Marine forests sway,
sheltering, pristine, unchanged.
For how much longer?
Giant kelp forests are some of the most diverse, productive and dynamic ecosystems on the planet. A marine algae (not a plant), giant kelp anchors itself to the seabed and grows up towards the surface, with some species growing up to 30-60 centimetres vertically a day to reach heights of 45 meters. Whilst typically found in temperate and polar coastal oceans, deep water kelp forests have been discovered in clear tropical waters where the sunlight can penetrate far enough below the water surface for the kelp to grow, potentially as far down as 200 meters.
Kelp forests are home to a vast number of species, from those living in the surface canopy to those on the seafloor. This makes them key areas to protect for species richness, much like rainforests and coral reefs. Yet many kelp forests are under threat due to marine pollution, water quality, kelp harvesting, overfishing, invasive species and climate change.
This makes the recent survey of kelp forests in southern South America heartening. Friedlander et al. (2020) re-surveyed 11 locations at the easternmost extent of Tierra del Fuego and compared their findings to surveys originally conducted in 1973. They found no differences in kelp densities or anchor diameter. Sea urchins, if not kept in check, can decimate kelp forests but the researchers also found no difference in sea urchin numbers. Additionally, comparisons of satellite imagery showed no long-term trends over the past 20 years.
It’s thought that the remoteness of the location has meant these kelp forests have been relatively unaffected by human disturbance, although increases in sea temperature as a result of climate change are likely to have an impact in the future.
A note about ‘Holdfast’ – The title refers to both the wish that kelp forests such as the one surveyed in this study persist and survive, and to the root-like mass that anchors kelp to the seafloor which is known as the kelp’s holdfast.
Original research: http://dx.doi.org/10.1371/journal.pone.0229259