Abundance Of Green Algae Research Articles

Palaeoenvironmental analysis of the Langshan Formation in the Xiongba area

The mid-Cretaceous Langshan Formation is a massive limestone unit, outcropping typically in the northern Lhasa block. A Xiongba section, measured near the type section of the Langshan Formation, is here described. The succession consists of orbitolinids limestone, where eight microfacies have been recognized. The lower part of the Langshan Formation consists of discoidal orbitolinids with other heterotrophic associations, including echinoderms, sponge spicules, and bivalves. In contrast, the upper part of the Langshan Formation features conical orbitolinids with an abundance of green algae and small benthic foraminifers. We interpret the morphological changes in orbitolinids as being influenced by bathymetry. Consequently, the microfacies variations in the Langshan Formation in the Xiongba section represent a shallowing upward sequence.

Weaving scientific and local knowledge on climate change impacts in coastal Kenya, Western Indian Ocean

Climate change poses severe threats to coastal social-ecological systems (SES) worldwide. Recent calls recognize the importance of including Indigenous and local knowledge (ILK) in research on climate change impacts. Yet studies that have attempted to weave ILK and scientific knowledge have seldom considered the gendered nature of climate change impacts. Building on the literature on gender and climate change and knowledge pluralism, this study contributes to addressing this research gap by exploring local knowledge on climate change impacts and its relation to scientific knowledge through a gendered approach and focusing on the Western Indian Ocean region, and more specifically on Kenya. We adopted a mixed methodology combining qualitative and quantitative approaches. We found evidence of pronounced climate change impacts on coastal SES both in the scientific literature and in local reports. Our findings highlight that there is an extensive overlap between information derived from scientific and local knowledge systems. Importantly, our study revealed reports of change that were only provided by SSF communities, namely changes in coastal dynamics, a decrease in rainfall, and a decrease in the abundance of green algae. Although we found gendered variations in changes reported by SSF communities, gendered differences of climate change impacts on SSF were not detected in the reviewed literature. Overall, our results suggest that knowledge cross-fertilization generates a holistic, relational, and place-based view of climate change impacts, which may support sound and gender-inclusive adaptive policies. We conclude by suggesting key policy recommendations for climate adaptation and risk management

Interdisciplinary strategy to assess the impact of meteorological variables on the biochemical composition of the rain and the dynamics of a small eutrophic lake under rain forcing

Abstract. We present an interdisciplinary investigation of the links between the macro and microphysical properties of rain, the biochemical composition of rain, meteorological parameters, and their impacts on the phytoplankton dynamics of a mountain lake. In order to document this interdisciplinary scientific question, Lake Aydat in the French Massif Central mountains was fitted with a set of high-resolution atmospheric radars, a disdrometer, and a precipitation collector in 2020. In parallel, the lake was monitored via sensors and water sampling. To illustrate the potential of this novel experimental setup, we present a case study of a rain event that occurred in September 2020 and during which, three contrasting sub-periods were identified based on the type of rain (convective or stratiform). Using our high-temporal resolution monitoring, we show that the origin of the air mass mainly influences the chemical composition of the rain, which depends on the rain type. In contrast, the photosynthetic cell concentration in the rain is mainly influenced by meteorological variables, predominantly below-cloud scavenging. The very low concentrations of photosynthetic cells found in rain events cannot directly impact the lake's phytoplankton abundance. In contrast, the rain rate directly impacted the lake's thermal stratification during the convective event. The response of the phytoplankton depends on the genus and, interestingly, three cyanobacteria, Microcystis, Coelomoron, and Merismopedia, showed a systematic response to rain events with a sudden decrease in abundance at the lake surface immediately after rain events. In contrast, the abundance of green algae (Elakatothrix), picocyanobacteria (Synechocystis and Synechococcus), and diatoms (Asterionella and Melosira) gradually increased following the rain events, but with a lower intensity compared to the cyanobacteria species. These different phytoplankton responses to the same rainfall event could play a key role in phytoplankton dynamics in the temperate zone. Our results highlight the importance of high-frequency and time resolution monitoring of both atmosphere and lake to better understand the adaptive strategies of cyanobacteria following rain events.

Darriwilian–Sandbian (Middle–Late Ordovician) shallow warm-water deposits in the Upper Yangtze region, South China: A case study from the Qiaojia area, northeastern Yunnan Province

The Middle–Late Ordovician Nuoduo and Huadan formations are well exposed at Songliang of northeastern Yunnan Province, representing rare neritic carbonate sediments deposited in the Yangtze region, South China during that time. Detailed sedimentological analyses support the recognition of ten microfacies from the succession, including shale (MF 1), argillaceous mudstone/dolostone (MF 2), mollusk-ostracod wacke-packstone (MF 3), peloidal wacke- to pack-grainstone/dolostone (MF 4), ooid-cortoid-peloid pack-grainstone/dolostone (MF 5), peloidal bindstone (MF 6), bioclastic wacke-packstone (MF 7), green algae mud-wackestone to floatstone (MF 8), bioclast-lithoclast float-rudstone (MF 9) and green algae bindstone (MF 10). Types A, B and C of shallowing-upward sequences are constructed according to vertical associations of MFs. The Nuoduo Formation mainly comprises Type A and Type B, both being characterized by abundant peloids, ooids, cortoids and aggregate grains. MF 5 and MF 6 cap the Type A and Type B sequences, respectively, suggesting an overall restricted marine environment shifting cyclically from lagoon to shoal, or lagoon to tidal flat, respectively. Type C sequences, occurring in the topmost Nuoduo to Huadan formations, contain various green algae indicative of open-sea, euphotic subtidal zones. The transition from A and B to C sequences is marked by ferruginous ooidal intervals, possibly correlated to relative sea-level rise and/or tectonic activities. A continuous neritic, warm-water environment is proposed for this area from late Middle to Late Ordovician, with the Nuoduo Formation filling the absence of warm-water deposits in the tropical or subtropical Yangtze region during Middle Ordovician. The increasing diversity and abundance of green algae in the Huadan Formation might represent a global radiation event of marine flora during the studied interval. Unique fossils and environments distinct from those of the interior Yangtze region are documented here, leading to a better understanding of the Ordovician System regionally and globally.

Comparative account on phytoplankton functional community dynamics in the Alappuzha mud bank region (southwest coast of India) by HPLC-CHEMTAX and microscopy approaches

Phytoplankton community composition and its temporal dynamics were evaluated in the Alappuzha near shore waters (<15 m depth), including mud bank region, located along the southwest coast of India, using HPLC-derived marker pigments and microscope-based species composition data. The study has shown a characteristic phytoplankton succession pattern, wherein an exceptional increase in chlorophyll a (Chl a, >10 mg m−3), observed in the whole study region during the peak southwest monsoon (SWM - July) period, apparently unveiled the biological manifestation of nutrient enrichments facilitated by the coastal upwelling phenomenon. A conspicuous increase in fucoxanthin (a biomarker for diatoms) perceived across the study region clearly indicated the preponderance of diatoms (mainly Thalassiosira sp., Skeletonema costatum, Trieres mobiliensis, Nitzschia sp. etc.), particularly during the peak SWM period. The CHEMTAX calculations have shown the significant contribution of Chl a (av. 76% of total Chl a) from diatoms, regardless of seasons, compared to other taxonomic groups. Furthermore, the combined results of HPLC-CHEMTAX analyses have demonstrated the seasonal occurrence of various small-sized phytoplankton functional groups (PFGs), specifically cyanobacteria, cryptophytes and chlorophytes, along with the predominant large-sized PFGs, i.e. diatoms (mostly) and dinoflagellates. The relative increase in zeaxanthin prevalent during the warm periods (Pre-SWM and Post SWM) signified the presence of cyanobacteria. By contrast, during the SWM period, a conspicuous increase in Chl b and alloxanthin recorded in the whole study region indicated the abundance of green algae and cryptophytes, respectively. Likewise, a nominal increase in peridinin (a marker for dinoflagellates) prevalent during the onset of SWM was apparently due to the proliferation of dinoflagellates, Tripos furca and Prorocentrum micans (microscopically confirmed). Even though the overall CHEMTAX results clearly complemented the microscopy derived phytoplankton composition data, especially the abundance of large sized PFGs, (i.e. diatoms and dinoflagellates), this particular analysis could enable the portrayal of seasonal dynamics of small-sized PFGs (mainly cyanobacteria and cryptophytes) as well, as this information is highly significant as far as the study region is concerned.

Effects of guanotrophication and warming on the abundance of green algae, cyanobacteria and microcystins in Lake Lesser Prespa, Greece.

Lake Lesser Prespa in Greece is a vital breeding habitat for the Dalmatian and Great White Pelican and a shelter for numerous rare and endemic species. However, eutrophication processes are distressing the lake system and the outbreaks of cyanobacterial blooms during the warm months may pose a threat to aquatic organisms due to the presence of microcystins (MCs). In this study we hypothesize that nutrients (eutrophication), nutrient-rich pelican droppings (guanotrophication) and warming (climate change) can affect the algal growth and MCs production in the water layer of Lake Lesser Prespa. Seston collected from three lake sites was incubated at ambient (20°C) and high (30°C) temperature with or without the addition of nutrients (nitrogen (N), phosphorus (P)), or pelican droppings. Results showed increased chlorophyll-a at higher temperature (30°C). N addition yielded higher chlorophyll-a levels than the non-treated water or when only P was added. The addition of both N and P as well as the addition of pelican dropping resulted in the highest chlorophyll-a at both temperatures. Notably, in the dropping-treatments, cyanobacteria and MCs were promoted while changes were evoked in the relative contribution of toxic MC-variants. Guanotrophication may thus influence the cyanobacterial dynamics and most likely their toxicity profile at Lesser Prespa.

DETECTION OF ALGAL BLOOM IN THE COASTAL WATERS OF BORACAY, PHILIPPINES USING NORMALIZED DIFFERENCE VEGETATION INDEX (NDVI) AND FLOATING ALGAE INDEX (FAI)

Abstract. Boracay is a top tourist island in the Philippines known for its 4-km beach with powdery white sand. Recently, abundance of green algae, an indicator of high nutrient discharge, along the coastal waters of the island had led to concerns on its water quality and prompted its closure to allow ample time for rehabilitation. This study examined the algal bloom along the coastal waters of Boracay through the determination of Normalized Difference Vegetation Index (NDVI) and Floating Algae Index (FAI). ENVI and SNAP software were used to process the satellite images of Boracay obtained from its pre-closure to its reopening. Necessary corrections such as scaling to Top of Atmospheric radiance were applied. NDVI was calculated using orthotile images to determine vegetation and FAI was calculated using Sentinel-2A images. Secondary data showed that the coliform level decreased from 1 million to 18.1 MPN per 100 mL after the rehabilitation of Boracay. Lower NDVI and FAI index values were observed during the reopening of the island. The NDVI value decreased while the FAI value slightly increased on the 1st month of closure which was late dry season. Both NDVI and FAI values increased to their maximum during early wet season and eventually decreased during the reopening of Boracay. Results showed that the abundance of algae had lowered after the rehabilitation of Boracay. However, fluctuating NDVI and FAI values showed the possible seasonal effects on the algal bloom in the island. Further studies considering the other factors on algal blooms may be done.

Towards a dystrophic lake: The history of Smolak Lake (northern Poland) on the basis of geochemical and biological data

This study presents a multi-proxy reconstruction of the evolution of Smolak Lake from harmonic to dystrophic conditions. The lake’s history and environmental conditions, such as zooplankton and vegetation compositions, trophic state, water temperature and water level fluctuations, are discussed. Smolak Lake is located in the southern part of the Masurian Lakeland, northern Poland. A 350 cm core comprising thick sediments (Sm profile) are mainly composed of homogenous organic gyttja and dy was taken from the lake and analysed for geochemical and biological (cladoceran and pollen) proxies. Radiocarbon data show that the sediments accumulated from the Late Glacial (Younger Dryas period) to recent times. Based on the results of pollen data, six local pollen assemblage zones were recognized. The subfossil cladoceran fauna in the sediments are represented by 25 species belonging to four families. Five zones of Cladocera development were distinguished. The Cladocera species indicate the initial oligotrophic status of the lake and its subsequent slight increase in trophic status. From ~9000 yr cal BP (at the beginning of the Atlantic period), Smolak Lake began a fast transition to a dystrophic state. At this time, the amount of total organic carbon (TOC) in the sediments significantly increased to above 50%, and deposits containing more than 97% water were transformed into dy. The sedimentation rate was extremely low, i.e., 0.08–0.2 mm/yr. Dystrophic conditions are also reflected in the Cladocera and pollen found in the core during this period: Cladocera composition was dominated by species very resistant to acid conditions (e.g., Alonella excisa); the abundance of green algae was at its lowest level and dominated by only one genus (Botryococcus); no hydrophytes were found; and rush vegetation disappeared. Currently, Smolak Lake is a shallow, humic lake characterized by brown water and the presence of floating mats. This study shows that it’s current status is a result of it’s small, relatively undisturbed catchment, which should be protected in order to maintain this unique dystrophic habitat.

Phosphorus and nitrogen effects on microbial euendolithic communities and their bioerosion rates

Cages and fertilizers were used at Glover’s Atoll, Belize to test the relative importance of nitrogen (N) and phosphorus (P) to microbial euendolithic communities (bacteria, algae and fungi) and their bioerosion rates of Strombus gigas shells after 56-days of exposure. By the end of the experiment, the abundance of green algae was higher than cyanobacteria and fungi in N and N+P treatments, although green algae did not increase proportionally with increasing N concentrations, suggesting that green algae were co-limited by P and N. In contrast, cyanobacteria abundance increased with increasing P concentration, suggesting that cyanobacteria were P-limited. Fungi were not significantly affected by the addition of nutrients. Microbioerosion rates in the N and N+P treatments were 2-times greater than rates in the P treatment and 15-times greater than the control treatment. Results demonstrate that increased nutrient concentrations on coral reefs may increase microbioerosion rates, and variations in nutrient ratios can modify microborers community composition.

An in situ toxicity assay with the local phytoplankton community

The present study describes an approach for toxicity estimates based on the in situ exposure of the local phytoplankton community immobilized in calcium-alginate beads. The assay was deployed in an acid mine drainage-impacted system, at a reference site and an impacted site. Abundances and growth rates of major taxonomic groups (green algae, flagellates, diatoms, and cyanobacteria) and of the entire community were measured. The ecological relevance of classical toxicity estimates was evaluated by performing in situ and laboratory assays with the standard species Pseudokirchneriella subcapitata and Chlorella vulgaris. Site waters were tested without and with nutrient enrichment, to discriminate toxic effects from those caused by nutrient limitations. Despite the occurrence of growth-limiting conditions for the local phytoplankton within the alginate matrix, an impact of the mine effluent on the community was detected. The growth of the community and of all taxonomic groups, except for the cyanobacteria, was less at the impacted site than at the reference site, although adding nutrients partially compensated for the effluent detrimental effects. Shifts in the community structure were also provoked by the mine effluent; decreases in the abundance of green algae were paralleled by increases in the abundance of flagellates and diatoms, but mainly of cyanobacteria. Effects on the growth of both standard species of green algae were in conformity with those on the local phytoplankton, probably because the latter was dominated by green algae. Although future improvements regarding the cell immobilization technique should be attempted, the proposed easy and inexpensive approach to assess both the growth and the structure of local phytoplankton communities will allow more environmentally realistic site-specific assessments of water quality.

The effect of environmental parameters and cyanobacterial blooms on phytoplankton dynamics of a Portuguese temperate Lake

The increasing occurrence of cyanobacterial blooms in freshwaters is of great concern due to the ability of many cyanobacteria to produce cyanotoxins. In the present work, the eutrophied Vela Lake (Central Portugal), used for recreational purposes and as a water source for agriculture, was monitored every fortnight between 2000 and 2001. Phytoplankton diversity and densities were measured and correlated to environmental parameters. A seasonal phytoplanktonic succession was observed and it was mainly correlated with conductivity, temperature, total suspended solids and nutrients availability (particularly phosphorus). Diatoms were dominant during winter months (inferior temperatures and higher nutrients availability) followed by green algae in early spring and then cyanobacteria from late spring until early autumn (less nutrient availability and higher temperatures). A massive cyanobacterial bloom of Aphanizomenon flos-aquae occurred early in May 2001 and was preceded by the lowest nitrogen levels measured in the water during all the study period. At the time of this bloom senescence, dissolved oxygen was severely depleted and a massive death of ichthyofauna was recorded. A Microcystis aeruginosa bloom was also detected in July 2001 and it occurred following a rapid decrease in abundance of green algae and diatoms. By considering not only the environmental parameters but also the occurrence of cyanobacterial blooms as explanatory variables in a canonical correspondence analysis, the variance explained for the phytoplanktonic assemblage during the study period was increased in about 7% achieving a total of 61.0%, indicating a correlation that may be due to the known competitive advantage and/or allelopathy of the bloom-forming cyanobacteria towards microalgae.

Response of cyanobacterial mats to nutrient and salinity changes

Cyanobacterial mats (CBM), complex assemblages of cyanobacteria, bacteria and algae, are important ecosystem components of oligotrophic marshes in limestone-based regions of the Caribbean. We conducted a mesocosm experiment and evaluated the response of CBM to factorial combinations of low, medium and high phosphorus, nitrogen and salinity. Changes in composition of the main species groups of cyanobacteria and algae, primary production, cellular nutrients and enzymatic activities were recorded as response variables. The redundancy analysis with concentrations of P, N and salinity as explanatory variables showed that the primary production of CBM and the amount of phytoplankton expressed as Chl a were best explained by concentration of P, with less significant positive effect of N and a negative effect of salinity. Abundance of green algae and Chroococcales was positively correlated with increasing concentrations of P and N and reached 27.6% and 21.9%, respectively, in high P and high N treatment at the end of experiment. N 2-fixation averaged 75 and 175 nmol C 2H 4 cm −2 min −1, at low nitrogen and medium or high P, respectively, and it was negatively correlated with nitrogen concentration and positively correlated with abundance of a group of heterocytous cyanobacteria from genus Nostoc. At low N concentrations, increasing P concentrations supported higher N 2-fixation. Activity of the alkaline phosphatase, APA, was negatively correlated with P and salinity and positively with N. We also found a significant negative correlation between the APA activity and the P content of the mat. At high P and N concentrations, the mats were impacted by grazing, had a tendency to disintegrate and become shaded out by a massive growth of phytoplankton. We confirmed an overall negative effect of nutrient increase on CBM.

Novel derivatives of 9,10-anthraquinone are selective algicides against the musty-odor cyanobacterium Oscillatoria perornata.

Musty "off-flavor" in pond-cultured channel catfish (Ictalurus punctatus) costs the catfish production industry in the United States at least 30 million US dollars annually. The cyanobacterium Oscillatoria perornata (Skuja) is credited with being the major cause of musty off-flavor in farm-raised catfish in Mississippi. The herbicides diuron and copper sulfate, currently used by catfish producers as algicides to help mitigate musty off-flavor problems, have several drawbacks, including broad-spectrum toxicity towards the entire phytoplankton community that can lead to water quality deterioration and subsequent fish death. By use of microtiter plate bioassays, a novel group of compounds derived from the natural compound 9,10-anthraquinone have been found to be much more selectively toxic towards O. perornata than diuron and copper sulfate. In efficacy studies using limnocorrals placed in catfish production ponds, application rates of 0.3 micro M (125 micro g/liter) of the most promising anthraquinone derivative, 2-[methylamino-N-(1'-methylethyl)]-9,10-anthraquinone monophosphate (anthraquinone-59), dramatically reduced the abundance of O. perornata and levels of 2-methylisoborneol, the musty compound produced by O. perornata. The abundance of green algae and diatoms increased dramatically 2 days after application of a 0.3 micro M concentration of anthraquinone-59 to pond water within the limnocorrals. The half-life of anthraquinone-59 in pond water was determined to be 19 h, making it much less persistent than diuron. Anthraquinone-59 appears to be promising for use as a selective algicide in catfish aquaculture.

On the abundance of epiphytic green algae in relation to the nitrogen concentrations of biomonitors and nitrogen deposition in Finland

Green algae have become considerably more abundant in the years 1985–1995 in Finland and their distribution area has expanded northwards. Green algae on conifers were most abundant in southern Finland where the nitrogen deposition is highest. Correlations were observed between the abundance of green algae and a modelled nitrogen and sulphur deposition as well as the nitrogen concentration of the biomonitors. The increased abundance of green algae in Finland may be caused by several concurrent changes which have taken place in the environment and which have all promoted the occurrence of green algae. A slight rise in mean annual temperature, the long-term stability of nitrogen deposition, and the clear fall in the amount of sulphur deposition have probably all increased the growth and abundance of green algae. At a local level, the differences in microclimate have also effect on the abundance of green algae and the microclimate varies, inter alia, by the nutrient-richness of the habitat, the predominant tree species, stand age and stand density.

A method for facilitating the use of algae growing on tree trunks as bioindicators of air quality

The abundance of epiphytic green algae has been observed to correlate strongly with air quality in several studies. In contrast to lichens, the abundance of green algae is difficult to measure accurately by visual observation. A new method based on photography and digital image processing was developed to estimate the chlorophyll content of algae growing on the bark of pine. Calibration data for the method was collected from polluted areas by spectrophotometric analysis of chlorophyll density.