FN Archimer Export Format
PT J
TI Topographic Analysis of Intertidal Polychaete Reefs (Sabellaria alveolata) at a Very High Spatial Resolution
BT 
AF Brunier, Guillaume
   Oiry, Simon
   Gruet, Yves
   Dubois, Stanislas
   Barillé, Laurent
AS 1:1;2:1;3:2;4:3;5:1;
FF 1:;2:;3:;4:PDG-ODE-DYNECO-LEBCO;5:;
C1 Institut des Substances et Organismes de la Mer (ISOMer), UR 2160, Nantes Université, F-44000 Nantes, France
   Société Sciences naturelles de l’Ouest de la France, Nantes, 12 rue Voltaire, F-44000 Nantes, France
   DYNECO LEBCO, IFREMER, Centre de Bretagne, F-29280 Plouzané, France
C2 UNIV NANTES, FRANCE
   SSNOF, FRANCE
   IFREMER, FRANCE
SI BREST
SE PDG-ODE-DYNECO-LEBCO
IN WOS Ifremer UPR
   DOAJ
   copubli-france
   copubli-univ-france
IF 5
TC 12
UR https://archimer.ifremer.fr/doc/00744/85556/90679.pdf
LA English
DT Article
DE ;honeycomb worm reef;intertidal;multispectral UAV;Sabellaria alveolata;SfM photogrammetry;topographic analysis
AB In temperate coastal regions of Western Europe, the polychaete Sabellaria alveolata (Linné) builds large intertidal reefs of several hectares on soft-bottom substrates. These reefs are protected by the European Habitat Directive EEC/92/43 under the status of biogenic structures hosting a high biodiversity and providing ecological functions such as protection against coastal erosion. As an alternative to time-consuming field campaigns, a UAV-based Structure-from-Motion photogrammetric survey was carried out in October 2020 over Noirmoutier Island (France) where the second-largest known European reef is located in a tidal delta. A DJI Phantom 4 Multispectral UAV provided a topographic dataset at very high resolutions of 5 cm/pixel for the Digital Surface Model (DSM) and 2.63 cm/pixel for the multispectral orthomosaic images. The reef footprint was mapped using a combination of two topographic indices: the Topographic Openness Index and the Topographic Position Index. The reef structures covered an area of 8.15 ha, with 89% corresponding to the main reef composed of connected and continuous biogenic structures, 7.6% of large isolated structures (<60 m2), and 4.4% of small isolated reef clumps (<2 m2). To further describe the topographic complexity of the reef, the Geomorphon landform classification was used. The spatial distribution of tabular platforms considered as a healthy stage of the reef in contrast to a degraded stage was mapped with a proxy that consists in comparing the reef volume to a theoretical tabular-shaped reef volume. Epibionts colonizing the reef (macroalgae, mussels, and oysters) were also mapped by combining multispectral indices such as the Normalised Difference Vegetation Index and simple band ratios with topographic indices. A confusion matrix showed that macroalgae and mussels were satisfactorily identified but that oysters could not be detected by an automated procedure due to their spectral complexity. The topographic indices used in this work should now be further exploited to propose a health index for these large intertidal reefs. 
PY 2022
PD JAN
SO Remote Sensing
SN 2072-4292
PU MDPI AG
VL 14
IS 2
UT 000746190200001
DI 10.3390/rs14020307
ID 85556
ER

EF