Ecology of the Epiphytic Potentially Harmful Dinoflagellate Ostreopsis cf. ovata (Fukuyo) from Coastal Waters off Alexandria Egypt

Abstract

Despite macroalgae epiphytes play an important role in algal habitats, available information from Alexandria coastal waters is scarce. To evaluate the role of environmental factors on the inventory of the ephyphytic Ostreopsis c.f ovata cells, its abundance on the thalli of 14 different macroalgae collected from two sites at Abou Qir rocky area was done on the basis of sampling carried out for one year. The annual maximum Ostreopsis cf. ovata cell abundance was observed in May (late-spring), reaching the maximum on the green macroalgae Ulva linza in July (mid-summer). Analysis of variance showed significant difference of abundance between seasons and hosts. Water temperature and NO 2 , NO 3 and PO 4 seem the major factor affecting on abundance of Ostreopsis c.f ovata. The present study documented the significant importance of Ulva sp. as the suitable host of O. ovata in Alexandria waters, in contrasting with others in the Mediterranean Sea that show O. ovata most often found on Phaeophyta and Rhodophyta.

Exploring the Role of Macroalgal Surface Metabolites on the Settlement of the Benthic Dinoflagellate Ostreopsis cf. ovata

“…The macroalgae colonized by O. cf. ovata were shown to differ throughout the year (Aligizaki and Nikolaidis, 2006;Battocchi et al, 2010;Hosny and Labib, 2019) likely in link to the macroalgal seasonality that modifies both their distribution and chemotypes (Paix et al, 2019) as well as their related bioactivity (Salvador Soler et al, 2007). In addition, the growth of O. cf.…”

“…Ostreopsis cf. ovata has been shown to thrive on the surface of various species of macroalgae across the Mediterranean Sea, including Chlorophyta (Battocchi et al, 2010;Accoroni et al, 2015;Hosny and Labib, 2019), Rhodophyta (Vila et al, 2001;Battocchi et al, 2010;Cohu et al, 2013;Blanfuné et al, 2015;Hosny and Labib, 2019;Gémin et al, 2020) and Phaeophyceae (Vila et al, 2001;Battocchi et al, 2010;Cohu et al, 2013;Blanfuné et al, 2015;Hosny and Labib, 2019;Gémin et al, 2020), without any clear species preference. Remarkably, some Phaeophyceae of the family Dictyotaceae are usually characterized by a low abundance of O. cf.…”

“…Remarkably, some Phaeophyceae of the family Dictyotaceae are usually characterized by a low abundance of O. cf. ovata as for instance Taonia atomaria, Dictyota fasciola, or Padina pavonica (Blanfuné et al, 2015;Hosny and Labib, 2019;Gémin et al, 2020). The antifouling properties of some specialized metabolites produced by Dictyotaceae have been proposed to drive the settlement and development of O. cf.…”