REPRODUCTIVE CYCLE OF CALYPTRAEA (TROCHITA) TROCHIFORMIS (GASTROPODA: CALYPTRAEIDAE) AT LA HERRADURA BAY, COQUIMBO, CHILE, USING AN EGGCAPSULE PRODUCTION INDEX

Abstract

Theannual reprod uctive eyeleof a subtidal populationof thebroodergastropod Calyptraea (Trochita) trochiforinis (Bom, 1778) is described throughout monthly sampling between february 1989 and march 1990 at Herradura Bay (29°58'55" S, 71°22’20''O), Coquimbo, Chile. Continuous production oí egg-capsule was detected. The numberof egg-capsules with early embryos (eggs trocophore) divided by the female shell length was regarded as an egg-capsule production índex. Such índex ranged between 0.68 1.01 capsules mm',decreasingduringsummermonths (<0.88 capsules mm1). A positiveand significant linear relationship between shell length of female (LO and number of egg-capsules (NC) was found (NC = 3,28 + 0,79 LO. Size of smalles females with egg capsules was 28 mm. The low valúes of this índex during the summer season are likely due lo: negative effeets of the increase of the sea water temperature, canalization of energy mainly to growth in detriment of reproduction, and, a reduction of the dissolved oxygen in the sea water by Coastal upwelling.