Systematics, Biology & Seasonal Abundance of Plankton in Karachi Coastal Waters

Abstract

INTRODUCTION : Fourty five species were identified during period of this workout of which only seven plantonic copepods and the one chaetognath occurred regularly . Of the parasitic plantonic copepoda two new species i.e Cymbasoma tirmiziaw and cybasoam williamsoni were described and published . Reprints of the papers regarding the two new species have already been submitted to the Pakistan science foundation . Systematic Account Class Crustacea Sub class Branchiopoda Order Diplostraca Sub order Cladocera 1. Evadne pergestine 2. Penelia avirostris

Remarks : These two species start occurring in the plankton from march and last till June .This is a regular annual feature .Only one of the two dominates at one time . Small numbers of another cladoceran belonging to the genus podon were also found during the same period but the species could not be confirmed

Sub class Ostracoda 1. Asterope mariae 2. Philomedas lilljebogi 3. Pyrocpris sinuosa 4. Cypridine megalops

Remarks : These specie occurred in small numbers sporadically . Two more Ostracoda belonging to the genus Euconchoecia and the genus condonocera also occurred but their species could not be determined .

Sub class Copepods Sub order Calanoida

1. Acartia plumosa 2 .A. spinicauda 3.A. pacifica 4. Temora discaudata 5.T.stylifera 6.Centropage doresispinature 7.C. furcatas 8.C.velifivcate 9.Tortonus forcipatus 10.Paracalanus parvus 11.Calanus pauper 12.Rhincalanus cornutus 13. Undinula vulagaris

Remarks : Species numbered 1,2,4,6,7,10 and 13 occurred regularly and their abundance and distribution is described in Tables 7-27 in part iii . Species numbering 2,3,5,8, nd 9 are offshore species and their abundance in channel area is only in peak of the south west monsoon season ( also see tables 28-39 in part iii . Species nos 11,12 and 13 are of rare occurrence . Genere as Eucalanus Canadacia , Euchaeta , Acrocalanus and pontella also occured but could be identified to species . Another species resembling to Pleurommama indica was of rare occurrence but could not be confirmed . Suborder Cyclopoida

Remarks : Speciemens pertaining to species of the Genera , Oithona , Oncea and Coryceus occurred of which oithona sprciemens were most abundant . However species could not be confirmed . Remarks : Specimens belonging to Genera , Macrostella , Clytemnestra and Ecterpina occurred but could not be identified to species level . Suborder Monstrilloida 1. Monstrillopsis dubia 2. Cybasoma reigidum 3. C.tirmiziae 4. C.williamosi Remarks : These are the reproductive adult phases of parasitic copepods which are only occasionally hauled during nettings . Of these last two species are now to science . Sub class Malacostraca Order Peracrids Sub order Cumacae 1. Cuma scorpiodes 2. C.edwardsii 3. Cumella pygmae 4. Leucon acutirostris

Remarks : These species are benthic and occur only in night hauls occasionally . They did occur on several occasions on Manora channel plankto and as such may called tychoplankters . Order Eucarida Suborder Deecapoda 1. Lucifer typus 2. L.orientalis 3. L.penicillifer 4. L.henseni

Remarks : Lucifers occurred only in May , June and July . The paper regarding these species has been published and a reprint has already been sent to Pakistan Science foundation . Phylum Chaetognatha 1. Sagitta enflata 2. S.hexaptera 3. S.neglecta 4. S.bedoti 5. S.regularis 6. S.pulchra 7. S.bipunchata 8. S.robusta 9. S.pacifica 10. Pterosagitta draco 11. Krohnitta subtilis 12. K.pacifica 13. Spadella cephlophtera Remarks : The chaetognaths did occur almost regularly except Sagitta enflata which occurred regularly throughout the period of study (see part iii for breeding and Growth of S.enflata ) Phylum Protozoa Class . Mastigophore Order . Dinoflagellata 1.Ceratium tripos Remarks : This species occurs in the Feb.attainting highest numbers in March and lasting till the end of April .