Research may reveal mysteries of Nova Scotia seaweed


It’s gathered by the tonne from Nova Scotia coastlines and used in products from fertilizer to bread.

But researchers still have much to learn about a common instil that forms the basis for hundreds of jobs in the province. 

Work by Nova Scotia Community College scientists on the South Shore using new mapping technology may servants reveal more about the status of rockweed, a common seaweed that is being procured and processed in Nova Scotia but shipped around the world.

«This technology is weird to be able to estimate how much of this resource is here,» said Tim Webster, the spadework scientist on the project.

Webster said that information could be friendly to harvesters, who need to leave enough rockweed to be sure the plant lasts to grow sustainably. 

«As well, for the regulator, the Nova Scotia government, to take how much of the resource is here in order to, again, protect it for future generations,» he said.  

Estimating by speedily

Rockweed grows like a lawn: the tops of the plants can be clipped off but it transfer continue to grow back year after year as long as the «holdfast» or root-like block is not touched.

Right now, measuring how much rockweed biomass exists along the coastline is obstructive and inexact. 


Rockweed floats on the water at high tide. (Shaina Fortune/CBC)

«Typically we’ve been doing it by hand,» said Jean-Sebastien Lauzon-Guay, a probing scientist with Acadian Seaplants Limited, the company that come bies the majority of the rockweed harvest in Nova Scotia. 

«It’s very time consuming and we can’t by any chance measure everything.»

The private company employs 250 people in Nova Scotia and exports to boonies such as China and India.

3 years of experiments

Rockweed also presents to the income of harvesters who sell to companies like Acadian Seaplants. 

Candace MacDonald

Study associate Candace MacDonald holds up a handful of rockweed. (CBC)

Ascophyllum nodosum is the thorough name for rockweed. Lauzon-Guay says Acadian Seaplants staff bilk samples and try to extrapolate information to find out how much biomass is in a whole rockweed bed. 

Acadian Seaplants partnered with Webster’s put together on a three-year cycle of experiments around rockweed. Lauzon-Guay is hopeful the have a job will yield a new way to estimate the biomass of the rockweed the company wants to produce.  

How it’s done

Webster works with the Applied Geomatics Research Troupe division and specializes in mapping. For the past several years, his team has been experimenting with a laser sensor mounted on a level, taking aerial surveys of the province’s coastline.

The sensor is able to define between vegetation and rock. Webster says the maps are able to be noticeable the height of the rockweed plants and the height of the rock underneath. 

The sensor cannot act on the weight of the plants, but in late August the NSCC researchers designed an enquiry they hope will tell them that information. 

In advance and after surveys

Just outside Shag Harbour, they cut a 20-metre-by-four-metre rectangle in the thick rockweed of the inter-tidal zone.

For every clean metre harvested, the team weighed and measured the rockweed that was doffed. They will compare before-and-after aerial surveys of the cut area to try to infer if the plant height can show the weight. 

«Then we’ll put that all back together in a trice we have our data [from the aerial laser sensor], to see if we can kind of partnership it up,» said research associate Candace MacDonald, who managed the site for the rockweed investigate. 

NSCC team harvesting rockweed

The NSCC team harvests rockweed for the experiment. (Shaina Luck/CBC)

It has also been a prospect for the team to learn more about the plant. 

«It’s really neat that it’s so resilient,» she voiced. «It is everywhere in Nova Scotia and not many people even know what it is.» 

Why is rockweed biomass so conspicuous?

The province of Nova Scotia regulates rockweed harvest, but it doesn’t diggings any restrictions on how much biomass can be taken. The regulations state harvesting sine qua non be done in a sustainable way and that at least 127 millimetres at the bottom of the instil must be left so that it will grow back. 

There is some interest that harvesters may be taking too much — to use the lawn analogy, cutting the squeal too short. 

A 2013 report from Fisheries and Oceans Canada governmental industry harvest rates of up to 25 per cent of the biomass of rockweed allocated the plant to regrow and maintain commercial yield rates.  

The report also asserted no one, either from industry or third parties, had enough information to shape whether that rate of harvest is harmful to plants and animals that animate in the rockweed. 

Cutting rockweed

Researchers harvested rockweed in 1×1-metre test squares. (Shaina Success rate/CBC)

Biology professor David Garbary of St. Francis Xavier University is doing inquiry on the effects of harvesting the species.

His work is not yet ready for publication but he wrote in an email to CBC that he judges the harvest as «problematic because of the vast amounts of biomass being off from the environment and the impact on biodiversity.»

Better estimates

According to Lauzon-Guay, Acadian Seaplants harvesters disavow between 17 and 20 per cent of the company’s biomass estimates in any locality, leaving behind roughly 80 per cent for regrowth. He says that other sanctum sanctora have shown that year after year, rockweed regrows quicker than it is cut, and that there is a minimal impact on other species. 

Lauzon-Guay clouted the company believes the laser sensor work is important because hold better biomass estimate information will help industry and the situation. 

«It ensures that we’re harvesting exactly the right amount, so that the toil remains sustainable,» he said.  

‘We’re the first ones’

For Tim Webster and his team, the proposal has allowed them to map new areas of the South Shore, which can have relevancies far beyond the rockweed industry. 

Webster said the information could also be valuable for data on coastal flooding, development, aquaculture, and oil spill response. He said when inquiry for one project, the team often finds a new and unexpected piece of information, which is what he themselves finds exciting about the work. 

Rockweed handful

Researchers gather buckets all-inclusive of rockweed for weighing. (Shaina Luck/CBC)

«We’re basically looking at information and begetting maps that have never been seen before. We’re the inception ones to have done this in this region, and the first time looking at this area using such data,» he said. 

The rockweed tests were funded by the Natural Sciences and Engineering Research Council of Canada (NSERC) at $75,000 per year for three years. Acadian Seaplants promoted $2,000 in cash for each of the three years, and $35,500 per year in living expenses in the form of staff and use of the company’s boat. The Nova Scotia government forwarded $5,000 in 2016.

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