Contents lists available at ScienceDirect Aquatic Toxicology journal homepage: www.elsevier.com/locate/aqtox Embryotoxic eﬀects of dissolved okadaic acid on the development of Longﬁn yellowtail Seriola rivoliana J. Le Du, D. Tovar-Ramírez ⁎ , E.J. Núñez-Vázquez Centro de Investigaciones Biológicas del Noroeste (CIBNOR), La Paz, Baja California Sur, Mexico ARTICLE INFO Keywords: Okadaic acid Seriola rivoliana Phosphatases Embryotoxicity ABSTRACT In the context of global climate change where harmful algal blooms (HABs) might become more frequent and more severe, several studies have been conducted on the perturbation of embryonic development of marine animals by microalgal toxins. Okadaic acid (OA) and analogs (DSP toxins) produced by dinoﬂagellates of the genera Dynophysis and Prorocentrum are known to disturb embryogenesis. This study investigated the impact of dissolved DSP toxin (OA and Dinophysistoxin 1, DTX-1) exposure on embryo development of Longﬁn yellowtail Seriola rivoliana. Eggs were exposed to diﬀerent concentrations of dissolved DSP toxins (low treatment: at 120 μgl -1 OA eq; high treatment 175 μgl -1 OA eq.). The ﬁrst objective was to study the global toxic eﬀect of DSP toxins with hatching percentages. Secondly, the eﬀect of these toxins was investigated at molecular and functional level by measuring expression of responsible genes for bone morphogenetic protein (BMP) and proliferating cell nuclear antigen (PCNA) measuring phosphatase enzyme (serine/threonine and alkaline phosphatases) activities. Our results showed drastic mortalities induced by DSP toxins in both low and high concentration treatments. Activities of both protein and alkaline phosphatases were signiﬁcantly inhibited by DSP toxin treatments, whose eﬀects on gene expression were less evident, but levels of BMP expression in eggs treated with the lowest toxin concentration were signiﬁcantly diﬀerent from that in the control treatment. This work revealed an embryotoxic eﬀect of DSP toxins resulting in high mortality of eggs. Phosphatase inhibition could have participated in part in these global eﬀects by perturbing the regulation of pathways related to em- bryogenesis and resulting in a perturbation of gene expression. 1. Introduction The Longﬁn yellowtail Seriola rivoliana is a benthopelagic ﬁsh cir- cumglobally distributed with a high commercial value and interest for sport ﬁshing. In the past few years, projects farming Seriola genus de- veloped to expand and diversify ﬁsh production in diﬀerent countries (Sinche-Chele et al., 2009; Avilés-Quevedo and Castello-Orvay, 2004). Their reproduction at an industrial scale has not been fully controlled yet. Fish are farmed in semi-culture conditions (e.g. outgrowth of ju- veniles from their natural environment), which takes place in ﬂoating cages and remains dependent on natural stock (Sinche-Chele et al., 2009). In its natural environment, S. rivoliana produces pelagic eggs with embryonic development in the water column. At this stage, where development cannot be delayed, ﬁsh are very vulnerable to environ- mental stressors. Among them are marine toxins which are chemical metabolites produced by marine animals and algae. These toxic com- ponents are largely employed by species to protect themselves or to perturb the biology of other species, thus aﬀecting embryo development by causing cell toxicity and perturbing their metabolism. The reproduction of marine invertebrates or vertebrates can be perturbed by marine toxins at diﬀerent levels, but more speciﬁcally several studies have been focused on perturbation of embryonic de- velopment by microalgal toxins (Vasconcelos et al., 2010). Therefore, it becomes important to investigate the eﬀects of toxins, produced in HAB on marine species biology to evaluate the resulting social and economic impact of these potential perturbations. Dinoﬂagellates of the genera Dynophysis and Prorocentrum can pro- duce a toxin called okadaic acid (OA) and its analogs, which are known to induce diarrheic shellﬁsh poisoning (DSP) when consumed by hu- mans (Yasumoto et al., 1985). More recently, this toxin has also been considered for its potential impact on the biology of aquatic animals and its eﬀects on ﬁtness and dependent functions. Ajuzie (2008) has shown that OA exposure on sea bass (Dicentrarchus labrax) juveniles can aﬀect their survival. His results indicated that Prorocentrum lima ex- posure can induce a non-feeding behavior, and its ingestion can induce death by aﬀecting and damaging gills and liver. Eﬀects on reproduction http://dx.doi.org/10.1016/j.aquatox.2017.07.012 Received 28 February 2017; Received in revised form 10 July 2017; Accepted 19 July 2017 ⁎ Corresponding author. E-mail address: dtovar04@cibnor.mx (D. Tovar-Ramírez). Aquatic Toxicology 190 (2017) 210–216 Available online 21 July 2017 0166-445X/ © 2017 Elsevier B.V. All rights reserved. MARK