Lavalli: Survival and growth of Homarus amencanus fed plankton diets 



65 



Brine Shrlmp/Unfiltered Seawater 



Brine Shrimp/Filtered Seawater 



Mesoplankton 



Meso/microplankton 



Starved 



~ 



* No Data Available 

 **/•*• Died Before Molting 



18 18 19 



i * m — i i 



Initial Weights Final Weights 



WEIGHT MEASUREMENTS TAKEN 



Figure 3 



Initial (Stage V) and final (Stage IX) mean wet weight measurements (g) 

 for lobsters on the five diets: brine shrimp in unfiltered seawater, brine 

 shrimp in filtered seawater, mesoplankton (95-1000 ^m) in filtered seawater, 

 meso/microplankton combination (25-95jjm), and starved. Bars indicate 

 standard deviation values. ( a ) Two lobsters missed in weighing schedule. 

 ( h ) One lobster missed in weighing schedule. 



caridean shrimp zoea, Centropages and 

 Calanns copepods, dinoflagellates, and juve- 

 nile nemertea. The meso/microplankton 

 combination diet typically consisted of cen- 

 tric and pennate diatoms with occasional in- 

 stances of fragments of marine algae and 

 crustaceans. 



Discussion 



The results clearly indicate that early juve- 

 nile American lobsters are not capable of 

 extending survival on a diet consisting most- 

 ly of diatoms, despite their common pres- 

 ence in stomach content analyses (Herrick 

 1895, Williams 1907, Herrick 1911). Larger 

 planktonic organisms are required for sur- 

 vival and growth. This result is not entirely 

 surprising even though Lavalli and Barshaw 

 (1989) showed that post-larval and early 

 juvenile (Stage V) American lobsters could 

 remove particles from the water down to a 

 size of at least 70^m. Other crustaceans fed 

 on phytoplankton can gain some nutrients 

 and extend their survival in periods of low 



Brine Shrimp/Unaltered Seawater 



Brine Shrimp/Filtered Seawater 



Mesoplankton 



Meso /microplankton 



Starved 



• No Data Available 

 ••/»*• D,ed Before Molting 



15b 



CARAPACE MEASUREMENTS TAKEN 



Figure 4 



Initial (Stage V) and final 

 (Stage IX) mean carapace 

 length measurements (mm) 

 for lobsters on the five diets: 

 brine shrimp in unfiltered 

 seawater, brine shrimp in fil- 

 tered seawater, mesoplank- 

 ton (95-lOOO^m) in filtered 

 seawater, meso/microplank- 

 ton combination, and starved. 

 Bars indicate standard devia- 

 tion values. ( a ) Two lobsters 

 missed in carapace-length 

 measuring schedule. ( b ) One 

 lobster missed in carapace- 

 length measuring schedule. 



