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Articles by I. Johan
Total Records ( 3 ) for I. Johan
  A.S.M. Saifullah , M.K. Abu Hena , M.H. Idris , A.R. Halimah and I. Johan
  The composition and diversity of phytoplankton were studied along with physico-chemical parameters of water of two mangrove-dominated estuaries i.e., Kuala Sibuti (KS) and Kuala Nyalau (KN), Sarawak, Malaysia. A total of 46 species of phytoplankton with the mean density of 147000 cells L-1 were recorded from KS estuary i.e., 3 species of Cyanophyceae; 22 species of Bacillariophyceae; 20 species of Dinophyceae and 1 species of Chlorophyceae. The recorded mean density of phytoplankton was 113000 cells L-1 with 33 species from 19 genera from KN estuary, in which 19 species were from Bacillariophyceae; 12 species were from Dinophyceae; 1 species was from Cyanophyceae and 1 species was from Chlorophyceae. In both the estuaries, the species composition was found to be in an order of Diatom>Dinoflagellate>Cyanophyceae>Chlorophyceae. Canonical Correspondence Analysis (CCA) revealed that the abundance of Bacillariophyceae and Dinoflagellates was influenced by salinity and conductivity along with ammonium and phosphate while the abundance of Chlorophyceae was influenced by temperature, TDS, DO and pH in KS. The influence of salinity and conductivity along with PO4 and NH4 on the abundance of Bacillariophyceae, Dinoflagellates and Chlorophyceae were observed in KN.
  I. Johan , M.K. Abu Hena , M.H. Idris and A. Arshad
  The abundance and composition of copepod was carried out in the coastal waters of Bintulu, Sarawak, Malaysia on March 2005. Samples were collected using conical plankton net with the mesh size of 153 μm. Copepod identified comprised of four orders namely, Calanoida, Cyclopoida, Harpacticoida and Poecilostomatoida. A total of 49 species belonging to 26 genera were identified. Nine most abundant species were Paracalanus crassirostris, Paracalanus elegans, Temora stylifera, Temora turbinata, Oncaea venusta, Corycaeus andrewsi, Corycaeus subtilis, Paracalanus parvus and Paracalanus denudatus. The first four species mentioned were the most abundant species and they accounted for over 50% of the total numbers of identified copepods. Copepod species which were rare and low in abundance included Delius nudus, Acrocalanus gracilis, Tortanus forcipatus, Centropages orsini, Corycaeus dahlia, Copilia mirabilis, Labidocera minuta, Microstetella rosea and Cosmocalanus darwini. Cosmocalanus darwini is new record to Malaysian waters. Species richness and diversity tends to increase towards the offshore while abundance increased towards the inshore stations.
  I. Johan , W.O. Wan Maznah , M. Mashhor , M.K. Abu Hena and S.M.N. Amin
  Investigation on copepod communities in Perai river estuary was conducted from November 2005 to May 2006. Five stations were established for monthly sampling and were located from the river mouth to the upper reaches of the river. Copepod samples were collected from vertical tows using a standard zooplankton net. The Perai river estuary was slightly stratified and salinity decreases significantly from the mouth of the river towards the upper reaches of the river. A total of 28 species of copepods were recorded and comprised of 14 families, Paracalanidae, Oithonidae, Corycaeidae, Acartiidae, Calanidae, Centropagidae, Eucalanidae, Pontellidae, Pseudodiaptomidae, Tortanidae, Ectinosomatidae, Euterpinidae, Clausidiidae and Cyclopidae. A total of 10 species showed high positive affiliation towards salinity (R>0.60), Acartia spinicauda, Euterpina acutifrons, Microsetella norvegica, Oithona nana, Oithona simplex, Paracalanus crassirostris, Paracalanus elegans, Paracalanus parvus, Pseudodiaptomus sp. and Hemicyclops sp. The copepod species Pseudodiaptomus dauglishi were negatively affiliated towards salinity (R = -0.71). The copepod assemblages classified into two distinct groups according to salinity regimes, euryhaline-polyhaline group (25 marine affiliated species) and oligohaline-mesohaline group (3 freshwater affiliated species).
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