Emergence Trap 



95 urn 

 mesh 



sail cloth 



20.5cm 



Figure 1.— Diagram of emergence trap used in this study. 



species when possible; numbers of major taxa and 

 groups are presented here for simpHcity and com- 

 parative purposes. 



Results 



The zooplankton caught in the traps at Alhgator 

 Reef were dominated by copepods. Other taxa and 

 categories that were collected included chaeto- 

 gnaths, nematodes, ostracods, polychaetes, cuma- 

 ceans, isopods, amphipods, and mysids, as well as 

 numerous others that were less common or fre- 

 quently caught (Table 1). Many of these groups, such 

 as the harpacticoid copepods, are well known as ben- 

 thic or near-bottom forms. Others, such as the 

 calanoid copepods, are known as primarily plank- 

 tonic animals that are sometimes observed close to 

 the bottom or other substrate. Many larval forms 

 of benthic macroinvertebrates were captured, espe- 

 cially settling stages, such as barnacle cyprids and 

 megalopae. 



Comparisons of the total mean numbers of animals 

 caught by each trap type and at each location show 

 that approximately 4 times as many animals were 

 caught by reentry traps as by emergence traps and 

 that about twice as many animals were captured at 

 the 7 m site as at the 20 m site (Table 1). Twelve 

 common groups together accounted for 97.9% of 

 all the animals caught. The results of two-way 

 ANOVAs showed that reentry traps captured sig- 

 nificantly more harpacticoid and cyclopoid copepods, 

 ostracods, mysids, polychaetes, and nematodes than 

 emergence traps, while the emergence traps cap- 

 tured significantly more calanoid copepods and 

 isopods (Table 2). Significantly more cumaceans, 

 gammarid amphipods, polychaetes, and nematodes 

 were captured at the 20 m site than at the 7 m site, 

 while significantly more calanoid copepods and chae- 

 tognaths were captured at the shallower location 

 (Table 2). The two-way ANOVAs showed significant 

 interaction effects between the trap types and sam- 

 pling locations on the numbers of harpacticoid and 



840 



