Satellite-derived mapping of kelp distribution and water optics in the glacier impacted Yendegaia Fjord (Beagle Channel, Southern Chilean Patagonia)

Huovinen, Pirjo; Ramírez, Jaime; Palacios, Mauricio; Gómez, Iván

doi:10.1016/j.scitotenv.2019.135531

Cited by 28 publications

(33 citation statements)

References 51 publications

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“…Our high-resolution validation confirmed that RGB cameras mounted on UAVs can be successfully used for giant kelp monitoring [18]. The length of the canopy blades floating on water (minimum length of an individual blade = 13.85 cm, M. Palacios personal communication) makes fronds and canopies easily detectable with spatial resolutions of 10 cm.…”

Section: Notes On Uav Surveyingsupporting

confidence: 63%

“…Our methodology successfully isolates giant kelp from the surrounding ocean and land except for green algae (Ulvophyceae). Ulvophyceae is a conspicuous class of algae found in intertidal environments such as estuaries or rocky areas [45] that has a similar spectral reflectance to giant kelp [43] and can share the same habitat only when giant kelp forests occur on shallow rocky intertidal areas [18]. Hence, in these geographical contexts, our map cannot distinguish between giant kelp and Ulvophyceae.…”

Section: Introductionmentioning

confidence: 95%

“…However, it is difficult to clearly distinguish kelp canopies from open ocean water in satellite imagery because of factors like: sun glint, breaking waves, sediments, dissolved organic matter or phytoplankton blooms that also contribute to water reflectance [14]. Techniques and sensors used for kelp mapping have included aerial photogrammetry [11,15], Landsat Multispectral Scanner System (MSS) [16], Landsat Thematic Mapper (TM) [13,14], Landsat Operational Land Imager (OLI) [17], Sentinel-2 [18], Satellite Pour l'Observation de la Terre (SPOT) [19,20], and aircraft multispectral sensors with spatial resolutions~2m [17,21]). Methodologies employed to detect kelp canopies using such imagery have been varied: from using thresholds of band brightness value ratios to indices such as the Normalised Difference Vegetation Index (NDVI; [13]) to methods such as unsupervised classification [19,20], supervised maximum likelihood classification [16,17,22], Principal Component Analysis (PCA; [13]), Spectral Mixture Analysis (SMA; [18,23]), and particularly Multiple Endmember Spectral Mixture Analysis (MESMA; [14,24]), which has been effective in studying different characteristics of kelp ecology, such as genetic differentiation within geographic clusters [25], long-term biomass trends [26], fish, invertebrate and algae assemblages in kelp communities [27], and biogeochemical [28] and physical [14] dynamics.…”

Section: Introductionmentioning

confidence: 99%

“…This persistence has been associated with abiotic factors, such as water depth, the presence of a rocky substrate, substrate topology, and connectivity between the forests [38]. In contrast, variability is associated with ocean dynamics, such as wave height and sea-surface temperature ( [14], more than seasonality), tidal ranges, or zenith angles [18]. Therefore, the central areas of forests should provide optimal material to build a global map of giant kelp.…”

Section: Introductionmentioning

confidence: 99%

“…(c) The use of Unmanned Aerial Vehicles (UAV) for coastal habitat mapping is a simple, cost-effective and reliable technology [39] that has been successfully used to map and validate intertidal biogenic reefs [40], saltmarsh biomass [41], and algal blooms [42]. Recent surveys to detect macroalgae in temperate coastlines have shown that RGB (additive primary colors-red, green, and blue-model) and multispectral cameras mounted on UAVs produce accurate imagery able to detect water turbidity and a range of taxonomical groups of algae in surface or shallow water, with the exception of spectrally similar species [18,43]. To our knowledge, there are yet no standardized protocols for marine or coastal mapping with UAVs [42].…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

A High-Resolution Global Map of Giant Kelp (Macrocystis pyrifera) Forests and Intertidal Green Algae (Ulvophyceae) with Sentinel-2 Imagery

et al. 2020

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Giant kelp (Macrocystis pyrifera) is the most widely distributed kelp species on the planet, constituting one of the richest and most productive ecosystems on Earth, but detailed information on its distribution is entirely missing in some marine ecoregions, especially in the high latitudes of the Southern Hemisphere. Here, we present an algorithm based on a series of filter thresholds to detect giant kelp employing Sentinel-2 imagery. Given the overlap between the reflectances of giant kelp and intertidal green algae (Ulvophyceae), the latter are also detected on shallow rocky intertidal areas. The kelp filter algorithm was applied separately to vegetation indices, the Floating Algae Index (FAI), the Normalised Difference Vegetation Index (NDVI), and a novel formula (the Kelp Difference, KD). Training data from previously surveyed kelp forests and other coastal and ocean features were used to identify reflectance threshold values. This procedure was validated with independent field data collected with UAV imagery at a high spatial resolution and point-georeferenced sites at a low spatial resolution. When comparing UAV with Sentinel data (high-resolution validation), an average overall accuracy ≥ 0.88 and Cohen’s kappa ≥ 0.64 coefficients were found in all three indices for canopies reaching the surface with extensions greater than 1 hectare, with the KD showing the highest average kappa score (0.66). Measurements between previously surveyed georeferenced points and remotely-sensed kelp grid cells (low-resolution validation) showed that 66% of the georeferenced points had grid cells indicating kelp presence within a linear distance of 300 m. We employed the KD in our kelp filter algorithm to estimate the global extent of giant kelp and intertidal green algae per marine ecoregion and province, producing a high-resolution global map of giant kelp and intertidal green algae, powered by Google Earth Engine.

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Section: Notes On Uav Surveyingsupporting

confidence: 63%

Section: Introductionmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A High-Resolution Global Map of Giant Kelp (Macrocystis pyrifera) Forests and Intertidal Green Algae (Ulvophyceae) with Sentinel-2 Imagery

et al. 2020

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A species distribution model of the giant kelp Macrocystis pyrifera: Worldwide changes and a focus on the Southeast Pacific

Gonzalez‐Aragon,

Rivadeneira,

Lara

et al. 2024

Ecology and Evolution

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Worldwide climate‐driven shifts in the distribution of species is of special concern when it involves habitat‐forming species. In the coastal environment, large Laminarian algae—kelps—form key coastal ecosystems that support complex and diverse food webs. Among kelps, Macrocystis pyrifera is the most widely distributed habitat‐forming species and provides essential ecosystem services. This study aimed to establish the main drivers of future distributional changes on a global scale and use them to predict future habitat suitability. Using species distribution models (SDM), we examined the changes in global distribution of M. pyrifera under different emission scenarios with a focus on the Southeast Pacific shores. To constrain the drivers of our simulations to the most important factors controlling kelp forest distribution across spatial scales, we explored a suite of environmental variables and validated the predictions derived from the SDMs. Minimum sea surface temperature was the single most important variable explaining the global distribution of suitable habitat for M. pyrifera. Under different climate change scenarios, we always observed a decrease of suitable habitat at low latitudes, while an increase was detected in other regions, mostly at high latitudes. Along the Southeast Pacific, we observed an upper range contraction of −17.08° S of latitude for 2090–2100 under the RCP8.5 scenario, implying a loss of habitat suitability throughout the coast of Peru and poleward to −27.83° S in Chile. Along the area of Northern Chile where a complete habitat loss is predicted by our model, natural stands are under heavy exploitation. The loss of habitat suitability will take place worldwide: Significant impacts on marine biodiversity and ecosystem functioning are likely. Furthermore, changes in habitat suitability are a harbinger of massive impacts in the socio‐ecological systems of the Southeast Pacific.

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Glacial retreat and rising temperatures are limiting the expansion of temperate kelp species in the future Arctic

Niedzwiedz

Bischof

2023

Limnology & Oceanography

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Kelps act as ecosystem engineers on many polar rocky shore coastlines. The underwater light climate and temperature are the main drivers for their vertical and latitudinal distribution. With temperatures rising globally, an Arctic expansion of temperate kelp species and an accelerating glacial melt is predicted. It was our aim to investigate the effects of retreating glaciers and rising temperatures on the potential habitat of kelps in Arctic fjords. We analyzed the underwater light climate of areas being influenced by different stages of glacial retreat (sea-terminating glacier, land-terminating glacier, coastal water) in Arctic Kongsfjorden. We observed reduced light intensities and a changed spectral composition in glacial meltwater plumes, potentially resulting in an upward shift of the lower depth limit of kelp, counteracting the predicted biomass increase in the Arctic. Furthermore, we studied temperature-related changes in light-use characteristics in two kelp species (Alaria esculenta, Saccharina latissima) at 3 C, 7 C, and 11 C. Rising temperatures lead to a significant increase of the compensation irradiance of A. esculenta. The dark respiration of S. latissima increased significantly, correlating with a decreasing carbon content. We detected no differences in photosynthetic rates, although the chlorophyll a concentration of A. esculenta was $ 78% higher compared to S. latissima. Ultimately, temperatureinduced changes in kelps light-use characteristics might lead to a changed species composition, as we found A. esculenta better adapted to polar conditions. We conclude that the deterioration of the underwater light climate and the temperature increase may drive substantial changes of the future Arctic kelp forest structure.

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Satellite-derived mapping of kelp distribution and water optics in the glacier impacted Yendegaia Fjord (Beagle Channel, Southern Chilean Patagonia)

Cited by 28 publications

References 51 publications

A High-Resolution Global Map of Giant Kelp (Macrocystis pyrifera) Forests and Intertidal Green Algae (Ulvophyceae) with Sentinel-2 Imagery

A High-Resolution Global Map of Giant Kelp (Macrocystis pyrifera) Forests and Intertidal Green Algae (Ulvophyceae) with Sentinel-2 Imagery

A species distribution model of the giant kelp Macrocystis pyrifera: Worldwide changes and a focus on the Southeast Pacific

Glacial retreat and rising temperatures are limiting the expansion of temperate kelp species in the future Arctic

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