Variation in species diversity of deep-water megafauna assemblages in the Caribbean across depth and ecoregions.

Iván Hernández-Ávila,Frank A Ocaña,Edlin Guerra-Castro,Carolina Bracho,Daniel Pech,Martin Rada,Steffen Kiel

doi:10.1371/journal.pone.0201269

Abstract

Diversity patterns of the deep-sea megafauna in the Caribbean Basin and the Guiana ecoregion were analyzed in order to test the hypothesis of species richness variation as a function of depth and the hypothesis of non-differences between ecoregions by analyzing spatial patterns of five taxa and a merged assemblage. Collections of five taxa (corals, sea stars, sea urchins, sea lilies and gastropods) were obtained from seven oceanographic expeditions aboard the R/V Pillsbury at 310 stations between 60 and 7500 m depth. Data were sorted according to depth zones and ecoregions and were analyzed in order to estimate species richness, changes in species composition and distinction of β-diversity by species turnover or by nestedness. The observed patterns of diversity were consistent between taxa and their assemblage: Species richness increased from the continental shelf (60–200 m deep) to the slope (200–2000 m deep), followed by a decrease at the continental rise-abyssal zone. We detected marked changes in species composition according to depth ranges. Changes in species composition in relation to ecoregions were also detected. In general, the Caribbean Basin lacks important physical barriers, causing high deep-sea ecosystem connectivity; however, variation in composition could be related to changes in environmental conditions associated with productivity and/or continental influences.

Highlights

The Caribbean Sea is an important hotspot of marine shallow and deep-water diversity in the Atlantic Ocean [1, 2]
The polynomic regression showed no clear pattern of unimodal species richness at continental slopes, but in some cases indicated bimodal species richness (Fig 2), whose peaks varied according to ecoregion
Higher species richness was observed on the continental slope than on the continental shelf and in the continental rise-abyssal range (t-test, p < 0.05, in all cases) (Fig 3)

Summary

Introduction

The Caribbean Sea is an important hotspot of marine shallow and deep-water diversity in the Atlantic Ocean [1, 2]. The diversity of deep-water megafauna such as corals [3], echinoderms [4] and other taxa [5] in the area tends to be higher than in other Atlantic provinces. This semi-enclosed sea of 2.75x106 km has an average depth of 2400 m with approximately 6% of the area corresponding to shallow-water and shelf depth (< 200 m). Diversity of Caribbean deep-water megafauna analysis, decision to publish, or preparation of the manuscript

Methods

Results

Discussion

Conclusion