First Evidence of Inbreeding, Relatedness and Chaotic Genetic Patchiness in the Holoplanktonic Jellyfish Pelagia noctiluca (Scyphozoa, Cnidaria).

none6Genetic drift and non-random mating seldom influence species with large breeding populations and high dispersal potential, characterized by unstructured gene pool and panmixia at a scale lower than the minimum dispersal range of individuals. In the present study, a set of nine microsatellite markers was developed and used to investigate the spatio-temporal genetic patterns of the holoplanktonic jellyfish Pelagia noctiluca (Scyphozoa) in the Southern Tyrrhenian Sea. Homozygote excess was detected at eight loci, and individuals exhibited intra-population relatedness higher than expected by chance in at least three samples. This result was supported by the presence of siblings in at least 5 out 8 samples, 4 of which contained full-sib in addition to half-sib dyads. Having tested and ruled out alternative explanations as null alleles, our results suggest the influence of reproductive and behavioural features in shaping the genetic structure of P. noctiluca, as outcomes of population genetics analyses pointed out. Indeed, the genetic differentiation among populations was globally small but highlighted: a) a spatial genetic patchiness uncorrelated with distance between sampling locations, and b) a significant genetic heterogeneity between samples collected in the same locations in different years. Therefore, despite its extreme dispersal potential, P. noctiluca does not maintain a single homogenous population, but rather these jellyfish appear to have intra-bloom localized recruitment and/or individual cohesiveness, whereby siblings more likely swarm together as a single group and remain close after spawning events. These findings provide the first evidence of family structures and consequent genetic patchiness in a species with highly dispersive potential throughout its whole life cycle, contributing to understanding the patterns of dispersal and connectivity in marine environments.Aglieri G; Papetti C; Zane L; Milisenda G; Boero F; Piraino SAglieri, Giorgio; Papetti, C; Zane, L; Milisenda, Giacomo; Boero, Ferdinando; Piraino, Stefan

Pelagia benovici sp. nov. (Cnidaria, Scyphozoa): a new jellyfish in the Mediterranean Sea

A bloom of an unknown semaestome jellyfish species was recorded in the North Adriatic Sea from September 2013 to early 2014. Morphological analysis of several specimens showed distinct differences from other known semaestome species in the Mediterranean Sea and unquestionably identified them as belonging to a new pelagiid species within genus Pelagia. The new species is morphologically distinct from P. noctiluca, currently the only recognized valid species in the genus, and from other doubtful Pelagia species recorded from other areas of the world. Molecular analyses of mitochondrial cytochrome c oxidase subunit I (COI) and nuclear 28S ribosomal DNA genes corroborate its specific distinction from P. noctiluca and other pelagiid taxa, supporting the monophyly of Pelagiidae. Thus, we describe Pelagia benovici sp. nov. Piraino, Aglieri, Scorrano & Boero

Chaotic genetic structure and past demographic expansion of the invasive gastropod Tritia neritea in its native range, the Mediterranean Sea

© The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Boissin, E., Neglia, V., Baksay, S., Micu, D., Bat, L., Topaloglu, B., Todorova, V., Panayotova, M., Kruschel, C., Milchakova, N., Voutsinas, E., Beqiraj, S., Nasto, I., Aglieri, G., Taviani, M., Zane, L., & Planes, S. Chaotic genetic structure and past demographic expansion of the invasive gastropod Tritia neritea in its native range, the Mediterranean Sea. Scientific Reports, 10(1), (2020): 21624. doi:10.1038/s41598-020-77742-3.To better predict population evolution of invasive species in introduced areas it is critical to identify and understand the mechanisms driving genetic diversity and structure in their native range. Here, we combined analyses of the mitochondrial COI gene and 11 microsatellite markers to investigate both past demographic history and contemporaneous genetic structure in the native area of the gastropod Tritia neritea, using Bayesian skyline plots (BSP), multivariate analyses and Bayesian clustering. The BSP framework revealed population expansions, dated after the last glacial maximum. The haplotype network revealed a strong geographic clustering. Multivariate analyses and Bayesian clustering highlighted the strong genetic structure at all scales, between the Black Sea and the Adriatic Sea, but also within basins. Within basins, a random pattern of genetic patchiness was observed, suggesting a superimposition of processes involving natural biological effects (no larval phase and thus limited larval dispersal) and putative anthropogenic transport of specimens. Contrary to the introduced area, no isolation-by-distance patterns were recovered in the Mediterranean or the Black Seas, highlighting different mechanisms at play on both native and introduced areas, triggering unknown consequences for species’ evolutionary trajectories. These results of Tritia neritea populations on its native range highlight a mixture of ancient and recent processes, with the effects of paleoclimates and life history traits likely tangled with the effects of human-mediated dispersal.This project was funded by the European FP7 CoCoNet project (Ocean.2011-4, grant agreement #287844) and we are grateful to the whole CoCoNET consortium. We are grateful to the following people for their critical help with logistics and field work ‘Antheus srl (Lecce, Italy)’; S Bevilacqua, G Guarnieri, S Fraschetti and T Terlizzi (University of Salento, Italy); L Angeletti and M Sigovini (ISMAR, Italy); D Shamrey (IBSS, Sevastopol); A Anastasopoulou, MA Pancucci-Papadopoulou and S Reizopoulou (HCMR, Greece) and E Hajdëri (Catholic University ‘Our Lady of Good Counsel’, Tirana). Thank you to J Almany for English corrections. This is ISMAR-CNR scientific contribution n1987. E Boissin was supported by a European Marie Curie postdoctoral fellowship MC-CIG-618480

Are anti-jellyfish nets a useful mitigation tool for coastal tourism? Hindsight from the MED-JELLYRISK experience

The mitigation of coastal hazards, notably jellyfish blooms, has assumed great significance in recent years in view of the potential detrimental impact of such hazards on the welfare of coastal communities. This is especially true in a basin such as the Mediterranean with a very high degree of coastal settlement and dependence on coastal economic activities. Within the MED-JELLYRISK project and over the course of two summers (2014 and 2015), a total of 15 anti-jellyfish nets within several Mediterranean tourist hotposts were installed in Italy (islands of Lipari, Salina, Ustica, Lampedusa and Favignana), Spain (two beaches on the island of Ibiza), Tunisia (beaches at Monastir and Hammamet) and Malta. Manufactured in 25m-long modules, the nets were specifically designed to exclude individuals of jellyfish species from the enclosed bathing areas, and were installed on shallow sandy and rocky bottoms from the coastal fringe down to a water depth of 2.5m. The performance of the same nets was monitored through scientific surveys inside and outside the net-enclosed areas. In parallel, the colonization of fouling organisms on the submerged sections of the nets was investigated, and the public perception of the installed nets was assessed through ad hoc questionnaires deployed on the beaches. Useful hindsight for coastal managers, concerning best sites and conditions for deployment, net design and materials, has been gained from this experimental anti-jellyfish net deployment effort within the MED-JELLYRISK project.peer-reviewe

Unmasking Aurelia species in the Mediterranean Sea: an integrative morphometric and molecular approach

Molecular analyses have led to an increased knowledge of the number and distribution of morphologically cryptic species in the world's oceans and, concomitantly, to the identification of non-indigenous species (NIS). Traditional taxonomy and accurate delimitation of species’ life histories and autecology lag far behind, however, even for the most widely distributed taxa, such as the moon jellyfish Aurelia (Cnidaria, Scyphozoa) species complex. Here we analysed mitochondrial cytochrome c oxidase subunit I (COI) and nuclear 28S ribosomal RNA (28S) gene sequences to assign polyps, ephyrae, and medusae collected in the Mediterranean Sea to different phylogenetic species. We find evidence for three Aurelia species, none of which are referable to the type species of the genus, Aurelia aurita (Linnaeus, 1758), and describe the anatomical, morphometric, and developmental variation within and between them. We identify Aurelia coerulea von Lendenfeld, 1884 and Aurelia solida Browne, 1905 as established non-indigenous species in the Mediterranean Sea. We describe Aurelia relicta sp. nov., an endemic species currently unique to a population in the marine lake of Mljet (Croatia). These results demonstrate the usefulness of integrative approaches in resolving taxonomic uncertainty surrounding cryptic species complexes, identifying patterns of marine biodiversity, and recognizing non-indigenous species in marine ecosystems

First Evidence of Inbreeding, Relatedness and Chaotic Genetic Patchiness in the Holoplanktonic Jellyfish Pelagia noctiluca (Scyphozoa, Cnidaria)

Genetic drift and non-random mating seldom influence species with large breeding populations and high dispersal potential, characterized by unstructured gene pool and panmixia at a scale lower than the minimum dispersal range of individuals. In the present study, a set of nine microsatellite markers was developed and used to investigate the spatiotemporal genetic patterns of the holoplanktonic jellyfish Pelagia noctiluca (Scyphozoa) in the Southern Tyrrhenian Sea. Homozygote excess was detected at eight loci, and individuals exhibited intra-population relatedness higher than expected by chance in at least three samples. This result was supported by the presence of siblings in at least 5 out 8 samples, 4 of which contained full-sib in addition to half-sib dyads. Having tested and ruled out alternative explanations as null alleles, our results suggest the influence of reproductive and behavioural features in shaping the genetic structure of P. noctiluca, as outcomes of population genetics analyses pointed out. Indeed, the genetic differentiation among populations was globally small but highlighted: a) a spatial genetic patchiness uncorrelated with distance between sampling locations, and b) a significant genetic heterogeneity between samples collected in the same locations in different years. Therefore, despite its extreme dispersal potential, P. noctiluca does not maintain a single homogenous population, but rather these jellyfish appear to have intra-bloom localized recruitment and/or individual cohesiveness, whereby siblings more likely swarm together as a single group and remain close after spawning events. These findings provide the first evidence of family structures and consequent genetic patchiness in a species with highly dispersive potential throughout its whole life cycle, contributing to understanding the patterns of dispersal and connectivity in marine environment

Anti-predator responses of the Mediterranean anemone goby, Gobius incognitus, acutely and chronically exposed to ambient (∼380 μatm) and high (∼850 μatm) CO2 sites off a volcanic CO2 vent in Vulcano island, Italy

An in situ reciprocal transplant experiment was carried around a volcanic CO2 vent (Vulcano Island, Aeolian Archipelago, Italy) to evaluate the anti-predator responses of an anemone goby species exposed to ambient (∼380 μatm) and high (∼850 μatm) CO2 sites during two sampling surveys on May 17th – June the 2nd 2019, and 9–18 September 2019. Behavioral observations followed a well-established protocol adopted previously for other fish species, which consisted in recording gobies responses before and after the presentation of a predator (i.e. predator stimulus). Specifically, for each replicate a 4-min pre-stimulus presentation period was followed by a 4-min post-stimulus presentation period during which each fish was exposed to the visual and olfactory cues of an adult painted comber S. scriba. During the pre- and the post-stimulus periods we measured: the activity level, as the amount of time (sec) spent by the fish swimming in the entire experimental compartment; (ii) the time spent (sec) by the fish actively swimming or resting at 20 cm from the predator compartment (no predator zone); (iii) the shelter use, as the total time the fish spent near the anemone (i.e. less than 5 cm); (iv) the minimum approach distance, as the mean smallest distance (cm) of the fish centroid from the shelter (A. viridis)

Fish-Anemone association recorded at ambient (∼380 μatm) and high (∼850 μatm) CO2 sites off a volcanic CO2 vent in Vulcano island, Italy

Density of Gobius incognitus and Anemonia viridis quantified by scuba diving in replicated belt transects (3m long and 1m wide) positioned at 1–2 m depth on mixed sandy/rocky substrates at the ambient (∼380 μatm) and high (∼850 μatm) CO2 sites. Fish/anemone association was also recorded in the two sites under different CO2 conditions (Ambient and High CO2)

Density of the painted comber Serranus scriba, a goby predator, at an ambient (∼380 μatm) and high (∼850 μatm) CO2 sites off a volcanic CO2 vent in Vulcano island, Italy

This data set contains the density of the painted comber predator Serranus scriba at two CO2 sites (Ambient and High CO2). The density of the predator was visually assessed in replicate 10 × 2 m belt transects at 1–3 m depth on mixed sandy/rocky bottoms in the two CO2 condition sites (ambient, n = 19; high-CO2, n = 22)