Abstract
The health of the sea urchin Paracentrotus lividus, a key species in the Mediterranean Sea, is menaced by several pressures in coastal environments. Here, we aimed at assessing the reproductive ability of apparently healthy P. lividus population in a marine protected area affected by toxic blooms of Ostreospsis cf. ovata. Wide-ranging analyses were performed in animals collected prior to and during the bloom, as well as at several times thereafter, during the reproductive season. Adults showed a low fertilization rate, along with high nitric oxide (NO) levels in the gonads and the nitration of the major yolk protein toposome, which is an important player in sea urchin development. Serious developmental anomalies were observed in the progeny, which persist several months after the bloom. NO levels were high in the different developmental stages, which also showed variations in the transcription of several genes that were found to be directly or indirectly modulated by NO. These results highlight subtle but important reproductive flaws transmitted from the female gonads to the offspring with the NO involvement. Despite a recovery along time after the bloom, insidious damages can be envisaged in the local sea urchin population, with possible reverberation on the whole benthic system.
Highlights
Ostreopsis bloom might have long-term effects on the reproductive ability of natural sea urchin population inhabiting highly affected sites
Ostreopsis and sea urchins were collected at the Marine Protected Area (MPA) Gaiola previous to the bloom (June 2012), during the bloom (July 2012, 2013), and at several times thereafter, during the reproductive season (October 2013, February and April 2014), capturing blooms of the toxic microalga in 2012 and 2013
The wide ranging combination of morphological and functional observations reported in this study revealed a significant impairment of reproductive ability in natural populations of sea urchins inhabiting an MPA that is affected by intense and recurrent harmful algal blooms (HABs) produced by the dinoflagellate O. cf. ovata
Summary
Ostreopsis bloom might have long-term effects on the reproductive ability of natural sea urchin population inhabiting highly affected sites. This aspect is relevant considering the potential decline of this important species as a consequence of environmental changes, predation and overexploitation[16,17]. We aimed at elucidating the reproductive functionality of a P. lividus population inhabiting the Gaiola MPA. The role of nitric oxide (NO) in P. lividus reproduction and offspring development was explored, considering the pivotal biological functions of NO in regulating fundamental processes in marine organisms[20,21,22] and in mediating the response of P. lividus to several stress agents, including metal ions and toxic diatom aldehydes[23,24,25]
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