(1) Depth profiles were established relating linear distance 

 from the reef and depth. 



(2) A quadrant frame (0.6m2) was employed for quantitative 

 analysis of the vegetation along the transect lines. The 

 species composition, per cent occurrence, size and/or 

 standing crop (grams dry weight/0. Gm^) of the plants with- 

 in the quadrants were recorded at approximately 15m (transect 1) 

 or 9m (transect 2) Intervals. The plant materials were 



sorted and identified in the habitat, and then dried and 

 weighed by the two support personnel. 



(3) A series of cages (see above section for dimensions) was 

 placed at different intervals (3, 60, 120 and 180m) 

 along transect 2, in order to exclude fish grazing and 

 evaluate the regrowth of seaweeds. 



Prior to positioning the cages, a 0.6m2 area was denuded and retained for 

 evaluation of species composition and biomass. The cages were fixed so 

 that 0.3m^ of the denuded area was within the cage. 



Two other studies were conducted from the habitat. The first was an 

 extension of the quadrant studies. A 15m rope was drawn out perpendicular 

 to the line transect (transect 2), with 7.5m north and south of the line. 

 Observations were then made in a rectangular area of 15 x 9m or 135m'^. 

 The shortest dimension of the rectangle (i.e., 9m) was oriented along the 

 transect line from east to west. Twenty separate 15 x 9m areas were 

 studied from - 180m. Representative samples of all the different 

 species present within an area were collected for subsequent identifica- 

 tion and enumeration. In addition, approximately 100 specimens of 

 several larger algae (i.e., Udotea conglutinata , Avrainvillea nigricans and 

 Halimeda incrassata ) were collected to determine the length of their thalli. 

 After all of the previous studies were completed, selected specimens of 

 algae from the sandy flat area were transported to the reef in order to 

 observe the feeding habits and/or specificity of the reef fish. 



NUMBER OF SPECIES AND BIOMASS AT VARIOUS DEPTHS 



Figure 2 is a comparative Illustration of the number of subtidal species 

 found at different depths in the Virgin Islands and in New England. The 

 depth distribution curve for the former area is a compilation of over 

 40 dives in Great Lameshur Bay, and it represents a "typical" situation 

 where a shallow water reef community is present. The New England informa- 

 tion has been rpeviously summarized by Mathleson, Hehre and Reynolds 

 (in press), and it Is based upon three years of diving observations at 

 Jeffrey Point, New Hampshire. Several points are obvious when one com- 

 pares the two distributional curves. Foremost, there is a conspicuous 

 reduction in species numbers in the immediate vicinity (depths) of the 

 reef. Above and below the reef the species numbers are higher. A 

 conspicuous increase in species was evident from 13.5 - 19.5m, No reduc- 

 tion in species numbers was recorded in shallow waters of nearby locations 

 which lacked coral reefs (e.g., Lesser Lameshur Bay). The distributional 



VI-109 



