Geomorphological Classification of the Benthic Structures on a Tropical Continental Shelf

Enatielly R Goes,Tereza C Araújo,Craig J Brown

doi:10.3389/fmars.2019.00047

Enatielly R Goes, Tereza C Araújo + Show 1 more

Open Access

https://doi.org/10.3389/fmars.2019.00047

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Abstract

Geomorphological research offers a valuable first step to understand the complexity of seafloor patterns that are likely to support particular fauna, thereby providing value for future targeted studies on benthic communities and habitats. The objective of this study is to perform a geomorphological classification for a tropical continental shelf, located in the north of the State of Pernambuco, Brazil, using Benthic Terrain Modeler (BTM), as a first step to characterize benthic habitats. The classification of the seabed is based on the bathymetry, broad-scale and fine-scale BPI (Benthic Positioning Index), seafloor slope, and a decision table containing definitions and thresholds appropriate to the data input. The relationships between morphology and the deposition of surface sediments were also investigated. Results from the BTM analysis revealed eight types of benthic structures: Flat Plains, Depressions, Gentle Slopes, Steep Slopes, Flat Ridge Tops, Rock Outcrop Highs, Local Pinnacles in Depressions and Local Pinnacles on Broad Flats. The results from this study may therefore assist in selecting priority areas to investigate, supporting to better marine spatial planning in the region, and, in the future, collaborate to determine biodiversity patterns in Brazilian waters.

Highlights

Geomorphological research is a tool to understand the complexity of seafloor patterns
Based on the grids of bathymetry, slope, Bathymetric Position Index (BPI) broad-scale and fine-scale, and the decision table (Table 1), eight classes of benthic structures were differentiated by the Benthic Terrain Modeler (BTM) (Figure 3)
Eight geomorphological classes are defined by the BTM, recognized as benthic structures (Figure 5)

Summary

Introduction

Geomorphological research is a tool to understand the complexity of seafloor patterns. These patterns can condition a number of environmental characteristics, such as light incidence, exposure to currents and waves, nutrient availability, substrate, erosion, or sediment deposition (Post, 2008; Verfaillie et al, 2009; Harris, 2012), providing a range of spatiotemporal influences on the habitat suitability of an area for benthic fauna and flora (Post et al, 2011; Lecours et al, 2015). Other studies have utilized (geo) statistical methods to examine the relationship between physical, chemical and biological characteristics of the seafloor to spatially define habitats with similar characteristics (e.g., Brown et al, 2012; Lecours et al, 2016). Spatial scale in defining habitat is often a complicating factor (see discussion in Lecours et al, 2015), with several seafloors habitat mapping studies adopting a landscape-scale approach analogous to mapping biophysical patterns in the terrestrial

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