DENSITY-DEPENDENT GROWTH INHIBITION IN LOBSTERS,HOMARUS(DECAPODA, NEPHROPIDAE)

Open Access
Publisher Website
Google Scholar
Abstract
A density dependent inhibitory effect upon the growth of juvenile lobsters was studied in 2 semi-recirculating seawater-table systems in which controlled metabolite gradients were established by varying rate of makeup flow. Each system contained 8 columns of 45 compartments each. H. americanus 5th-stage juveniles were placed in the compartments in rows 5-10, 20-25 and 35-40, numbering from the incurrent end of each system, and 4th-stage H. americanus .times. H. gammarus F1 hybrids were placed in all other compartments. At the end of 93 days hybrids immediately downstream from the older animals were an average of 15% shorter than those 5 rows downstream. No effect of metabolite accumulation could be demonstrated. Analysis by a compartmental model indicated that the growth-inhibitory effect was chemical and was due either to a rapidly decaying, continuously produced inhibitor with a half-life of about 1 min, or to an inhibitor pulsed in production or release. Decreased growth in the middle of the blocks of older animals demonstrated that the effect was neither species- nor age-specific. The effect is substantially different from other growth-inhibitory phenomena previously described in Crustacea.