Distribution of benthic centric diatom Pleurosira laevis (Compère, 1982) in different substrate type and physical and chemical variables

Abstract

Aim This contribution reports the first regional occurrence of Pleurosira laevis in the Masuleh River, Iran and additionally describes the pattern of occurrence along the Masuleh River and among four substrate types. The aim of this study was to assess the effects of substrate type and physical and chemical variables on distribution of centric diatom P. laevis. Methods At each station, triplicate samples were collected from 4 substrata. Epilithic (assemblages on rock), epidendric (assemblages on wood), epipsammic (assemblages on sand), and epipelic (assemblages on mud) diatom and water quality sampling was done four times at 5 stations. Physical and chemical variables including total nitrate, total phosphate, silicate, Fe2+, EC, and pH were also determined. Samples preserved in 2% for formalin solution and transferred to the laboratory, boiled with acid (HNO3: H2SO4; 2:1), centrifuged, identified, and counted. Cluster analysis was performed to indicate the main differences and similarities in diatom abundance amongst substrates sampled and amongst sampling stations. Results The highest (12.54 ± 1.54) and lowest (0.74 ± 0.10) abundance was obtained from wooden and muddy substrates at stations S5 and S4, respectively. The highest abundance was observed in the wooden substrate among all of sampling stations where showed significant differences (P < 0.05) with the other substrates. The hierarchical clustering based on relative abundance of P. laevis distinguished two clusters amongst the four substrate types. Rougher and more stable substrates (wood, sand, and stone) clearly separated from smooth and unstable substrates (mud). Based on relative abundance of P. laevis on rougher substrates, epidendric and epipsammic species had the highest similarity. Results of Pearson correlation showed that relative abundance of P. laevis had a significant correlation with EC, TN, TP, and Fe2+ concentrations (P < 0.05) whilst no significant correlation was observed with pH, temperature, and SiO2 concentration (P > 0.05). Conclusion We conclude that wood substrata can be substituted for one another during field surveys. Results from this study demonstrate that the type and roughness of the substrate both influence the attachment of P. laevis and its subsequent growth conditions.

Morphological plasticity in response to salinity change in the euryhaline diatom Pleurosira laevis (Bacillariophyta)

“…Taxonomic implications. The striae per 10 lm of P. laevis reported in previous studies ranges from 12 to 18 in 10 lm (e.g., Bourrelly and Manguin 1952, Al-Saadi et al 1979, Fr ankov a-Koz akov a et al 2007, Cavalcante et al 2013, Mamanazarova and Gololobova 2017, Park et al 2017, with an exceptional case in that P. laevis found in Iran had 9-12/ 10 lm (Sharifinia et al 2016). The striae densities in most of the valves observed in this study, from 13 to 19, fit well within this range.…”

“…2017), with an exceptional case in that P. laevis found in Iran had 9–12/10 μm (Sharifinia et al. 2016). The striae densities in most of the valves observed in this study, from 13 to 19, fit well within this range.…”

Mining salinisation of rivers: its impact on diatom (Bacillariophyta) assemblages

“…the Colorado River in the Grand Canyon region (Crayton & Sommerfeld 1979), the Great Lakes (Wujek & Welling 1981) or the Maumee River in Ohio (Kociolek et al 1983). Later, the species was reported in Europe (Sims 1996;Gómez 2008;Perez et al 2009), Asia (Joh 2010;Karthick & Kociolek 2011;Sharifinia et al 2016) and South America (Metzeltin & García-Rodríguez 2003). Recently, P. laevis was found in the Zarafshan River, which is one of the largest rivers in Uzbekistan (Mamanazarovaa & Gololobova 2017).…”

“…Pleurosira laevis is mainly associated with brackish or marine environments where its populations grow along with an increase in the chloride levels of the water (Wujek & Welling 1981;Kociolek et al 1983). In Sharifinia et al (2016), this species occurred in sites that were characterised by conductivity that ranged from slightly over 600 to 1000 μS cm -1 . In our study, P. laevis comprised 73% of all of the identified diatom taxa in the Bolina River and 21% in the Mleczna River, although the values of their salinity (periodically exceeded 40 000 and 7000 μS.cm -1 , respectively) and noticeable concentration of sulfates (550 and almost 300 mg.dm -3 , respectively).…”