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BODY SIZE I NDEX 



Figure 2. — Frequency of relative body size for successful (open 

 bar) and unsuccessful (solid bar) prawns in the prior resident 

 experiment. A body size index of one indicates one Macro- 

 hrachium rosenbergii was larger than the other in one body trait 

 but smaller in the other two body traits. 



partners (Kolmogorov-Smirnov Two Sample Test: 

 D max = 11,/? = 18,P = 0.01). 



SiniiiltaneoLi,>> Introduction Experiment 



A similar effect of size on shelter use was ob- 

 served in the simultaneous introduction experi- 

 ment (Figure 3; r, = 0.579, P<0. 001). Once again 

 larger animals used the shelters more often than 

 their smaller partners. 



Aggressive behavior was observed only on the 

 day of introduction. The nip and push occurred 



more often than the shove or tete-a-tete ( Figure 4). 

 Generally aggressive interactions were limited to 

 a few (one to three) bouts per 15 min (Figure 5), 

 and these bouts were usually one or two aggres- 

 sive acts long (Figure 6). 



Prior Resident Experiment by Simultaneous 

 Introduction Experiment 



A Kolmogorov-Smirnov chi-square approxima- 

 tion (Goodman 1954; Siegel 1956) revealed that 

 animals of the simultaneous introduction experi- 

 ment were more aggressive on the day of introduc- 

 tion than were animals in the prior resident exper- 

 iment on the day of immigration (x^ = 15.54, 

 P<0.002 for number of bouts/animal per 15-min 

 period; x^ - 13.877, P<0.002 for number of ag- 



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LU LU 



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12 3 4 



BODY SIZE INDEX 



5 



Figure 3. — Correlation between frequency of shelter use and 

 body size index for Macrobrachium rosenbergii, from the simul- 

 taneous introduction experiment. A body size index of one indi- 

 cates one animal was larger than the other in one body trait but 

 smaller in the other four body traits. 



Figure 4. — Frequency by type of aggressive acts observed on the 

 first day after introduction for the experiment on simultaneous 

 Macrobrachium rosenbergii introduction. Frequency equals the 

 number of aggressive acts by 17 animals. 



1 5i 



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z 



LU 



Z) 



O 



S 5- 



01 2345678 



NUMBER OF BOUTS PER 15 MINUTES 



Figures. — Frequency of number of aggressive bouts per animal 

 during the 15-min period of observation after simultaneous in- 

 troduction of male Macrobrachium rosenbergii (14 pairs). 



908 



