## 3 Results and Discussion
### Biological Sampling
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & \multicolumn{6}{c}{**Time**} \\ \cline{2-7}
**ORGANISM** & **5/4/2016** & **7/4/2016** & **13/4/2016** & **18/4/2016** & **22/4/2016** & **25/5/2016** \\  & **18:05–18:22** & **18:13–18:31** & **17:48–18:13** & **17:34–18:01** & **17:20–17:49** & **16:20–16:43** \\ \hline
**PROTOZOA** & & & & & & \\ _Favella_ sp. & 565 & 198 & 734 & 0 & 85 & 85 \\ _Tintintopsis_ sp. & 0 & 148 & 0 & 44 & 42 & 0 \\ _Euttititititititi_ sp. & 0 & 49 & 0 & 0 & 0 & 85 \\ _Leputtititititititi_ sp. & 0 & 0 & 0 & 44 & 169 & 339 \\ _Gloigierna_ sp. & 0 & 0 & 0 & 0 & 127 & 0 \\ \hline
**CRUSTACEAN** & & & & & & \\ Naupplius (stadia) & 31,572 & 9390 & 15,327 & 5909 & 3558 & 6693 \\ _Olthous_ sp. & 1864 & 890 & 1468 & 1313 & 1567 & 2711 \\ _Microsetella_ sp. & 395 & 148 & 184 & 88 & 0 & 85 \\ _Paracalanus_ sp. & 339 & 593 & 1010 & 1007 & 1779 & 1949 \\ _Corycareus_ sp. & 0 & 0 & 92 & 44 & 0 & 0 \\ _Acartia_ sp. & 0 & 0 & 0 & 0 & 169 \\ \hline
**UROCHORDATE** & & & & & & \\ _Okopleura_ sp. & 169 & 99 & 0 & 0 & 0 & 1017 \\ \hline
**CHATOGNATH** & & & & & & \\ _Sagita_ sp. & 0 & 0 & 92 & 0 & 0 & 0 \\ \hline
**NEMATODE** & & & & & & \\ Nematoda Larvae (sp1) & 0 & 0 & 0 & 44 & 42 & 169 \\ \hline
**GASTROPDS** & & & & & & \\ Gastropoda Larvae (sp1) & 169 & 49 & 642 & 481 & 381 & 508 \\ \hline
**PELECYPODS** & & & & & & \\ Pelecypoda Larvae (sp1) & 169 & 445 & 367 & 88 & 42 & 85 \\ \hline
**POLYCHAETE** & & & & & & \\ Polychaeta Larvae (sp1) & 0 & 346 & 734 & 0 & 297 & 0 \\ \hline The number of Taxa & 8 & 11 & 10 & 10 & 11 & 12 \\ Abundance (ind m\({}^{-3}\)) & 35,242 & 12,355 & 20,650 & 9062 & 8089 & 13,895 \\ Diversity Index & 0.49 & 1.02 & 1.06 & 1.15 & 1.55 & 1.58 \\ Uniformity Index & 0.24 & 0.42 & 0.46 & 0.50 & 0.65 & 0.64 \\ Dominance Index & 0.81 & 0.59 & 0.56 & 0.46 & 0.28 & 0.30 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: The abundance of zooplankton (ind m\({}^{-3}\)) based on laboratory analysis for 6-day observation. The species of zooplankton were constituting the SSL, which caused deviations in the MVBS from the mean of different depth. Based on the result of biological collection and identification, it was found that the strong backscatter value might be caused by the most abundant type of zooplankton which was categorized as crustacean zooplankton. The most abundant and dominant species comprising the SSL were _Oithona_ sp., _Paracalanus_ sp., _Microsetella_ sp., _Corycareus_ sp., and in the form of nauplius stadia. The same results were shown in other research, with cyclopoids and calanoid being the dominant zooplankton in this location [52]. Among these species, _Oithona_ sp. was the most abundant with the average density of 1636 ind m\({}^{-3}\) followed by _Paracalanus_ sp. with 1113 ind m\({}^{-3}\). The average body length of the _Oithona_ sp. and _Paracalanus_ sp. were 0.74 mm and 0.39 mm, with a maximum of 1.09 mm and 0.93 mm, respectively. This species of zooplankton hence was considered to be the main scatterers in the observed area. DVM is typical behavior of the crustaceans [10] and based on the net-sampling and laboratory analysis; it is possible that the identified crustacean was moving in the observed area. _Oithona_ has been described as the most ubiquitous and abundant copep in the world's oceans [53] and also _Paracalanus_[54]. The diversity index shows that zooplankton species were found to be diverse, showed by values greater than 1. The dominance index also proves that there was a species that dominated other groups, shown by the value below 1 which was indicated by the high abundance of zooplankton from _Oithona_ sp. and _Paracalanus_ sp. from each net-sampling. The uniformity index shows low (<0.40) and medium (0.40-0.65) categories of the uniformity of zooplankton types.