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

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.