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The culturable aerobic heterotrophic benthic bacterial population and community structure in relation to the physico-chemical parameters in the continental slope of the Bay of Bengal was studied. In addition, diversity indices were calculated and pretsunami (in 2004) and post-tsunami (in 2005) diversity values were compared. Sediment samples were collected from two cruises in the depth zone of 214-1000 m (10°36′ N-20°01′ N and 79°59′ E-87°30′ E). The vertical distribution of the total heterotrophic bacterial population during both cruises was higher in the top section (0-3 cm) of the sediment. The average total heterotrophic bacterial population was in the range of 0.42-37.38 × 10 CFU/g to 1.66-19.73 × 10 CFU/g dry sediment weight during the two cruises, respectively. The limiting physico-chemical factors were sediment pH, sediment temperature, TOC, porosity, and clay as revealed from multiple regression ( r = 0.75) and BIOENV (Partial Correlation ρω = 0.447) analyses. The shannon-Wiener index (H′ log e), Simpson index ( D), Margalef index ( d) and Pielou's evenness index ( J′) were found to be higher in the 1000 m depth stations. Cluster analysis showed that the 500 m depth stations clustered either with the 200 m or with the 1000 m stations. The 200 m depth stations never formed a cluster with the 1000 m stations. Pre-tsunami diversity indices at two depth ranges (200 m and 1000 m) were higher than those of the post-tsunami indices, which was quite evident from the cluster analysis as well. This study confirms the effect of the tsunami surge in the sediments of the continental slope of the Bay of Bengal in the marine ecosystem, which is also attributed to the temporal variation of the heterotrophic bacterial population and diversity. [ABSTRACT FROM AUTHOR]

In the laboratory, under choice situation, C. longitarsus preferred shells with greater shell width and shell weight. The correlation coefficient values calculated between the crab and shell parameters in the laboratory sample showed that this hermit crab selects a shell of suitable dimension for its occupation. In the multiple regression equations calculated with carapace length against the three shell variables aperture width, shell width and shell weight which are deemed to be important for hermit crabs, the regression coefficient of the variables varied much. The unsealed first principal component explained 84·9% of the total variability of the shell parameters and scaled first principal component explained 95·8% of shell parameters. The scaled first principal component was found to be a reliable estimator of shell size and the hermit crab, if given a choice, selected a shell of suitable dimension which fits its body quite closely. [ABSTRACT FROM AUTHOR]

The development of the larvae of the marine hermit crab Clihanarius clibanarius (Herbst) reared in the laboratory (salinity 34‰±1‰ and temperature 28°C ±1°C) is reported. Four zoeal stages and a glaucothoe were observed during development. Characteristics of the larval stages are described and compared with other known species of this genus. The time taken for development from hatching to glaucothoe is given. [ABSTRACT FROM AUTHOR]