Table 2.— f-value and mean of larval densities for deplh and lime of day from 

 four-way analysis of variance of lobsler larvae data collected at stations EB-B 

 and EB-C using log,o(« + 1) transformed abundance per 1 .000 m J . 





Stage 





Depth 







Time o 



" day 







F-value 



M 



ean 



lvalue 





Mean 





Year 



Surface Bottom 



Day 





Night 



'1977 



I 



26.41" 



0.18 



0.08 



11.16" 



0.09 





0.17 





II 



38.29" 



0.09 



0.02 



19.53" 



0.08 





0.03 





HI 



31.09" 



0.07 



0.01 



10.99** 



0.57 





0.03 





IV 



26.75" 



0.06 



0.01 



1.34 



0.04 





0.03 





Total 



88.24" 



0.28 



0.11 



1.S0 



0.19 





0.21 



M978 



I 



4.28** 



0.11 



0.07 



0.14 



"0.09 





0.08 





11 



1.08 



0.05 



0.04 



4.95* 



0.06 





0.03 





111 



4.98* 



0.05 



0.03 



1.81 



0.04 





0.03 





IV 



104.39** 



0.20 



0.03 



12.83** 



0.14 





0.08 





Total 



67.04** 



0.34 



0.12 



6.50* 



0.26 





0.20 



•Means significantly different at 95% level. 

 "Means significantly different at 99% level. 

 1 14 June through 2 August. 

 : 15 June through 17 August. 



Table 3.— f-value and mean of larval densities 

 for time of day from three-way analysis of 

 variance using log lu (n + l) transformed abun- 

 dance per 1,000 m". 





Stage 



lvalue 



Mean 



Year 



Day Night 



'1977 



1 



2.18 



0.26 0.23 





II 



32.78** 



0.19 0.11 





III 



17.54** 



0.13 0.08 





IV 



1.10 



0.06 0.05 





Total 



17.01** 



0.41 0.32 



•'1978 



1 



0.13 



0.10 0.11 





II 



4.02* 



0.08 0.06 





III 



0.03 



0.06 0.06 





IV 



23.19" 



0.06 0.14 





Total 



15.37** 



0.39 0.28 



•Means significantly different at 95% level. 

 "Means significantly different at 99% level. 

 1 14 June through 2 August. 

 M5 June through 17 August. 



14 





1977 

 SURFACE 







- 



12 











- 



10 



- 



o DAY 











- 







• NIGHT 



















NS NOT SAMPLED 















E 6 



- 















- 



o 

 o 



O 4 



<r 

 £ 2 



- 



j 



1 



I 





1 





i 



- 



I 



I' 



1 • 





NS NS 





l 













- 



1977 

 NEAR-BOTTOM 









- 



a 



o 6 

 a 



< 



i « 



S 2 



■N 



- 



NSNS j 



JI 



s 



4S NS NS 



- 



• 



W 10 





1978 

 SURFACE 







_ 



Z 



< A 



z 

 3 6 













- 



2 

 " 4 



3 



2 





i 



1 



I H 





NS SS 



- 



4 





1976 

 NEAR-BOTTOM 







- 



2 





NS MS . . | | > 







- 







s 



<S NS NS 





EB-C 

 STATION 



Figure 4.— Vertical and diel distribution of lobsler larvae. Mean and standard 

 deviation of all surveys by station, depth, and lime of day. 



larval densities were noted however in some near-bottom 

 samples (Fig. 4). Day-night differences show no consistent 

 pattern at these stations (Table 2). 



When surface density at all four stations was compared 

 using three-way ANOVA (Table 3), daytime density was 

 significantly greater than night abundance for all stages 

 combined. For the individual stages where significant dif- 

 ferences were noted, day abundances were consistently higher 

 (Table 3). 



Geographical Distribution 



Average surface abundance in 1977 and 1978 was greatest 

 at the offshore stations for stages I- III; and was approximately 

 equal (1977) or greater (1978) at inshore stations for stage 

 IV larvae as indicated by three-way ANOVA (Fig. 5). Dis- 

 tribution of stage IV larvae was patchy, with 41% of all stage 

 IV larvae collected in two samples from EB-A and EB-B in 

 1978. 



The 1979 study was designed to examine broader geographic 

 distribution of lobster larvae in Block Island Sound. The mean 

 abundance of stage I lobster larvae in this study was generally 

 higher along the Point Judith transect and decreased succes- 

 sively along each of the western transects (Fig. 6, Table 4). 



A one-way ANOVA indicated that mean density of stage I 

 larvae was significantly different between stations at the 95% 

 level (F = 2.78, df = 11, 108). Station abundance means 

 were ranked and a Student-Newman-Keuls test performed to 

 determine significant groups. Abundance of stage I larvae was 

 significantly higher at stations in the eastern end of Block 

 Island Sound and at the offshore station EB-E. From 1 to 1 1 

 June (the last sampling date) the proportion of later stage 

 larvae steadily increased along all transects. Because sampling 

 was terminated in 1979 before the later stages would normally 

 peak, no further conclusions can be drawn with respect to 

 their distribution. However, the proportion of older larvae 

 was greater along western transects while the proportion of 

 stage I larvae remained higher along the eastern transects 

 (Table 4). 



