Why is the Pūpūkea MLCD Biologically Special?
The Pūpūkea MLCD is one of the very few places in Hawai‘i where an unchannelized stream flows into an MLCD and where both marine and terrestrial resources are actively managed. Although far from the ancient Hawaiian ahupua‘a management system, it is a step in that direction.
The entire Pūpūkea MLCD receives high wave activity in the winter months, mobilizing underwater boulders even at depths of 40 feet. Therefore it is educationally valuable as a study of high-wave impact zones because the wave activity has a profound affect on the ecology of the MLCD. Coral cover is relatively low, for example, and those that do live in the area are species that can withstand pounding waves.
Submarine caves are scattered around the MLCD and general area, including around the northeast point of the Pūpūkea cove.
Pūpūkea (Sharks Cove) is one of the most popular shore-entry destinations for snorkelers and SCUBA divers on O‘ahu, second only to Hanauma Bay. Pūpūkea has a depth of about 20 feet at the mouth of the cove. Diving is considered to be better outside the cove, where depths slope to about 45 feet. Waters just around the “tables” at Kalua-Māua are about 15 feet deep, and diving is considered to be better farther out at 30 to 45 feet.
The coral reef communities of the Pūpūkea MLCD have to contend with large swells every winter. So the coral cover is relatively low (10%) and includes mainly wave-resistant species. Encrusting coral dominate. According to a University of Hawai‘i CRAMP study, the most common corals in the MLCD are pōhaku puna (lobe coral) and cauliflower coral. Also present are crust coral, corrugated coral, and blue rice coral. CRAMP also reported finding the rare coral Montipora studeri in the area.
A recent statewide study of the 11 MLCDs titled “Marine Protected Areas in Hawai‘i” was conducted by Friedlander, Brown, Monaco, and Clark. The final report was dated March 9, 2005. Results showed that in the Pūpūkea MLCD, overall fish weight was four times higher in the MLCD compared to the outside areas open to fishing. Of the eleven MLCDs tested, Pūpūkea fell somewhere around the middle in relation to fish weight and reef life. Fish weight outside the MLCD was considered low (likely due to overfishing).
Major fish found in the MLCD were māikoiko (whitebar surgeon), mai‘i‘i (brown surgeon), na‘ena‘e (orange band surgeon), and umaumalei (orange spine unicornfish). No major apex fish such as ulua, or ‘omilu were found outside the MLCD. Hinalea (saddle wrasse) lau wiliwili (milletseed butterfly fish) and mai‘i‘i (brown surgeon) were common.
The University of Hawai‘i CRAMP study found that the most abundant fishes were the hinalea (saddle wrasse), while the mai‘i‘i (brown surgeon) had the highest biomass.