Abstract:
The present status and population changes, the relationship between the environmental
factors and ecological service of Holothuria (Halodeima) atra Jager, 1833 in the marine plant genetic
conversation area, Mo Ko Samaesarn, Sattahip district, Chonburi province were investigated bimonthly
from January 2017 to November 2017. The results show that the average number of population and the
averagedensity of H. (H.) atra were 84.5 individuals and 0.42 individual/m
2
,respectively. In details, the
number of individuals is highest in November (144individuals), followed by May (135 individuals) and
June (99 individuals) whereas the lowest number of individuals is in January (35 individuals). It is
consequently indicated that population number of H. (H.) atra changed throughout the period of study
and is positively correlated with the amount of suspension in the sea water (R=0.909). In addition, the
fission of H. (H.) atra occurred throughout the year and the monthly incidence of fission was highest in
March (80%). The tidal pool of Haad Tein could support about 100-200 individuals/40 m2
of H. (H.)
atra. If it is more than that, they migrate to subtidal zone. H. (H.) atra lives in sandy sediment and eats
organic matter in sediment on the sea floor by constancy throughout both day and night. In terms of
ecological service of H. (H.) atra, the mean organic matter in the surrounding sediment, in digestive
tract and in feces was 0.78±0.11%, 1.76±0.26% and 0.85±0.16%, respectively. The amount of organic
matter in digestive tract was significantly different from that of the surrounding sediment and the feces
at the 0.05 level. So, the role of H. (H.) atra in the ecological service is recycling of organic matter in
sediment, which benefits to benthic animals. The quality of the sea water in Haad Teinis relatively good
compared with the standard of sea water for natural resource conservation.