The Development of Plankton Acoustics Descriptor in Inner Ambon Bay by Using Biosonic Echosounder DT-X.

Abstract

Plankton is a very important organism in the food chain of the water coloum. The aim of this research is to analyze some of the physical parameters of waters that suspected influenced the acoustic parameters of plankton, to get acoustic parameter values from plankton by using split beam echosounder for quantification and identification plankton and developed an acoustic descriptors to identification and quantification activities community of plankton. The research was carried out in March 2012, located in Inner Ambon Bay waters, Ambon Island, Moluccas province, at the position of 128o12’792” - 128o12’ 792” BT and 3o38’795” - 3o38’874” LS. The depth of the waters at the site of the research are 25,17-27.00 meters with an average depth of 25,93 meters. Water temperature is 28,84 – 30,10oC with average 29,43oC where during the daytime is 29,37oC, and at night is 29,48oC. The salinity average of each measurement range between 33,53-33,62 PSU, where the salinity at the surface of sea water are 31,76- 32,67 PSU and at bottom the waters are 33,80-33,89 PSU. The density of water are 1.019,79-1.019,39 kg.m-3. Average of the waters turbidity every observation are 0,949-0,957 NTU with the highest value is 0,921 and at the lowest is 1,005 NTU. The community of phytoplankton found in research locations are 26 genus consists of 6 classes that are classified in the class Bacillariophyceae (4 genera), Ciliatea (2 genera), Coscinodiscophyceae (10 genera), Cyanophyceae (1 genus), Dynophyceae (6 genera) and Fragilariophyceae (3 genera). The identification of zooplankton samples results, obtained the composition of zooplankton species in research location are 41 types consists of 6 phylum, which was the Arthropod, Chaetognatha, Cnidarians, Echinoderms, Molluscs and Annelids. There were 43 acoustics echogram data has been processed 7038 polygons to get 7 variable descriptors in 3 categories, namely morfometrik (high), bathymetric (depth and relative height) and energetic (Sv, skewness and kurtosis, Sa). K-means Cluster analysis results showed that the variables of Scattering volume and skewness were very influential in form a cluster while another variables. Discriminant analysis has shown that the contribution of 7 descriptors are used to form the descriptors are Sv (> 20%), Sa, depth and kurtosis contributed to 15-20%, and skewness contributed under 10- 14.99%. The discriminant function model is obtained from the results of this research provide the precision for 9 sampling time groups is 26.3% for classification.