Community Structure Parameters Research Articles

Microbial community of soda Lake Van as obtained from direct and enriched water, sediment and fish samples

Soda lakes are saline and alkaline ecosystems that are considered to have existed since the first geological records of the world. These lakes support the growth of ecologically and economically important microorganisms due to their unique geochemistry. Microbiota members of lakes are valuable models to study the link between community structure and abiotic parameters such as pH and salinity. Lake Van is the largest endroheic lake and in this study, bacterial diversity of lake water, sediment, and pearl mullet (inci kefali; Alburnus tarichi), an endemic species of fish which are collected from different points of the lake, are studied directly and investigated meticulously using a metabarcoding approach after pre-enrichment. Bacterial community structures were identified using Next Generation Sequencing of the 16S rRNA gene. The analysis revealed that the samples of Lake Van contain high level of bacterial diversity. Direct water samples were dominated by Proteobacteria, Cyanobacteria, and Bacteroidota, on the other hand, pre-enriched water samples were dominated by Proteobacteria and Firmicutes at phylum-level. In direct sediment samples Proteobacteria, whereas in pre-enriched sediment samples Firmicutes and Proteobacteria were determined at highest level. Pre-enriched fish samples were dominated by Proteobacteria and Firmicutes at phylum-level. In this study, microbiota members of Lake Van were identified by taxonomic analysis.

Rangelands and crop fallows can supplement but not replace protected grasslands in sustaining Thar Desert's avifauna during the dry season

1. The Indian Thar Desert has lost much of its grasslands over the last few decades, mainly due to land-use change from pastoralism to agriculture. Expanding croplands and intensifying grazing pressures are popularly hypothesized to be the major drivers of biodiversity loss in the region. Our study aims to investigate the effects of contemporary land-use change on bird communities of the Western Thar Desert.2. We surveyed 59 randomly laid line transects in a ~2000 sq.km study area, to quantify parameters of bird community structure in three predominant land-cover types viz. protected grasslands, rangelands, and fallow croplands. Fieldwork for the study was conducted in the dry season (winter and summer) between December 2018 and April 2019.3. During winter, overall bird species richness and abundance was highest in protected grasslands followed by fallow croplands and rangelands. Protected grasslands also had a higher abundance of diet and habitat specialists. Compared to protected grasslands, density was lower in fallow croplands and rangelands for 35% and 10% of species, respectively. A majority of the negatively affected species were insectivorous grassland specialists.4. Contrary to the pattern in winter, overall bird species richness, abundance, composition, and guild structure in summer was similar across the three land-use types. Only one of the 17 analysed species had significantly lower density in modified land-use types.5. Overall, protected grasslands were the best habitat for birds and specifically important for diet and habitat specialists, more so during the winter. Rangelands and fallow croplands sustained most generalists at comparable densities but had severe negative impacts on specialist species.6. Synthesis and application: Our results point out that low-intensity agro-pastoral land-uses can supplement, but not replace, protected areas in conservation of Thar Desert's avifaunal diversity. This is in consonance with the idea of managing dryland habitats as agro-grassland mosaics with embedded protected areas, in order to reconcile human needs and biodiversity conservation at a landscape scale.

Phenotypic plasticity may mediate habitat filtering in a forest edge community

A key process determining community assembly is habitat filtering, which reduces the range of trait values and thus leads to trait convergence. Habitat filtering is often assumed to involve a reduction in species richness, but such trait convergence could also result from phenotypic plasticity. By allowing more species in the community to show the ‘right' phenotype and pass the filter, phenotypic plasticity could maintain species richness despite trait convergence. If phenotypic plasticity plays this role, environmental changes should modify trait distribution but not species composition or richness. We tested this hypothesis in a forest edge community recently invaded by the alien shrub Rubus praecox. We measured functional traits beneath Rubus canopy (Rubus‐invaded community) and in adjacent microsites naturally free from Rubus (original community), comparing trait dispersion and community structure parameters. We also characterized the microenvironments to seek functional explanations for the observed phenotypic changes. The functional dispersion parameter FDis showed habitat filtering in the Rubus‐invaded community (trait convergence), while in the original community it did not differ from a null model. Species richness and composition did not differ between the two communities. Soil characteristics were similar in both communities but light availability was greatly reduced in the Rubus‐invaded community. A principal component analysis of community‐weighted means of functional traits showed that phenotypic changes between communities were mostly consistent with functional responses to shading, including an increase in specific leaf area and a reduction in flavonoid concentration in the Rubus‐invaded community. We verified the conditions necessary to infer that phenotypic plasticity mediates the outcome of habitat filtering driven by Rubus in the study system, i.e. plasticity would explain species persistence despite trait convergence. Phenotypic plasticity, often subsumed within intraspecific variation in community assembly studies, should be considered individually to improve our understanding of the causes and consequences of habitat filtering.

Lichen community structure and richness in three mid-elevation secondary forests in Costa Rica

Introduction: Lichen diversity, community structure, composition and species abundance have been used as indicators of the integrity and ecological continuity of tropical forest ecosystems. Objectives: To assess corticolous lichen species composition, diversity, and ecological importance of three forested stands differing in time of abandonment as indicators of how passive restoration influences the lichen community assemblage. Methods: We surveyed individual lichens on tree stems of a reference old secondary forest and a young secondary forest (50 and 14-year-old natural regeneration after pasture abandonment, respectively), and in a 35-year-old exotic cypress tree plantation, in the oriental Central Valley, in Orosí, Costa Rica. Standard diversity, similarity indexes, and the importance value index were calculated. An NMDS analysis was performed on the community structure parameters and in a presence-absence matrix. Results: We found 64 lichen species in 25 families with 42, 21, and 23 species, and 20, 10, and 15 families, in the young and old secondary forests, and the cypress plantation, respectively. Cryptothecia sp. possessed the highest importance across sites. More than 87 % of the species are rare. The combined IVI of the top three families were: 36, 48.5, and 74.8 % in the young and old forests and the Cypress plantation sites, respectively. Overall, Arthoniaceae is in the top three families. The young forest had the highest species richness, but the old forest presented the best evenness. Similarity and diversity indexes suggest a particularly low resemblance in the lichen communities but a smooth gradient differentiation between the three forests, which was confirmed by the NMDS test. The homogeneity test identified great differences in ecological importance and composition. Conclusions: This region contains a distinctive assemblage of species resulting in a strong community differentiation by site, reflecting the influence of ecophysiological and microclimatic factors that define lichen establishment and survival and suggesting a great regional beta diversity, within a fragmented landscape. Greater connectivity and passive restoration strategies resulted in greater diversity and a more heterogeneous community structure on both forests than the corticolous community of the abandoned plantation. Protection of forest fragments will maximize the integrity of future forests.

Effects of fragmented mangroves on macrozoobenthos: a case study of mangrove clearance for powerline right-of-way at Oproama Creek, Niger Delta, Nigeria

Mangroves are vulnerable to varying magnitudes of degrading impact by human activities. Despite the many benefits of mangrove ecosystems, mangroves in the Niger Delta region are often cleared for electric powerline and oil pipeline rights-of-way, recreation, road construction, housing and farming. The study assessed the impacts of mangrove clearance on physico-chemical parameters of interstitial water and macrozoobenthic primary community structure in Oproama Creek, Nigeria, from February to July 2016. Three stations were selected for the study: two stations in more natural and undisturbed mangroves and one station at a mangrove clearing (for a national grid powerline right-of-way). Species richness and diversity were slightly higher at the undisturbed mangrove sites than the cleared site. Removal of mangrove canopy shade alters microclimate temperature regime and other temperature-dependent parameters, imposing thermal stress on stenothermal taxa and ancillary stressors that compositely affected primary community structure indices. Deliberate loss of mangroves through clearing waterfront vegetation as a driver for improved visual monitoring and enhanced security in the Oproama Community in the Niger Delta is reported for the first time. The wider implications of mangrove clearance and fragmentation on ecosystem-based goods and services are discussed. Limiting mangrove spatial loss owing to construction of an electric tower cutline within coastal landscape is strongly recommended.

The Cooling and Humidifying Effects and the Thresholds of Plant Community Structure Parameters in Urban Aggregated Green Infrastructure

The cooling and humidifying effects of urban aggregated green infrastructure can provide essential services for city ecosystems, regulating microclimates or mitigating the urban heat island effect. However, the optimal thresholds of plant community structure parameters for maximizing the associated cooling and humidifying effects remain unclear. In this paper, we use the method of dummy variable regression to measure plant communities in an urban aggregated green infrastructure. By examining the relationships between the cooling and humidifying effects and plant community structure parameters (i.e., canopy density, porosity, and vegetation type), we introduce optimal thresholds for the parameters. We find that canopy density has a significantly positive correlation with both cooling and humidifying effects, while porosity has a positive correlation with cooling and a negative one with humidifying. Different vegetation types have distinct influences on cooling and humidifying effects. When the canopy density is between 0.81 and 0.85 and the porosity is between 0.31 and 0.35, the cooling and humidifying effects of the plant communities reach their peak. Additionally, the greening coverage rate and spatial types of urban aggregated green infrastructure have influences on cooling and humidifying effects. The findings can help us to better understand the relationships between plant community structure parameters and their temperature regulation functioning for urban aggregated green infrastructure. This study provides guidelines and theoretical references for the plant configuration of future urban green spaces.

Driving factors influencing the rhizobacteriome community structure of plants adapted to multiple climatic stressors in edaphic savannas

The natural variation of multiple abiotic stresses in hyper-seasonal edaphic savanna provides a unique opportunity to study the rhizobacteriome community structure of plants adapted to climate change-like conditions in the humid tropics. In this study, we evaluated changes in soil, plant and rhizobacteriome community structure parameters across seasons (wet and dry) in two edaphic savannas (SV-1 and SV-5) using four dominant plant species. We then examined relationships between rhizobacteriome community structure and soil properties, plant biomass, and conventional and novel root traits. We further hypothesized that plants adapted to the Aripo Savanna had a core rhizobacteriome, which was specific to plant species and related to root foraging traits. Our results showed that cation exchange capacity (CEC) and the concentration of micronutrients (Fe, Cu and B) were the only soil factors that differed across savanna and season, respectively. Plant biomass traits were generally higher in the dry season, with a higher allocation to root growth in SV-5. Root traits were more plastic in SV-5, and network length-distribution was the only root trait which showed a consistent pattern of lower values in the dry season for three of the dominant plant species. Rhizobacterial community compositions were dominated by Proteobacteria and Acidobacteria, as well as WPS-2, which is dominant in extreme environments. We identified a shared core rhizobacteriome across plant species and savannas. Cation exchange capacity was a major driver of rhizobacterial community assemblies across savannas. Savanna-specific drivers of rhizobacterial community assemblies included CEC and Fe for SV-1, and CEC, TDS, NH4+, NO3−, Mn, K, and network length-distribution for SV-5. Plant factors on the microbiome were minimal, and host selectivity was mediated by the seasonal changes. We conclude that edaphoclimatic factors (soil and season) are the key determinants influencing rhizobacteriome community structure in multiple stressed-environments, which are ecologically similar to the Aripo Savanna.

Wildfire does not affect the dung beetle diversity of high-altitude Mediterranean habitats

Wildfires represent an important factor in the disturbance in Mediterranean ecosystems, although the effects of wildfires on the insect communities of mountain environments remain largely unknown. This research investigated the effect of fire on dung beetles in a Mediterranean high-altitude area, located in Central Italy (1500 m elevation). Sampling in each of the three main vegetation types of the study area (conifer plantation, beechwood forest and grassland) used pitfall traps during Spring to Autumn. For each habitat, three burnt and three unburnt sites were sampled. We considered the following community structure parameters: abundance, richness, Shannon diversity and Simpson diversity. Effects of fire, habitat and sampling period were investigated using generalised mixed-effects models. Abundance, species richness and diversity were higher in the grassland than in the two forest habitats and June was the month with the lowest values because of the late emergence of insects at high altitudes. Fire negatively affected dung beetle abundance, but not diversity. Forest habitats were less favourable to dung beetle recolonisation than the secondary grassland. Thus, dung beetles are sensitive to vegetation type, but not to fire, possibly because of their high recolonisation capabilities and preference for open habitats.

Ecometric estimation of present and past climate of North America using crown heights of rodents and lagomorphs

Studies of large herbivorous mammal (ungulate) communities have revealed an association between increased tooth crown height (hypsodonty) and a shift to more arid environments over the Cenozoic. Ecometric analyses have also been used to examine the relationship between current climate conditions and crown height of these communities, and very successfully used to estimate past precipitation. Small herbivorous mammals (rodents and lagomorphs) have been shown to similarly adapt to changing habitats over the Cenozoic, but did so millions of years earlier than larger mammals. Here, we have utilized ecometric methods to examine the relationships between rodent and lagomorph crown height and diversity with current climate conditions, finding strong correlations of community structure parameters with climate, particularly mean annual temperature, maximum temperature of the warmest month, and minimum temperature of the coldest month. We applied the resultant regression equations to well-sampled fossil localities from North America, spanning over 37 million years, allowing estimation of climate conditions in deep time. As expected, estimates show a general pattern of decrease in both precipitation and temperature across North America from 37 Ma to the present. Overall, these findings provide a new broadly-applicable proxy for estimation of Cenozoic climate conditions at a local scale.

Estrutura e síndromes de dispersão da vegetação arbórea em floresta nativa e agrofloresta, na Amazônia Meridional: Structure and dispersal syndromes of forest and agroforest

The choice of native species used in the management of agroforestry systems for the recovery of anthropized environments, are fundamental for maintaining biodiversity and ecological processes. In this study, we evaluated the structural complexity and diversity of plants in a teak agroforestry, compared to a native forest tangent to the planted area. Thus, we set up 33 plots in the area of ​​native forest and 24 in agroforestry, both with dimensions of 10 × 10 m, at Fazenda Sao Nicolau, Cotriguacu, Mato Grosso, Brazil. We collected data on the structure of vegetation and calculated the descriptive phytosociological parameters of the community structure. We used i) PCoA to evaluate the floristic similarity between native forest and agroforestry, ii) GLM to determine the influence of the canopy opening on the vegetation structure, and iii) ANOVA to analyze the structural characteristics by dispersion syndrome. We registered 395 tree individuals belonging to 98 species and 35 families, including the exotic species Tectona grandis. We considered abundance and the basal area in relation to the dispersion syndrome, where we noticed, the zoocoria significantly higher when compared to anemocoria and autocoria. Thus, we consider the zoochoric dispersion syndrome as a factor that best explains the relationship between the types of forests in the Southern Amazon.

Bacterial and Fungal Community Dynamics and Shaping Factors During Agricultural Waste Composting with Zeolite and Biochar Addition

Bacterial and fungal communities play significant roles in waste biodegradation and nutrient reservation during composting. Biochar and zeolite were widely reported to directly or indirectly promote microbial growth. Therefore, the effects of zeolite and biochar on the abundance and structure of bacterial and fungal communities and their shaping factors during the composting of agricultural waste were studied. Four treatments were carried out as follows: Run A as the control without any addition, Run B with zeolite (5%), Run C with biochar (5%), and Run D with zeolite (5%) and biochar (5%), respectively. The bacterial and fungal community structures were detected by high-throughput sequencing. Redundancy analysis was used for determining the relationship between community structure and physico-chemical parameters. The results indicated that the addition of biochar and zeolite changed the physico-chemical parameters (e.g., pile temperature, pH, total organic matter, ammonium, nitrate, and water-soluble carbon) during the composting process. Zeolite and biochar significantly changed the structure and diversity of bacterial and fungal populations. Moreover, the bacterial community rather than the fungal community was sensitive to the biochar and zeolite addition during the composting process. Community phylogenetic characteristics showed that Nocardiopsaceae, Bacillaceae, Leuconostocaceae, Phyllobacteriaceae, and Xanthomonadaceae were the predominant bacterial species at the family-level. Chaetomiaceae and Trichocomaceae were the two most dominant fungal species. The pH, total organic matter, and nitrate were the most important factors affecting the bacterial and fungal population changes during the composting process.

Relating groundfish diversity and biomass to deepsea corals and sponges using trawl survey catch data

Deep-sea corals and sponges (DSCS) inhabit the world’s oceans and are often associated with high fish abundance. However, the precise nature and extent of any association is difficult to quantify and remains poorly understood. We investigated associations between DSCS and demersal fish using data from the Northwest Fisheries Science Center’s bottom trawl survey (2003-2015). General linear mixed models showed that average species density of groundfish was slightly higher and groundfish biomass slightly lower in tows with DSCS. Multivariate analyses were used to examine relationships among fish community structure, DSCS biomass, and environmental parameters (depth, latitude, bottom temperature). No strong correlations occurred between the community structure of groundfish and DSCS biomass; instead, bottom temperature and depth were the primary drivers of community composition. However, indicator species analysis also showed various species-specific associations with DSCS. Specifically, some flatfish species exhibited relationships with coral and sea pen biomass, whereas some rockfishes were associated with high sponge biomass. Our results provide information on the broad-scale associations among DSCS and demersal fishes that may be useful for developing studies focused on the functional value of DSCS as essential fish habitat and the role they play in groundfish life history and ecology.

Community structure and condition of seagrass meadows in Ayau Islands, Raja Ampat Regency

Seagrass meadows are an important component of coastal ecosystems, providing many ecosystem services beneficial for human well-being. Basic information about seagrass meadows in Indonesia is relatively limited, particularly in the eastern part of Indonesia, such as the remote Ayau Islands in Raja Ampat. In this paper, we reported the community structure and condition of seagrass meadows in Ayau Islands surveyed during Nusa Manggala Expedition in November 2018. We conducted the seagrass survey using quadrat transect method at five locations, i.e. Reni, Rutum, Abidon, Kanober, and Dorehkar. In the survey, we assessed parameters of community structure, including habitat extent, species composition, seagrass cover, seagrass density, macroalgae and epiphyte cover. We also recorded environmental parameters, i.e. substrate types, water clarity, salinity, water temperature, and nutrient (phosphate and nitrate). Our study showed that seagrass meadows in Ayau Islands are multispecies meadows, composed of two to five species. In overall, five species recorded in Ayau Islands are Cymodocea rotundata, Enhalus acoroides, Halodule pinifolia, Halophila ovalis, and Thalassia hemprichii. The most common species is T. hemprichii as it can be found in all locations. Meadows in Reni, Rutum, and Dorehkar are in a healthy condition, while in Abidon and Kanober are in less healthy condition. This information is of significance as baseline information needed for seagrass conservation planning.

Are redundancy indices redundant? An evaluation based on parameterized simulations

Abstract Functional redundancy is considered a major component of the insurance mechanism, which theoretically maintains ecosystem stability by preventing the loss of ecosystem functions with species loss. Over the past decades, examination of functional trait patterns to elucidate processes of community stability and ecosystem functioning have stimulated considerable amount of research in ecology. As a result, a multitude of indices have been developed, describing community functional structure with various levels of overlap in their methodology. Here, we review the set of indices that have been suggested to measure the level of redundancy in traits among species in ecological communities. We first evaluate the correlations among redundancy indices and classical indices of community taxonomic and functional structure (species richness, Simpson diversity, functional richness, evenness and divergence). Second, we estimate the predictive power of these indices in terms of community vulnerability to species loss. Finally, we assess the sensitivity of the results to scenarios with different species loss orders. We simulated communities with different levels of taxonomic and functional structure (richness, evenness and divergence). Then, we simulated four scenarios of species loss order (abundance, functional uniqueness, environmental sensibility and random). The vulnerability of communities was estimated by the changes in community structural parameters (functional richness, functional divergence and biomass) as species were progressively removed from the initial communities. Our results showed that four out of the five redundancy indices tested were strongly correlated (Pearson R > ∣0.6∣) with at least one of the classical indices of community structure. Those correlations partly explained why the redundancy indices did not outperform classical indices in predicting community vulnerability to species loss. The fifth redundancy index (FredD) was the least correlated with classical indices of community structure (Pearson R

Factors structuring spatio-temporal dynamics of macrobenthic communities of three differently modified tropical estuaries

Tropical estuaries of industrialized northwest coast of India, subject to seasonal and multifarious anthropogenic interventions, are poorly studied. Three estuaries, Ulhas, Amba and Savitri were investigated seasonally to identify the principal factors among natural and anthropic stressors that shaped spatio-temporal macrobenthic patterns. The macrobenthic community structure and chemical parameters differed significantly between estuaries, zones and seasons. Multivariate dispersions were significant between the estuaries whereas for the zones and seasons, significant variability was nonexistent. Multivariate regression analysis indicated that both natural and anthropogenic drivers influenced the spatio-temporal variability of macrobenthos of Ulhas and Amba. In Savitri, no anthropogenic factor was significantly influential. Salinity explained a greater proportion of the variability of macrobenthic structure than other factors in all estuaries. The pollution tolerant species responded largely to salinity changes and were observed to inhabit specific salinity zones. Thus, the spatio-temporal patterns of the estuarine macrobenthos were primarily dictated by the salinity.

Lactobacillus plantarum improves the efficiency of sheep manure composting and the quality of the final product

The addition of exogenous microorganisms is one approach with potential that may also overcome the problem in northern China of slow composting in autumn and winter due to low environmental temperatures. This study investigated the use of supplements of Lactobacillus plantarum (L. plantarum), strains P-8 and LP-10, on the efficiency of sheep manure composting and the quality of the final product. The composting process lasted eight weeks and, during this time, changes in multiple physical-chemical parameters and the compost microbiome were monitored. Microbiota-encoded functions, community structure and physical-chemical parameters were distinct between the two groups. ‘Composting microbiota maturation index’ was proposed to quantitatively compare the impact of maturation on composting microecology. The rapid improvement in composting rate (4 weeks) and quality of the final product suggest that this approach could provide both technological and economic benefits. This work reveals the tremendous potential of L. plantarum as a promoter in composting.

Community structure of target reef fish at four tiny islands coral reefs in inner Kotania bay, Maluku Province, Indonesia

Study on community structure of target reef fish at four tiny islands coral reefs in inner Kotania bay was conducted from September 2017 to February 2018. Underwater Visual Census method was used to collect and examine data concerning several parameters of target reef fish community structure. At least 18 families of target reef fish which consist of 37 genera and 105 species were found during the study. Good and excellent categories of coral reefs condition had higher species richness and individual abundance of target reef fish, while lower in fair category. Seven target reef fish species have a wide distribution, while other 15 species were limited. In general, target reef fish community at four tiny islands coral reefs had high species diversity and evenness indexes with low species dominance value. It can be concluded that target reef fish community in the area in stable or in steady state condition.

Biogeography and fish community structure in Irish estuaries

Estuaries represent important transitional waters where marine and freshwater ecosystems meet and mix. Estuaries are dynamic systems due to their tidal nature and their ecology is expected to shift with climate change and the arrival of new species. Spatially extensive descriptive studies that provide temporal baselines for species distribution and abundance, and associated environmental variables deliver a comprehensive reference point against which to monitor change. To provide this biogeographic context for Ireland, which is surrounded by temperate Atlantic waters, the biogeography and fish community structure of Irish estuaries was examined using a large dataset comprised of 208,313 individual fish, 80 different species sampled from 37 estuaries from 2008–2017.Species richness was strongly correlated with the area of shallow littoral and subtidal habitats. Estuaries at higher latitudes tended to have lower species richness in shallow littoral areas. Estuary mouth width and proportion of subtidal area were both positively related to species richness in subtidal habitats. The main driver of estuary clustering is the changing proportion of estuarine species versus marine migrants. The results show a dominant group of larger, more open estuaries where marine migrants consistently dominate the fish population.This study confirms the role of marine migrants in contributing to fish community composition in estuaries and highlights the vital nursery function that Irish estuaries perform for estuarine-dependent marine fish species. The associations between fish community structure and broad-scale environmental parameters provide a time stamped baseline for monitoring future climate change impacts on estuarine fish assemblages in Ireland.

Comparison of Particulate Organic Carbon to Chlorophyll-a Ratio Based on the Ocean Color Satellite Data at the Ieodo and Socheongcho Ocean Research Stations

Lee, D.; Jeong, J.-Y.; Jang, H.K.; Min, J.-O.; Kim, M.J.; Youn, S.H.; Lee, T., and Lee, S.H., 2019. Comparison of particulate organic carbon to chlorophyll-a ratio based on the ocean color satellite data at the Ieodo and Socheongcho ocean research stations. In: Jung, H.-S.; Lee, S.; Ryu, J.-H., and Cui, T. (eds.), Advances in Remote Sensing and Geoscience Information Systems of Coastal Environments. Journal of Coastal Research, Special Issue No. 90, pp. 267-271. Coconut Creek (Florida), ISSN 0749-0208.The Ieodo ocean research station (IORS) and the Socheongcho ocean research station (SORS) have been operated in South Korea to carry out a research across multiple disciplines. The IORS and the SORS are affected by various water masses such as Tsushima Warm Current (TWC), Yellow Sea Warm Current (YSWC) and Changjiang Diluted Water (CDW). Therefore, the IORS and the SORS are suitable for the research on the physio-ecological response of phytoplankton to environmental changes. The particulate organic carbon to chlorophyll-a ratio (POC:Chl-a) has been widely used for an indicator of the ecological and physiological conditions of the phytoplankton. The purpose of this study is to investigate the POC:Chl-a ratio and its controlling factors at the IORS and the SORS by using satellite dataset. At the IORS, POC:Chl-a ratio ranged from 166.16 to 431.20, and the average was 322.14 ± 46.35. On the other hand, at the SORS, POC:Chl-a ratio ranged from 131.92 to 703.98, and the average was 385.05 ± 123.95. The POC:Chl-a ratio was higher at the SORS from autumn to winter. However, POC:Chl-a ratio in the IORS showed similar ranges in every month. The difference in POC:Chl-a ratio between the IORS and the SORS appear to be caused by differences of environmental conditions such as light intensity, temperature, and nutrients. However, to reveal the detailed relationship between environmental conditions and POC:Chl-a ratio, a further study on seasonal variations of the phytoplankton community structure and several environmental parameters would be warrant.

Solvent Extraction Techniques of Lipid from Algal species in Wastewater Treatment Station

Biodiesel production process relies of various key steps one of which is the lipid extraction from microalgae cells using economic techniques. In this study, Algal community structure and physicochemical parameters of the wastewater ‎treatment plant (Beni-Suef, Egypt), are determined from March 2016 to February ‎‎2017. In this study, we focused on the lipid extracted from wild mixed culture of Chlorella sp. which is the dominant from December 2016 to February 2017. Lipid content and fatty acid profiling of Chlorella sp. are investigated using three different methods (1) conventional extraction (CE), (2) ultrasonic assisted extraction (UAE) and (3) microwave assisted solvothermal extraction (MASE). MASE showed the highest lipid yield of ‎37.9±0.13%. SEM micrographs showed that MASE had the most distributive effect for algae cells compared to UAE and CE. Six different solvents are tested for MASE technique namely hexane: isopropanol (3:2), hexane: ethanol (1:1), chloroform: methanol (1:1), diethyl ether, ethanol and methanol. A strong linear relation between the direct electric constant and yield percent is obtained with methanol showing the highest yield. The GC-analysis of extracted lipids shows that methanol resulted in the highest percentage of palmitic acid (45.5%). The chemical composition of extracted lipids shows ‎promise towards further conversion to biodiesel.‎