I. If ocean eddies or other currents acting to reduce 

 dispersal are predictable in time and space and meet 

 other basic criteria (i.e., the eddies persist at least 

 2.5 months and remain near islands) then: 



A. Spawning of coastal marine species with planktonic 

 larvae is expected to be synoptic with the time 

 that eddies are most probably present. 



B. Recruitment of pre- juveniles to the reef also will 

 be concurrent with eddies in time and space. 



II. If eddies occur but are unpredictable, dissolve sooner 

 than 2.5 months, or move far away, then: 



A. Spawning will be independent of eddy occurrence. 



B. Recruitment probably will be greatest when eddies 

 occur near shore but also will be unpredictable. 



The complex process of offshore transport and return of lar- 

 vae to coasts involves quasi-continuous exchange of recently 

 spawned eggs being swept offshore and older larvae being brought 

 back. Ocean currents affecting the transportation of larvae must 

 not only bring fish to hospitable coasts but also must do so 

 within time scales appropriate to larval developmental periods. 

 Larvae must not merely be brought back nearshore but must be 

 returned at a time when they can undergo metamorphosis and settle 

 onto reefs. Among the significant questions remaining are: What 

 is the mechanism by which larvae return to coastal habitats? Are 

 pre- juveniles (post-larvae) able to "home-in" on some cue and 

 actively swim some distance from sea to shore or is passive drift 

 the sole mechanism? 



A CONCEPTUAL MODEL FOR THE EFFECT OF MESOSCALE OCEAN CURRENTS 

 ON THE LIFE CYCLE OF REEF FISHES 



Our research to date has led us to formulate a working con- 

 ceptual model for the processes discussed above. In summary, 

 reproduction and recruitment of coastal fishes occurs to some 

 degree all year but with peaks during the spring-summer months in 

 Hawaii, with a phase lag of a few months between first reproduc- 

 tion and first recruitment. The offshore currents are variable 

 in both space and time (fairly rapid to quasi-steady) , and typi- 

 cally consist of one or more eddies and/or fronts and currents. 

 These mesoscale features will, in certain places, make contact 

 with sections of coasts on islands in the Hawaiian Archipelago. 

 This creates locations where offshore water is swept onto the 

 reef and locations where water is swept off. Thus, reef habitats 

 may be either near the source of steady incoming offshore water 

 or be situated further down stream along the same path. While an 

 eddy is quasistationary in adjacent offshore waters, all nearby 

 coastal currents are dominated by the eddy flow field, and drift- 

 ing particles are likely to be entrained. At other places or 



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