It is not our intent here to review past works on plankton 

 communities. The open ocean dynamics of plankton migrations and 

 global distributions are well known and have been extensively 

 discussed by others (e.g., Reid e_t aj,. 1978, Wiebe e_t al. 1976, 

 Cox and Wiebe 1979, Wiebe and Boyd 1978, Boyd et a_l. 1978) . 

 Among the remaining questions is how the physical dynamics 

 interact with the biological dynamics (e.g., reproductive pat- 

 terns, swimming and energetic abilities of the plankton, etc. ) to 

 form and maintain a "patch" (Haury e_t al . 1978) . Evidence for 

 the role of ocean eddies in trapping planktonic organisms can be 

 obtained by sampling zooplankton densities inside and outside of 

 eddies. In the few cases where such discrete sampling has been 

 done, the general result has shown higher abundances of zooplank- 

 ton in eddies than in surrounding waters (Uda 1957, Uda and 

 Ishino 1958, Wiebe ejt al. 1976, Ortner £t al. 1978). Other 

 planktonic populations can become trapped inside eddies and tran- 

 sported out of the species' normal range as the eddies move 

 (Wiebe et al. 1976, Ortner e_t a_l. 1978, Boyd et al. 1978, Wiebe 

 and Boyd 1979, Cox and Wiebe 1979) . Loeb (1979) presented data 

 on larvae and mesopelagic fishes which accumulate inside the 

 North Pacific Gyre (also, Reid e_t al. 1978) . 



REEF FISHES SPAWNING STRATEGIES 



The longstanding belief that tropical marine animals spawn 

 continuously throughout the year without seasonal variation no 

 longer appears generally valid. Distinct peaks of reproduction 

 have now been documented for marine fishes in several tropical 

 localities (Munro e_t al. 1973, Watson and Leis 1974, Johannes 

 1978, Lobel 1978, Nzioka 1979). In the absence of strong and 

 recognizable seasonal fluctuations characteristic of the tem- 

 perate latitudes, annual periods of peak reproduction by tropical 

 coastal marine species are difficult to explain. 



We have collected data and examined evidence which suggests 

 that seasonal reproduction by certain tropical species may be in 

 phase with variable offshore quasigeostrophic mesoscale circula- 

 tion. This circulation is a major environmental factor determin- 

 ing the fate of the planktonic larvae of coastal species. The 

 model species is one which lives its adult life in coastal marine 

 habitats but whose larvae are planktonic in offshore waters. 

 This is typical for a majority of reef fishes. Such species may 

 spawn seasonally in response to natural selection acting on the 

 survival of planktonic offspring. These offspring float with 

 ocean currents which advect and disperse them. 



Past emphasis has been on the idea that widespread transport 

 of planktonic larvae across long distances is an evolutionary 

 adaptation reducing the susceptibility of a population or lineage 

 to extinction by local catastrophes (Vermeij 1978) . The ecology 

 of some shore fishes, however, suggests the possibility that 

 transport of offspring far from the site of origin or native 

 habitat may not always be favored by Natural Selection. The 

 "lottery" hypothesis, described by Sale (1977, 1978, 1982) , is 

 based on experimental field evidence showing that the availabil- 

 ity of living sites limits the numbers of pomacentrid fishes and 



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