Ecological studies on the tropical limpet Cellana testudinaria (Linnaeus, 1758) : influence of environmental factors on the rocky shore benthos of the Big Kai Island, Southeast Molluccas, Indonesia
The present study addresses the effects of environmental factors (seawater temperature, salinity, humidity, precipitation, insolation, air temperature, wave action, and tidal cycle) on the ecology of the patellid limpet Cellana testudinaria at the intertidal rocky shore of Ohoiwait (Big Kai Island, Southeast Molluccas, Indonesia). The distribution, abundance and biomass of the intertidal limpet C. testudinaria are described separately for the high, middle and low shore levels. Analysis of variance showed significant density differences among shore levels, months, as well as a significant interaction between shore levels and months. The analysis of the successive frequency distributions suggested that the population consisted of 4 to 5 distinct age groups (cohorts) at any given time, and that two new cohorts recruited during the one-year investigation period. An analysis to determine the growth pattern using the FiSAT software showed that the longevity of C. testudinaria extended up to 2 years. The values of von Bertalanffy growth parameters (L?, K and t0), estimated from size-frequency distributions, were 33.1 mm, 1.4 yr-1, and 0.09, respectively. The present study also highlights the fact that the recruitment of C. testudinaria was highly variable between months and shore levels. The mean mortality of C. testudinaria was estimated, using three different methods, to be 94 % per year (Z = 2.81). A study on the reproduction of C. testudinaria indicated that the population consisted of 50 % neuters (incl. juveniles as well as adults with resting gonads and, hence, doubtful sex), 30 % adult males and 20 % adult females. The annual population production of C. testudinaria was estimated by the mass specific growth rate method to be 2.81 g m-2 or 60.7 kJ m-2 yr-1. The annual biomass turnover ratio (production to biomass ratio, P/B) was 2.77 yr-1. An examination of the body dimensions of C. testudinaria indicated that specimens collected from the three different shore levels were significantly different in shell length, width, height, distance from apex to anterior margin, distance from apex to posterior margin, and body weight.
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