Calcifying structure of the sea urchin Arbacia lixula living at CO2 vents

GONZÁLEZ-DELGADO, S.; EPHERRA, L.; SOSA, N.; HERNÁNDEZ, C.A.; HERNÁNDEZ, J.C.

LAs Palmas de Gran Canarias

Simposio; VIII International Symposium on Marine Sciences (ISMS 2022); 2022

Facultades de Ciencias del Mar en España

Abstract: Ocean acidification (OA) has important repercussions on the physiological andecological functions of marine animals, especially calcifying species such as sea urchins,and is therefore considered one of the major threat to marine life (Byrne & Hernández,2020). This study aims to determine the effects of OA on the black sea urchin Arbacia lixulausing a long-term natural experiment, the CO2 vent system off the coast of Fuencaliente onthe island of La Palma (Canary Islands). In this area, there is a large tide-dependent pHfluctuation, with the pH dropping to 7.2 units at the point of emission (González-Delgado etal., 2021). In addition, these emissions generate a natural pH gradient in the surroundings,comparable to the scenarios predicted by the IPCC in the future due to climate change(IPCC, 2021). A total of 108 individuals of A. lixula were collected by snorkelling between2 and 5 m depth to study the external morphometry of its skeleton and the Aristotle's lantern,the fracture force and its mineralogy following this pH gradient. It was observed that in thepH zone with the highest fluctuation, sea urchins had a smaller body size and Aristotle'slantern, but showed a more fracture resistant skeleton. Also, they have a slightly higherpercentage of Mg in the calcite of the skeleton and lantern. These results have shown howthese natural laboratories, analogues of future oceans, are essential to understand the realconsequences of acidification on calcareous organisms.