A new signal of marine tropicalization in the Macaronesia region: First record of the mesophotic macroalga Avrainvillea canariensis A. Gepp & E.S. Gepp in the Madeira archipelago

Abstract

Mesophotic green algal meadows of Avrainvillea canariensis are firstly reported for Madeira island. This represents a northern expansion of the species by nearly 500 km turning the species a Macaronesian endemism. The meadows of A. canariensis were found in a sandy bottom in the South coast of the island of Madeira, inside the Marine Park of Cabo Girao, covering an estimated area of 50 m(2) at a depth range 25-30 m. The collected specimens reached about 12 cm in height and were found clustered, forming distinct patches. Since this type of subtidal surveys in soft bottoms are scant in Madeira, we cannot evaluate whether this is a recent colonization. Yet, this new record can be another clear sign of climate change effects in the madeiran benthic communities, a process previously documented in the Macaronesia region with the arrival and subsequent settlement of other warm water marine species.