Pirzada Jamal Ahmed Siddiqui

CYTOMORPHOLOGICAL CHARACTERIZATION OF THE PLANKTONIC DIAZOTROPHIC CYANOBACTERIA TRICHODESMIUM SPP. FROM THE INDIAN OCEAN AND CARIBBEAN AND SARGASSO SEAS1

Trichodesmium Ehrenberg species were collected in the Caribbean Sea, Sargasso Sea, and coastal areas of Tanzania (Indian Ocean). The specimens were divided into five species on the basis of morphometric characters such as cell dimensions and colony formation: T. tenue Wille, T. erythraeum Ehrenberg, T. thiebautii Gomont, T. hildebrandtii Gomont, and T. contortum Wille. In addition, Trichodesmium sp., a spherical colony of uncertain taxonomic position was examined. The cell structure of each species was investigated by means of light, scanning electron, and transvnission electron microscopy. Particular attention was paid to the presence and ultrastructural arrangement of gas vacuoles and glycogen fiber clusters (GFCs). This resulted in identification of two major groups of species: 1) T. tenue, Trichodesmium sp. with spherical‐shaped colonies, and T. erythraeum with GFCs and more or less localized gas vacuoles; and 2) T. thiebautii, T. hildebrandtii, and T. contortum lacking GFCs and with gas vacuoles spread at random. The species within each group were further characterized with respect to the dimension of the gas vesicles, cylindrical bodies, scroll bodies, and a new cellular inclusion body, Differences in colony formation and cell dimensions correlated with specific ultrastructural characters in five of the six forms. This is the first ultrastructural study comparing different forms of Trichodesmium sampled at geographically remote areas and shows that one species appears identical regardless of the sampling site. Some of the species had not been investigated earlier, and probably more species are to be identified and analyzed.

Maximum sustainable yield estimates of Ladypees, Sillago sihama (Forsskål), fishery in Pakistan using the ASPIC and CEDA packages

Using surplus production model packages of ASPIC (a stock-production model incorporating covariates) and CEDA (Catch effort data analysis), we analyzed the catch and effort data of Sillago sihama fishery in Pakistan. ASPIC estimates the parameters of MSY (maximum sustainable yield), Fmsy (fishing mortality), q (catchability coefficient), K (carrying capacity or unexploited biomass) and B1/K (maximum sustainable yield over initial biomass). The estimated non-bootstrapped value of MSY based on logistic was 598 t and that based on the Fox model was 415 t, which showed that the Fox model estimation was more conservative than that with the logistic model. The R2 with the logistic model (0.702) is larger than that with the Fox model (0.541), which indicates a better fit. The coefficient of variation (cv) of the estimated MSY was about 0.3, except for a larger value 88.87 and a smaller value of 0.173. In contrast to the ASPIC results, the R2 with the Fox model (0.651–0.692) was larger than that with the Schaefer model (0.435–0.567), indicating a better fit. The key parameters of CEDA are: MSY, K, q, and r (intrinsic growth), and the three error assumptions in using the models are normal, log normal and gamma. Parameter estimates from the Schaefer and Pella-Tomlinson models were similar. The MSY estimations from the above two models were 398 t, 549 t and 398 t for normal, log-normal and gamma error distributions, respectively. The MSY estimates from the Fox model were 381 t, 366 t and 366 t for the above three error assumptions, respectively. The Fox model estimates were smaller than those for the Schaefer and the Pella-Tomlinson models. In the light of the MSY estimations of 415 t from ASPIC for the Fox model and 381 t from CEDA for the Fox model, MSY for S. sihama is about 400 t. As the catch in 2003 was 401 t, we would suggest the fishery should be kept at the current level. Production models used here depend on the assumption that CPUE (catch per unit effort) data used in the study can reliably quantify temporal variability in population abundance, hence the modeling results would be wrong if such an assumption is not met. Because the reliability of this CPUE data in indexing fish population abundance is unknown, we should be cautious with the interpretation and use of the derived population and management parameters.

Sperm whale, Physeter macrocephalus , stranding on the Pakistani coast

Sperm whales (Physeter macrocephalus) occur frequently in stranding records worldwide. However, none have been reported along the Pakistani coastline to date. This paper documents the first reported stranding of a sperm whale on the Pakistani coast. Ultimately, this finding is important in the planning of Pakistan’s Biodiversity Action Plan and its National Conservation Strategy for marine mammals.

Morphotaxonomy and seasonal distribution of planktonic and benthic Prorocentrales in Karachi waters, Pakistan Northern Arabian Sea*

Morphotaxonomy and seasonal abundance of dinoflagellates of the genera Prorocentrum and Mesoporos (Prorocentrales) were studied from nutrient-rich waters, Karachi Harbor and the mouth of the Manora Channel, Pakistan during May 2002–July 2003. Using both light and scanning electron microscopy, 13 species of Prorocentrales were identified according to cell shape, size, ornamentation of thecal plates, and architecture of apical platelets, apical pore area, marginal pores, and intercalary bands. P. sigmoides, P. arcuatum, P. scutellum, P. donghaiense, P. balticum, P. minimum, P. emarginatum, P. lima, P. faustiae, and Mesoporos perforatus constitute new records for sindh coast of Pakistan. The most abundant species were P. minimum/P. balticum (4.5×103 cells/L), P. micans (1.1×103 cells/L), P. gracile / P. sigmoides (2.5×10 2 cells/L) and P. donghaiense (6.6×103 cells/L) at temperatures of 29–31°C and salinities of 35–40. Maximum abundance was observed in winter and lower abundance in summer. There was no significant change in the distribution of species between stations except for the benthic species which occurred close to Karachi Harbor waters. Significant positive correlations were observed between Prorocentrum spp. and temperature ( R2 =0.27) and negative correlations with salinity ( R2 =−0.32) except for P. minimum and P. emarginatum which has negative correlation with temperature (R2 =−0.24) and positive with salinity (R2 =0.08, 0.19). The finding of potential okadaic-acid producing species of benthic Prorocentrum call for monitoring for possible human health problems in this region.

Distribution, diversity and abundance of coral communities in the coastal waters of Pakistan

We assessed the distribution, diversity and abundance of corals in Pakistani waters. A total of 29 hard coral species (eight families and 14 genera), one black coral species and eight soft coral species (three families and seven genera) were recorded from 18 dive sites at nine locations along the coastline. Distribution of hard corals was extremely poor at Mubarak Village and Sandspit, and corals were not found at Goth Abdul Rehman, Gadani (Kuchiani) and Buleji. Moderately rich coral communities were recorded at Churna Island and at more exposed sites around Astola Island. By contrast highly diverse hard coral communities, with up to 80% cover, were found only at the northern sheltered side of Astola Island where Favites complanata, Favites pentagona, Coscinaraea monile and Porites nodifera were the most abundant species. Favites complanata was recorded from most dive sites at Astola Island. Porites nodifera and Pocillopora damicornis , and to a lesser extent Porites harrisoni, Leptastrea pruinosa and Psammocora obtusangulata formed large single species stands. No ‘true’ coral reef was found at any dive site; however, the formation of proto-reefs was evident around Astola Island. Soft corals were dominant at most exposed sites, particularly at Ormara (Roadrigues Shoals) and Jiwani. By comparing diversity with other locations in the region, corals distribution and growth appear to be fairly poor in Pakistan.

Cuvier's beaked whale, Ziphius cavirostris, remains recovered on the Pakistani coast.

*University Marine Biological Station, Millport, KA28 0EG, Scotland. †WWF-Pakistan, Karachi, Pakistan. ‡Marine Reference Collection and Resource Centre, University of Karachi, Pakistan. ∫Centre of Excellence in Marine Biology, University of Karachi, Pakistan. §School of Biological Sciences, University of Aberdeen, Scotland. ¶Department of Environmental Science and Policy, George Mason University, Virginia, USA. #Corresponding author, e-mail: mauvisgore@netscape.net

Sargassum swartzii extracts ameliorate memory functions by neurochemical modulation in a rat model

Recently, considerable attention has been paid to drug exploration from natural sources for treating memory loss, a major manifestation of various neurodegenerative diseases. Increasing evidences implicate brain serotonin metabolism in learning and memory, supporting the notion that targeting 5-HT (5-hydroxytryptamine) and its receptors would be beneficial in the treatment of cognitive disorders. In the present study, behavioral and neurochemical effects were examined following administration of Sargassum swartzii extracts in albino Wistar rats. Increase in spatial working memory and recognition memory was exhibited by the seaweed-treated rats as compared to controls. Plasma tryptophan, brain 5-HT, and 5-hydroxyindoleacetic acid levels were measured using HPLC–ECD, and a significant increase in brain 5-HT metabolism was observed in the seaweed-treated rats. The increase in memory functions following repeated administration of S. swartzii extracts is suggested to be due to the increased serotonergic neurotransmission in the brain of seaweed-treated rats.

Antidepressant-like deliverables from the sea: evidence on the efficacy of three different brown seaweeds via involvement of monoaminergic system

Brown seaweeds exhibit several health benefits in treating and managing wide array of ailments. In this study, the antidepressant-like effect of methaolic extracts from Sargassum swartzii (SS), Stoechospermum marginatum (SM), and Nizamuddinia zanardinii (NZ) was examined in forced swimming test (FST), in rats. Oral administration of SS, SM, and NZ extract (30–60 mg/kg) exhibited antidepressant-like activity in FST by reducing immobility time as compared to control group, without inducing significant change in ambulatory behavior in open field test. In order to evaluate the involvement of monoaminergic system, rats were pretreated with the inhibitor of brain serotonin stores p-chlorophenylalanin (PCPA), dopamine (SCH23390 and sulpiride), and adrenoceptor (prazosin and propranolol) antagonists. Rats receiving treatment for 28 days were decapitated and brains were analyzed for monoamine levels. It may be concluded that the extracts of SS, SM, and NZ produces antidepressant-like activity via modulation of brain monoaminergic system in a rat model. Antidepressant-like activities of selected brown seaweeds via modulation of monoaminergic system.

Quaternary fossil coral communities in uplifted strata along the Balochistan coast of Pakistan: understanding modern coral decline in the Arabian Sea

Uplifted reefs due to being important palaeoclimate archives and a rich source of information on past physical and geochemical changes globally have become the centre of marine research. The uplifted fossil Quaternary coral communities of Jiwani and Gwadar are perfect places to study the palaeoclimatic and geological changes that have shaped the Balochistan coast. Studies on the palaeodiversity of corals along the Makran coast of Pakistan are lacking. In the present study, the samples collected using line intercept method from four uplifted sites (Balochistan coast: one at Gwadar and three at Jiwani) were analysed. The relative distribution and diversity of scleractinian fossil corals was determined, and the factors responsible for coral decline along Pakistan coast were compared with modern coral distribution and diversity. A total of 48 fossil coral species were recorded in nine families and 22 genera. High coral diversity was recorded in the uplifted landward sites of Jiwani and Gwadar headland. Terraces close to the shore at Jiwani had lower diversity. The corals seem to be Quaternary: most likely Pleistocene to Holocene. The modern fauna lacks many species recorded in the fossil community, thus suggesting a faunal turnover in diversity and redistribution of coral fauna which may be linked with past geological events and increasing anthropogenic pressure.

Growth rates of dinoflagellates along the Karachi coast assessed by the size fractionation method

Abstract The in situ growth rates of dinoflagellates along the Karachi coast off Pakistan was studied by the size fractionated method during winter (February 2006) and summer (May 2007). The growth rate per day ranged from -2.87 to 2.3 d-1 (20 species) in winter and from 1.20 to 1.95 d-1 (13 species) in summer. Growth rates (μmax d-1) of the dominant species were as follows: Prorocentrum gracile, Prorocentrum minimum, Prorocentrum arcuatum (1.0-1.10), Protoperidinium steinii (0.92), Gonyaulax spinifera (0.69), Dinophysis acuminata (2.3), Dinophysis caudata (0.92), Ceratium lineatum, Prorocentrum micans (1.95), Gyrodinium sp. (1.88), Ceratium furca (1.70), and Alexandrium ostenfeldii (1.34). The declining growth rates were observed for Pyrophacus stein (-1.10), Scrippsiella trochoidea (-1.61 to -0.82), Prorocentrum donghaiense (-1.94) and Karenia mikimotoi (-2.48). Our results suggest that a higher temperature induce an increase in dinoflagellate growth rates.