Community structure of hermatypic corals at Maro Reef in the northwestern Hawaiian Islands: A unique open atoll

Abstract

Percent cover of shallow-water (< 20m) scleractinian corals at Maro Reef, an open atoll with no perimeter reef in the Northwestern Hawaiian Islands (NWHI), was quantified from analysis of imagery recorded along more than 81 km of benthic habitat by towed divers and at 18 sites surveyed with video transects and photoquadrats. Colony densities and size class distributions were determined from censuses within belt transects at the same sites. All three methods showed statistically significant differences in total coral cover and relative abundance of coral genera among four geographic sectors characterized by different exposure to prevailing wave regimes. Massive and encrusting growth forms of Porites dominated coral cover and density throughout all sectors, with Montipora the next most dominant genus. Patterns of highest coral cover differed from that of most other classic and open atolls in the NWHI. Populations of Pocillopora, though contributing little to percent cover, attained the largest colony sizes of any reef system in the NWHI surveyed with similar methods. Numerous indicators, including coral percent cover, recovery from bleaching, low coral disease prevalence, rarity of crown-of-thorns seastars, and high larval recruitment rates suggest healthy coral communities at Maro Reef, although the predicted accumulation of marine debris from outside sources remains problematic. These data enable the most comprehensive quantitative description of coral communities at Maro Reef produced to date and are a valuable baseline for assessing change.

Coral Diversity and the Severity of Disease Outbreaks: A Cross-Regional Comparison ofAcroporaWhite Syndrome in a Species-Rich Region (American Samoa) with a Species-Poor Region (Northwestern Hawaiian Islands)

“…All Acropora sp., with a colony center within one meter on either side of the transect line (25 m × 2 m), were enumerated and placed into one of seven size classes: <5 cm, 5-10, 10-20, 20-40, 40-80, 80-160, and >160 cm. These protocols have been used successfully in other studies to document size class structure within the NWHI [54][55][56][57]. Colonies were identified to species whenever possible.…”

The Occurrence of Coral Species Reported as Threatened in Federally Protected Waters of the US Pacific

“…Of the 39 species recorded within the Marine National Monuments and National Wildlife Refuges (NWR) (Table 4), the highest numbers of Red List threatened coral species have been recorded from Kingman Reef NWR (24) and Palmyra Atoll NWR (21) in the Pacific Remote Islands MNM followed by Rose Atoll NWR and MNM (17). In the Islands Unit of the Mariana Trench MNM, the highest number of Red List threatened coral species has been recorded at Asuncion Island (7).…”

Status of Coral Reef Communities on Two Carbonate Platforms (Tun Sakaran Marine Park, East Sabah, Malaysia)

“…The cellular patterns are of different sizes and scales: cells 20 m in diameter, larger cells 200 m in diameter, and the largest (on Selakan Bank) about 1 km in diameter [12,13]. These reef patterns may occur (1) on fringing reefs, notably in the Arabian Gulf, in the Red sea [14,15], and in Madagascar [16], (2) on barrier reefs in New Georgia [17], in Belize [18], on the Great Barrier Reef [19][20][21], and in Mayotte [16], and (3) on atolls in Hawaii (Maro reef, [22]), in Fiji, in French Polynesia [23,24], and in Kiribati (Caroline/Millennium, [25]). According to Montaggioni [23] and Purkis and Riegl [15], the reticulated shape of the mesh reef could mimic a preexisting karst topography, inherited from an episode of lower sea level.…”