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For the present paper 35 specimens of sea mullet (Mugil cephalus) from different age groups were investigated. The material was collected between May 2010 - September 2011 along the coast, the main points are two: Varna Bay and the mouth of the river Veleka. The main objective of the study was to establish the food spectrum of mullet, and thus a connection could be made between food components. The methods which were used and defined to study the food spectrum and the relationship between different food components are as follows: frequency of occurrence and dominance index of the nutritional components; the filling index and stomach emptiness index, as well as selectivity coefficient of a meal.Results showed that detritus, zoobenthos (Rissoa sp. and Trochammina inflate - 71.43%) and macrophytes (Cladophoraceae family - 63.64%) dominated in stomachs. Several potential toxic species were also found: Amphora coffeaeformis, Pseudo-nitzschia delicatissima, Pseudo-nitzschia seriata, Prorocentrum cordatum, E. pyriformis, P. minimum, Protoperidinium crassipes. The results for the frequency of occurrence (pF) showed that the most common in the stomach of a mullet of the macrophytes are the species of family Ulvaceae - 45.5% ; family Cladophoraceae - 45.5% ; of phytoplankton - Navicula spp (109,09%).; of zoobenthos: Nematoda g.sp. - 42.9% and Trochammina inflate - 28.6 %. The low emptiness index (0.0857) defines the grey mullet as an often eating fish. The small fish reaching up to 3-4 cm eat phytoplankton and zooplankton. Until now, research on the food spectrum of sea mullet by the Bulgarian sector of the Black Sea have not been conducted. [ABSTRACT FROM AUTHOR]

Yessotoxin is one of the shellfish toxins leading to mussel farm closures in the Adriatic Sea of Italy. Two putative Gonyaulax spinifera strains GSA0501 and GSA0602 are known as yessotoxins producers, but their identities have remained elusive since 2005. To address this gap, we established five Gonyaulax strains by incubating sediments from the Adriatic Sea and subsequently isolating single cells. Both cyst and theca morphology were examined using light and scanning electron microscopy. In addition, LSU and/or SSU rRNA gene sequences were obtained for all strains. Two strains produce cysts resembling Spiniferites mirabilis and one strain was related to S. scabratus. The other two strains are described as Gonyaulax montresoriae sp. nov., characterized by a high cingular displacement and overhang, along with two unequal antapical spines. Cysts of G. montresoriae are pear-shaped, showing a smooth surface and exclusively gonal processes with perforations at the base, the latter similar to S. lazus. LSU rRNA gene sequence comparison suggests that the G. spinifera strain GSA0501 isolated from the Adriatic Sea in 2005 should also be identified as G. montresoriae. Maximum likelihood and Bayesian inference analyses based on LSU and SSU rRNA gene sequences reveal that G. montresoriae is monophyletic, and close to several toxic strains of presumable Gonyaulax spinifera from the Adriatic Sea and New Zealand, whose taxonomic positions are uncertain. One strain of G. montresoriae was examined for yessotoxin production using LC-MS/MS, and found to produce predominantly yessotoxin at a concentration of 3.0 pg cell -1 . Our results highlight the rich diversity and risks associated with Gonyaulax species in the Mediterranean Sea., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Hermesinum adriaticum is a rare marine and brackish flagellate that is of considerable interest due to its markable and fossilizable siliceous skeleton. Based on this skeleton, Hermesinum was initially considered a microalga of the Dictyochophyceae (Ochrophyta, Stramenopiles). Later on, it was assigned to the Ebriida due to its similarity to Ebria tripartita. The taxonomic assignment of the Ebriida, however, changed several times until it was placed within the Thecofilosea (Cercozoa, Rhizaria), based on genetic data of E. tripartita. We sequenced the 18S marker gene sequence of Hermesinum and confirm the close relationship of Ebria and Hermesinum., (© 2022 The Authors. Journal of Eukaryotic Microbiology published by Wiley Periodicals LLC on behalf of International Society of Protistologists.)

Coastal harmful algal blooms (HABs), commonly termed 'red tides', have severe undesirable consequences to the marine ecosystems and local fishery and tourism industries. Increase in nitrogen and/or phosphorus loading is often regarded as the major culprits of increasing frequency and intensity of the coastal HAB; however, fundamental understanding is lacking as to the causes and mechanism of bloom formation despite decades of intensive investigation. In this study, we interrogated the prokaryotic microbiomes of surface water samples collected at two neighboring segments of East China Sea that contrast greatly in terms of the intensity and frequency of Prorocentrum-dominated HAB. Mantel tests identified significant correlations between the structural and functional composition of the microbiomes and the physicochemical state and the algal biomass density of the surface seawater, implying the possibility that prokaryotic microbiota may play key roles in the coastal HAB. A conspicuous feature of the microbiomes at the sites characterized with high trophic state index and eukaryotic algal cell counts was disproportionate proliferation of Vibrio spp., and their complete domination of the functional genes attributable to the dissimilatory nitrate reduction to ammonia (DNRA) pathway substantially enriched at these sites. The genes attributed to phosphorus uptake function were significantly enriched at these sites, presumably due to the P i -deficiency induced by algal growth; however, the profiles of the phosphorus mineralization genes lacked consistency, barring any conclusive evidence with regard to contribution of prokaryotic microbiota to phosphorus bioavailability. The results of the co-occurrence network analysis performed with the core prokaryotic microbiome supported that the observed proliferation of Vibrio and HAB may be causally associated. The findings of this study suggest a previously unidentified association between Vibrio proliferation and the Prorocentrum-dominated HAB in the subtropical East China Sea, and opens a discussion regarding a theoretically unlikely, but still possible, involvement of Vibrio-mediated DNRA in Vibrio-Prorocentrum symbiosis. Further experimental substantiation of this supposed symbiotic mechanism may prove crucial in understanding the dynamics of explosive local algal growth in the region during spring algal blooms., (Copyright © 2021 Elsevier Ltd. All rights reserved.)