[Coral-List] Surveying coral reef biomass in 3D
Niklas Kornder
niklaskornder at googlemail.com
Thu Jul 1 06:21:01 UTC 2021
Dear listers,
I would like to inform you on our most recent publication in Coral Reefs
entitled ‘Implications of 2D versus 3D surveys to measure the abundance
and composition of benthic coral reef communities’ (see below for full
publication details).
A paramount challenge in coral reef ecology is to estimate the abundance
and composition of the communities residing in such complex ecosystems.
Traditional 2D projected surface cover estimates neglect the 3D
structure of reefs and reef organisms, overlook communitiesresiding in
cryptic reef habitats (e.g. overhangs, cavities), and thus may fail to
represent biomass estimates needed to assess trophic ecology and reef
function. We show that different abundance metrics (2D cover, 3D surface
area, biovolume, biomass) lead to markedly different perspectives on
benthic reef community composition on 12 coral reef slopes on the island
of Curaçao (Southern Caribbean). Approximately half of the surveyed
reef’s surface and biomass is ‘hidden’ in cryptic habitats. Where 2D
cover was dominated (52 % of total benthos) by non-calcifying
phototrophs (macroalgae, turf algae, benthic cyanobacterial mats), their
contribution to total reef biomass was minor (3.2 %). In contrast, where
sponges represented only 1.6 % of the benthos on 2D-projected reefs,
they were estimated to be the largest benthic group (53 %) in terms of
biomass, most of which cryptic and thus undetected in traditional surveys.
Our new report includes:
* a guide to surveying reefs in 3D using open-source software + action
cameras (GoPros)
* biomass conversions for all major benthic coral reef taxa from
surface area and biovolume to ash-free dry weight, organic carbon,
and organic nitrogen
Without disregarding traditional coral point counts and Co., we propose
new types of baselines for more comprehensive reef community assessments
serving various ecological questions. As traditional surface cover data
overlooked ~50 % of the reef’s biomass (mainly cryptic fauna that
differs from exposed benthic communities), such 3D baselines can aid in
the evaluation of the contributions of different taxa in biogeochemical
processes and community dynamics.
I look forward to presenting an overview of this work at the upcoming
ICRS in session 11c and we are happy to discuss the outcomes of our paper.
Kornder NA, Cappelletto J, Mueller B, Zalm MJ, Martinez SJ, Vermeij MJ,
Huisman J, de Goeij JM (2021) Implications of 2D versus 3D surveys to
measure the abundance and composition of benthic coral reef communities.
Coral Reefs. DOI: 10.1007/s00338-021-02118-6.
Cheers, on behalf of all the authors,
Niklas Kornder
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