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Average and maximum length, diameter and biovolume of Eremosphaera cells observed in Lake Tanganyika in 2003 at all sites
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Abstract In the framework of a planktological and ecological study in Lake Tanganyika, East Africa (CLIMLAKE, 2001–2005), variations of cell abundance and size were observed in a green alga, Eremosphaera tanganyikae, at two study sites, one in the north basin of the lake (off Kigoma, Tanzania) and the other in the south basin (off Mpulungu, Zambi...
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Citations
... Furthermore, H. poli has a stronger preference for animal food sources, especially zooplankton. In the winter, H. poli consumes more green algae, likely due to its abundant growth during the rainy season (Stoyneva et al. 2007). Variations in food supply play a significant role in controlling the population dynamics of benthic animals, especially sea cucumbers, which deposit on the ocean floor and are among the most important consumers of detrital matter. ...
This study investigated the seasonal variations in the proximate composition, fatty acid profile, lipid nutritional quality, and diet composition of Holothuria poli collected from Monastir Bay. Our findings revealed significant seasonal variations in protein, lipids, and ash contents, with the highest protein levels recorded during the summer and peak lipid levels observed in winter. Total monounsaturated fatty acids peaked in both winter and summer, while total saturated fatty acids reached their maximum in autumn. These variations in biochemical compositions were closely linked to the sea cucumber's dietary preferences. Our results demonstrated that H. poli exhibits a diverse diet, consuming bacteria, detritus, diatoms, zooplankton, and algae, with notable seasonal fluctuations. Moreover, the EPA + DHA content and the atherogenic (AI), thrombogenic (TI), and hypocholesterolemic/hypercholesterolemic (H/H) indexes align with the ranges characteristic of high-quality seafood, though marked variations are evident among seasons. A principal component analysis illuminated the dynamic seasonal shifts in Holothuria poli's dietary habits and lipid nutritional characteristics, offering valuable insights into its ecological adaptations and potential repercussions for marine food webs. These findings underscore the intriguing interplay between fatty acid composition, lipid nutritional quality, dietary preferences, and environmental factors in sea cucumbers. ARTICLE HISTORY
... Furthermore, H. poli has a stronger preference for animal food sources, especially zooplankton. In the winter, H. poli consumes more green algae, likely due to its abundant growth during the rainy season (Stoyneva et al. 2007). Variations in food supply play a significant role in controlling the population dynamics of benthic animals, especially sea cucumbers, which deposit on the ocean floor and are among the most important consumers of detrital matter. ...
This study investigated the seasonal variations in the proximate composition, fatty acid profile, lipid nutritional quality, and diet composition of Holothuria poli collected from Monastir Bay. Our findings revealed significant seasonal variations in protein, lipids, and ash contents, with the highest protein levels recorded during the summer and peak lipid levels observed in winter. Total monounsaturated fatty acids peaked in both winter and summer, while total saturated fatty acids reached their maximum in autumn. These variations in biochemical compositions were closely linked to the sea cucumber's dietary preferences. Our results demonstrated that H. poli exhibits a diverse diet, consuming bacteria, detritus, diatoms, zooplankton, and algae, with notable seasonal fluctuations. Moreover, the EPA + DHA content and the atherogenic (AI), thrombogenic (TI), and hypocholesterolemic/hypercholesterolemic (H/H) indexes align with the ranges characteristic of high-quality seafood, though marked variations are evident among seasons. A principal component analysis illuminated the dynamic seasonal shifts in Holothuria poli's dietary habits and lipid nutritional characteristics, offering valuable insights into its ecological adaptations and potential repercussions for marine food webs. These findings underscore the intriguing interplay between fatty acid composition, lipid nutritional quality, dietary preferences, and environmental factors in sea cucumbers.
... The growth and decay processes of phytoplankton are dependent on the cell size (Morabito et al., 2007). In particular, phytoplankton cell size and community structure play an important role in physiological performance along vertical light gradients and influence sinking rates and nutrient uptake by single species (Kaiblinger et al., 2007;Stoyneva et al., 2007. The high diversity of phytoplankton shapes exhibited represents an evolutionary compromise for increased grazing resistance and optimized sinking rates (Luigi, 2008). ...
... This results in accurately considering that there is more than one cell on the image (e.g., difference between Skeletonema sp. and Cerataulina sp.). We observe that length correlates with lower salinity as winter mixing helps sustain large, non-motile cells (Stoyneva et al. 2007). Bigger organisms, whether as individual cells or chains also have an advantage against predation; data on copepods and zooplankton in Narragansett Bay show that increases in size occur right after increases in zooplankton concentration (Supporting Information Fig. S5). ...
Functional traits are increasingly used to assess changes in phytoplankton community structure and to link individual characteristics to ecosystem functioning. However, they are usually inferred from taxonomic identification or manually measured for each organism, both time consuming approaches. Instead, we focus on high throughput imaging to describe the main temporal variations of morphological changes of phytoplankton in Narragansett Bay, a coastal time‐series station. We analyzed a 2‐yr dataset of morphological features automatically extracted from continuous imaging of individual phytoplankton images (~ 105 million images collected by an Imaging FlowCytobot). We identified synthetic morphological traits using multivariate analysis and revealed that morphological variations were mainly due to changes in length, width, shape regularity, and chain structure. Morphological changes were especially important in winter with successive peaks of larger cells with increasing complexity and chains more clearly connected. Small nanophytoplankton were present year‐round and constituted the base of the community, especially apparent during the transitions between diatom blooms. High inter‐annual variability was also observed. On a weekly timescale, increases in light were associated with more clearly connected chains while more complex shapes occurred at lower nitrogen concentrations. On an hourly timescale, temperature was the determinant variable constraining cell morphology, with a general negative influence on length and a positive one on width, shape regularity, and chain structure. These first insights into the phytoplankton morphology of Narragansett Bay highlight the possible morphological traits driving the phytoplankton succession in response to light, temperature, and nutrient changes.
... produces a defensive organ called trichocyst which is used to escape from the prey, thus acting as a grazer deterrent (Lebret et al., 2012). Defence against grazers involves numerous policies such as large cell volume (Stoyneva et al., 2007), delayed germination of cysts, toxin production (Gustaffson and Hansson, 2004), and release of allelopathic compounds against grazers (Hansson et al., 2007), mechanisms by which reduction in feeding rates of microzooplankton differed between algal species and strains (Xu and Kiorboe, 2018). Water temperature varied from 29.5 °C (2017 Po-M) to 31.2 °C (2018 Pre-M) during the non-monsoon periods of the study. ...
The Netravathi estuary is a micro- to mesotidal, tropical, shallow estuary with an abundant density of phytoplankton. The impact of the zooplankton grazing rate and the selected environmental variables on the phytoplankton community structure was studied seasonally from 2017 to 2019. Microplanktons of centric diatoms such as Skeletonema costatum and Cosinodiscus radiatus dominated during monsoon seasons, whereas dinoflagellates such as Peridiniumsp. and Ceratium furca were observed in high numbers at the estuary during non-monsoon seasons. Water temperature showed a strong association with grazing rates of microzooplankton (r = 0.910). Canonical correspondence analysis studies established an intensification in grazing rate during non-monsoon seasons by calanoid copepods which in turn occasioned the reduction of microplanktons belonging to diatoms. Moreover, during monsoon seasons, diminution in grazing rates of calanoid copepods coupled with the presence of micro larvae as a secondary consumer of zooplankton resulted in the proliferation of centric diatoms. The grazing behaviour of microzooplankton affected the phytoplankton species diversity of the estuary in a negative manner (D = 0.29 in 2017 Pre-M, D = 0.76 in 2019 Pre-M). Selective grazing behaviour of calanoid copepods concerning temperature alteration exerted a strong influence in determining the phytoplankton community structure of the estuary to a great extent.
... The subsequent algal counts were done on the same microscope using the Thoma blood-counting chamber, conducting eight counts for each site. The abundance of each species was estimated in both cell numbers and biomass, the last by using the stereometrical approximations and subsequent weight recalculation [53,54,56,57]. Since it was supposed that for the estimation of toxin concentrations the biomass is a better parameter than cell numbers [58], only biomass data were presented here. ...
Bulgaria, situated on the Balkan Peninsula, is rich in small and shallow, natural and man-made non-lotic waterbodies, which are threatened by blooms of Cyanoprokaryota/Cyanobacteria. Although cyanotoxins in Bulgarian surface waters are receiving increased attention, there is no information on microviridins and their producers. This paper presents results from a phytoplankton study, conducted in August 2019 in three lakes (Durankulak, Vaya, Uzungeren) and five reservoirs (Duvanli, Mandra, Poroy, Sinyata Reka, Zhrebchevo) in which a molecular-genetic analysis (PCR based on the precursor mdnA gene and subsequent translation to amino acid alignments), combined with conventional light microscopy and an HPLC analysis of marker pigments, were applied for the identification of potential microviridin producers. The results provide evidence that ten strains of the genus Microcystis, and of its most widespread species M. aeruginosa in particular, are potentially toxigenic in respect to microviridins. The mdnA sequences were obtained from all studied waterbodies and their translation to amino-acid alignments revealed the presence of five microviridin variants (types B/C, Izancya, CBJ55500.1 (Microcystis 199), and MC19, as well as a variant, which was very close to type A). This study adds to the general understanding of the microviridin occurrence, producers, and sequence diversity.
... Being phytoplankton, they are the major source of atmospheric oxygen and are a key player in organic carbon xation on earth. Diatoms are very sensitive to the nutrient content, temperature, seasonal variation [1], pH (Potential of hydrogen), Biological Oxygen Demand (BOD), Chemical Oxygen Demand (COD) and the availability of silica in water. These factors have an impact on the growth of diatom biomass and show speci city towards all these parameters. ...
Purpose:
Drowning is the third unnatural cause of death in India. Drowning death is still considered as one of the most difficult to investigate, it requires the expertise in the pathophysiology and limnology. Long procedural protocol in laboratory analysis of vital organs and the site to obtain the victim and site-relation that creates a burden on the investigating agency. The presence of diatoms in the vital organs of the body helps to establish the pre- or post-mortem drowning death and the appearance of site-specific/unique diatoms for a region aids into locating the exact drowning site. The onsite identification can be solved by studying the diversity and preparing the diatoms map (D-map). Availability of D-map can help to reduce the investigation time and helps in confirmation of the drowning site.
Methods:
In the present study, samples were collected from the 12 water bodies in Aurangabad region M.S. India, and were acid digested, using Aqua regia solution containing HNO3: H2SO4 in 1:3 proportion in 20ml of water sample. Slides were prepared, mounted and microscopic analysis was performed using light and inverted phase microscope.
Results:
The D-map was generated and it featured 55 identified species, amongst the members of Nitzschia, Navicula and Cymbella were commonly found in many water bodies, while Craticula, Gomphonema, Tibetiella, Melosira, Pleurosira, and Mastogloia were restricted to only single water body. These unique diatoms can be used as site-specific indicators in drowning investigation of Aurangabad region. This study generated diatomic map for experimental water body present in Aurangabad region.
Conclusion:
These D-maps will be helpful in dispense a significant information about water bodies and their common as well as unique flora with a qualitative and quantitative distribution of diatoms. D- Map generated in this study can be harnessed to update knowledge of diatomology or diatoms database and generated data will aid in drowning investigation.
... The microphotographic documentation was done by a Moticam 2.0 mp camera supplied by Motic Images 2 Plus software programme. For algal counts from each site, at least four non-permanent slides were examined on Thoma counting chamber, with the abundance of each species estimated in both cell numbers and biomass, the last by using the stereometrical approximations and subsequent weight recalculation (rott, 1981;stoyneva et al., 2007;stoynevagärtner et al., 2019;raDKova et al., 2020). ...
The summer phytoplankton structure of ten Bulgarian waterbodies was studied by HPLC analysis of marker pigments, light microscopy (LM) and PCR amplification of mcyB and mcyE gene sequences. The aim was to detect biodiversity and spread of toxigenic strains of potential microcystin producers and the important bloom-forming genus Microcystis in particular. The screening was done in three waterbodies, where Microcystis had already been found (Lakes Ezerets and Durankulak and Reservoir Koprinka), three waterbodies from which it had not been reported (Reservoirs Shilkovtsi, Zhrebchevo, Suedinenie) and four reservoirs that were sampled for the first time (Malka Smolnitsa, Plachidol 2, Preselka, Duvanli). LM and HPLC data similarly showed that cyanoprokaryotes contributed significantly to the total phytoplankton composition (29%) and biomass (15–87%) in nine sampled waterbodies. Microcystis aeruginosa, M. natans, M. smithii, M. wesenbergii, Microcystis spp., M. cf. comperei and M. pseudofilamentosa, were identified using LM (the last two tropical species were found for the first time in the country). Despite the low contribution of Microcystis to the phytoplankton diversity (1–4 taxa per sample) and to the total phytoplankton biomass (< 0.01–0.5%), 57 toxigenic strains of this genus were revealed by PCR, most of which demonstrated high similarity with NCBI M. aeruginosa and M. wesenbergii strains.
... The potential MC-producers were outlined after [16,35,36]. The quantitative contribution of each species was estimated using the method of the stereometrical approximations [37] on Thoma blood-counting chamber with cell considered as the main counting unit [23,38]. ...
The rising interest in harmful cyanoprokaryote blooms promotes an increase of phycological and ecological research on potentially toxic species and their hazardous substances. The present study aimed to identify the main microcystin (MC) producers and their contribution to the phytoplankton of shallow waterbodies in Bulgaria, applying different methods. The sampling was performed in August 2019 in nine lakes and reservoirs, two of which (reservoirs Kriva Reka and Izvornik 2) were studied for the first time. The high contribution of cyanoprokaryotes to the total species composition and phytoplankton abundance was proved by light microscopic (LM) observations and HPLC analysis of marker pigments. The LM identification of potential MC-producers was supported by PCR amplification of mcyE and mcyB genes. The MCs amounts, detected by HPLC-DAD, varied by sites with a range from undetectable concentrations to 0.46 µg L−1 with only one recorded variant, namely MC-LR. It was found only in the reservoirs Mandra and Durankulak, while toxigenic MC-strains were obtained by PCR from five more waterbodies. Both LM and PCR demonstrated that the MC-producers were Microcystis aeruginosa and M. wesenbergii, despite their occurrence in low amounts (<0.5–5% of the total biomass) when filamentous cyanoprokaryotes dominated.
... Previous studies of light availability control rarely directly measured the sinking loss of phytoplankton, considering it as merely a small constant that would not signifi cantly infl uence the biomass in the column. However, this presumption is questionable because the specifi c sinking loss rate of a given taxon may vary due to the change in cell (or colony) shape and size, as well as the specifi c density, and it may further infl uence the loss process (Jezberová and Komárková, 2007;Stoyneva et al., 2007;Chen et al., 2011). In particular, phytoplankton cell (or colony) size varied with the light gradient (Jezberová and Komárková, 2007;Kaiblinger et al., 2007). ...
Harmful algal blooms in eutrophic waters pose a serious threat to freshwater ecosystems and human health. In-situ light availability control is one of the most commonly used technologies to suppress algae in lakes and reservoirs. To develop a better understanding of the effects of light on algal growth, specific density, colony size and sinking loss, Anabaena flos-aquae (cyanobacteria) and Scenedesmus obliquus (green algae) were evaluated in varying light scenarios. The results showed that the specific density and colony size of these two species varied during growth, and there were obvious differences among the light scenarios. At the end of exponential phase, S. obliquus incubated under light-limited condition maintained a higher specific density and formed larger aggregates, whereas A. flos-aquae formed a longer filament length. Both species exhibited higher sinking loss rates with lower light availability. These results implied that the sinking loss rate was not always constant but should be considered as a variable response to the change of light availability, and in-situ light availability control might result in a significant increase of the sinking loss of algae due to the change of size and specific density, thereby further affecting the algal biomass in the water column.
