D i r e c t underw ater m ethods w ere used to ca rry out an ecological an d ocean ographic study o f a coral-reef tract. T h e reef tract, called the H opetow n reef, is located o ff E lb o w C a y , one o f a ch ain o f sm all islands th a t parallels the coasts o f L ittle an d G rea t A b a c o islands. T h e geological evid ence gathered suggests th a t the ch ain o f small islands is part o f a ridge form ed from a lithified w in d -laid sand dune over a line of coral remains. T h e reef studied is established at the edge o f a w a v e -cu t bench. A nalyses o f the reef sediments disclose a gradient o f sedim ent size from the reef barrier to the shore, w ith the greatest concentration of ben th ic anim als in the finer, more even-sized sediments in the shoreward h a lf of the reef area. T em p eratu re an d salinity gradients did not exceed the lim its o f tolerance for the coral anim als. L ig h t, th rough its influence on the sym biotic zooxanthellae, lim its the developm ent of the coral-reef grow th to less than 50 feet. L ig h t also influences the d epth an d position o f m a n y o f the corals. T h e d a ta gathered in d icate th a t w av e a c tiv ity plays a significant role in coral grow th and hence in horizontal zonation. T id a l currents flush the reef area co m p letely tw ice d aily an d are im portant in controlling the am oun t of sedim ent deposited throughout the reef. T h e zones of the reef were established b y sam plin g an d m easuring along a transect across the reef area. T h e significant organisms an d th e ecological factors most im portant to each zone w ere established. T h e zones identified were the S e a -F a n -S u r f Zone, M o n ta str e a -D e e p -W a te r Z one, A cropora p a lm a ta -A c tiv e -W a v e Zone, P o rites-M o d era te-W a v e Z on e, an d the E ch in o id -W e a k -W a v e -A c tio n Zone. Several distinctive phases m a y b e found in the various zones o f w h ich the cavern phase is most distinctive. W ith in the lagoon area betw een the line of sm all islands an d the m ain island shore, six m ajor types o f ecological association w ere identified. T id a l flow and bottom structure are the m ost im portant physical factors in these relationships. In sum m ary, the stu dy indicates the im portance of the slope o f the bottom in the reef area to the over-all structure of the d evelop in g reef. O f m ajor im portance to the developm ent o f B ah am ian coral reefs is the presence o f a ridge seaw ard o f the m ain island masses an d w hether or n o t the rid ge is subm ergent or em ergent. T h is factor w ill also regulate the position an d d e velopm en t of the coral reef. T h e conclusion is reached th at seaw ard o f the m ain reef barrier the reef masses m a y be entirely self-built. In the rem ainder of the reef, the reef structures m a y h a ve had a nucleus o f either a truncated section o f the island mass or a collapsed portion o f a cliff th a t h a d fallen into the sea. F in ally, the rapid erosion o f E lb o w C a y indicates th a t all...
From 1972 through 1981, 7,008 rock bass Ambloplites rupestris were tagged at sites along the southern shore of Lake Ontario; 854 tags (12.2%) were returned by anglers or recovered in the tagging program. Mean time and distance between tagging and recapture were 238 days and 15.5 km. Mean distance between release and recapture sites increased with time. One fish was taken 241 km from the release point. Rock bass tagged and recaptured in the prespawning period dispersed further than those tagged and recaptured after spawning. The predominantly eastward current along the southern shore of Lake Ontario had little overall effect on rock bass movements, but localized current patterns were reflected in dispersal. When dispersal from sites influenced by a thermal power‐plant discharge was compared to that from control sites, slightly more rock bass stayed in warmer plume areas than in nonplume areas, although few remained long in any one location. As has been found with other animal species, dispersal of the rock bass was best described by the theoretical regression curve Y = A exp(bXc); Y is the number of recaptures; A, b, and c are constants; and X is distance in km. Dispersal became more randomly distributed (c = 2) as time between release and recapture increased. Received May 20, 1982 Accepted May 27, 1983
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