SynopsisEstimates of the rates of secondary production by the individual macrofaunal invertebrates of two Indian beaches are presented and these are combined to give an estimate of the energy flow through the macrobenthos of the two beaches. The production by individual species and by the macrofauna as a whole is compared with that of other tropical, and of temperate beaches, and it is concluded that a similar biomass in the tropical beaches produces a rate of turnover of biomass some ten times that of the temperate beaches. Values of production to biomass ratios (P/B) and of elimination to biomass ratios (E/B) for the invertebrates of sandy substrata in various geographical areas are reviewed and the use of these ratios in comparisons of productivity, and their relationship to mortality and longevity are discussed.
Observations were made on 2 beaches during the premonsoon period (January to March) when conditions were relatively stable. The beach below the berm at Cochin is 14 m wide with a slope of I in 8.5, and at Shertallai 40 m wide with a slope of I in 16. The well-sorted sand has a mean particle size of 275 ~ at Cochin and 175 ~ at Shertallai. The amount of chlorophyll attached to sand grains is very small. Chlorophyll in the water varies between 0.9 and 13.0 ~g/1. Carbon in the sand amounts to 210 to 630 ~.g/g, and in the water to 355 to 3660~g/1. Throughout observations, the water temperature remained about 3t ~ but on the dry sand surface it reached 50 ~ Fauna zonation on the 2 beaches is similar to that of other tropical beaches; crabs of the genus Ocypode and the isopod Eurydice sp. occur at high water mark, the polychaetes of the genera Glycera, Onuphis, Scoloplos and Lumbrinereis in the mid-intertidal region and below; the tidal migrants Bullia melanoides (Gastropods), Donax incarnatus and D. spiculum (Bivalvia) and Emerita holthuisi (Crustacea) inhabit the wash zone of the surf. The average biomass is 0.73 g carbon/m 2 at Shertallai and 0.85 g C/m 2 at Cochin, where fewer species are present. This compares with a value of 0.63 g C/m 2 for a sandy beach on the west coast of Scotland.
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