Friedlander AM et al. (2020), Kelp forests at the end of the earth: 45 years ...

ECB-ART-48529

PLoS One 2020 Jan 01;153:e0229259. doi: 10.1371/journal.pone.0229259.

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Kelp forests at the end of the earth: 45 years later.

Friedlander AM , Ballesteros E , Bell TW , Caselle JE , Campagna C , Goodell W , Hüne M , Muñoz A , Salinas-de-León P , Sala E , Dayton PK .

Abstract
The kelp forests of southern South America are some of the least disturbed on the planet. The remoteness of this region has, until recently, spared it from many of the direct anthropogenic stressors that have negatively affected these ecosystems elsewhere. Re-surveys of 11 locations at the easternmost extent of Tierra del Fuego originally conducted in 1973 showed no significant differences in the densities of adult and juvenile Macrocystis pyrifera kelp or kelp holdfast diameter between the two survey periods. Additionally, sea urchin assemblage structure at the same sites were not significantly different between the two time periods, with the dominant species Loxechinus albus accounting for 66.3% of total sea urchin abundance in 2018 and 61.1% in 1973. Time series of Landsat imagery of the region from 1998 to 2018 showed no long-term trends in kelp canopy over the past 20 years. However, ~ 4-year oscillations in canopy fraction were observed and were strongly and negatively correlated with the NOAA Multivariate ENSO index and sea surface temperature. More extensive surveying in 2018 showed significant differences in benthic community structure between exposed and sheltered locations. Fish species endemic to the Magellanic Province accounted for 73% of all nearshore species observed and from 98-100% of the numerical abundance enumerated at sites. Fish assemblage structure varied significantly among locations and wave exposures. The recent creation of the Yaganes Marine Park is an important step in protecting this unique and biologically rich region; however, the nearshore waters of the region are currently not included in this protection. There is a general lack of information on changes in kelp forests over long time periods, making a global assessment difficult. A complete picture of how these ecosystems are responding to human pressures must also include remote locations and locations with little to no impact.

PubMed ID: 32160219
PMC ID: PMC7065750
Article link: PLoS One

Genes referenced: impact LOC100887844 LOC115924199 LOC115925287

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	Fig 1. Sampling locations around Isla de los Estados and Mitre Peninsula.Red–locations sampled in 1973 and 2018; green– 2018 sampling only. Circles represent exposed locations; triangles represent sheltered locations. Data from GEBCO Compilation Group (2019) GEBCO 2019 Grid (doi:10.5285/836f016a-33be-6ddc-e053-6c86abc0788e) and Natural Earth, free vector and raster map data @ naturalearthdata.com.
	Fig 2. Kelp canopy density from Landsat imagery.a) Mean proportional kelp canopy density at the trimester time scale for both site (black) and regional (blue) scales. b) Mean proportional kelp canopy density with a 2-year running mean at both the site (black) and regional (blue) scales along with the 2-year running mean of the NOAA Multivariate ENSO Index (MEI), lagged by one year. c) Relationship between the site scale mean proportional kelp canopy density and MEI shown in b. Red line shows the linear fit between the variables. d) Relationship between the regional scale mean proportional kelp canopy density and MEI shown in b. Red line shows the linear fit between the variables.
	Fig 3. Lessonia vadosa at Isla de los Estados, 1973 and 2018.
	Fig 4. The bivalve mollusk Gaimardia trapesina growing on the fronds of Macrocystis pyrifera.
	Fig 5. Principle coordinates analysis of benthic invertebrate community composition based on density (number of individuals.m-2) by location and exposure.Data were ln(x+1)-transformed prior to analyses. Vectors are the relative contribution and direction of influence of benthic components to the observed variation among sites (Pearson Product movement ≥ 0.5).
	Fig 6. Principle coordinates analysis of fish assemblage composition based on density (number of individuals.m-2) by location.Data were ln(x+1)-transformed prior to analyses. Vectors are the relative contribution and direction of influence of fish assemblage components to the observed variation among sites (Pearson Product movement ≥ 0.5). P. = Patagonotothen spp.