Pediastrum Simplex Research Articles

A Comparative Study of Phytoplankton Communities and Eutrophication Status in Two Urban Ponds Within Dhaka Metropolis

Changes in physicochemical water quality and plankton biomass over time can clearly indicate the eutrophication status of a water body. Urban ponds are particularly susceptible to cultural and natural eutrophication, making it essential to study their water quality and phytoplankton biomass. This study examined two urban ponds within the University of Dhaka campus: Shahidullah Hall Pond (SH-pond) and Museum Pond (Mu-pond). Common phytoplankton in both ponds included species like Pediastrum simplex, Melosira granulata var. angustata, Synedra nana, Ceratium sp., and Ceratium furcoides, along with zooplankton such as Brachionus sp., Keratella cochlearis, and copepod nauplii. The higher diversity of zooplankton compared to phytoplankton suggests that zooplankton overgrazing has reduced phytoplankton species composition. The study’s results indicate a clear trend of eutrophication in both ponds. Over three decades, SH-pond showed increases in water temperature (4.5°C), alkalinity (0.32 meq/L), dissolved oxygen (6.84 mg/L), soluble reactive phosphorus (21.35 μg/L), nitrate (137.77 μg/L), and chlorophyll-a (23.76 μg/L), with water transparency decreasing by 67 cm. Eutrophication indicators like dissolved oxygen, nitrogen, phosphorus, and phytoplankton biomass (chlorophyll-a) increased by 1.9, 1.82, 2.23, and 2.21 times, respectively, suggesting significant eutrophication in Sh-pond. In contrast, over 26 years, Mu-pond data showed decreases in water temperature (2.66°C), pH (0.18), conductivity (31 μS/cm), silica (12.17 mg/L), and chlorophyll-a (12.4 μg/L), but increases in dissolved oxygen (7.61 mg/L), soluble reactive phosphorus (1.16 μg/L), and nitrate nitrogen (170.75 μg/L). This suggests a slower rate of eutrophication in Mu-pond. Human intervention is a critical factor influencing eutrophication in urban ponds, highlighting the need for effective management systems. Dhaka Univ. J. Biol. Sci. 33(2): 15-26, 2024 (July)

Cypermethrin insecticide residue, water quality and phytoplankton diversity in the lychee plantation catchment area

<abstract> <p>Lychee plantation areas are typically located at varying elevations on mountains to ensure proper drainage. This placement has direct effects on stream and river water flows and consequently influences pesticide residue, water quality and aquatic biodiversity. This research aims to examine the relationships between cypermethrin residue, water quality and phytoplankton diversity in the lychee plantation catchment area in Phayao Province, Thailand, from January to May 2022. The study area was divided into six sampling sites. Water samples were collected for the investigation of cypermethrin residual, physicochemical and biological water quality parameters. The water quality index was used as an overall measurement of water quality. The study also examined the diversity of phytoplankton species and the relationship among cypermethrin residue, water quality and phytoplankton diversity were studied using canonical correspondence analysis. The findings revealed an increasing trend of cypermethrin residue, with the maximum concentration reaching 29.43 mg/L in March. The trend of decreasing water quality scores from Station S1 to Station S5 indicated the influence of land use changes and human activities, especially in the community area (S5), which was characterized by deterioration of water quality. A total of 174 phytoplankton species were categorized into 5 divisions, with Chlorophyta accounting for 61.49% of the total, followed by Bacillariophyta (28.16%) and Cyanophyta (6.32%). The highest Shannon's diversity index and evenness were observed at Stations S3 and S4, respectively. The canonical correspondence analysis revealed an interesting relationship among cypermethrin residue, ammonia nitrogen, chlorophyll a and three algal species: <italic>Pediastrum simplex</italic> var. <italic>echinulatum</italic>, <italic>Pediastrum duplex</italic> var. <italic>duplex</italic> and <italic>Scenedesmus acutus</italic> at Station S3. This research implies that pesticide residue and water quality have a direct impact on phytoplankton distribution, illustrating the environmental challenges that occur in various geographical areas. This information can be applied to assist in the development of future sustainable land use management initiatives.</p> </abstract>

Plankton distribution patterns and the indicative significance of diverse cave wetlands in subtropical karst basin

In subtropical karst area, small wetlands are widely distributed owing to the well-developed karst and the high degree of groundwater-surface water interaction. However, detailed plankton community composition, spatial-temporal dynamics, and its assembly mechanism were rarely discussed. To address these, plankton distribution patterns and its relationship with hydrological conditions and environment gradients were analyzed to discover the biological characteristics of wetlands in a typical karst basin in South China. The results showed that the wetlands were diverse in types due to the hydrogeological background. Water quality evaluation according to major ions analyses showed good results, with significant differences among samples and a poor status when measured by biotic indicator such as Escherichia coli. During high and low-flow condition, a total of 163 and 162 species of phytoplankton, and a total of 62 and 36 species of zooplankton, respectively were observed. The dominant species of phytoplankton communities in low-flow condition metamorphosed from Cyclotella sp. to Navicula sp. and Cocconeis placentula; and Pediastrum simplex to Ankistrodesmus spiralis. The metamorphosis in zooplankton community was from Difflugia globulosa to Strobilidium sp. Comparing with other karst water in different climate regimes, the number of plankton species in the subtropical karst wetland was the highest, which is related to the high and stable water temperature, large karst underground spaces, and frequent interaction between groundwater and surface water. The abundance, biomass and community semblance of plankton were increased with an increase in nutrients, precipitating improvement in hydrodynamics and light intensity. This study also suggested that the plankton in karst cave wetlands in subtropical area were characterized by low diversity, attributable to the calcium-rich and weakly alkaline, but poor nutrient status of the water environment, as well as drew attention to the possible functions of wetlands in relation to the quality of connected river.

The Diversity of Phytoplankton in a Combined Rice-Shrimp Farming System in the Coastal Area of the Vietnamese Mekong Delta

An assessment of varying density, species composition and dynamics of phytoplankton in a combined rice-shrimp culture was carried out in My Xuyen district, Soc Trang province in the Vietnamese Mekong delta. Water was sampled six times at six separate locations within the culture system, on days 1, 20, 34, 57, 68, and day 81 of the rice-shrimp crop cycle. The results showed the abundance of 95 phytoplankton species belonging to five phyla including Cyanophyta, Chlorophyta, Bacillariophyta, Euglenophyta, and Pyrrophyta. The values of Shannon–Wiener index indicated high phytoplankton diversity, while the water quality ranged from medium to good. A Cluster Analysis showed that the phytoplankton density variation can be divided into three distinct periods. The initial phase of crop growth was dominated by Pandorina morum, Pediastrum simplex, Eudorina elegans, Oscillatoria limosa, and Anabaena circinalis. The midstage, reproductive phase of crop growth was dominated by Scenedesnus acuminatus, Pediastrum duplex, Closterinm setaceum, Scenedesnus quadricauda, and Actinastnum hantzschii. Whereas Scenedesnus acuminatus, Scenedesnus quadricauda, Closterinm closterioides, Staurastrum arcuatum, Euglena nhrenbergii, and Phacus lnsmorensis were dominant at the end of crop cycle. The findings provide useful information on phytoplankton assemblages in a typical rice-shrimp culture, which has recently gained popularity as an adaptive livelihood system.

Sedimentary Pediastrum record of middle–late Holocene temperature change and its impacts on early human culture in the desert-oasis area of northwestern China

Although the pattern of Holocene temperature variations in central Asia is complex, it is clear that temperature played a fundamental role in influencing humidity conditions and regional human activity. We reconstructed temperature changes using Pediastrum species data, verified by clumped isotopes (Δ47), in the carbonates of sediment cores recovered from Bosten Lake in Xinjiang Province, northwestern China. Combined with archaeological data, the results indicate an unusually warm climatic interval that peaked at ∼4.7–4.3 kyr and promoted human occupation of the Altai Mountains. The climate cooled during 4.2–4.1 kyr and 3.6–3.5 kyr, as indicated by the decrease or absence of Pediastrum simplex. These cold events may have triggered the southward human migration out of the Altai region, resulting in the widespread distribution of archaeological sites at lower latitudes, in the Tienshan Mountains, and in the desert-oasis areas of the Tarim Basin in southern Xinjiang. Our data support the notion that a series of cultural transitions across the monsoonal Loess Plateau and Tibetan Plateau of China may have been linked to temperature changes during the middle to late Holocene.

The rise and fall of primary producers and consumers in a multiply-stressed shallow lake (Lake Qilu, China) over the last 200 years

In this multi-proxy palaeo study, the response of primary producers and consumers to anthropogenic disturbances in a large shallow lake was investigated. Overall, eutrophication and water-level changes (partly inferred by bisaccate pollen grains) are well-reflected in changes in sedimentation rates of pigments, diatom and cladoceran species composition and other proxies (e.g. Rhabdocoela oocytes). In particular, the stepwise decrease in relative abundance of Pediastrum simplex compared to P. boryanum/P. duplex proved to be a good indicator for eutrophication intensity. Furthermore, reductions in the body size (i.e. coenobia diameter) of Pediastrum simplex were clearly related to phases of low visibility that were caused by lake damming in the 1950 s and by accelerating eutrophication in the 1990 s. During the latter period, strong algal growth led to turbid conditions, which are indicated by the co-occurrence of the diatoms Fragilaria crotonensis, Aulacoseira ambigua and A. granulata, the green algae Staurastrum sp. as well as the cladoceran Anthalona cf. milleri. This study highlights that subfossil remains, which are often found in, for instance, standard cladoceran analysis (green algae such as Pediastrum spp. and Staurastrum spp. or bisaccate pollen grains), can add valuable information to the reconstruction of past environmental conditions and biotic response. Such better and more holistic understanding of freshwater ecosystems is crucial to meet future challenges in a rapidly changing world.

Trophic status, phytoplankton diversity, and water quality at Kafr El-Shinawy drinking-water treatment plant, Damietta

Abstract This work aims to study the seasonal fluctuation in physicochemical characteristics, trophic status, and some pollutants influencing phytoplankton diversity, and water quality at a compact Kafr El-Shinawy drinking-water treatment plant, Damietta – Egypt seasonally during 2018. Phytoplankton distribution was affected by the trophic status of water, level of pollutants, and physicochemical treatment processes of water. The predominance of phytoplankton species, especially Aphanizomenon flos aquae (Cyanophyta), Gomphosphaeria lacustris (Cyanophyta), Microcystis aeruginosa (Cyanophyta), Nostoc punctiforme (Cyanophyta), Oscillatoria limnetica (Cyanophyta), Pediastrum simplex (Chlorophyta), and Melosira granulata (Bacillariophyta) in treated water was much less than that in raw water. Trihalomethanes (THMs) levels in treated waters were higher than in raw water, while lower concentrations of heavy metals were recorded in treated water. Intracellular levels of microcystins were lower, whereas the extracellular levels were higher in treated water than raw water, and the former recorded the highest level in raw water during summer. Hence, the levels of dissolved microcystins and THMs in treated water were higher especially during summer, the season of luxurious growth of Microcystis species. Trophic state index (TSI) was relatively high in raw water compared with treated water due to high concentrations of nutrients (total-P, total-N, nitrite, nitrate, and ammonia) in raw water.

Phytoplankton heterogeneity in subtropical-semiarid reservoir with special reference to spring cyanobacterial bloom

Lake Nasser plays a fundamental role in both local and national economy. Phyto-plankton represents one of the most interesting groups in water habitats and aquatic food chains. The present work aimed to estimate the spatiotemporal variation in phytoplankton structure, biovolume and carbon content in Khor Ramla and Khor Abu-Simbel of Lake Nasser; during the highest water level in early autumn and the lowest water level in late spring. Nine stations along each khor have been studied in 2014. A total of 180 phytoplankton taxa related to four algal divisions were identified. These divisions are: Chlorophyta (94 taxa), Cyanophyta (52 taxa), Bacillariophyta (32 taxa) and Dinophyta (2 taxa). Microcystis comperei, M. aeruginosaand Lyngbya limnetica were the dominant cyanophytes. Cosmarium spp.,Coelastrum reticulatum, Oocystis borgei, Eutetramorus fottii, Ankistrodesmus spiralis, Pediastrum simplex, Euastrum sp. andDictyosphaerium pulchellum represented the most abundant species of chlorophytes. Diatoms were dominated mainly by Aulacoseira granulata, A. ambigua, A. muzzanensis, Cyclotella ocellata, C. glomerata and Cymbella affinis.In spring, the average total biovolume of Khor Abu-Simbel (81.63 mm3/l) was higher than that of Khor Ramla (1.94 mm3/l). In autumn, the average total biovolumes in Khor Ramla (3.65 mm3/l) and Khor Abu-Simbel (3.09 mm3/l) were slightly different. Cyanophyta was dominant in both studied khors along the study period with obvious blooming at all stations of Khor Abu-Simbel during spring. In Khor Abu-Simbel, the carbon content of all groups during spring was higher than that of autumn, except for diatoms. In Khor Ramla, the carbon content of cyanobacteria and diatoms increased in autumn, while in Dinophyta and Chlorophyta the values increased in spring. A detailed discussion of the factors lead to the dominance and blooming of cyanobacteria in Lake Nasser was given. Canonical Correspondence Analysis (CCA) clarified that a combination of physical, chemical and biological factors rather than a single factor acted in harmony to control the composition and dynamics of phytoplankton community in Khor Abu- Simbel and Khor Ramla in Lake Nasser.

Trophic status of water and level of pollutants as measures of efficiency of water treatment regime at Kafr El-Shinawy drinking-water treatment plant, Damietta

This work aims to study the seasonal fluctuation in physicochemical characteristics, trophic status, and some chemical and biological pollutants influencing phytoplankton diversity, and water quality in raw and treated water at Kafr El-Shinawy drinking-water treatment plant, Damietta - Egypt seasonally during 2018. Phytoplankton distribution was affected by the trophic status of water, level of pollutants, and physicochemical treatment processes (coagulation, flocculation and sedimentation) of water. The predominance of phytoplankton species, especially Aphanizomenon flos aquae (Cyanophyta), Gomphosphaeria lacustris (Cyanophyta), Microcystis aeruginosa (Cyanophyta), Nostoc punctiforme (Cyanophyta), Oscillatoria limnetica (Cyanophyta), Pediastrum simplex (Chlorophyta), and Melosira granulata (Bacillariophyta) in treated water was much less than in raw water. Trihalomethanes (THMs) levels in treated waters were higher than in raw water. On the contrary, lower concentrations of heavy metals were recorded in treated water. Phytoplankton cells exhibited a bioaccumulation capacity for heavy metals especially Mn, Zn, and Fe in both raw and treated water. Intracellular levels of microcystins were lower (0.003 - 0.011µg L−1) whereas the extracellular levels were higher (1.00 – 2.01 µg L−1) in treated water than raw water, and the former recorded the highest level in raw water during summer (1.3 µg L−1). Hence, the levels of dissolved microcystins and THMs in treated water were higher than the allowable limit, especially during summer, the season of luxurious growth of Microcystis species.

Phytoplankton functional groups in a monomictic reservoir: seasonal succession, ecological preferences, and relationships with environmental variables.

The seasonal succession of phytoplankton functional groups (PFGs), their ecological preferences, relationships between environmental variables and PFGs, and ecological status were investigated in the Batman Dam Reservoir, a warm monomictic reservoir, located in the Tigris River basin of Turkey. Altogether 60 species, 19 functional groups, and 10 prevailing functional groups were identified, and prevailing functional groups showed strong seasonal changes. Centric diatoms Cyclotella ocellata (group B) and Aulacoseira granulata (group P) were dominant in the spring, with water mixing and low temperature. Groups F (Elakatothrix gelatinosa, Elakatothrix gelatinosa, and Sphaerocystis schroeteri), J (Pediastrum simplex and Coelastrum reticulatum), G (Eudorina elegans and Volvox aureus), LM (Ceratium and Microcystis), and H1 (Aphanizomenon flos-aquae and Anabaena spiroides) dominated the phytoplankton community from summer to mid-autumn, with thermal stratification. Groups H1 and P became dominant in the late autumn, with the breakdown of stratification. With the deepening of the mixing zone, groups P and T (Mougeotia sp.) were dominant in the winter. The reservoir was meso-eutrophic according to trophic state index values based on total phosphorus (TP), chlorophyll a, Secchi depth and total nitrogen, habitat preferences of PFGs, and diversity indices of phytoplankton. Redundancy analysis (RDA) revealed that NO3-N, SiO2, TP, pH, and water temperature (WT) were the most important environmental factors controlling PFGs in the BDR. Weighted averaging regression results indicated that among PFGs, groups F and T had a narrower tolerance range for WT, pH, and SiO2, while groups G and T had a narrower tolerance range for TP and NO3-N.

PROSPECTING THE FIRST CULTURE COLLECTION OF ALGAE OF THE PERNAMBUCO SEMIARID, BRAZIL

The growing concern about the shortage of fossil fuels drives the search for new sources of sustainable energy. Microalgae are considered promising in this area, since they are sources of third generation biofuels and protein. The present study aimed at describing and isolating species from the native phytoplankton communities of four reservoirs in the Pernambuco semiarid, making them available for experiments that can evaluate the biotechnological potential and meet the demands of the region. The collections occurred in water bodies located in the Pernambuco semiarid and the identification of the taxa occurred based on morphological characters using specific literature. A total of twenty-one taxa were identified, eight of them Cyanophyceae (Anabaena sp., Aphanocapsa elachista, Chroococcus dispersus, Dolichospermum sp., Merismopedia sp., Microcystis aeruginosa, Pseudanabaena limnetica, Synechococcus sp.), ten Chlorophyceae (Chlorella sp., Cosmarium bioculatum, Desmodesmus spp., Dictyosphaerium sp., Pediastrum duplex, Pediastrum simplex, Pseudokirchineriella subcapitata, Scenedesmus sp., Staurastrum leptocladum, Trochiscia sp) and only one of the following classes Bacillariophyceae (Aulacoseira granulata), Euglenophyceae (Trachelomonas volvocida) and Dinophyceae (Ceratium furcoides). The bioprospection of microalgae in the semiarid region of Pernambuco has made possible the formation of a bank of strains, important for fictional studies and obtaining biomass of species with biotechnological potential.

PENGARUH INTENSITAS MUSIM HUJAN TERHADAP KELIMPAHAN FITOPLANKTON DI WADUK BENING SARADAN

This study aims to determine the effect of the intensity of the rainy season to the abundance of phytoplankton in the reservoir Bening Madison County. As well as exploit some results of research on the abundance of phytoplankton as a medium of learning materials were shaped poster on the types of phytoplankton. This study uses a quantitative approach to the exploration technique. There are six points each station with two sample replicates. The results showed that in Reservoir Bening Saradan found 16 species of phytoplankton that is Synedra acus, Synedra ulna, Navicula grevillei, Tetragonodium verum, Crucigenia rectangularis, Ulothrix cylindricum, Nitzchia paleaceae, Ceratium candelabrum, Goniochloris sculpta, Scenedesmus ocuminatus, Navicula sp, Nitzchia acicularis, Spirulina major, Ceratoneis acus, Pediastrum simplex, Pleurota eniumtrabecula. Phytoplankton abundance is the most ubiquitous class Bacillariophyceae. Phytoplankton abundance is influenced by monsoon intensity 40,9%. While 59,1% of other factors influenced the agricultural wastes that contain elements of N, P, K, which can improve nutrient. The highest phytoplankton abundance in December is 138,64 ind/l with 12 species of phytoplankton. The number of rainy days in the December low at 25/31 days allows a maximum of phytoplankton photosynthesis. Lowest phytoplankton abundance in February which is 65,14 ind/l. Phytoplankton abundance is directly proportional to the intensity of the rainy season. The number of higher intensity, phytoplankton abundance is also higher, and vice versa. Physical and chemical conditions Bening Reservoir categorized according to the results of research in the waters of the state are less fertile and less than optimal for the growth ofphytoplankton.

Insights from pollen, non-pollen palynomorphs and testate amoebae into the evolution of Lake Simcoe

Comparing the distribution of little-known non-pollen palynomorphs (NPP) with pollen and testate amoebae (thecamoebians) in a long piston core from the main basin of Lake Simcoe illustrates their potential as paleolimnological indicators. Sediments rich in spruce and pine pollen in core LS07 PC5 contain sparse, low-diversity microfossil assemblages recording cold, oligotrophic waters (mainly the testate amoeba Difflugia oblonga, the desmid genus Cosmarium, and Pediastrum integrum). Marked climate warming reconstructed from pollen data using transfer functions is associated with a sharp increase in algal NPP abundance and diversity, including Botryococcus spp., the desmid genus Staurastrum, and Pediastrum simplex. A Centropyxis-dominated testate amoeba fauna, and sparse, low-diversity NPP record slightly brackish conditions attributed to the early Holocene drought. Diverse benthic desmid and Pediastrum spp. (including P. brevicorne) floras, together with abundant Botryococcus, record warm, mesotrophic waters associated with a hemlock-maple-beech pollen assemblage from which January temperatures several degrees warmer than today were reconstructed. A decline in NPP abundance and diversity and the re-establishment of a Centropyxis-dominated testate amoeba fauna supports drought as a cause for the regional “hemlock decline”. The most marked change in aquatic microfossil assemblages coincides with anthropogenic impact. The appearance of dinoflagellate cysts and a marked increase in difflugiid testate amoebae (notably Cucurbitella tricuspis) records eutrophication below the ragweed rise that is attributed to the agricultural activities of the Wendat Nation. Two phases of anthropogenic impact are distinguished within the ragweed zone: (1) an NPP assemblage nearly devoid of desmids but rich in Peridinium wisconsinense and Pediastrum boryanum, attributed to Euro-Canadian land clearing and agriculture, and (2) an assemblage rich in Botryococcus, Peridinium willei/P. volzii, Codonella cratera, and meso-eutrophic desmids with planktonic life habits, is attributed to urbanization and industrialization.

A preliminary investigation of relationship between modern <italic>Pediastrum</italic> and the level of Xingyun Lake, central Yunnan, and its implications for the interpretation of the fossil record

Fossil Pediastrum is frequently found in Quaternary lacustrine deposits and has attracted much attention because it can be well preserved and easily identified. However its palaeoenvironmental significance is unclear. Several studies suggest that the occurrence of a large amount of Pediastrum indicates a gradually decreasing lake-level, while others point out that Pediastrum mainly occurs in the deep areas of lakes. Thus clarifying the relationship between Pediastrum and lake levels is of great importance for improving the reliability of palaeoenviromental reconstruction. In this study, we investigated the occurrence of Pediastrum in Xingyun Lake, a semi-enclosed shallow fault and eutrophic lake located in central Yunnan Province, southwest China. We obtained 4 lake surface water samples at water depths of 4, 4.5, 5.2 and 6.5 m; 16 water samples collected at various depths within the water column at the deepest part of the lake; and 10 lake surface sediment samples taken at different water depths from the lake shore to the deepest part using a Grab sampler. We present the results of Pediastrum analysis of samples of both the lake water and surface sediments of Xingyun Lake and discuss the relationship between the Pediastrum distribution and the lake-level/water depth. The variation of the fossil records during the past 3000 years is also reported. The results show that two types of Pediastrum were identified in the water and lake sediment samples, including Pediastrum boryanum and Pediastrum simplex . The concentration of Pediastrum in the water samples is extremely low, varying from 2 to 6 grains mL - 1. Spatially, the concentrations of Pediastrum in the surface lake water samples exhibit little change with increasing water depth. In terms of the depth variation within the water column in the deepest part of the lake, the Pediastrum concentration of the bottom sample is the highest, which may be related to the effects of resuspension and redeposition of lake sediments caused by wind-induced turbulence in shallow water. With respect to the lake surface sediment samples, the Pediastrum content is relatively high. The concentration of Pediastrum varies from 60700 to 104000 grains g - 1, with an average of 81000 grains g - 1; and the relative percentage abundance ranges from 66%–80%, averaging around 76%. Interestingly, both the concentration and percentage content of Pediastrum in these samples exhibit no significant relationship with water depth. Based on comparison of the results from Xingyun Lake with those of other workers, we conclude that the relationship between the Pediastrum distribution and water depth inferred from the lake sediments of several relatively larger lakes mentioned in previous studies may be caused by depositional processes: turbulence resulting from wave activity in these larger lakes could result in the resuspension of Pediastrum in shallow water and its focusing into deeper areas. However, whether or not there is a large quantity of Pediastrum living in the lake water may be related to the physicochemical status of the lake water, determined by factors such as the river input, nutrient level, temperature, pH and salinity. In addition, these factors may vary between different lakes in different regions. Therefore, the variation of Pediastrum content cannot be used as an indicator of water depth or lake-level without careful consideration of these factors. In addition, it needs to be used in the context of multi-proxy studies. Both the percentage and the concentration of fossil Pediastrum in the sediments of Xingyun Lake exhibit distinct features over the last 3000 years: very low values before 2000 cal a BP followed by a rising trend, and then an abrupt increase after 1500 cal a BP. This is consistent with variations in the intensity of human activity revealed by frequent high-amplitude fluctuations in mean grain-size and by an abrupt increase in magnetic susceptibility. In addition, the abrupt changes in fossil Pediastrum in Xingyun Lake precede those of mean grain-size and magnetic susceptibility, suggesting that the Pediastrum from the Xingyun Lake sediments may be a sensitive indicator of the process of lake water eutrophication caused by human activities.

Preliminary observations on the preservation of organic-walled algae in shallow, freshwater lakes from south–central Missouri, USA

Algal palynomorphs can provide key ecological information about aquatic environments, yet the preservation potential for most varieties of algae is poorly understood. Cores from Pine Forest and Bray Area lakes, two man-made lakes in the Rolla area of south–central Missouri, USA, provided an opportunity to relate the algal palynomorphs in the top 9 cm of sediments to the processes that lead to preservation. By comparing algal palynomorphs in the sediments to the algal crop in the water, this study seeks to assess the effects of taphonomy on the assemblage in a palynological sample. The lakes were ecologically monitored four times in one year (late fall, spring, summer, winter) to determine the algal crop, and surficial sediment was sampled in Pine Forest Lake once in early winter. The annual average abundance of algae in the lake water was compared with sediment data, and statistical techniques (Kruskal–Wallis test, Mann–Whitney U-test and Pielou's Equitability index) were used to determine ecological stability in the sediments. While Sphaerocystis and Ceratium hirundinella did not apparently preserve well, moderate to high preservation potential was determined for Staurastrum and Botryococcus. In addition, Pediastrum simplex var. pseudoglabrum, P. integrum and P. boryanum var. pseudoglabrum were well preserved in the sediments. This preliminary study shows that a highly abundant algal species in the water may not be well preserved in the sediment. Therefore, higher resolution studies are needed to further explore the preservation potential of algae in lake sediments.

The response and detoxification strategies of three freshwater phytoplankton species, Aphanizomenon flos-aquae, Pediastrum simplex, and Synedra acus, to cadmium.

The response and detoxification mechanisms of three freshwater phytoplankton species (the cyanobacterium Aphanizomenon flos-aquae, the green alga Pediastrum simplex, and the diatom Synedra acus) to cadmium (Cd) were investigated. The cell growth of each species was measured over 10 days, and chlorophyll a fluorescence, Cd bioaccumulation (including surface-adsorbed and intracellular Cd), and phytochelatin (PC) synthesis were determined after 96-h exposures. The growth of the three phytoplankton species was significantly inhibited when Cd concentrations were ≥5 mg L(-1). Compared with P. simplex, greater growth inhibition in S. acus and A. flos-aquae occurred. The changes in chlorophyll fluorescence parameters including the maximal quantum yield of PSII (Fv/Fm) and relative variable fluorescence of the J point (Vj) demonstrated that the increase in Cd concentration damaged PSII in all three species. After 96-h exposures, the accumulation of surface-adsorbed Cd and intracellular Cd increased significantly in all three species, with the increase of Cd concentrations in the media; total cadmium accumulation was 245, 658, and 1670 times greater than that of the control in A. flos-aquae, P. simplex, and S. acus, respectively, after exposure to 10 mg L(-1). Total thiols exhibited a similar trend to that of Cd accumulation. PC3 was found in A. flos-aquae and P. simplex in all Cd treatments. Glutathione (GSH) and PC2 were also produced in response to exposure to high concentrations of Cd. PC4 was only discovered at exposure concentrations of 10 mg L(-1) Cd and only in S. acus. The intracellular Cd/PCs ratio increased in all three phytoplankton with an increase in Cd concentrations, and a linear relationship between the ratio and the growth inhibition rates was observed with P. simplex and S. acus. Our results have demonstrated that metal detoxification mechanisms were dependent on the species. This study suggested that the variance of metal detoxification strategies, such as cadmium accumulation and PCs, might be an explanation why algal species have different sensitivity to Cd at various levels.

KELIMPAHAN JENIS FITOPLANKTON DI INLET DAN OUTLET WADUK BENING SEBAGAI BAHAN PENYUSUN MEDIA PEMBELAJARAN BERBENTUK POSTER

This study aimed to determine the abundance of phytoplankton in the waters of the inlet and outlet Reservoirs Bening. Hamlet Village Petung Pajaran Saradan District of Madison County as well as exploit some results of research on the abundance of phytoplankton as a medium of learning materials were shaped poster on the types of phytoplankton. This study uses the exploratory research is directly done by observing and identifying body shapes, locomotor and body color that is in the phytoplankton Reservoir Bening in the inlet and outlet by taking samples at two points each station with three replications samples. Phytoplankton that have been filtered observed under the microscope and then identified the species and grade as well as documented. Calculated amount of phytoplankton abundance at each inlet and outlet areas. The results showed that the abundance of phytoplankton in the inlet and outlet. Phytoplankton abundance in the inlet area of the Month December to February respectively is 330 ind/l, 286.291 ind/l, and 258.892 ind/l, while the abundance of phytoplankton in the area of the outlet of the Month December to February respectively Tutut 130.844 ind/l, 112.200 ind/l, and 98.430 ind/l. Phytoplankton species in the Reservoir Bening Saradan found 12 species of phytoplankton that is, Synedra ulna, Tetragonodium verum, Synedra acus, Surirella elegans, Ceratium, Surirella sp, Pediastrum simplex, Chlorocytrium lemnae, Nitzia palea, Crucigenia rectangularis, grevillei Navicula, Scenedesmus acumatus. Phytoplankton abundance is the most ubiquitous class Bacillariophyceae species Synedra acus.

Chlorophyll ratio analysis of the responses of algae communities to light intensity in spring and summer in Lake Erhai

Algae biomass and community structure can reflect the current situation of a lake, especially in response to changes in light intensity. The relationship between chlorophyll a (Chl a) and chlorophyll b (Chl b) ratio and the proportion of Chlorophyta within the algae community were analyzed in this study. Results showed that light was more intense in August than in March. Algae density in August was greater than in March. The concentration of Chl a and b was influenced by light intensity level. In March, Microcystis and Kirchneriella sp dominated surface water, where the light intensity was over 216 μmol m−2 s−1, Gloeocapsa, Dictyospaerium pulchellum, and Scenedesmus dominated intermediate water, where the light ranged from 36 to 216 μmol m−2 s−1. Asterionella formosa Hassall and Mougeotia scalaris dominated near the bottom, where the light was below 36 μmol m−2 s−1. In August, Microcystis and Selenastrum reinsch dominated surface water, where the light was above 18 μmol m−2 s−1. Chroococcus, Chlorella, and Scendesmus quadricauda dominated intermediate water, where light ranged from 90 to 180 μmol m−2 s−1. Anabaena spirioides and Pediastrum simplex dominated bottom water, where the light was below 90 μmol m−2 s−1. According to the mean value of Chlorophyta density and algae cell density in three different water levels, the ratio of Chlorophyta and algae community declined from March to August, ranging from 12.35–21.41 to 4.28–11.19 %. The mean value ratio of Chl b and Chl a in three different water levels showed the same tendency from March to August, ranging from 18.05–21.77 to 15.15–17.44 %. These variations in chlorophyll ratio and Chlorophyta ratio indicated that the structure of the algae community structure was influenced by differences in light intensity.

An assessment of the effects of hospital wastes released to Nilwala river, Matara

Wastewater from hospitals either treated or partially treated can alter water quality and biological diversity in adjacent water. This study focused to assess effects of hospital wastes discharged from the General Hospital Matara to the Nilwala River. Two sampling sites were located upstream of the entrance of wastewater while two sites were located downstream of the entrance of wastewater discharge and one site was selected at the entrance of the wastewater channel. Water, sediment and plankton samples were collected biweekly during February to April, 2012. Nitrate, phosphate, pH and Cu concentrations in water sampled from the hospital wastewater discharging canal were significantly (One-way ANOVA, p<0.05) different from the other sampling sites. However, Cu concentration in surface water did not exceed the EU limits of 0.0005-0.112mg/l for fisheries and aquatic life and similarly water pH did not exceed the maximum allowable limit (6-8.5) for fisheries and aquatic life in Sri Lanka. Mean concentration of Cu in sediment collected at the entrance of the wastewater channel was 0.75±0.05 mg/g dw. Although total coliform concentration (MPN/100ml) did not vary significantly among the sampling sites, it was relatively low (39.66±17.7) at the waste discharging canal due to the presence of disinfectants in hospital wastewater. Pediastrum simplex was the most abundant phytoplankton species at all the five sampling sites. Cladocera was the most abundant group of zooplankton in all the sites except at the entrance of wastewater discharging canal and Protozoa was the most abundant group present at the wastewater discharging canal. According to rotated matrix of Principle Component Analysis (PCA) water pH, PO4−3, NO3−, TDS, Salinity and Zooplankton abundance can be considered as important parameters at the study site of wastewater entrance (site 3). The toxicity (72h EC50) of hospital wastes on Pediastrum simplex was 0.08 Toxic Units (TU) and it was not an acute toxic effect on the alga when compared with hazard classification systems for wastes discharge into the aquatic environment. DOI: http://dx.doi.org/10.4038/jur.v2i1-2.7852 J. Univ. Ruhuna 2014 2:33-39

Assessment of growth rate, chlorophyll a fluorescence, lipid peroxidation and antioxidant enzyme activity in Aphanizomenon flos-aquae, Pediastrum simplex and Synedra acus exposed to cadmium.

In this study, the effects of cadmium on the cyanobacterium Aphanizomenon flos-aquae, the green alga Pediastrum simplex and the diatom Synedra acus was evaluated on the basis of growth rate, chlorophyll a fluorescence, lipid peroxidation and antioxidant enzyme activity. The EC50 values (effective concentration inducing 50% of growth inhibition) of cadmium in A. flos-aquae, P. simplex and S. acus were 1.18±0.044, 4.32±0.068 and 3.7±0.055mg/L, respectively. The results suggested that cadmium stress decreases growth rate and chlorophyll a concentration. The normalized chlorophyll a fluorescence transients significantly increased at cadmium concentrations of 5.0, 10.0 and 20.0mg/L, but slightly decreased at concentrations of 0.2, 0.5 and 1.0mg/L. The chlorophyll fluorescence parameters showed considerable variation among the three species, while lipid peroxidation and antioxidant enzyme activities showed a significant increase. Our results demonstrated that blockage of electron transport on the acceptor side of photosystem II is the mechanism responsible for cadmium toxicity in freshwater microalgae, and that the tolerance of the three species to cadmium was in the order green alga P. simplex>diatom S. acus>cyanobacterium A. flos-aquae.