We are all bombarded by the growing campaigns to preserve our terrestrial forests, be it tropical to temperate. However, not far from our rocky shores, lurks a sub sea hub of activity, in the swaying fronds (algal leaves) of our kelp forests. Made famous by the Californian giant kelp, which can grow up to 45m in one growing season, kelp species of many sorts and sizes can imitate the complex habitat provided by a tropical rainforests and even coral reefs.
The physical structure of the kelps provides shelter and creates favourable conditions for the fauna and flora which has become reliant upon these properties. The different structural properties of kelps can be classified under three ‘guilds’; canopy, stipitate and prostrate.
Canopy: larger of the species which typically grow long surface reaching canopies.
Stipitate: shorter in height and grow on a rigid stipe (supporting stalk) to protect the vulnerable fronds from the benthos of a few metres in length but grow in thick fields on the sea floor.
Prostrate: also shorter than canopy species, grow in the shallows and tend to cover the sea floor with their fronds.
It is the co-existence of these guilds, and the many species which are classified by these structural terms, which create such diverse habitats for a diverse assemblage of inhabitants. It is not only the presence of variable niches for the creatures of a kelp forest, but the contrasting conditions they provide in an energetic coastal environment. Shading from the fronds allows favourable conditions for those benthic algal species that are adapted to low light to thrive. Dampening of the vigorous coastal currents allows for increased sedimentation and reduced erosion, which in turn impacts benthic productivity and recruitment of macrofauna.
Macrofauna associated with these forests have in some cases developed a reliance on this unique forest habitat. From limpets which have adapted to live in the cavities of the kelp stipe to the killer whales who hunt on the otters who forage in these slippery canopies.
We are now aware of the biodiversity these uniquely kelp driven ecosystems behold, but with the looming possibility that such species might be grown on a large-scale to provide our every energy need, it begs the question… can these man-made seaweed farms provide some habitat that may shelter and enhance local biodiversity?
As these cultured seaweeds will be hanging sub-surface structures they may not stimulate the benthic assemblages associated with classic kelp forests, but they can facilitate the pelagic macrofaunal species associated with such species, and may impact the benthos below in a similar manner to that of the anchored natural kelp beds. Even if these niches were to be exploited by local communities, kelp farms should take seriously the methods for harvesting and the timing if the benefits of these almost artificial reefs are to be reaped.
Just some more algal food for thought…
When we think ’emissions’ we think car exhausts and industrial cooling towers.Wrong. 20-30% of global emissions are a consequence of losses and degradation of natural ecosystems’ Trumper et. al.(2009).
CARBON COLOUR KEY
“Brown Carbon” Green house Gases (a gas which absorbs radiation and traps heat in the earth’s atmosphere, e.g. CO2)
“Black Carbon” The particles leftover from incomplete combustion of fossil fuels (soot and dust), which has a greater effect on radiation transmission. This in turn can directly and indirectly reduce the albedo effect of global snow and ice.
“Green Carbon” Carbon incorporated into plant biomass and the soils below.
and our friend…
“Blue Carbon“- carbon captured by the world’s ocean critters, and over half of all carbon in living organisms resides here, under the glassy and deceiving barren big blue. Important coastal vegetation habitats such as mangroves and seagrasses which acquire the carbon stored in marine sediments are being lost at a rate 5-10 times higher than the rainforests (Nellemann et. al. , 2009).
So what has this carbon rainbow got to do with seaweeds?… Well it has been noted in the ‘Blue Carbon’ UNEP Report that biofuels from land crops often replace natural and more efficient carbon capturing ecosystems (grasslands and forests), producing more CO2 than the replacement of fossil fuels.
Could seaweed culture for the production of biofuels be carried out on a large-scale without the degradation of what carbon capture was already going on? Could it possibly even enhance the carbon capturing ability of a local environment by increasing sedimentation and acting as an artificial habitat for creatures that call kelp home?…these are yet unanswered questions.However what is clear, is the ability of marine vegetation to naturally store CO2 which is being prematurely released into the atmosphere through ecosystem degredation.
So back to the blue carbon, unlike rainforests which store carbon for decades, the uptake of carbon by marine organisms (seaweed and seagrasses alike) can naturally lock up and store these green house gases for millions of years in seabed sediments, and have been doing so for the many years they have existed before us.
Just another reason to become a fan of all things algae. Blue Carbon.
Seaweed…It’s in your OJ first thing in the morning and your toothpaste last thing at night, and yet it’s not the most beloved of marine species.
With media giants such as Disney conjuring up the cute coral reef ambassador ‘Nemo’, it’s no wonder that seaweed lags in the popularity race that public awareness so often succumbs to. However, I hope this blog can offer an enthusing insight into the world of seaweed science, I think it’s about time we ’embrace the slime’!
I have only recently joined the Scottish Marine Institute as a PhD research student, and will be working on the environmental impacts of large-scale seaweed farms for biofuel production. It’s not the most glamorous of marine biologist jobs, but coming from a dairy farming background the wellies are a welcome working accessory.
Seaweedscience to follow!