Occurrence of epibenthic dinoflagellates in relation to biotic substrates and to environmental factors in Southern Mediterranean (Bizerte Bay and Lagoon, Tunisia): An emphasis on the harmful Ostreopsis spp., Prorocentrum lima and Coolia monotis

Hela Ben Gharbia; Mohamed Laabir; Abdelouahed Ben Mhamed; Sonia Khadija Maïté Gueroun; Mohamed Néjib Daly Yahia; Habiba Nouri; Charaf M'Rabet; Abdessalem Shili; Ons Kéfi-Daly Yahia

doi:10.1016/j.hal.2019.101704

Occurrence of epibenthic dinoflagellates in relation to biotic substrates and to environmental factors in Southern Mediterranean (Bizerte Bay and Lagoon, Tunisia): An emphasis on the harmful Ostreopsis spp., Prorocentrum lima and Coolia monotis

Harmful Algae. 2019 Dec:90:101704. doi: 10.1016/j.hal.2019.101704. Epub 2019 Nov 21.

Authors

Hela Ben Gharbia¹, Mohamed Laabir², Abdelouahed Ben Mhamed³, Sonia Khadija Maïté Gueroun⁴, Mohamed Néjib Daly Yahia⁵, Habiba Nouri⁶, Charaf M'Rabet⁷, Abdessalem Shili⁸, Ons Kéfi-Daly Yahia⁷

Affiliations

¹ Research Group on Oceanography and Plankton Ecology, Tunisian National Institute of Agronomy (INAT), 43 Avenue Charles Nicolle, IRESA- Carthage University, LR18ES41 (Tunis El Manar University), Tunis, 1082, Tunisia. Electronic address: hela.bg@hotmail.fr.
² Center for Marine Biodiversity, Exploitation and Conservation (MARBEC), Institut de Recherche pour le Développement (IRD), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Centre National de la Recherche Scientifique (CNRS), Montpellier University, Place Eugène Bataillon, CC093, Montpellier, Cedex 5, F-34095, France.
³ National Institute for Fisheries Research, Central laboratories, Bd Sidi Abderrahmane Ain Diab 2, Casablanca, Morocco.
⁴ Faculty of Sciences of Bizerte, Laboratory of Aquatic Systems Biodiversity and Functioning, 7021 Zarzouna, Carthage University, Bizerte, Tunisia.
⁵ Department of Biological and Environmental Sciences, College of Arts and Sciences, Qatar University, PO Box 2713, Doha, Qatar.
⁶ Institut de Recherche pour le Développement (IRD), 2 Rue Des Sports-El Menzah 1, BP 434, Tunis, 1004, Tunisia.
⁷ Research Group on Oceanography and Plankton Ecology, Tunisian National Institute of Agronomy (INAT), 43 Avenue Charles Nicolle, IRESA- Carthage University, LR18ES41 (Tunis El Manar University), Tunis, 1082, Tunisia.
⁸ Tunisian National Institute of Agronomy (INAT), 43 Avenue Charles Nicolle, IRESA-Carthage University, Tunis, 1082, Tunisia.

PMID: 31806162
DOI: 10.1016/j.hal.2019.101704

Abstract

Harmful events associated with epibenthic dinoflagellates, have been reported more frequently over the last decades. Occurrence of potentially toxic benthic dinoflagellates, on the leaves of two magnoliophytes (Cymodocea nodosa and Zostera noltei) and thalli of the macroalgae (Ulva rigida), was monitored over one year (From May 2015 to April 2016) in the Bizerte Bay and Lagoon (North of Tunisia, Southern Mediterranean Sea). The investigated lagoon is known to be highly anthropized. This is the first report on the seasonal distribution of epibenthic dinoﬂagellates hosted by natural substrates, from two contrasted, adjacent coastal Mediterranean ecosystems. The environmental factors promoting the development of the harmful epibenthic dinoflagellates Ostreopsis spp., Prorocentrum lima and Coolia monotis were investigated. The highest cell densities were reached by Ostreopsis spp. (1.9 × 10³ cells g^-1 FW, in October 2015), P. lima (1.6 × 10³ cells g^-1 FW, in June 2015) and C. monotis (1.1 × 10³ cells g^-1 FW, in May 2015). C. nodosa and Z. noltei were the most favorable host macrophytes for C. monotis (in station L2) and Ostreopsis spp. (in station L3), respectively. Positive correlations were recorded between Ostreopsis spp. and temperature. Densities of the epibenthic dinoflagellates varied according to the collection site, and a great disparity was observed between the Bay and the Lagoon. Maximum concentrations were recorded on C. nodosa leaves from the Bizerte Bay, while low epiphytic cell abundances were associated with macrophytes sampled from the Bizerte Lagoon. The observed differences in dinoflagellate abundances between the two ecosystems (Bay-Lagoon) seemed not related to the nutrients, but rather to the poor environmental conditions in the lagoon.

Keywords: Environmental factors; Epibenthic dinoflagellates; Macrophytes; Southern Mediterranean.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Bays
Dinoflagellida*
Ecosystem
Mediterranean Sea
Tunisia