeup, comparing corals from four different locations including samples from the WesPac bed.

An interesting development occurred during the research cruise. Baco shared dive time at French Frigate Shoals with marine biologist Frank Parrish of the National Marine Fisheries Service. With funding from NURP, Parrish is studying the endangered Hawaiian monk seal. The researchers observed species in the coral beds that are known to be prey of seals, and seals in the surface water's above the site. The seals could potentially use the coral beds as a fishing ground. The observation prompted fisheries and industry managers to amend harvest regulations to protect the forage habitat.

Results of the genetic analysis will take time to complete. However, researchers believe that it is not too soon to begin establishing additional coral bed refugia. "We expect to find that the WesPac Refugium is not reseeding precious coral beds on the main Hawaiian Islands," Baco said. "This suggests that a number of refugia should be established along the entire archipelago." Information gathered from the study is sure to substantially improve the management of the Hawaiian coral fishery as a sustainable resource, the researchers said.