you're reading...

Climate Change

Size Matters in Kelp Forests – Big, Dense Populations Are Better Equipped to Recover from Disturbance

A Kelp Forest (NOAA

Kelp are habitat-forming species, the “ecosystem engineers” of our coasts. Standing metres tall and sheltering coastal habitats from the full force of the ocean’s waves, kelp provide a refuge for a variety of marine animals and create a forest ecosystem similar to what you might find in the temperate latitudes on land. They are nursery grounds for squid, sharks, and other egg-layers, the hunting grounds of urchins, seals, and grazing snails, and they sequester massive amounts of carbon in their giant fronds while pumping out vital oxygen for the animals living among them. Kelp forests also support healthy dive-tourism industries in coastal nations around the world.

Like many terrestrial forests along the coasts, kelp forests seem to be controlled by changing levels of disturbance over time. Where I live, on the spruce-dominated Atlantic coast of Nova Scotia Canada, patches of native Acadian forest are opened up by wind action, which results in so-called early-succession species, like birch, popping up in the newly-formed sunny patches. Eventually, these are replaced by mid and late-succession species like spruce, oak, and hemlock, forming the final stage in the forest’s development (until the next wind-fall anyway). In the neighbouring kelp forest, storms and large waves act in the same way to remove individual kelp fronds and carve out new space for other kinds of algae, anemones, and sponges. Eventually, the kelp will return, but much like terrestrial old-growth forests, they need time to re-establish themselves.

Ecklonia radiata, on a beach in Murramarang National Park at low-tide (Donald Hobern

Facing both an increased frequency and severity of local disturbances due to climate change, on top of coastal pollution and other human influences, many researchers are concerned for the future of our kelp forests and the diverse ecosystems they support. It’s important that scientists understand the ecosystem dynamics that control kelp forests so that we can effectively work to conserve and restore them.

In Australia, researchers are looking at possible feedback mechanisms that might hinder kelp restoration.

Ecklonia radiata, or E. rad as I’m now calling it, is the most common kelp found in Australasia. It’s not as tall as some other species, but it does support a high level of biodiversity in this temperate reef system and, like other kelp, is under threat from climate change, grazing invasive species, urbanization, and pollution. Most research on the resilience of E. rad, and most kelp species, has focused on how they respond to very extreme or very frequent disturbances, with researchers diving down to the forest bed to open up experimental patches and watching for recovery. That’s important, because we need to know how many kelp will return after one or many extreme events. But, we also need to consider how populations respond as a whole, and how remaining adult kelp might help or hinder new kelp from establishing after a disturbance.

Layton et. al. from the Institute for Marine and Antarctic Studies at the University of Tasmania wanted to see how different sizes and densities of individual kelp might affect the odds of a forest surviving through disturbance.

Experimental kelp patches from Layton et. al.’s work off Maria Island, Tasmania. (Layton et. al., 2020)

They took young kelp fronds from natural patches close to their research site and planted them in experimental patches of differing sizes and densities, from low (about half that of the natural patch) to high (about double). After 90 days the researchers found significant differences in survival between the patches. Large patches, of more than 1m2, seemed to have greater overall survival, whereas smaller patches lost individual kelp to grazing animals or wave action. Denser patches, those with more individual fronds per square metre, also seemed to have greater individual survival. These large dense forests produced more new (baby) kelp, which were themselves more likely to survive due to the protection of the adults. Patches under 1m2  didn’t produce surviving babies, regardless of kelp density and even when the researchers tried planting the microscopic babies there, illustrating the need for healthy adult individuals to promote new kelp growth. The team also noted that while some planted babies did survive in the larger patches, large patches with low density of adult kelp showed no natural recruitment, meaning young kelp only established in these patches because of the researchers’ interventions.

Kelp need large and relatively dense populations if they’re going to grow and survive over time. Small gaps in the dark kelp canopy can promote the establishment of new baby kelp, just like how wind promotes the establishment of birch in my backyard, but large disturbances that create big barren patches will make it harder for kelp to return to these areas. Without the kelp, these patches of ocean floor can be taken over by other algae or grass species that don’t support the same diversity of marine life, with kelp re-establishment taking years.

Survival of adult kelp planted in experimental patches of differing sizes and densities (Layton et. al., 2020)

That is, if the forest doesn’t experience another significant disturbance…

As our kelp forests face increasing storm activity, rising ocean temperatures, and polluted runoff from the land, it’s unlikely these open patches will be given the opportunity to adequately recover their former kelp canopies, and this is likely a big reason behind why scientists are seeing kelp declines worldwide.

Research like Layton et. al.’s shows us that it’s not enough to just plant restored kelp beds. We need to work with the kelp’s natural ecology to ensure we’re actually conserving and promoting the growth of new individuals. By protecting existing large kelp forests and working with scientists to restore those impacted by human activities, we may still be able to save our coastlines, kelp-dependent fisheries, and unparalleled biodiversity of marine-life.


Article: Layton C, Shelamoff V, Cameron MJ, Tatsumi M, Wright JT, Johnson CR (2019) Resilience and stability of kelp forests: The importance of patch dynamics and environment-engineer feedbacks. PLoS ONE 14(1): e0210220. https://doi.org/10.1371/journal.pone.0210220


No comments yet.

Post a Comment


  • by oceanbites 3 months ago
    Happy Earth Day! Take some time today to do something for the planet and appreciate the ocean, which covers 71% of the Earth’s surface.  #EarthDay   #OceanAppreciation   #Oceanbites   #CoastalVibes   #CoastalRI 
  • by oceanbites 4 months ago
    Not all outdoor science is fieldwork. Some of the best days in the lab can be setting up experiments, especially when you get to do it outdoors. It’s an exciting mix of problem solving, precision, preparation, and teamwork. Here is
  • by oceanbites 5 months ago
    Being on a research cruise is a unique experience with the open water, 12-hour working shifts, and close quarters, but there are some familiar practices too. Here Diana is filtering seawater to gather chlorophyll for analysis, the same process on
  • by oceanbites 6 months ago
    This week for  #WriterWednesday  on  #oceanbites  we are featuring Hannah Collins  @hannahh_irene  Hannah works with marine suspension feeding bivalves and microplastics, investigating whether ingesting microplastics causes changes to the gut microbial community or gut tissues. She hopes to keep working
  • by oceanbites 6 months ago
    Leveling up - did you know that crabs have a larval phase? These are both porcelain crabs, but the one on the right is the earlier stage. It’s massive spine makes it both difficult to eat and quite conspicuous in
  • by oceanbites 7 months ago
    This week for  #WriterWednesday  on  #Oceanbites  we are featuring Cierra Braga. Cierra works ultraviolet c (UVC) to discover how this light can be used to combat biofouling, or the growth of living things, on the hulls of ships. Here, you
  • by oceanbites 7 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Elena Gadoutsis  @haysailor  These photos feature her “favorite marine research so far: From surveying tropical coral reefs, photographing dolphins and whales, and growing my own algae to expose it to different
  • by oceanbites 8 months ago
    This week for  #WriterWednesday  on Oceanbites we are featuring Eliza Oldach. According to Ellie, “I study coastal communities, and try to understand the policies and decisions and interactions and adaptations that communities use to navigate an ever-changing world. Most of
  • by oceanbites 8 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Jiwoon Park with a little photographic help from Ryan Tabata at the University of Hawaii. When asked about her research, Jiwoon wrote “Just like we need vitamins and minerals to stay
  • by oceanbites 8 months ago
    This week for  #WriterWednesday  on  #Oceanbites  we are featuring  @riley_henning  According to Riley, ”I am interested in studying small things that make a big impact in the ocean. Right now for my master's research at the University of San Diego,
  • by oceanbites 8 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Gabby Stedman. Gabby is interested in interested in understanding how many species of small-bodied animals there are in the deep-sea and where they live so we can better protect them from
  • by oceanbites 9 months ago
    This week for  #WriterWednesday  at  #Oceanbites  we are featuring Shawn Wang! Shawn is “an oceanographer that studies ocean conditions of the past. I use everything from microfossils to complex computer models to understand how climate has changed in the past
  • by oceanbites 9 months ago
    Today we are highlighting some of our awesome new authors for  #WriterWednesday  Today we have Daniel Speer! He says, “I am driven to investigate the interface of biology, chemistry, and physics, asking questions about how organisms or biological systems respond
  • by oceanbites 9 months ago
    Here at Oceanbites we love long-term datasets. So much happens in the ocean that sometimes it can be hard to tell if a trend is a part of a natural cycle or actually an anomaly, but as we gather more
  • by oceanbites 10 months ago
    Have you ever seen a lobster molt? Because lobsters have exoskeletons, every time they grow they have to climb out of their old shell, leaving them soft and vulnerable for a few days until their new shell hardens. Young, small
  • by oceanbites 11 months ago
    A lot of zooplankton are translucent, making it much easier to hide from predators. This juvenile mantis shrimp was almost impossible to spot floating in the water, but under a dissecting scope it’s features really come into view. See the
  • by oceanbites 11 months ago
    This is a clump of Dead Man’s Fingers, scientific name Codium fragile. It’s native to the Pacific Ocean and is invasive where I found it on the east coast of the US. It’s a bit velvety, and the coolest thing
  • by oceanbites 12 months ago
    You’ve probably heard of jellyfish, but have you heard of salps? These gelatinous sea creatures band together to form long chains, but they can also fall apart and will wash up onshore like tiny gemstones that squish. Have you seen
  • by oceanbites 12 months ago
    Check out what’s happening on a cool summer research cruise! On the  #neslter  summer transect cruise, we deployed a tow sled called the In Situ Icthyoplankton Imaging System. This can take pictures of gelatinous zooplankton (like jellyfish) that would be
  • by oceanbites 1 year ago
    Did you know horseshoe crabs have more than just two eyes? In these juveniles you can see another set in the middle of the shell. Check out our website to learn about some awesome horseshoe crab research.  #oceanbites   #plankton   #horseshoecrabs 
WP2Social Auto Publish Powered By : XYZScripts.com