Efecte de la temperatura sobre la capacitat de Paracentrotus lividus per al biocontrol de Rugulopteryx okamurae

Abstract

The Mediterranean is the sea with the most invasive species in the world, mainly due to

the amount of activities carried out there (aquaculture and overcrowding, among others)

and the presence of the Suez Canal. This is one of the main reasons why the biodiversity

of the ecosystems in this sea is being depleted. One of the most recent examples is the

invasion of Rugulopteryx okamurae, an algae from the northwestern Pacific that is

spreading alarmingly across the southern Iberian Peninsula. This study seeks to

determine what role the expected rise in temperatures in the coming years will play in

this invasion, both in terms of the direct impact on the growth of the invasive algae and

the indirect impact through the effect of temperature on native herbivores, specifically

the sea urchin Paracentrotus lividus, as these could act as biocontrol agents on the

algae.

Specifically, two experiments were carried out: in the first, the thermotolerance of R.

okamurae was determined. The results indicate that the optimum growth point is

between 16°C and 24°C; below this (10°C and 14°C) there is no growth of the algae and

above 26°C it is unable to survive. This study also served to establish the temperature

range for the second experiment, in which individuals of P. lividus were subjected to

14°C, 18°C, 22°C, and 26°C, and the consumption of R. okamurae was measured. The

results indicate that P. lividus is capable of consuming the invasive algae and that this

consumption is independent of temperature.

The study offers a new perspective, focusing on how the invasion of R. okamurae could

evolve in the coming years, taking into account not only environmental conditions but

also biotic factors such as herbivory. It has been observed that temperature is a key

factor in its expansion and that the P. lividus could exert biological control over the algae

under certain circumstances. The study contributes to our understanding of the

mechanisms of interaction between native and invasive species and highlights the need

for further research into sustainable strategies to curb the spread of R. okamurae in the

Mediterranean

14