MOLLUSCS FROM THE UPPER MESOPHOTIC ZONE IN A SCARCELY KNOWN REEF OF THE WESTERN EQUATORIAL ATLANTIC

Cristiane Xerez Barroso,Helena Matthews-Cascon,Frederico Tapajós De Souza Tâmega,João Eduardo Pereira De Freitas,Wilson Franklin Júnior,Paula Spotorno

doi:10.32360/acmar.v54i2.61276

Cristiane Xerez Barroso, Helena Matthews-Cascon + Show 4 more

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https://doi.org/10.32360/acmar.v54i2.61276

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Abstract

Despite the increasing focus on biodiversity of mesophotic coral ecosystems (MCEs) on a global scale, some biological groups, such as molluscs, are still poorly investigated. The taxonomic diversity of the molluscan fauna of a scarcely known MCE of the Western Equatorial Atlantic, Northeastern Brazil, was surveyed. Samples were collected along the shallower strata of the upper mesophotic zone (between 33-36 m depth). Twenty-one taxa (nine species of gastropods, ten species of bivalves, and two taxa of chitons) were listed, two of which (Novastoa sp. and Thylaeodus sp.) are potential endemic species. A new northern limit of distribution of Persicula moscatellii was established and seven species had new bathymetric records for living specimens (Barbatia domingensis, Barbatia cancellaria, Lamychaena hians, Leiosolenus bisulcatus, Pinctada imbricata, Hipponix incurvus, and Persicula moscatellii). Hipponix costellatus are the most representative species with 49 individuals, followed by Lima caribaea with six individuals. The present work is the first contribution to the knowledge of the molluscan fauna associated with consolidated substrates from this little-known MCE. Keywords: mesophotic coral ecosystems, tropical reef, molluscan diversity, Brazilian Province, conventional SCUBA.

Highlights

Mesophotic coral ecosystems (MCEs) occur in tropical and subtropical regions between depths of 30 and 150 m, and are characterised by the presence of light-dependent corals and other organisms typically associated with reef environments (Hinderstein et al, 2010; Pyle & Copus, 2019)
These ecosystems are distributed from the Great Amazon Reef System (GARS) (5°N) to at least 24°S, including the MCEs in oceanic sites, such as the São Pedro and São Paulo Archipelago, Rocas Atoll, Fernando de Noronha Archipelago, and Vitória-Trindade Chain (Amado-Filho et al, 2016, Francini-Filho et al, 2018, 2019; Pinheiro et al, 2017; Rosa et al, 2016)
The present study reported three new records of occurrence for the gastropods Persicula moscatellii Boyer, 2004, whose previous northern limit on the Brazilian coast was the Rio Grande do Norte State; and the vermetids Novastoa sp. and Thylaeodus sp., two potential endemic species registered for the first time in the Ceará State

Summary

Introduction

Mesophotic coral ecosystems (MCEs) occur in tropical and subtropical regions between depths of 30 and 150 m, and are characterised by the presence of light-dependent corals and other organisms typically associated with reef environments (Hinderstein et al, 2010; Pyle & Copus, 2019). In Brazilian waters (South-western Atlantic), MCEs are diversified in structural composition, comprising octocoral or black coral forests, rhodolith beds, sponge bottoms, rocky reefs, and other biogenic reefs (Francini-Filho et al, 2019; Soares; Tavares & Carneiro, 2019). In this region, these ecosystems are distributed from the Great Amazon Reef System (GARS) (5°N) to at least 24°S, including the MCEs in oceanic sites, such as the São Pedro and São Paulo Archipelago, Rocas Atoll, Fernando de Noronha Archipelago, and Vitória-Trindade Chain (Amado-Filho et al, 2016, Francini-Filho et al, 2018, 2019; Pinheiro et al, 2017; Rosa et al, 2016).

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