ABSTRACT
Coral recruitment was examined on terracotta tiles deployed for four six-month periods between March 2001 and April 2003 on the West Fore Reef at Discovery Bay, Jamaica. During each sampling period, four tiles were deployed on each of two arrays at six depths ranging from 3 m to 33 m. Only three Acropora spat recruited to the tiles over the sampling period. The Acropora spat recruited during only one of the four six-month sampling periods and at only one depth, 3m. That represents a density of 8 spat m(-2) at 3 m depth for one six-month sampling period. Acropora recruitment represented <1 % of the total spat recruiting to the tiles deployed at 3 m during the four sampling periods. Density of acroporids on the West Fore Reef is low. Only one Acropora colony (an A. palmata) was recorded during Point-Quarter surveys of coral cover and density at depths of 3 m, 9 m, 14 m and 19 m. Considering the paucity of acroporid colonies and the infrequent settlement of acroporid spat on the West Fore Reef, it is unlikely that the historic abundance of A. palmata and A. cervicornis will return soon.
Subject(s)
Animals , Anthozoa/physiology , Demography , Ecosystem , Seasons , Sexual Behavior, Animal/physiology , Biodiversity , Culture Media , Environmental Monitoring , Jamaica , Population Density , Population Dynamics , Reproduction/physiologyABSTRACT
Long-term, high accuracy seawater temperature data sets are essential in studies assessing environmental changes that may alter coral reef communities. Located at the approximately the same latitude, the subsurface seawater temperature (S3T) off Discovery Bay, Jamaica (DBJ) and the U.S. Virgin Islands (USVI) had the same overall mean temperature. The USVI S3T during the winter months is approximately 0.5 degrees C warmer than DBJ, while May - July at DBJ is approximately 1 degrees C warmer than USVI S3T. With the passing of tropical storms in 1995 and 1997 in the USVI S3T dropped as much as 1.5 degrees C within a 20 hr period and did not revert to the previous temperature during that calendar year. Mean monthly S3T during 2000 and 2001 in the USVI was > 0.5 degrees C warmer than during similar periods in the early 1990s. Mean monthly S3T during 1999-2002 at DBJ was 0.27 degrees C cooler than during 1994-1995.
Subject(s)
Environmental Monitoring , Seawater , Temperature , Jamaica , Seasons , United States Virgin IslandsABSTRACT
Puerulus settlement of the western Atlantic spiny lobster, Panulirus argus, was monitored using modified Witham collectors from December 1996 to March 1998 at seven sites around St. Thomas, U.S. Virgin Islands. A total of 605 pueruli were collected from 553 samples for a catch per unit effort (CPUE) for all sites of 1.09 pueruli. The greatest settlement occurred on sites within a recently declared marine reserve, which had an overall CPUE of 1.77 pueruli. Settlement in non-reserve sites was much lower with an overall CPUE of 0.31 pueruli. Pueruli recruitment declined 67 at inshore sites and 53 at offshore sites between July 1992 - April 1994 and February 1997 - March 1998. Also, only 10 of months sampled in 1997-98 had a CPUE > 0.5 compared to 55 in a previous study in 1992 - 1993. Despite the decline in pueruli CPUE in 1997-98 compared to 1992-94, the commercial lobster catch in the 2000-01 fishing season, and by inference the adult lobster population (legal lobster size in the US Virgin Islands is > or = 3.5 cm carapace length), remained stable.