Relationship between marine epilithic diatoms and environmental variables in oligotrophic bay, NE Mediterranean

Abstract

The taxonomic composition and structure of a marine epilithic diatom community were sampled from the bottom of the two sites at monthly intervals from January to December 2011 in the small semi-enclosed oligotrophic Neum Bay in Bosnia and Herzegovina (Middle Adriatic). Altogether, 264 diatom taxa (species and infraspecific taxa) within 69 genera were identified. Among them, 149 and 203 taxa occurred in samples from the shallow (0.5 m depth) and deep (8 m depth) sites, respectively. The monthly distribution of most of the diatoms was irregular and high numbers of sporadic taxa were found. SIMPER analysis indicated that the difference between shallow and deep sites could be largely attributed to the frequently recorded diatom taxa and those with high percentage abundances. They were Halamphora coffeiformis, Caloneis excentrica, Cocconeis scutellum var. scutellum, Licmophora flabellata, Licmophora gracilis, Licmophora sp., Navicula abunda, Rhabdonema adriaticum, and Striatella unipunctata. Canonical Correspondence Analysis (CCA) showed that temperature, oxygen saturation (O 2 /O 2 ′), silicate concentration (SiO 4 ), and salinity were the most important factors influencing diatom community structure in the bay.

Epilithic diatom communities from areas of invasive Caulerpa species (Caulerpa taxifolia and Caulerpa cylindracea) in the Adriatic Sea, NE Mediterranean

“…scutellum agree with a study from Neum Bay in Bosnia and Herzegovina in which, although no strong seasonal variation of diatom taxa was observed, C. scutellum var. scutellum showed high contributions in the winter-spring diatom communities (Hafner et al, 2018). These results contrast those of the study of benthic diatoms on natural substrata from the Aegean Sea (Turkey) by Çolak Sabanci (2012b) where C. scutellum did not show any kind of seasonality.…”

“…Autumn, as the period of the greatest species diversity, appears to coincide with the maximum toxicity (Dumay et al, 2002) observed for C. taxifolia. Hafner et al (2018) observed for the Adriatic an increase in species diversity index in the samples from the depth of 0.5 m in the warm summer months, while the highest diversity was associated to the samples from the depth of 8 m in October.…”

“…scutellum was registered in all samples although with some differences in spatial distribution in relation to sampling periods. Generally, C. scutellum is indeed the most frequently recorded diatom taxon on all (epiphytic, epilithic, epizoic) different substrata (Car et al, 2012;Çolak Sabanci, 2012b;De Stefano et al, 2000Hafner et al, 2018;Sullivan, 1984;Totti et al, 2007).…”

“…Benthic diatom communities of the Italian North Adriatic have been well studied on an artificial hard substrates at two stations, one in the Gulf of Trieste (Bartole et al, 1991-94) and the other in Venice lagoon (Tolomio & Andreoli, 1989;Tolomio et al, 1991), and in natural sediment samples from the Gulf of Trieste (Sdrigotti et al, 1999;Welker et al, 2002;Cibic et al, 2007;Franzo et al, 2014, Rogelja et al, 2018, the Venice lagoon (Tolomio et al, 1999(Tolomio et al, , 2002Facca et al, 2002a, b;Tolomio, 2004;Facca & Sfriso, 2007), the coast from Ancona to the Po delta (Totti, 2003), between Rimini and Pesaro (Franzo et al, 2015), and in the Lesina lagoon (Gambi et al, 2003). While an extensive literature on microphytobenthic species of the Italian seas exists (see Cibic & Facca, 2010 and references therein), only limited information is available on the composition of epilithic assemblages grown on either natural or artificial substrates in marine coastal waters of the eastern Middle and South Adriatic, e.g., epilithic diatoms from stones in the oligotrophic Neum Bay in Bosnia and Herzegovina (Hafner et al, 2018) and along Albanian coastal wetlands (Miho & Witkowski, 2005). The only study on benthic diatoms from areas with the invasive species C. taxifolia in the Middle Adriatic was focused on morphology and valve ultrastructure of a newly described marine epiphytic diatom, Cocconeis caulerpacola (Car et al, 2012).…”

Benthic diatoms species richness at Dvuyakornaya Bay and other coastal sites of Crimea (the Black Sea) under various environments

“…The study of the benthic diatom taxocene structure in various marine biotopes is highly relevant due to the key role of Bacillariophyta in coastal ecosystem functions. Evaluation of diatom species richness represents an important task for bioindication purposes and to determine species conservation priorities (Keck et al, 2016;Hafner et al, 2018;Nevrova et al, 2015;Stenger-Kovacs et al, 2014, 2016. With coastal marine ecosystems being under increasing anthropogenic impact, a primary task involves the assessment of taxonomical diversity and comparative evaluation of taxocene structure in biotopes with varying levels of pollution.…”