Recurrent blooms of Heterosigma akashiwo (Raphidophyceae) in the Piraquê Channel, Rodrigo de Freitas Lagoon, southeast Brazil

Abstract

Six blooms of Heterosigma akashiwo (Raphidophyceae) were observed from March 2007 through March 2008 in the Rodrigo de Freitas Lagoon, a semi-confined eutrophic system located in Rio de Janeiro state, southeast Brazil. Vegetative cells of H. akashiwo analysed by optical and electron microscopy showed morphology as described in the literature. The blooms (2.8 × 10 4 to 4 × 10 8 cell.L -1 ) were restricted to the middle section of the Piraquê Channel, which is situated in the northeastern part of the lagoon and receives freshwater inflow. The salinity of subsurface water and the channel depth showed significant negative correlations with H. akashiwo abundances, and appeared to restrict the blooms to this compartment of the lagoon. No fish mortality was associated with the H. akashiwo blooms, nor were brevetoxins detected in a cell extract obtained from the bloom observed on 19 March 2007.Keywords: morphology, taxonomy, blooms, urban coastal lagoon, Rio de Janeiro. ) foram restritas à zona intermédia do canal Piraquê, que se situa na parte nordeste da lagoa e recebe aporte de água doce. A salinidade da sub-superfície da água e a profundidade do canal apresentaram correlação negativa significativa com a abundância de H. akashiwo e parecem determinar a formação de florações restritas a este compartimento da lagoa. Não houve mortalidade de peixes durante as florações de H. akashiwo e não foi detectada a presença de brevetoxinas em um extrato celular obtido a partir da floração observada em 19 de março de 2007. Florações recorrentes de

Spring bloom of the raphidophycean Heterosigma akashiwo in the Golden Horn Estuary at the northeast of Sea of Marmara

“…This shows a little negative relationship between salinity and H. akashiwo. During this study, the excessive bloom of H. akashiwo occurred in the salinity level of 16.4 psu, compatible with the tolerance of this species to low salinities previously reported by various researchers (Branco et al 2014;Taylor and Haigh, 1993). Salinity levels between 14.0 and 16.0 psu appears to be more appropriate for excessive H. akashiwo bloom as shown also in this study area and salinitiy levels higher than 17.0 psu may considerably limit the growth of the H. akashiwo.…”

A new recorded of red tide forming species; Heterocapsa triquetra, Gymnodinium impudicum, Heterosigma akashiwo and Thalassiosira rotula in Alexandria Waters, Egypt

“…The present temperature range (Table 1) is relatively higher than the range (24.4 to 30.9°C) reported by Branco et al (2014) for its massive occurrence. However, this species was previously registered eurythermal and euryhaline (Strom et al, 2013;Branco et al, 2014), offers some advantages to be a strong competitive member of the phytoplankton species assemblage, signaling its resilient ability to survive in different habitats (Bronicheski, 2014). Measured temperature seems among the most critical environmental factors that regulate the bloom dynamics; significant positive correlation found with abundance (r = 0.353, p ≤ 0.01), supporting other results (Li and Smayda, 2000).…”

Massive Blooms of Chattonella subsalsa Biecheler (Raphidophyceae) in a Hypereutrophic, Tropical Estuary—Guanabara Bay, Brazil

“…Remarkably, little is known of the identity of the causative microalgae blooming in the bay's waters. The nearby coastal area of the Atlantic Ocean and other estuarine systems north and southward from the Guanabara Bay entrance, notably the Rodrigo de Freitas Lagoon, characterized by high nutrient levels and very limited water exchange with the ocean, have recurrent blooms of harmful species, including the fish-killer raphidophyte Heterosigma akashiwo, with multiple records of massive fish-kills (Branco et al, 2014;Castro et al, 2016).…”