S.No SPECIES St I St II
 I Bacillariaphycea (diatoms) Cells/1  
  Family : Coscinodisceae    
1 Coscinodiscus apiculatus + +
2 Coscinodiscus centralis * *
3 C. centralis + ++
4 C.concetricus + +
5 C.granii + +
6 C.gigas +++ +++
7 C.radiatus + +
8 C.thori * +
9 Cyclotella sp +++ ++
10 Diploneis sp. + +
11 Planktoniella sol + +++
12 Planktoniella sp ++ +++
13 Skeletonema costatum + ++
14 Thalassiosira sp +++ +++
 II Family: Triceratiinae (Diatoms)    
1 Ditylum brightwelli ++ +++
2 Ditylum sp +++ +
3 Triceratium reticuatum * +++
4 Triceratium sp +++ ++
III Family: Chaetoceraceae (Diatoms)    
1 Chaetoceros affinis * +
2 C. curvicetus ++ ++
3 C.decipiens ++ +++
4 C. messanensis + +
5 C.diversus ++ +++
6 C.indicus + +++
7 C.comosum * +
8 Bacteriostrum furcatum ++ +
 IV Family: Biddulphoidae (Diatoms)    
1 Biddulphia biddulphia + +++
2 B.heteroceros * +++
3 B.reticulata ++ +++
4 B. pulchella + +++
5 Odentella sinensis ++ +++
6 O.mobiliensis + ++
 V Family:Eucambiinae (Diatoms)    
1  Eucambia sp * +
 VI Family: Solenoidae (Diatoms)    
1 Leptocylindrus danicus * +
2 Rhizosolenia cylindrus ++ +++
3 R.imbricata + ++
4 R. styliformis ++ +
 VIII Family: Euodicidae (Diatoms)    
1 Hemdiscus sp + +
 IX Order:Pennales (Diatoms)    
  Family: Naviculaceae    
1 Pleurosigma angulatum + ++
2 P.elongatum ++ +++
3 P.depressum + +++
4 Nitzshia longissima + +
5 Pseudo-nitzschia sp. * +
6 Navicula sp ++ +++
 X Family:Fragilariaceae (Diatoms)    
1 Thalassiothrix sp ++ +++
2 Rhabdonema arcuatum + ++
Table 1: List of phytoplankton species in Muthupettai during April 2008 – March 2009.0