Showing 4 results for Phytoplankton
Volume 3, Issue 3 (9-2015)
Abstract
The main diatomic structure-forming species of the Zayandehrud Reservoir was investigated by collecting samples from the surface, five, seven and 10 m depths from January 2011 to October 2012 along four linear transects. Asterionella formosa Hassall, Cyclotella ocellata Pantocsek and Fragilaria crotonensis Kitton were revealed as the three structure-forming species among diatomic algae in the reservoir. The number of these diatomic cells increased from the reservoir banks to its central areas, but their abundance was non-uniformly distributed at the 10-meter water column at different sites, except for C. ocellata that showed a practically uniform distribution at the peak of its maximum growth. Overall, the frequency and cover of these structure-forming diatoms changed under the influence of different abiotic variables such as electrical conductivity (EC) and nitrate (NO3-N).
Volume 7, Issue 1 (1-2019)
Abstract
Aims: Green algae (Chlorophyta), as a diverse group of algae, has almost omnipresent distribution in the Caspian Sea and plays an important role in ecosystem functioning. The aim of this study was to investigate the spatial and temporal distribution and biomass trend of planktonic green microalgae (Chlorophyta) in southeast of the Caspian Sea.
Materials & Methods: This experimental study was performed by sampling water from south of the Caspian Sea in Mazandaran province during the winter 2015 and summer 2016. Water sampling was done along two half-lines perpendicular to the estuaries of "Tajan" and "Babolrood" rivers in 8 stations and 4 depths (less than 1, 5, 10, and 20 m) in the euphotic zone, at 8 stations along the linear transects. Settlement method was applied to the preserved samples in formaldehyde 4%, in order to the qualitative and quantitative analysis of phytoplankton. The biomass of Chlorophyta was calculated, using the geometric shape method. The data were statistically analyzed, using PRIMER 6 and SPSS 19 software and the diagrams were drawn by Excel 2013.
Findings: Of total 29 identified Chlorophyta species, 28 species were present in the summer with the highest abundance of Chlorella sp. (1395×105±671×104 N/m3) and, 19 species were observed during the winter, with the highest abundance of Binuclearia sp. (456×105±155×104 N/m3). Binuclearia sp. also showed the highest biomass in both seasons.
Conclusion: The diversity of Chlorophyta is influenced by seasonal variations. Estuaries are the richest stations in terms of abundance and biomass of planktonic Chlorophyta in summer.
Seyedeh Laili Mohebbi-Nozar, Mohammad Sediq Mortazavi, Fereshteh Seraji, Behnam Daghooghi, Reza Dehghani, Golamali Akbarzadeh,
Volume 9, Issue 2 (4-2020)
Abstract
The aim of the present study was to identify the phytoplankton species which producing domoic acid and okadaic acid toxins in coastal waters of Banar Abbas city, and to determine the concentration of domoic acid and okadaic acid toxins in water and shellfish samples.Water sampling was performed in winter 2015 and summer 2016 from coastal areas overlooking the discharge of municipal and industrial effluents. Shellfish were collected from the coasts of Bandar Abbas and Bandar-e- Lengeh. Phytoplankton toxins were measured by kit method and instrumental analysis based on ELIZA method.Pseudonitzschia delicatissima, Pseudo-nitzschia pungens and Pseudo-nitzschia seriata were identified in the production of domoic acid, while Dinophysis caudate and Prorocentrum Lima were recorded as okadaic acid producers in the coastal waters of Bandar Abbas. Water-soluble okadaic acid showed significantly higher concentrations than domoic acid. Instudied shellfish samples (Circenita callipyga, Barbatia candida, Telescopium telescopiumandThalessa savignyi), the measured concentrations of okadaic acid ranged from 59.8 ± 2.38 to 121.96 ± 28.25 μg / kg. This value for domoic acid was from 0.85 to 83.59 ± 38.72 μg / kg.Compared to the guideline values, the observed concentrations of okadaic acid and domoic acid toxins in the studied shellfish were lower than the allowable level. But this value was recorded for the water-soluble domoic acid above the allowable value, which requires continuous monitoring to achieve the quantitative and qualitative pattern of phytoplankton toxins in order to support the safety of the marine ecosystem users in Hormozgan province.
Gholamali Akbarzadeh Chomachaei, Fereshteh Saraji, Hadi Koohkan, Siyamak Behzadi, Mohammad Darvishi, Seyedeh Laili Mohebbi-Nozar,
Volume 12, Issue 1 (12-2022)
Abstract
In this study, the possible impact Asian sea bass fish (Lates calcarifer) cages culture on the population structure of phytoplankton in the coastal waters of Qeshm Island.Water sampling was done monthly for a period of six months in three stations from October 2018 to March 2019.The results showed that the mean Variations of total abundance of phytoplankton at the location of fish cages culture compared to the Reference station had a significant increase (P <0.05). At the location of cages culture, the Trophic status level was high (<5), the risk of eutrophication status (<4) and the value of trophic efficiency coefficient were high. According to the analysis of Simper test, Among the Forty-one genera identified, Noctiluca sp. with a relative abundance of % 82.37, contribution rate of 21.8% with high algal bloom at the location of cages in autumn season and then the genera Chaetoceros sp., Nitzschia sp. and Coclodinium sp. with a relative abundance of less than 10 percent in differentiating the population structure of phytoplankton have played a significant role in the dissimilarity of the population structure of phytoplankton between stations In general, in this study, the effects of fish farming activities on the population structure of phytoplankton are ineffective, but it causes the abundance of some species, available nutrients, increases the trophic level, and the probability of harmful algal blooms in the location of the cages culture.
