New and rare coastal fishes in the Azores islands: occasional events or tropicalization process?

Abstract

Seven coastal fish species are newly reported for the remote north Atlantic archipelago of the Azores: Mediterranean sand eel Gymnammodytes cicerelus, bar jack Caranx ruber, two-banded seabream Diplodus vulgaris, bastard grunt Pomadasys incisus, unicorn leatherjacket filefish Aluterus scriptus and longspined porcupinefish Diodon holacanthus. The occurrence is also confirmed for 19 species that had been hitherto cited occasionally for the region, totalling a list of two elasmobranchs and 23 teleosts. Diplodus vulgaris, which appears to have recently colonized the islands, as well as roughtail stingray Dasyatis centroura and golden grey mullet Liza aurata, re-cited based on new records, are frequent or common coastal species in the Azores. The remaining 22 species, exceptional or rare in the region, are of tropical or subtropical affinity and find their northernmost distribution limit within the central and north-east Atlantic Ocean precisely in the Azores. This biogeographical pattern contrasts with that of the Azorean coastal fish community and suggests a tropicalization process in the region in line with previous findings of similar patterns across the north-east Atlantic Ocean and the Mediterranean Sea. These novel data from the most isolated archipelago of the North Atlantic Ocean, located in a biogeographic boundary area where colonization opportunities are reduced, reinforce the need for long-term monitoring programmes of coastal fish communities and, in particular, of indicator species groups to improve understanding of the effects of climate change on marine communities.

Northernmost record of the pantropical portunid crab <em>Cronius ruber</em> in the eastern Atlantic (Canary Islands): natural range extension or human-mediated introduction?

“…After decades of ocean warming, an increasing number of works have postulated a tropicalization of species assemblages in temperate biogeographic transition zones such as southwestern Australia (Wernberg et al 2016), some parts of the Mediterranean (Horta Costa et al 2014), the NW of the Iberian Peninsula (Cuesta et al 2016) and the Macaronesian archipelagos in the northeastern Atlantic (Brito et al 2005, Wirtz et al 2008, Afonso et al 2013). This process has been associated with global warming in many cases (Perry et al 2005, Occhipinti-Ambrogi 2007, Wernberg et al 2016.…”

Northernmost record of Hacelia attenuata (Echinodermata: Asteroidea) in the Atlantic

“…Rodrigues (2012) reported various new species records for the area, most of which new northernmost records. Global warming is one possible reason for driving tropical and sub-tropical species to migrate to regions where previous climate was not warm enough (Afonso et al 2013). However, the same author, recorded new southernmost limits for other species in the same study area, suggesting that this may also reflect the reduced number of underwater surveys when compared to other places worldwide.…”

Seafarers or castaways: ecological traits associated with rafting dispersal in tropical reef fishes

“…Scenarios based on effects of ongoing climate‐change predict that seaweed rafts will perish faster and decline in abundance in the tropics (Macreadie et al ., ; Rothäusler et al ., ), lowering dispersal potentials for some species. However, increasing ocean temperatures should allow seaweed rafts to spread farther polewards (Rothäusler et al ., , ; Afonso et al ., ) assisting the potential for latitudinal range shifts by fish species that tend to associate with seaweed rafts. In addition, netballs, which do represent suitable flotsam habitat for some species that associate with seaweed rafts (Goldstein et al ., ), are much more persistent than floating seaweeds, and are distributed differently to seaweeds through the different oceans.…”