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Physiological Observations on a Diatom Skeletonema Costatum (greville) Cleve

S. Khan
Corresponding author:
Department of Fisheries Management, Bangladesh Agricultural University, Mymensingh-2202, Bangladesh

Y. Onoue
Faculty of Fisheries, Kagoshima University 4-50-20 Shimoarata, Kagoshima 890, japan 1 Present address: Department of Fisheries Management Bangladesh Agricultural University, Mymensingh-2202, Bangladesh

O. Arakawa
Faculty of Fisheries, Kagoshima University 4-50-20 Shimoarata, Kagoshima 890, japan 1 Present address: Department of Fisheries Management Bangladesh Agricultural University, Mymensingh-2202, Bangladesh

M. M. Haque
Department of Fisheries Management, Bangladesh Agricultural University, Mymensingh-2202, Bangladesh

Abstract/ Executive Summary:

A chain-forming diatom Skeletonema costatum (Greville) Cleve collected from Yatsushiro Sea, Japan was cultured to determine the optimum level of some Physico-chemical factors for their growth under laboratory conditions. Filtered and sterilized aged sea water enriched by adding nutrient solution (Provasoli 1968) was used as the culture medium. The plankton could tolerate a wide range of salinities (3-55 ppt). Optimum growth was observed at salinities of 20- 35 ppt, temperatures of 20-25T, light intensities of 80-120 j..!E m-2 sec-1 and pH between 7.5 and 8.0. Growth did not occur at salinities below 3 ppt and at temperatures above 30°C. From the present study, it is concluded that 5. costatum was extremely euryhaline and tolerable to very low salinities.

Keywords: Diatom, Skeletonema costatum, Physico-chemical factors, Euryhaline

Location: Yatsushiro Sea, Japan

Start Date:

End Date:

Program Area: Variety and Species

Commodity: Fish, Fish farming, Water salinity, Climate change

Objectives:

To determine the effects of temperature, salinity, light intensity and pH on the growth of Yatsushiro Sea's strain of 5. costatum.

Methodology:

5keletonema. costatum used in this study was collected in 1991 from Yatsushiro Sea, Japan. An axenic culture was established by using the micropipette washing method. Stock cultures were grown in Provasoli's ES medium (Provasoli ·1968) at 25 ± 1ºC, light intensity 60 µE m^-2 sec^-1 and photoperiod 12:12-h, L:D cycle. Growth was determined at temperatures from 15.-40°C in SOC intervals, salinities from 0-65 parts per thousand (ppt), pH from 6.5 to 9.5 in 0.5 intervals and with irradiance adjusted to 10, 20, 40, 80, 120 and 200 µE m^-2 sec 1. Two salinity series (one spanning 0-5 ppt in 1 ppt intervals to determine minimum salinity for growth, and the other 5-65 ppt in 5 ppt intervals) were established by evaporating filtered Kagoshima Bay water (34.6 ppt) to get higher salinity media and by di.luting with deionized water to get lower salinity media. The pH of the medium was adjusted by addition of 1 N HCI or 1 N NaOH. Culture media were autoclaved for 15 min at 121 ^oc, and aged for several days prior to inoculation. Before starting the experiment the algae were acclimated to the experimental condition for at least two generations. Cells of mid logarithmic growth phase were used for inoculation to ensure that the cells were nutritionally replete. Sterilized micropipette were used to transfer the inocula. Individual growth medium in the culture tubes was gently shaken once a day for accelerating growth and to avoid the settlement of algal cells. All growth studies were done in triplicate. The cell concentration was determined by direct counting by using a Sedgewick-Rafter chamber. Counts were made immediately after inoculation and then each other day up to 10 days. For reducing errors due to possible synchronous divisions counts were made at the same time each day. Division rates under different conditions were subjected to analysis of variance (ANOVA) (Statview S.E. + Graphics, Abacus. Concepts, Inc.). Significant differences among the means were determined using Duncan's multiple range test (DMRT) (Gomez and Gomez 1984).

Source of Information: Bangladesh J. Fish. Res., 2(2), 1998: 109-118

Article Link (Online Journal):

Funding Source:

Budget:

Total Budget (Tk.) :

Achievement/Findings:

From the present experiment, it is concluded that 5. costatum from Yatsushiro Sea, Japan is extremely euryhaline and tolerable to very low salinities. Optimum growth occurred under a narrow range of temperature and it was strongly inhibited at high temperatures. Nutrients are one of the most important environmental factors that influence growth of any alga. The nutrient dynamics in Yatsushiro Sea, Japan and their effects on growth of 5. costatum and other phytoplankton are needed to be studied.

Knowledge Management: Journal