Biogeography of endosymbionts (Symbiodiniaceae) associated with zoantharian species (Hexacorallia: Anthozoa) from the Macaronesia and Cape Verde ecoregions

Abstract

Populations of some zoantharian species (Cnidaria: Anthozoa) have been able to proliferate in locations where abiotic conditions hinder scleractinian corals’ survival. One of the contributing factors might be the advantageous host-symbiont associations that could lead holobionts to be more resilient to environmental variation, even in marginal-environments. However, few studies have addressed these Zoantharia–Symbiodiniaceae associations, especially little is known about their nature and distribution in the Atlantic Ocean. In this study, we use the large ribosomal subunit (LSU-rDNA) and Internal Transcribed Spacer 2 (ITS2) to examine the biodiversity and distribution of Symbiodiniaceae species within zoantharians that inhabit along the latitudinal gradient Madeira (40ºN)—Cape Verde (16ºN). Moreover, we determine the number of different endosymbionts genera inhabiting the same specimen, in order to estimate their ability to face alterations in the environment. The results showed that Symbiodiniaceae diversity increases towards the tropics, with a total of six ITS2 types belonging to Symbiodinium and Cladocopium, the latter being the most frequent genus. Furthermore, we have found a possible undescribed species inhabiting P. aff. clavata collected at Madeira Island, the northernmost limit of brachycnemic zoantharian distributions in the East Atlantic. These results, combined with the literature reviewed, constitute the first mention of the genus Symbiodinium in a species host that is not Zoanthus spp and for the archipelago of the Canary Islands. An appendix summarizing Zoantharia–Symbiodiniaceae distributions around the Atlantic is included to facilitate future research on these holobiont associations.

Environmental coastal research: a systematic review for Azores and Cabo Verde, two peripherical Macaronesian archipelagos

“…In this scenario, the risk of opportunistic biological invasion in coastal ecosystems (NIS) will increase (Halpern et al, 2007). The volcanic character of the Cape Verde archipelago together with the dry tropical climate unique in its ecoregion (Spalding et al, 2007) allows it to host a great diversity of coral species (Loṕez et al, 2019;Pulido Mantas et al, 2022;Zamora-Jordań et al, 2022). Cabo Verde has been described as one of the world's top ten coral reef biodiversity hotspots, although there are no reef-building (hermatypic) corals.…”