Geology topics

James P. Beets

Publications and source records attributed to James P. Beets.

3 recordsLinked to original sources

USGS2011

Predator biomass, prey density, and species composition effects on group size in recruit coral reef fishes

Group incidence and size are described for recruit parrotfishes, wrasses, and damselfishes on Hawaiian reefs over 3 years (2006–2008) at sites spanning the archipelago (20–28°N, 155–177°W). Coral-poor and coral-rich areas were surveyed at sites with both low (Hawaii Island) and high (Midway Atoll) predator densities, facilitating examination of relations among predator and recruit densities, habitat, and group metrics. Predator and recruit densities varied spatially and temporally, with a sixfold range in total recruit densities among years. Group (≥2 recruits) metrics varied with time and tracked predator and recruit densities and the proportion of schooling species. Groups often included heterospecifics whose proportion increased with group size. A non-saturating relationship between group size and recruit density suggests that the anti-predator benefits of aggregation exceeded competitive costs. Grouping behavior may have overarching importance for recruit survival—even at high recruit densities—and merits further study on Hawaiian reefs and elsewhere.

Hawai'i↗

USGS2008

Ecology of coral reefs in the US Virgin Islands

The US Virgin Islands (USVI ) in the northeastern Caribbean, consist of St. Croix (207 km 2 ), St. Thomas (83 km 2 ), St. John (52 km 2 ) and numerous smaller islands (Dammann and Nellis 1992). They are part of the Lesser Antilles and Leeward Islands on the eastern boundary of the Caribbean plate (Fig. 8.1). An extensive platform underlies St. Thomas and St. John and connects these islands to Puerto Rico and the British Virgin Islands. This platform extends about 32 km north of the islands and then slopes gradually to depths of over 300 m and eventually descends into the 8,000 m deep Puerto Rican Trench. South of the islands, the platform extends about 13 km and then abruptly drops off to over 4,000 m. St. Croix, about 60 km to the south, is on a separate platform which is much shallower than the northern Virgin Islands’ platform and extends less than 5 km from shore except on the east end of the island. The deepest part of the Virgin Islands Trough that separates St. Thomas and St. John from St. Croix is 4,200 m.

Virgin Islands↗

USGS1999

Management implications of fish trap effectiveness in adjacent coral reef and gorgonian habitats

A combination of visual census and trap sampling in St. John, USVI indicated that traps performed better in gorgonian habitat than in adjacent coral reef habitat. Although most families were seen more commonly in coral habitat, they were caught more often in gorgonian areas. Traps probably fished more effectively in gorgonian habitats, especially for migrating species, because traps provided shelter in the relatively topographically uniform environment of gorgonian dominated habitats. Recently, trap fishermen on St. John have been moving effort away from traditionally fished nearshore coral reefs and into a variety of more homogeneous habitats such as gorgonian habitat. Consequently, exploitation rates of the already over-harvested reef fish resources may be increasing. Reef fish managers and marine reserve designers should consider limiting trap fishing in gorgonian habitats to slow the decline of reef fisheries.

Environmental Biology of Fishes↗