Mesophotic reef geomorphology categorization, habitat identification, and relationships with surface cover and terrace formation in the Gulf of Aqaba

David K. Weinstein*, Raz Tamir, Netanel Kramer, Gal Eyal, Igal Berenshtein, Yonathan Shaked, Yossi Loya, Adi Torfstein

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

6 Scopus citations

Abstract

Antecedent topography such as relic reef terraces as well as biogenic carbonate relief-forming deposits ~30–150 m deep, referred to as mesophotic reefs, provide structural support for diverse mesophotic coral ecosystems (MCEs) that may serve as coral refuges for select light-dependent species. Although terraces at mesophotic depths are found globally, an understanding of their spatial distribution, formation, and relationship with living community composition and lithology is generally lacking. Herein, 2 × 2 m resolution bathymetry from the Gulf of Aqaba (GoA) was examined to define geomorphology features spanning mesophotic depths and compare geomorphology relationships to overlying benthic and lithologic cover. Analysis led to the production of a new map categorizing 12 geomorphology features, including upper mesophotic terraces harboring thriving MCEs. Additionally, a large collection of still imagery (1726 pictures) was obtained at 94 sites and used to define eight unique habitats at mesophotic depths and lithological and biological distribution patterns over vertical and horizontal scales. Study area benthic and lithologic cover was found to be significantly different between geomorphology features and related to GoA geomorphology as well as to seafloor depth and slope, and light attenuation. While these relationships indicated modern cover could not provide a model for producing most underlying geomorphology in the study area, results provided data needed to enhance understanding of geomorphology feature formation history and reef accretion at mesophotic depths. Study results also detailed benthic cover and geomorphology features critical for better identifying and mapping unknown MCE habitats, and for recognizing mesophotic reef spatial relationships and biodiversity patterns in the GoA. These results are especially important considering most northern GoA reefs act as potential refuges, but local anthropogenic development continually stresses shallow GoA reefs and most other shallow coral reefs around the globe continue to degrade.

Original languageEnglish
Article number107548
JournalGeomorphology
Volume379
DOIs
StatePublished - 15 Apr 2021

Funding

FundersFunder number
Gidon Winters
IUI
Interuniversity Institute for Marine Sciences
Israel National Bathymetric Survey
Israeli Nature and Parks Authority
H2020 Marie Skłodowska-Curie Actions796025
Israel Science Foundation1191/16
Horizon 2020

    Keywords

    • Bathymetry
    • Benthic cover
    • Coral rubble
    • Mesophotic coral ecosystems (MCEs)
    • Red Sea
    • Reef lithology

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