Browsing by Author "Golez, Ma. Salvacion N."
Population dynamics of the calanoid copepod, Acartia tsuensis in a brackish-water pond in the Philippines MSN Golez, A Ohno, JD Toledo, Y Tanaka & T Ishimaru -
Fisheries Science, 2002 - The Japanese Society of Fisheries ScienceThe occurrence pattern and population dynamics of Acartia tsuensis were investigated in a brackish-water pond in Panay Island in central Philippines by implementing both bi-monthly and daily sampling schemes. A. tsuensis occurred in the pond during the dry season (November-April) when the salinity of the water is in the range of 14 ~ 40 ppt but was completely absent at lower salinities. An almost constant rate of development from the nauplius 2 through to copepodite 5 stages of A. tsuensis was observed both in the pond and in the laboratory. The generation time ranged from 5.9~11.3 days. Fecundity had a positive linear corelation with chlorophyll a. Salinity and chlorophyll a affect the stage duration, mortality, and fecundity of A. tsuensis in the pond.
Preliminary investigation of feeding performance of larvae of early red-spotted grouper, Epinephelus coioides, reared with mixed zooplankton Larvae of red-spotted grouper, Epinephelus coioides, were reared in outdoor tanks with nauplii of copepods (mainly Pseudodiaptomus annandalei and Acartia tsuensis) and/or rotifers, Brachionus rotundiformis. Grouper larvae successfully started feeding on early stage nauplii even though their abundance was as low as approximately 100 individuals l-1 and showed better survival and growth thereafter compared to those fed with rotifers only. Incidence of feeding reached 100% on day 4 when nauplii were available and only on day 9 when rotifers were given alone. Larvae seemed to be poor feeders at the onset of feeding, attempting to capture any food organisms in the tank water. Selective feeding ability of larvae started from day 4 and the larvae then preferred to feed on medium- and large-size nauplii rather than on rotifers as they grew. Larvae appeared to have a better chance at surviving in the presence of early stage nauplii, which were probably caught more easily than rotifers.