Bivalve Diversity on the Continental Shelf and Deep Sea of the Perdido Fold Belt, Northwest Gulf of Mexico, Mexico

Nancy Yolimar Suárez-Mozo,Nuno Simões,Edlin Guerra-Castro,Victor Manuel Vidal-Martínez,M Leopoldina Aguirre-Macedo,Daniel Pech

doi:10.3390/d13040166

Abstract

Mollusk diversity in coastal areas of the Gulf of Mexico (GOM) has been studied extensively, but this is not the case for deep-water habitats. We present the first quantitative characterization of mollusks in shallow and deep waters of the Perdido Fold Belt. The data came from two research cruises completed in 2017. Sediment samples were collected from 56 sites using a 0.25-m2 box corer. We tested hypotheses about spatial patterns of α, β, and γ-diversity of bivalves in two water-depth zones, the continental shelf (43–200 m) and bathyal zone (375–3563 m). A total of 301 bivalves belonging to 39 species were identified. The two zones display similar levels of γ-diversity, but host different bivalve assemblages. In general, α-diversity was higher on the continental shelf, whereas β-diversity was higher in the bathyal zone. These patterns can be explained by the higher input of carbon (energy) to the near-coast shelf zone, as well as by the greater topographic complexity of habitats in the bathyal zone. These results enabled us to propose redirection of sampling efforts for environmental characterization from continental zones to the deep-water zone, especially in the context of environmental assessments during oil and gas exploration and production.

Highlights

Introduction iationsThe deep sea extends beyond the depth of the photic zone and the edge of the continental shelf, which lies at about 200 m depth [1,2]
We identified a total of 301 bivalve specimens belonging to 20 families, 28 genera and 39 species (Table 2)
Eight species were recorded in deeper waters (Sacella concentrica, Anadara secticostata, Bathyarca glomerula, Limopsis sulcata, Isognomon bicolor, Chione sp., Macoploma extenuata, and Caryocorbula contracta) and five species in shallower depths (Katedesmia polita, Tindaria amabilis, Hyalopecten strigillatus, Macoploma extenuata, and Cuspidaria rostrate)

Summary

Introduction

The deep sea extends beyond the depth of the photic zone and the edge of the continental shelf, which lies at about 200 m depth [1,2]. Nomenclature for bathymetric zones in the deep sea is not consistent and can differ depending on the taxonomic group being studied. The perception that deep-sea communities are “desert-like” and display low taxonomic diversity has changed in the last few decades [4]. It is known that these deep-water environments are rich in species, comparable to coastal marine habitats [2,5,6,7], and that the deep sea is highly complex and governed by interactions among multiple environmental factors [8,9]. A small proportion of deep-sea realm, has been studied, because its exploration is technically difficult and expensive [10,11]

Results

Discussion

Conclusion