Biogeographical zonation of rocky intertidal communities along the coast of Peru (3.5-13.5° S Southeast Pacific).

Bruno Ibanez-Erquiaga,Aldo S Pacheco,Claudia L Tejada,Marcelo M Rivadeneira,Carlo Nike Bianchi

doi:10.1371/journal.pone.0208244

Abstract

The biogeography of the Peruvian Eastern Pacific coast has been described based on oceanographic parameters and qualitative species occurrence data. This has generated disagreement about the limits and existence of different biogeographic units. In this study, the distribution of rocky-shore macrobenthic communities were recorded over 41 sites along the Peruvian coastline (3.5°S-13.5°S) and analyzed together with historic abiotic data in order to quantitatively evaluate the biogeographic zonation of rocky intertidal communities throughout the region and its relationship with environmental variables to propose an update bioregionalization. Clusters and non-metric multidimensional scaling were performed using Bray-Curtis dissimilarity matrices from abundance data to evaluate biogeographic patterns of dissimilarities of rocky-shore communities. Significant turnover of taxa among defined biogeographical units was tested using permutational multivariate dispersion. Relationships between of the biogeographical community’s structure and environmental factors were examined using Random Forest analysis on datasets available at Bio-Oracle and Jet Propulsion Laboratory—California Institute of Technology. Variation of community structure of 239 taxa depicted three biogeographical units along the region matching Panamic, transitional and Humboldt provinces. Beta diversity analysis indicated a significant turnover of taxa within the transitional unit. Random forest analysis showed a strong correlation between biogeographic units with phosphate, sea surface temperature, nitrate, dissolved oxygen, cloud fraction, and silicates. Our results set the putative limits of three biogeographic units for rocky-shore communities along the coast of Peru, providing base-line information for understanding further biogeographic changes on communities associated with the ongoing regional coastal cooling and impacts of El Niño events.

Highlights

Understanding the spatial patterns of biodiversity along latitudinal gradients is a major task in coastal biogeography [1, 2]
Analysis of rocky intertidal communities seems to be sharper than single taxa in delimiting biogeographic zonation since this level may greater capture environmental variation and ecological interactions, providing an improved resolution of spatial patterns [23,24,25]
non-metric multidimensional scaling (NMDS) ordination plots suggested that dissimilarity decreased as latitude increased

Summary

Introduction

Understanding the spatial patterns of biodiversity along latitudinal gradients is a major task in coastal biogeography [1, 2]. Analysis of rocky intertidal communities seems to be sharper than single taxa in delimiting biogeographic zonation since this level may greater capture environmental variation (e.g. wave stress and temperature gradients) and ecological interactions (e.g. invasion, predation and space competition), providing an improved resolution of spatial patterns [23,24,25]. The variation in beta diversity (turnover in taxa composition throughout a gradient [26]) could serve to complement community structure analyses due to compositional changes of the community between areas with contrasting environmental characteristics that act as filters [27, 28] Such filtering may occur at breaks and transitional zones at biogeographical boundaries [29, 30]

Methods

Results

Conclusion