416 



Fishery Bulletin 88(2). 1990 



In the mud substrate, however, the tethered lobsters 

 walked significantly more and bulldozed significantly 

 less than the untethered lobsters {t test, p<0.05. Fig. 

 1). (There was a trend in the tethered lobsters to 

 bulldoze less in all of the substrates). Also, in the mud 

 substrate most tethered lobsters were unable to make 

 or maintain a burrow. Only 7.7% (2/13) of the lobsters 

 had constructed a complete burrow, deep enough to 

 hide the lobster at the end of the 24-hour period. This 

 result was significantly different from the untethered 

 group in which 69.2% (9/13) had constructed burrows 

 by the end of the experiment (chi-square test, /j<0.05). 



Discussion 



These observations demonstrate a substrate-specific 

 difference in the effect of tethering on the burrowing 

 behavior of juvenile lobsters. While tethering did not 

 substantially effect the behavior or burrow construc- 

 tion of lobsters in peat or cobble, lobsters tethered in 

 mud spent more time walking, less time bulldozing, and 

 were unable to build and maintain a burrow as well as 

 the untethered lobsters. The tethered lobsters in mud 

 would therefore be more vulnerable to predation than 

 the untethered controls, since being without a burrow 

 has been demonstrated to increase mortality due to 

 predation (Barshaw and Lavalli 1988). Heck and 

 Thoman (1981), Heck and Wilson (1988), and Barshaw 

 and Able (In press) conducted predator-prey experi- 

 ments using tethered crabs as the prey. Neopanopi 

 sayi, Panopeus herbsti, Libinia diibia, Ovalipefs ocella- 

 tus, and Callinectes sapidus were tethered using similar 

 techniques as were used in our study. These investi- 



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 m 

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LU 

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cr 

 111 



Q. 



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 m 

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 111 

 a. 



(/) 



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> 



LU 

 (/) 



m 

 O 



UJ 



o 



DC 

 UJ 

 CL 



lOOn 



90 

 80 

 70 

 60 

 50 

 40 

 30 

 20 



loi 







100- 

 90- 

 80 

 70 

 60 

 50 

 40 

 30 

 20- 

 10- 



100 

 90- 

 80- 

 70 

 60- 

 50- 

 40- 

 30- 

 20- 

 10 

 



MUD 



 NOT TETHERED 

 TETHERED 



WLK BLD 



COBBLE 



PPF 



RST 



 NOT TETHERED 

 E3 TETHERED 



PPF RST 



 NOT TETHERED 

 E3 TETHERED 



WLK 



BLD 



PPF 



RST 



Figure 1 



Average percent of the 33 observations in which lobsters were ob- 

 served doing each behavior in each substrate. WLK = walk. BLD 

 = bulldoze, PPF = pleopod fan, RST = rest. 



