may improve detection, its possible application might be
restricted in specific periods of the year.
Detection and Conservation
Employing
KAP
enabled detection of tube aggregations as small
as 4 cm in diameter/length (post-noise reduction), whereas
smaller aggregations were not detected. This may result in
underestimation of total
L. conchilega
coverage and low-value
aggregations coverage, but should not impact the identifica-
tion of high-value concretions which are commonly targeted
for conservation monitoring (Rabaut, Vincx, and Degraer
2009). However, further development is necessary to (semi-)
automate the process as well as reduce bias in edge delinea-
tion to improve differentiation between aggregations of low
and high values, enabling application of the scoring system by
Rabaut, Vincx, and Degraer (2009) at a larger spatial scale.
Conclusions
Kite aerial photography and digital photogrammetry proved
suitable methods to map and monitor intertidal polychaete
aggregations, enabling the extraction of high-precision digital
elevation models and orthophoto mosaics to successfully
distinguish
L. conchilega
from bare sediments. Variable ac-
curacy (edge detection, large
RMSE
) however, warrants further
method improvement to enable scoring the ecological value
of
L. conchilega
aggregations and their classification as a reef
habitat. Nevertheless, the detection of high-value aggregations
is useful as these are commonly targeted for conservation
monitoring. In addition, further characterisation of reference
L. conchilega
aggregations
in situ
during acquisition may aid
method refining by enabling reductions of ambiguity that
may be present in the training sets for classification. Finally,
an analysis of the
NIR
spectrum as a proxy for surficial chl-a,
as well as using alternative colour spaces are promising ap-
proaches to improve detection accuracy in future work.
Acknowledgments
The first author would like to personally thank the people
who helped data collection for this work, namely, Niels Vi-
aene, Bart Beuselinck, Carl Van Colen, Francesca Pasotti, Nele
De Meester, Annamaria Vafeiadou, Liesb
Dresel, and Rebeca M. S. Alves, without
work would not be possible. She would
Timothy Nuttens and Annelies Vandenb
during data processing. The authors are also grateful to the
reviewer for the constructive feedback on this manuscript
which much improved the final text. This work was cofunded
through a MARES Grant (2012-1720/001-001-EMJD) using
infrastructure funded by EMBRC Belgium—FWO project
GOH3817N. MARES is a Joint Doctorate program selected un-
der Erasmus Mundus coordinated by Ghent University (FPA
2011e0016). Check
for extra information.
Authors contributions are as follows: Renata M. S. Alves, Cor-
nelis Stal, Marijn Rabaut, and Magda Vincx conceived and de-
signed the study. Renata M. S. Alves executed field work and
performed all data analyses with the help of Cornelis Stal,
Carl Van Colen, and Alain De Wulf. Renata M. S. Alves wrote
the paper with substantial contributions from all coauthors..
References
Aber, J. S., I. Marzolff and J. Ries. 2010. Small-Format Aerial
Photography: Principles, Techniques and Geoscience
Applications, 1st ed. ed. Elsevier Science.
Agisoft LLC. 2016. Agisoft PhotoScan Professional, Ed. v1.2.3. St.
Petersburg, Russia: Agisoft LLC.
Alves, R. M. S. 2017. Spatial Structure and Temporal Dynamics of
an Intertidal Population of the Marine Ecosystem Engineering
Worm
Lanice conchilega
(Pallas, 1766). Ph.D. Dissertation,
Ghent University.
Alves, R. M. S., J. Vanaverbeke, T. J. Bouma, Guarini, M. Vincx
and C. Van Colen. 2017. Effects of temporal fluctuation in
population processes of intertidal
Lanice conchilega
(Pallas,
1766) aggregations on its ecosystem engineering. Estuarine
Coastal and Shelf Science 188:88–98. <
ecss.2017.02.012>
Beeusaert-Braet BVBA. 2010. Flow form 4, Didakites. <
.
didak.com/shop/en/store/kites/one-line-kites/flow-form-4>
Accessed 6 November 2017.
Borsje, B. W., T. J. Bouma, M. Rabaut, P. M. J. Herman and S. J. M. H.
Hulscher. 2014. Formation and erosion of biogeomorphological
structures: A model study on the tube-building polychaete
Lanice conchilega
. Limnology and Oceanography 59:1297–
1309. <
>
Bryson, M., M. Johnson-Roberson, R. J. Murphy and D. Bongiorno.
2013. Kite aerial photography for low-cost, ultra-high spatial
resolution multi-spectral mapping of intertidal landscapes. PLoS
ONE 8:e73550.
>
CHDK. 2013. Canon Hack Development Kit—PowerShot D20.
Cheng, H.-D., X. H. Jiang, Y. Sun and J. Wang. 2001. Color image
segmentation: Advances and prospects. Pattern Recognition
34:2259–2281. <
De Smet, B., D’Hondt, P. Verhelst, J. Fournier, L. Godet, N. Desroy,
M. Rabaut, M. Vincx and J. Vanaverbeke. 2015. Biogenic reefs
affect multiple components of intertidal soft-bottom benthic
assemblages: The
Lanice conchilega
case study. Estuarine
Coastal and Shelf Science 152:44–55. <
ecss.2014.11.002>
Degraer, S., G. Moerkerke, M. Rabaut, G. Van Hoey, I. Du Four, M.
Vincx, Henriet and V. Van Lancker. 2008. Very-high resolution
side-scan sonar mapping of biogenic reefs of the tube-worm
Lanice conchilega
. Remote Sensing of Environment 112:3323–
3328. <
do and J. M. Anstee. 2005. Retrospective
ection in a shallow coastal tidal Australian
g of Environment 97:415–433.
.
05.02.017>
ESRI. 2014. ArcGIS Desktop v10.3. Redlands, Calif.: ESRI.
Evans, D. 2006. The habitats of the European Union habitats
directive. Biology and Environment, Proceedings of the Royal
Irish Academy 106B:167–173.
Foody, G. M. 2002. Status of land cover classification accuracy
assessment. Remote Sensing of Environment 80:185–201.
>
Friedrichs, M., G. Graf and B. Springer. 2000. Skimming flow induced
over a simulated polychaete tube lawn at low population
densities. Marine Ecology Progress Series 192:219–228. <https://
doi.org/10.3354/meps192219>
Garmin Ltd. 2011.
eTrex
Owner’s Manual for use with models 10, 20,
30. Olathe, Kans.: Garmin, Ltd.Godet, L., N. Toupoint, F. Olivier,
J. Fournier and C. Retière. 2008. Considering the functional
value of common marine species as a conservation stake: The
case of Sandmason worm
Lanice conchilega
(Pallas 1766)
(Annelida, Polychaeta) beds. Ambio 37:347–355.
Gonzales, R. C. and R. E. Woods. 2001. Digital Image Processing, 2d
ed. New Jersey: Prentice-Hall Inc.
Goodman, J. A., S. J. Purkis and S. R. Phinn. 2013. Coral Reef Remote
Sensing: A Guide for Mapping, Monitoring and Management.
Springer Science and Business Media.
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