@misc{10481/94140,
year = {2021},
url = {https://hdl.handle.net/10481/94140},
abstract = {Corals, coralline algae and vermetid gastropods are indirect (marine limiting) relative
sea level (RSL) indicators. The precision in sea-level reconstruction based on fossils of
those organisms depends on the likely paleodepth in which they grew. Constraining
such paleodepth, depends in turn on the available information on the habitats of their
living counterparts. Diverse genera, species and species assemblages of corals,
coralline algae and vermetid gastropods have historically been proposed as reliable
indicators of narrow shallow depth ranges. However, the increased information on
depth distribution of marine benthos in the last two decades has challenged some early
assumptions about depth ranges of taxa considered diagnostic of precise paleodepths.
Here, we test the reliability of coral, coralline algal and vermetid assemblages that have
been extensively used in RSL reconstructions in the light of data from Ocean
Biogeographical Information System (OBIS) and other recently published data. In the
Indo-Pacific province, these data support the use of the robust-branching and the
shallow, high-energy encrusting coral assemblages with a 0-10-m uncertainty. In both
cases many component species have unimodal distributions, and median and average
water depths are shallower than 10 m. The reliability of these coral assemblages as indicative of shallow water depths is strengthened when corals are encrusted by thick
plants of the coralline alga Porolithon gr. onkodes. According to OBIS data, coralline
algae of this species group in the Indo-Pacific are restricted to very shallow waters (95
% probability of occurrence shallower than 0.2 m and 99.6 % of records shallower than
6 m). However, such a narrow depth range, and the overall scarce data on coralline
algal species in the OBIS database are questionable due to difficulties of coralline algal
species identification with naked eye. A comprehensive survey of the modern
distribution of coralline algae at One Tree Reef (southern Great Barrier Reef) indicates
that P. gr. onkodes has a log-normal distribution with median depth of less than 5 m
and 95 % of occurrence probability of thick crusts (> 0.2 mm) shallower than 8.8 m.
Data on modern distribution of vermetids are scarce. In the OBIS database, vermetid
species are reported from relatively wide depth ranges. However, relatively high
densities (> 10 individuals/m2) on coral and coralline algal surfaces only occur from
above mean low tide to some 6 m depth. In the Western Atlantic-Caribbean province
Acropora palmata is the most precise RSL marker and no additional components of
fossil assemblages improve its paleodepth information. The confident use of coralgal
and vermetid assemblages as RSL indicators relies on the identification of fossil corals
and coralline algae at the species or species-group level. The scarcity of available data
highlights the need for further studies on distribution of coralline algal species and
vermetid in modern coral reefs from a variety of oceans and reef settings.},
title = {Quaternary coral, coralline algal and vermetid assemblages as sea-level indicators: a review},
author = {Braga Alarcón, Juan Carlos and Humblet, Marc and Ramos Estenzo, Dino Angelo and Dechnik, Belinda and Webster, Jody M.},
}