Assessment of Water Quality and Phytoplankton Structure of Eight Alexandria Beaches, Southeastern Mediterranean Sea, Egypt

This study aims to investigate the abundance, community, and structure of phytoplankton, physicochemical parameters, and some eutrophication state indices, to estimate the water quality of eight selected beaches along the Alexandria Coast, in the southeast of the Mediterranean Sea. The samples were collected monthly from 2019 to 2020. Nutrient values ranged from 1.54 to 33.21 µM for nitrate, 0.01 to 1.98 µM for nitrite, 0.12 to 9.45 µM for ammonia, 0.01 to 1.54 µM for phosphate, and 0.67 to 29.53 µM for silicate. Phytoplankton biomass was characterized by chlorophyll-a concentration, which fluctuated between 0.12 and 12.31 µg L−1. The annual phytoplankton average was 63.85 ± 17.83 × 103 cells L−1. Phytoplankton was highly diversified (228 taxa), and the most diversified group was diatoms (136 taxa), followed by a remarkably low number of Dinophyta (36 taxa). Diatoms reached maximum abundance in December. Meanwhile, a dense bloom of microalga Chlorella marina occurred in June on some beaches. High temperature, high dissolved inorganic nitrogen, and less-saline waters have supported green algal proliferation. The Shannon–Wiener diversity index (H’) showed that there was a qualitative seasonal difference in the composition of the phytoplankton community. Waters of beaches 1–3 were classified as between clean and moderately polluted; and beaches 4–8 varied between moderately and heavily polluted. The study revealed that human activities might have triggered the algal bloom and may be responsible for alterations in the Alexandria coast ecosystem.

Phytoplankton in relation to physico-chemical factors in Poyang lake, Jiangxi

Changes of phytoplankton structure and water quality were investigated in Poyang Lake from March 2014 to December 2019.The number of identified species in Poyang Lake was 187 belonging to 87 genera and 8 phyla (excluding undetermined species). Among them, Cyanophyta (74 species) had the maximum number of species, followed by Bacillariophyta (51 species) and Chlorophyta (36 species). The average numbers of phytoplankton cells were counted 2783.85 ± 458.5×104 cells/l. A total of 20 dominant species were identified in Poyang Lake, including 6 of Cyanobacteria, 6 of Diatoms, 7 of Chlorophyta, 1 of Cryptophyta and 1 of Dinoflagellates. Among phytoplankton, Cyanophyta cell density was the highest, accounting for 91.06%. Chlorophyta and diatoms accounted for 5.52 and 2.09%, respectively. The cell density of Xanthophyta was the lowest, accounting for only 0.03%. The four seasons showed obvious changes, and the order was summer - autumn - spring - winter. Algae were the most common, including green algae 153 (53%), diatoms 74 (26%), cyanobacteria 17 (17%), similar to other domestic studies. Bangladesh J. Bot. 50(3): 855-863, 2021 (September) Special

Improvement of Growth and Viability of Oreochromis niloticus in a Biofloc System Using Chlorella vulgaris

This study aimed to enhance Nile Tilapia growth using Chlorella vulgaris as a food additive in the biofloc system. Different concentrations of C. vulgaris were tested in four different treatments compared to control. The growth rate of Nile tilapia was parallel with C. vulgaris addition to the treatments. The best productive value (growth performance) for Nile Tilapia was recorded in T1 that was distinctly superior to the other treatments. The use of C. vulgaris in the biofloc system decreased feed conversion ratio (FCR) values; whereas the most significant value was observed at T1. Phytoplankton structure in Nile Tilapia gut was predominated with C. vulgaris representing 67.7% of the total phytoplankton crop. Statistical analysis also approved that the most important factor affecting Nile Tilapia growth was C. vulgaris addition, and some other chemical variables that affect phytoplankton’s growth such as PO4. In addition, muscle protein ratio of Nile Tilapia increased with increasing C. vulgaris concentrations. Our data concluded that increasing C. vulgaris concentration improved the growth performance of Nile Tilapia under the biofloc condition.

Effects of zebra mussels (Dreissena polymorpha) on phytoplankton under eutrophic conditions

We conducted two mesocosm experiments (2014 and 2017) to determine how invasive zebra mussels affected abundance and structure of phytoplankton community. Algae reaction was different for the introduction of D. polymorpha in 2014 and 2017. There was no influence of zebra mussels on the phytoplankton total abundance; however, it changed the biomass of individual taxa. Cyanoprokaryota reaction as a result the zebra mussels introduction was influenced by the initial phytoplankton structure and initial nitrogen and phosphorus concentrations in water. The biomass of Сyanoprokaryotа decreased at low N:P ratios and increased at high N:P ratios. Dreissena increased the biomass of large green filamentous algae, which is a poor food resource for zooplankton.

Microcystis species and their toxigenic strains in phytoplankton of ten Bulgarian waterbodies

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.

Phytoplankton succession of the Valaam archipelago lakes

The paper presents long-term material on the succession of phytoplankton collected on the lakes of the Valaam archipelago. The work was carried out on 11 lakes about Valaam archipelago, maintaining a natural mode of functioning. The lakes differed in the shape of the basin, depth, and features of the hydrochemical regime. Phytoplankton samples were taken once a month from May to October 1998–2019. In parallel with sampling, studies of the main limnological parameters were carried out. For lakes, a wide range of limnological parameters was revealed, such as transparency (0,3–4,6 m), active reaction of the environment (4,0–8,6), water color (27–296о according to Pt-Co scale), the content of total organic matter (10,8–63,8 mgO/dm3) and mineral phosphorus (0,001–0,646 mg/dm3). The phytoplankton structure varied significantly from lake to lake. In terms of abundance in most small lakes, cyanobacteria (in abundance) and rafidophyte (in biomass) algae dominated. Abundance of phytoplankton and biomass varied from 0.1 to 676.6 million cells/dm3 and from 0.1 to 105.2 mg/dm3, accordingly. In acidic polyhumous lakes, a simplification of the phytoplankton structure was noted. Representatives of the department of green algae (chlorococcal, volvox, ulotrix) dominated in these lakes throughout the season. In the seasonal dynamics of phytoplankton, one or two peaks were noted, which occurred in different years in different months, most often in June or September. It was shown that the variation in the structural parameters of the phytoplankton of lakes was determined by the specific catchment area, the depth of the reservoir, water transparency, color, electrical conductivity and nutrient content. To a large extent, the level of phytoplankton vegetation was also determined by the active reaction of the environment.

Response of phytoplankton to heavy pollution of water bodies

Phytoplankton structure was studied in five ponds (located in the Oleksandriya Nature Park, Ukraine), which significantly differed in the level of their contamination. The concentration of ammonium (NH4+-N) in the studied water bodies was 0.02–74.00 mg l−1, of nitrite (NO2−-N) – 0.002–1.750 mg l−1, nitrate (NO3−-N) – 0.13–58.00 mg l−1, inorganic compounds of phosphorus (Pinorg) – 0.041–0.160 mg l−1, chloride (Cl−) – 35.4–560.5 mg l−1, whereas the content of organic matter (PO and DO) – 4.4–10.4 and 18.0–81.0 mg O l−1, respectively. It has been found that the response of phytoplankton to heavy pollution consisted in changes in its species richness, taxonomic structure, species composition, quantitative indices, numbers and biomass structure, dimensional structure, pigment index, dominant complex, as well as changes in its ecological spectrum. Individual divisions of algae differed in their response to heavy pollution of water bodies, which was conditioned by the specificity of algae metabolism. Bacillariophyta and Cyanoprokaryota proved to be more sensitive to contamination, whereas Chlorophyta and Euglenophyta – more tolerant. The obtained data can be used to monitor the status of water bodies and their biota and to determine the type and intensity of contamination.