Vizzini, S. | bioRxiv Science

bioRxiv2023

The invasive brown seaweed Rugulopteryx okamurae (Dictyotales, Ochrophyta) continues to expand: first record in Italy.

The brown seaweed Rugulopteryx okamurae (Dictyotales, Ochrophyta), native to the Pacific Ocean and widely distributed in Asia, has been recently recognized as an emblematic case of biological invasion by marine macroalgae in European waters. Since 2015 and from the Strait of Gibraltar, R. okamurae has rapidly spread towards Atlantic and Mediterranean coastal areas exhibiting an invasive behaviour with significant ecological and economic impacts. Here, we report by morphology and genetics the first observation of this species in Italy along the north-western coast of Sicily (Gulf of Palermo), as drifted material and an established population on Posidonia oceanica, representing its new eastern distribution limit in the Mediterranean Sea, previously established in Marseilles (France). Furthermore, we have performed with the current introduced distribution of the species a favorability distribution model for the Mediterranean, which shows most of the western Mediterranean, including the Balearic archipelago, Corsica and Sardinia, central Mediterranean, including Sicily, and the northern coast of Africa together with eastern Mediterranean basin, as highly favorable for R. okamurae. Arrival of the species into this new area is suggested by means of sea currents and maritime traffic, including fishing activities, hypothesis supported by some of the ranked variables that entered the favorability model, i.e, current velocity, and proximity of fishing ports. These results are a warning that the species can cover large sea distances favored by sea currents, thus also threatening the ecosystems and marine resources of the central and eastern Mediterranean, highly favorable regions for the species. We suggest coordinated actions at the European level regarding prevention, among which those that have the complicity of the fishing sector should be considered, both because it is a highly affected sector and because it potentially has a very important role in the dispersion of the species.

plant biology↗

bioRxiv2022

Gobies inhabiting natural CO2 seeps reveal acclimation strategies to long-term acidification

Ocean acidification (OA) is known to affect the physiology, survival, behaviour, and fitness of various fish species with repercussions at the population, community, and ecosystem levels. Some fish species, however, seem to acclimate rapidly to OA conditions and even thrive in acidified environments. The molecular mechanisms that enable species to successfully inhabit high CO2 environments has not been fully elucidated especially in wild fish populations. Here, we used the natural CO2 seep in Vulcano Island, Italy to study the effects of elevated CO2 exposure on the brain transcriptome of the anemone goby, a species with high population density in the CO2 seep and investigate their potential for acclimation. When compared to fish from environments with ambient CO2, gobies living in the CO2 seep showed differences in expression of transcripts involved in ion transport and pH homeostasis, cellular stress, immune response, circadian rhythm, and metabolism. We also found evidence of potential adaptive mechanisms to restore the functioning of GABAergic pathways, whose activity can be affected by exposure to elevated CO2 levels. Our findings indicate that gobies living in the CO2 seep may be capable of mitigating CO2 induced oxidative stress and maintaining physiological pH while meeting the consequent increased energetic costs. The conspicuous difference in expression of core circadian rhythm transcripts could provide an adaptive advantage by increasing flexibility of physiological processes in elevated CO2 conditions thereby facilitating acclimation. Our results show potential molecular processes of acclimation to elevated CO2 in gobies enabling them to thrive in the acidified waters of Vulcano Island.

evolutionary biology↗