Assessment of the hyperspectral sensor CASI-2 for macroalgal discrimination on the Ría de Vigo coast (NW Spain) using field spectroscopy and modelled spectral libraries

Casal, Gema; Kutser, Tiit; Domínguez-Gómez, José Antonio; Sánchez-Carnero, Noela; Freire, Juan

doi:10.1016/j.csr.2013.01.010

Cited by 32 publications

(21 citation statements)

References 61 publications

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“…38 The presence of chlorophyll c was also detectable by a small shoulder near 630 nm. 43 The red algae had a common double-peak pattern around 600 and 650 nm in their reflectance spectra, all this resembling the studies performed in other parts of the world. 6,7,12,42 When raw reflectance values were considered, the variability within each broad taxonomic group was large and a statistical separation even among the broad macrophyte taxa was difficult.…”

Section: Discussionsupporting

confidence: 58%

“…13,49 In such habitats, it is already satisfying to separate only broad taxonomic groups in order to recapture the spatial distribution of coastal macrophyte communities. However, in more complex environments where biodiversity is higher and each species is characterized by a large natural within-species variability in reflectance spectra either due to genetic variation, seasonal cycles, or environmental conditions, 43,50 mapping the macrophyte communities at the species level may be impossible. To conclude, the potential of the spectral library approach depends, on one hand, on the representativeness of training data set and, on another hand, on the habitat complexity and associated biodiversity.…”

Section: Discussionmentioning

confidence: 99%

“…Low reflectance values appearing in shorter wavelengths from 400 to 500 nm were conditioned by pigments β-carotene and α-carotene. 43 Phycoerythrin absorbs strongly in the middle of the visible spectrum with absorption peaks near 495, 540, and 565 nm, depressing reflectance values in the green part of the spectrum and is, thus, almost complementary to chlorophyll in its absorption. 38 The presence of chlorophyll c was also detectable by a small shoulder near 630 nm.…”

Section: Discussionmentioning

confidence: 99%

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In-air spectral signatures of the Baltic Sea macrophytes and their statistical separability

Kotta

Remm

Vahtmäe

et al. 2014

J. Appl. Remote Sens

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Abstract. Many macroalgal species potentially have distinctive spectral signatures detectable using remote sensing. In order to map the spatial distribution of these species, their spectral properties have to be quantified and statistical differences between species need to be assessed. In the present study, we collected a spectral library of the key benthic macrophyte species in the Baltic Sea area and presented the methodology that allows quantifying statistical differences between their reflectance spectra. The results indicate that three broad groups of algaegreen, brown, and red algae-can be separated based on their optical signatures. In general, the between-species differences are too small to allow easy recognition of benthic algae based on their untransformed reflectance spectra. However, the distinctness of the studied species and taxa improves if standardized reflectance values are used. The best indicative spectral range was at 530 to 570 nm for the separation of species and of larger taxonomic units. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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Section: Discussionsupporting

confidence: 58%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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In-air spectral signatures of the Baltic Sea macrophytes and their statistical separability

Kotta

Remm

Vahtmäe

et al. 2014

J. Appl. Remote Sens

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“…Moreover, the Ría de Vigo is an upwelling driven system which acts as an extension of the continental shelf and channels the 3D variability of the adjacent ocean into a 2D-circulation along the Ría main channel which, in last term, modulates the hydrodynamic and biogeochemical responses (Figueiras et al, 2002). Taking into account both circumstances, our study site can be considered representative of the subtidal regime in the Ría, though it has to be recognized that there are different specific benthic habitats in the Ría (Casal et al, 2013;López-Jamar & Cal, 1990;Rodil et al, 2009) mainly driven by sea surface sediment type (Vilas et al 2005). As a future remark, it has been shown that changes in atmospheric pressure fields and associated wind patterns may decrease the intensity of upwelling-induced ecosystem production along many coastal systems (Barth et al, 2007).…”

Section: Nem: Importance Of Benthic Fluxes Mussel Culture and Fisheriesmentioning

confidence: 99%

Benthic fluxes, net ecosystem metabolism and seafood harvest: Completing the organic carbon balance in the Ría de Vigo (NW Spain)

Alonso-Pérez

Zúñiga

Arbones

et al. 2015

Estuarine, Coastal and Shelf Science

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Simultaneous direct measurements of primary production, pelagic and benthic respiration and vertical fluxes allowed, for the first time, the evaluation of the carbon metabolism in the Ría de Vigo (NW Spain) on seasonal and annual scales. With this aim, a total of 16 oceanographic cruises covering the main oceanographic conditions were carried out between April 2004 and January 2005. In addition, a 2D carbon budget, including extraction from mussel culture and fisheries activities, is proposed.The pelagic system was net autotrophic during the spring and summer periods and autotrophic or almost in balance during autumn and winter. Vertical fluxes of organic carbon were higher than net community production (NCP) during autumn and winter periods, probably due to resuspension processes and inputs of organic matter from continental runoff. Benthic mineralization is an important process in the Ría de Vigo, which gains significance during autumn and winter when benthic respiration accounts for 40% and 45% of the total respiration, respectively. The Ría de Vigo is net autotrophic on annual basis (317 ± 113 g C m -2 yr -1 ) even though the benthic metabolism reduces the NCP by 23%. Total annual carbon seafood harvest amounted 3% of the net ecosystem metabolism and it is dominated by mussel culture (89%).However, based on mean energy transfer efficiency between trophic levels of 10%, it is estimated that mussel culture and reported fish catches require up to 38% of the NCP.The organic carbon produced in situ at the Ría de Vigo and available for export to the adjacent shelf or to be buried in the sediment represents ¼ of the gross primary production and it is favoured during summer upwelling.3 HighlightsAn annual carbon budget including benthic fluxes and seafood harvest is proposed.The Ría de Vigo is net autotrophic on annual basis (317 ± 113 g C m -2 yr -1 ).Benthic remineralization reduces the autotrophy of the system by 23 %.Mussel culture and fisheries require 38 % of the net community production.Shelf carbon export and sediment burial account for ¼ of the gross primary production.

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“…A study to compare image-based and spectral library methods undertaken to classify shallow water habitats in the Baltic concluded that image-based methods were better (Vahtmaë & Kutser, 2013). Remote sensing was used in north-west Spain to try to detect benthic macroalgae at the species level using the hyperspectral sensor CASI-2 (Casal, Kutser, Domínguez-Gómez, Sánchez-Carnero, & Freire, 2013), but only a few species were discernible. The authors reported that it was possible to discriminate between red, green, and brown taxonomic groups in shallow water, however.…”

Section: Remote Sensingmentioning

confidence: 99%

A comparison of multispectral aerial and satellite imagery for mapping intertidal seaweed communities

Brodie

Ash

Tittley

et al. 2018

Aquatic Conservation

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Habitat‐forming seaweeds are vital components of marine ecosystems, supporting immense diversity and providing ecosystem services. Reports of major changes in the distribution and abundance of large brown seaweeds in the north‐east Atlantic are an increasing cause for concern, but a lack of consistent monitoring over time is a key impediment in obtaining reliable evidence of change. There is an urgent need to recognize change rapidly and efficiently in marine communities, which are increasingly affected by pressures of human population growth, climate change, and ocean acidification. Here, the potential for remote monitoring of seaweed habitats is investigated using freely available, high‐resolution aerial and satellite imagery. Three sources of imagery were used: (i) Channel Coastal Observatory (CCO) aerial imagery; (ii) aerial images from the Bing webmap server; and (iii) RapidEye multispectral satellite data. The study area, the Thanet Coast, is an area of chalk outcrop in south‐east England of high conservation status, and includes three Marine Conservation Zones. Eight habitat classes, including brown, red, and green algal zones, were recognized based on ground‐truthing surveys. A multi‐class classification model was developed to predict habitat classes based on the chromatic signature derived from the aerial images. The model based on the high‐resolution CCO imagery gave the best outcome (with a kappa value of 0.89). Comparing predictions for images in 2001 and 2013 revealed habitat changes, but it is unclear as to what extent these are natural variability or real trends. This study demonstrates the potential value for long‐term monitoring with remote‐sensing data. Repeated, standardized coastal aerial imaging surveys, such as those performed by CCO, permit the rapid assessment and re‐assessment of habitat extent and change. This is of value to the conservation management of protected areas, particularly those defined by the presence or extent of specific habitats.

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Assessment of the hyperspectral sensor CASI-2 for macroalgal discrimination on the Ría de Vigo coast (NW Spain) using field spectroscopy and modelled spectral libraries

Cited by 32 publications

References 61 publications

In-air spectral signatures of the Baltic Sea macrophytes and their statistical separability

In-air spectral signatures of the Baltic Sea macrophytes and their statistical separability

Benthic fluxes, net ecosystem metabolism and seafood harvest: Completing the organic carbon balance in the Ría de Vigo (NW Spain)

A comparison of multispectral aerial and satellite imagery for mapping intertidal seaweed communities

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