Increased primary plankton productivity was observed in a brackish water lagoon of Terengganu during the study period between January 1988 to December 1988. The lagoon is also the site for the fish cage culture activities of sea bass during the study period. An examination of water quality at the sampling stations during the study period indicated that both the organic and inorganic nutrients were high during the pre-monsoon period. The source of the nutrient in the lagoon was believed to be derived from the agro-based industrial effluents, fertilisers from paddy fields as well as untreated human and animal wastes. This coincided with the peak production of plankton in the surface waters of the brackish water lagoon. During this period both cultured and indigenous fish species were seen to suffer from oxygen asphyxiation (suffocation due to lack of oxygen). The primary productivity values ranged from 9 to 22 μg/L/h during the peak period while the microplankton species were composed of diatom, flagellates and dinoflagellates. Reduction in the primary productivity values were obtained with reduction in sallinity, specially during the peak monsoon months (November to March) corresponding to the Northeast monsoon period.
A body recovered from the water does not necessarily imply that death was due to drowning. The diagnosis of drowning is discussed together with the significance of the "diatom" and biochemical tests.
Detection of diatom frustules in bone marrow (diatom test) is used for diagnosing ante-mortem drowning where the usual signs of drowning are not present in dead bodies recovered from water. However, controversies over the reliability of diatom test results are continuing. There have been indications on the possibilities of diatoms entering into systemic circulation from atmospheric air, food and drink. While diatoms have been demonstrated in the gut content of edible marine forms such as shrimps and clams, the present study, for the first time, provides empirical evidence on the prevalence as well as abundance of diatom frustules in the samples of cooked non-vegetarian foodstuffs that impend human consumption in Kelantan, Malaysia. It is found that 50 g each of cleaned and cooked prawns and of clams impending human consumption contain about 8360 and 29,054 diatom frustules, respectively. A person accustomed to prawn and clam food would be ingesting an estimated 2 million diatoms in a single year. Considering the suggestion that detection of five diatom frustules in 10 g of bone marrow would suffice for concluding drowning as mode of death, and the fact that there is yet no proof that diatom frustules do not enter into the human systemic circulation through the digestive tract, the estimated number of diatom frustules routinely ingested acquires significance since entry of a few of such ingested frustules into the systemic circulation can lead to false positive test results. The findings of this research raise two important issues: first, population based routine food related diatom ingestion requires to be estimated, and, second, studies have to be initiated to categorically prove or disprove the possibility of entry of diatom frustules into the systemic circulation via the digestive tract.
The world’s biodiversity is not distributed uniformly throughout the globe. Some areas such as the tropical rainforests, seas and coral reefs teem with the varieties of life whereas others such as some deserts and polar regions are almost devoid of them (Gaston, 2000). Malaysia, with her tropical jungles and seas, is rich with biodiversity. She is fortunate to have had eminent pioneers such as Ridley (1967), Corner (1972), Soepadmo (1972) and Whitmore (1983) to study her flora and Medway (1968) and Lim (1991) to study her fauna taxonomy. Other pioneers in Malaysian biology included Berry, Dhaliwal and Mohsin. These pioneers are then ably followed by workers such as Latiff, Kiew, Go, Khoo, Davidson, Saberi, Omar, Jambari, Idris, Zekri, Teo, Marziah, Tan, Mukherjee, Shapor, Yusoff, Azmi and many others studying the various subdisciplines of biology. In addition to the more obvious large plants and animals, microorganisms and aquatic organisms had not been neglected either. Workers such as Nawawi, Verghese, Ho and Faridah are known
for their work on fungi while Fatimah, Phang, Japar and Anton had studied algae, seaweeds, diatoms and seagrasses. However, some of these workers have now either retired or are soon going to attain retirement age and the worrying part is that there are not many younger
workers keen to pursue research in taxonomy and biosystematics, a prerequisite to further studies in ecology, genetics, biotechnology which in turn are prerequisites for rational conservation, management and sustainable utilization of our rich biological resources. With each passing day species are becoming extinct sometimes without us even knowing that they had ever existed. Even in a developed country such as the USA, one third of her plant and animal species are at risk of extinction (McCann, 2000). Hence, taxonomic and biosystematic studies of our plants, animals and microbes whether terrestrial or aquatic, freshwater and marine, should be priority areas. So should studies on their reproductive biology, life cycles, physiology, feeding habits, migration patterns, predators and their sensitivities to environmental changes.
Elevated temperature affects marine benthic algae by reducing growth and limits the transport of electron or carbon fixation which may reduce the ability of the cell to use light. This resulting excess light energy may cause photoinhibition. In this study, the photosystem II of the benthic microalgal communities from Casey, eastern Antarctic were relatively unaffected by significant changes in temperatures up to 8ºC, along with high PAR level (450 μmol photons m–2 s–1). Similarly, the community was able to photosynthesize as the temperature was reduced to –5ºC. Recovery from saturating and photoinhibiting irradiances was not significantly influenced by temperatures at both –5ºC and 8ºC. These responses were consistent with those recorded by past experiments on Antarctic benthic diatoms and temperate diatoms which showed that climate change did not have a significant impact on the ability of benthic microalgae to recover from photoinhibitory temperature stress.
Many reports have revealed that the abundance of microalgae in shrimp ponds vary with changes in environmental factors such as light, temperature, pH, salinity and nutrient level throughout a shrimp culture period. In this study, shrimp cultivation period was divided into three stages (initial = week 0-5, mid = week 6-10 and final = week 11-15). Physical and chemical parameters throughout the cultivation period were studied and species composition of microalgae was monitored. Physical parameters were found to fluctuate widely with light intensity ranging between 182.23-1278 μmol photon m(-2)s(-1), temperature between 29.56°C -31.59°C, dissolved oxygen (DO) between 4.56-8.21 mg/l, pH between 7.65-8.49 and salinity between 20‰-30‰. Ammonium (NH4 (+)-N), nitrite (NO2 (-)-N), nitrate (NO3 (-)-N), and orthophosphate (PO4 (3-)-P) concentrations in the pond at all cultivation stages ranged from 0.017 to 0.38 mg/l, 0.24 to 2.12 mg/l, 0.06 to 0.98 mg/l and 0.16 to 1.93 mg/l respectively. Statistical test (ANOVA) showed that there were no significant difference (p<0.05) in nutrients concentrations among the cultivation stages. All nutrients concentrations however were still in the tolerable level and safe for shrimp culture. The chlorophyll a contents were found to range from 5.03±2.17 to 32.61±0.35 μg/l throughout the cultivation period. A total of 19 microalgae species were found in the shrimp pond, with diatoms contributing up to 72% of the species followed by Chlorophyta (11%) and Cyanophyta (11%). However, weekly species abundance varied through the study period. At the initial stage, when there were no shrimps in the pond, Anabaena spp. and Oscillatoria spp. (Cyanophyta) were the dominant species, followed by Chlorella sp. and Dunaliella sp. (Chlorophyta). When shrimps were introduced into the pond, Amphora sp., Navicula sp. Gyrosigma sp. and Nitzschia sp. (diatoms) started to exist. At the middle and towards the final stage of the shrimp culture period diatoms were the dominant species. The Chlorophyta (Chlorella sp.) domination took place only twice, which was at week 2 and 13. The absence of some of the coastal water microalgae species in the shrimp pond was most likely due to the fact that they could not tolerate the physicochemical factors of harsh environment. In this study, Cylindrotheca closterium was regarded as the most tolerant species among the microalgae due to its ability to exist for 6 weeks out of the 15 weeks of cultivation.
Three strains of the chain-forming diatom Skeletonema marinoi, differing in their production of polyunsaturated aldehydes (PUA) and nutritional food components, were used in experiments on feeding, egg production, hatching success, pellet production, and behavior of three common planktonic copepods: Acartia tonsa, Pseudocalanus elongatus, and Temora longicornis. The three different diatom strains (9B, 1G, and 7J) induced widely different effects on Acartia tonsa physiology, and the 9B strain induced different effects for the three copepods. In contrast, different strains induced no or small alterations in the distribution, swimming behavior, and turning frequency of the copepods. 22:6(n-3) fatty acid (DHA) and sterol content of the diet typically showed a positive effect on either egg production (A. tonsa) or hatching success (P. elongatus), while other measured compounds (PUA, other long-chain polyunsaturated fatty acids) of the algae had no obvious effects. Our results demonstrate that differences between strains of a given diatom species can generate effects on copepod physiology, which are as large as those induced by different algae species or groups. This emphasizes the need to identify the specific characteristics of local diatoms together with the interacting effects of different mineral, biochemical, and toxic compounds and their potential implications on different copepod species.
Field sampling was undertaken to investigate the occurrence of Pseudo-nitzschia Peragallo species in eight locations along the coast of Malaysian Borneo. A total of 108 strains of Pseudo-nitzschia species were isolated, and their morphology examined with SEM and TEM. Additionally, molecular data from nuclear-encoded partial LSU rDNA, and ITS regions, were characterized. A total of five species were confidently identified based on a combination of distinct morphological characteristics and supporting molecular evidence: P. brasiliana Lundholm, Hasle & Fryxell, P. cuspidata (Hasle) Hasle, P. dolorosa Lundholm & Moestrup, P. micropora Priisholm, Moestrup & Lundholm, and P. pungens (Grunow) Hasle var. pungens. However, one morphotype from Sarawak, while somewhat similar to P. caciantha, showed significant morphological distinction from this and any other of the currently described species. Most notably this morphotype possessed a characteristic pore arrangement in the poroids, with the fine pores in each perforation sector arranged in circles. Pair-wise sequence comparison of the LSU rDNA between this unidentified morphotype and P. caciantha Lundholm, Moestrup & Hasle, revealed 2.7% genetic divergence. Phylogenetic analyses strongly supported the monophyly of the morphotype. Based upon these supporting data it is here described as a new species, Pseudo-nitzschia circumpora sp. nov. A key to the six species of Pseudo-nitzschia from Malaysian Borneo is presented. Molecular signatures for all species were established based on structural comparisons of ITS2 rRNA transcripts.
Freshwater algae can be used as indicators to monitor freshwater ecosystem condition. Algae react quickly and predictably to a broad range of pollutants. Thus they provide early signals of worsening environment. This study was carried out to develop a computer-based image processing technique to automatically detect, recognize, and identify algae genera from the divisions Bacillariophyta, Chlorophyta and Cyanobacteria in Putrajaya Lake. Literature shows that most automated analyses and identification of algae images were limited to only one type of algae. Automated identification system for tropical freshwater algae is even non-existent and this study is partly to fill this gap.
Five years of data from 2001 until 2006 of warm unstratified shallow, oligotrophic to mesothropic tropical Putrajaya Lake, Malaysia were used to study pattern discovery and forecasting of the diatom abundance using supervised and unsupervised artificial neural networks. Recurrent artificial neural network (RANN) was used for the supervised artificial neural network and Kohonen Self Organizing Feature Maps (SOM) was used for unsupervised artificial neural network. RANN was applied for forecasting of diatom abundance. The RANN performance was measured in terms of root mean square error (RMSE) and the value reported was 29.12 cell/mL. Classification and clustering by SOM and sensitivity analysis from the RANN were used to reveal the relationship among water temperature, pH, nitrate nitrogen (NO3-N) concentration, chemical oxygen demand (COD) concentration and diatom abundance. The results indicated that the combination of supervised and unsupervised artificial neural network is important not only for forecasting algae abundance but also in reasoning and understanding ecological relationships. This in return will assist in better management of lake water quality.
A study on the morphology and phylogeny of 18 strains of Pseudo-nitzschia established from the Strait of Malacca, Peninsular Malaysia, was undertaken. Morphological data combined with molecular evidence show that they constitute three new species, for which the names, P. batesiana sp. nov., P. lundholmiae sp. nov., and P. fukuyoi sp. nov., are proposed. The three new species closely resemble species in the P. pseudodelicatissima complex sensu lato. Morphologically, P. batesiana differs from other species in the complex by having a smaller part of cell overlapping in the chain, whereas P. lundholmiae differs by having fewer poroid sectors and P. fukuyoi by having a distinct type of poroid sectors. Nucleotide sequences of the LSU rDNA (D1-D3) of the three new species reveal significant nucleotide sequence divergence (0.1%-9.3%) from each other and from other species in the P. pseudodelicatissima complex s.l. The three species are phylogenetically closely related to species in the P. pseudodelicatissima complex, with P. batesiana appearing as a sister taxon to P. circumpora, P. caciantha, and P. subpacifica; whereas P. lundholmiae and P. fukuyoi are more closely related to P. pseudodelicatissima and P. cuspidata. The three species show 2-3 compensatory base changes (CBCs) in their ITS2 transcripts when compared to the closely related species. The ITS2 with its structural information has proven its robustness in constructing a better resolved phylogenetic framework for Pseudo-nitzschia.
A new species of Pseudo-nitzschia (Bacillariophyceae) is described from plankton samples collected from Port Dickson (Malacca Strait, Malaysia) and Manzanillo Bay (Colima, Mexico). The species possesses a distinctive falcate cell valve, from which they form sickle-like colonies in both environmental samples and cultured strains. Detailed observation of frustules under TEM revealed ultrastructure that closely resembles P. decipiens, yet the new species differs by the valve shape and greater ranges of striae and poroid densities. The species is readily distinguished from the curve-shaped P. subcurvata by the presence of a central interspace. The morphological distinction is further supported by phylogenetic discrimination. We sequenced and analyzed the nuclear ribosomal RNA genes in the LSU and the second internal transcribed spacer, including its secondary structure, to infer the phylogenetic relationship of the new species with its closest relatives. The results revealed a distinct lineage of the new species, forming a sister cluster with its related species, P. decipiens and P. galaxiae, but not with P. subcurvata. We examined the domoic acid (DA) production of five cultured strains from Malaysia by Liquid chromatography-mass spectrometry (LC-MS), but they showed no detectable DA. Here, we present the taxonomic description of the vegetative cells, document the sexual reproduction, and detail the molecular phylogenetics of Pseudo-nitzschia sabit sp. nov.
Screening of the occurrence of potentially toxic diatoms was carried out at two sites of cage cultures in Tebrau Straits, Johor. Phytoplankton samples from Sungai Pendas and Teluk Sengat were collected using a 20 μm mesh plankton net and salinity was recorded in-situ. Nitzschia and Pseudo-nitzschia cells were isolated and established into clonal cultures. All cultures were tested for domoic acid using HPLC-UV analysis and verified by LC-MS analysis. Three Nitzschia spp. and one Pseudo-nitzschia sp. were identified from these locations. Toxic and non-toxic strains of Nitzschia navis-varingica are found at the cage culture areas. Cellular toxin content in the toxic strain of N. navis-varingica is 1.8 pg cell(-1). This is a new record from Malaysia and this species was isolated from estuarine water with salinity 28 PSU. The discovery of toxic Nitzschia species in Tebrau Straits indicates the potential for domoic acid accumulation in seafood.
This study was conducted to study the morphological features of species under the genus Chaetoceros isolated from the coastal waters of Pahang, Malaysia. The species were isolated, cultivated and viewed under light microscope (LM) and scanning electron microscope (SEM). Four taxa were successfully isolated and cultivated in pure culture, namely Chaetoceros affinis var. affinis, Chaetoceros affinis var. willei, Chaetoceros anastomosans and Chaetoceros baculites. Both varieties of C. affinis were considered as distinct taxa where both strains can be distinguished based on morphological characteristics. C. affinis var. affinis has a thick cell wall compared with C. affinis var. willei. C. anastomosans has special features including a silica bar on the intersection of setae and the production of mucous. The length of the aperture opening is a new record from this study. The new record obtained for C. baculites includes the size of the aperture, the terminal setae, spinal arrangement, the thinness of the cell wall and the location of the species in tropical waters. Detailed data on each species will be added to the taxonomic information for future studies.
Biofouling in canals and pipelines used for hydroelectric power generation decreases the flow capacity of conduits. A pipeline rig was designed consisting of test sections of varying substrata (PVC, painted steel) and light levels (transparent, frosted, opaque). Stalk-forming diatoms were abundant in both the frosted and transparent PVC pipes but negligible in the painted steel and opaque PVC pipes. Fungi were slightly more abundant in the painted steel pipe but equally present in all the other pipes while bacterial diversity was similar in all pipes. Photosynthetically functional biofouling (mainly diatoms) was able to develop in near darkness. Different biological fouling compositions generated differing friction factors. The highest friction factor was observed in the transparent pipe (densest diatom fouling), the lowest peak friction for the opaque PVC pipe (lowest fouling biomass), and with the painted steel pipe (high fouling biomass, but composed of fungal and bacterial crusts) being intermediate between the opaque and frosted PVC pipes.
Forty-eight isolates of Pseudo-nitzschia species were established from the Miri coast of Sarawak (Malaysian Borneo) and underwent TEM observation and molecular characterization. Ten species were found: P. abrensis, P. batesiana, P. fukuyoi, P. kodamae, P. lundholmiae, P. multistriata, P. pungens, P. subfraudulenta, as well as two additional new morphotypes, herein designated as P. bipertita sp. nov. and P. limii sp. nov. This is the first report of P. abrensis, P. batesiana, P. kodamae, P. fukuyoi, and P. lundholmiae in coastal waters of Malaysian Borneo. Pseudo-nitzschia bipertita differs from its congeners by the number of sectors that divide the poroids, densities of band striae, and its cingular band structure. Pseudo-nitzschia limii, a pseudo-cryptic species in the P. pseudodelicatissima complex sensu lato, is distinct by having wider proximal and distal mantles, a higher number of striae, and greater poroid height in the striae of the valvocopula. The species were further supported by the phylogenetic reconstructions of the nuclear-encoded large subunit ribosomal gene and the second internal transcribed spacer. Phylogenetically, P. bipertita clustered with its sister taxa (P. subpacifica + P. heimii); P. limii appears as a sister taxon to P. kodamae and P. hasleana in the ITS2 tree. Pairwise comparison of ITS2 transcripts with its closest relatives revealed the presence of both hemi- and compensatory base changes. Toxicity analysis showed detectable levels of domoic acid in P. abrensis, P. batesiana, P. lundholmiae, and P. subfraudulenta, but both new species tested below the detection limit.
The distribution of the toxic pennate diatom Nitzschia was investigated at four mangrove areas along the coastal brackish waters of Peninsular Malaysia. Eighty-two strains of N. navis-varingica were isolated and established, and their identity confirmed morphologically and molecularly. Frustule morphological characteristics of the strains examined are identical to previously identified N. navis-varingica, but with a sightly higher density of the number of areolae per 1μm (4-7 areolae). Both LSU and ITS rDNAs phylogenetic trees clustered all strains in the N. navis-varingica clade, with high sequence homogeneity in the LSU rDNA (0-0.3%), while the intraspecific divergences in the ITS2 data set reached up to 7.4%. Domoic acid (DA) and its geometrical isomers, isodomoic A (IA) and isodomoic B (IB), were detected in cultures of N. navis-varingica by FMOC-LC-FLD, and subsequently confirmed by LC-MS/MS, with selected ion monitoring (SIM) and multiple reaction monitoring (MRM) runs. DA contents ranged between 0.37 and 11.06pgcell-1. This study demonstrated that the toxigenic euryhaline diatom N. navis-varingica is widely distributed in Malaysian mangrove swamps, suggesting the risk of amnesic shellfish poisoning and the possibility of DA contamination in the mangrove-related fisheries products.
Marudu Bay, north coast of Sabah is characterized with mesotrophic water body and typical environmental parameters
throughout the year. The current study was undertaken to evaluate the effect of environmental parameters and nutrients
in mesotrophic water on the occurrence and distribution of potentially harmful phytoplankton species. The samplings
were conducted over a period of thirteen months, covering southwest monsoon (SWM), inter-monsoon (IM), and northeast
monsoon (NEM), at ten stations throughout the bay. Physical parameters (temperature, salinity, pH, dissolved oxygen,
current speed and secchi depth), biological parameters (cell densities of phytoplankton) and chemical parameters
(phosphate, nitrate, silicate and ammonia) were examined. The results indicated at least eight potentially harmful
phytoplankton species (Dinophysis caudata, D. miles, Ceratium furca, C. fursus, Prorocentrum micans, P. sigmoides, P.
triestinum and Pseudo-nitzschia sp.) were detected in north coast of Sabah. However, the potentially harmful phytoplankton
species contributed only about 1.3% of the total phytoplankton community. Under nutrient deprivation conditions, the
potentially harmful phytoplankton species distribution was mainly influenced by the ability to utilize other nitrogen
sources, cell mobility and toleration to low nutrients environments.
Two experiments were conducted to develop Acartia erythraea and Oithona brevicornis cultures: The performance of five microalgal diets to produce nauplii, copepodites and adults of A. erythraea; and the performance of the same diets to produce nauplii, copepodites and adults of O. brevicornis. The five different microalgal diets were Isochrysis galbana (IG), Chaetoceros affinis (CA), Chlorella marina (CM), Nannochloropsis oculata (NO) and mixed algae (mixture of IG, CA, CM and NO at an equal abundance to provide the exact cell density). The results indicated that the abundance of both A. erythraea and O. brevicornis was higher in tanks supplied with IG and mixed algae than the tanks supplied with CA, CM and NO. IG and mixed algal diets were statistically similar on the mean abundance for both A. erythraea and O. brevicornis. The maximum production of A. erythraea nauplii was observed on day 12 of culture period and the nauplii production decreased from day 13 onwards. The mean abundance of A. erythraea copepodites and adults increased along with time up to the end of the culture period. In the case of O. brevicornis nauplii, the maximum abundance was observed on day 9 day of culture period and the nauplii production decreased from day 10 onwards. The mean abundance of O. brevicornis copepodites and adults increased gradually from the beginning to the end of the culture period. Under the experimental conditions of this study, both IG and mixed algal diets can be recommended for the best growth performance of A. erythraea and O. brevicornis.