Reducing nitrate & phosphate levels in the Wye Catchment with substrate attached algae

[Matt_S]

I've started this thread to discuss the merits of using freshwater algae to reduce river nutrient levels. If you've been following the UK news recently and Paul Whitehouse's 'Our Troubled Rivers' on the BBC then I'm sure you've heard about the rapid decline in river water ecology due to high nitrate and phosphate levels from agricultural run-off & CSO (Combined Sewer Outflows). This is a global problem due to excessive fertiliser usage and poor waste water treatment (aka lack of investment replacing aging infrastructure). The RePhoKUs study of the Wye Catchment area is of particular interest to me since I used to camp, swim and fish in this river as a child and now in just a few years the ranunculus has all but gone and eutrophication is a real threat every summer, when algae blooms appear. Intensive poultry farming and agri businesses have capitalised on laxed planning requirements and enforcements.
So, what can be done? The Environment Agency and Ofwat are catching up, but could Citizen Science bridge the gap? Environmental campaigning bodies such as Friends of the Upper Wye and River Action are stepping in to provide data that the EA/NRW/DEFRA are lacking. I think we could go further than this and introduce non-point source absorption of nutrients in the river using attached filamentous algae such as horsehair (pithophora), water silk (spirogyra) and cotton algae (cladophora). This could be cultured in a similar way to kelp line seeding and supported in rivers on natural woollen rope, so there is no microplastic pollution risks. Natural rope from Welsh sheep used to clean up the Wye -how local is that!

SO DO YOU have any knowledge on filamentous algae, ranunculus and kelp seeding? If so, please get in touch. I would like to establish a group on UKAPS that can rise to this challenge.
Thank you, Matthew.

 

[MichaelJ]

Somewhat tangential to this. In our community we have had great success with Alum treatment of the lake we are living on (aluminum sulphate that removes phosphates through precipitation). In addition, the city put in a large stormwater infiltration basin a couple of years ago - essentially a huge rain garden to alleviate yard and agricultural run-off etc. from entering the lake. Last summer the lake was in great condition; crystal clear water, more natural vegetation than seen in years, plenty of fish, insects and amphibian wildlife (turtles and frogs). It's really been a great success. I am still a little worried about the long term effect of the Alum treatment and we may have to do the treatment again in a couple of years.... time will tell. Judging from the amount of ice fishing that's been going on this winter I would say the fish stock is in very good condition and it bodes well for the coming summer.

I know it's not directly applicable to situations on rivers, but still, things can be done.

Cheers,
Michael

 

[ScareCrow]

Hi @Matt_S, my guess is that the EA/NRW/DEFRA would probably lean towards dosing, as @MichaelJ mentions, rather than introducing vegetation to the river. The EA came under a lot of scrutiny around vegetation clearance when the Somerset levels flooded. Adding vegetation to the watercourse would require maintenance to ensure it's not causing problems that might increase flood risk.
Do you have land or ownership of a section of river that this or a similar scheme could be implemented on?
I'm not familiar with the area but would floating reed beds be an option? They've proven very successful in cleaning polluted waterways.

 

[Witcher]

using freshwater algae to reduce river nutrient levels.
[...]
eutrophication is a real threat every summer, when algae blooms appear.

Interesting idea overall, but doesn't the above (of course slightly taken out of overall context) sound like fighting plague with cholera? Don't you think massive introduction of other algae may led to (yet another) imbalance in the system which is already struggling?

 

[Nick potts]

Interesting idea overall, but doesn't the above (of course slightly taken out of overall context) sound like fighting plague with cholera? Don't you think massive introduction of other algae may led to (yet another) imbalance in the system which is already struggling?

It's always possible.

I see it the same as what we try and do in our tanks, encourage an easy-to-manage nutrient hog to outcompete a pest species. It is done more in saltwater with things like chaetomorpha and Caulerpa algae.

 

[Tyko_N]

and eutrophication is a real threat every summer, when algae blooms appear.

Do you have a lot of plankton feeding fish, like roach, in there? I would expect nutrient levels to be highest in spring and autumn due to more precipitation washing it into the water then, algae blooms might be more an effect of high temperatures and lack of zooplankton, and in some lakes around here they've had decent success with target-fishing for plankton eaters to increase zooplankton populations. It won't help with the nutrient levels, but it could allow more light to reach submerged plants and improve clarity.

 

[G H Nelson]

This might be of interest below....maybe something similar could be implemented with indigenous plants!

Using stem plants as a filtering aid at Start Up!

The subject of using fast-growing stem plants as part of a filtering aid has cropped up a few times recently. This idea has been around for a long time so not new, it has benefits especially for a new set - up. I try and cover at least 50% of the water surface minimum. 1. Improves water...

www.ukaps.org

hoggie

 

[Hanuman]

It's interesting how, we, humans, think we can always outsmart nature by coming up with fancy ideas when in fact all we would need to do is stop throwing so much s**t into the environment and treating it like it has unlimited resources. It's that simple. Nature would simply do the rest by itself and perhaps we could also help it a notch by replanting trees where we have totally slaughtered them.

 

[Witcher]

Nature would simply do the rest by itself

My most favorite is the Yellowstone wolves case:

 

[Nick potts]

It's interesting how, we, humans, think we can always outsmart nature by coming up with fancy ideas when in fact all we would need to do is stop throwing so much s**t into the environment and treating it like it has unlimited resources. It's that simple. Nature would simply do the rest by itself and perhaps we could also help it a notch by replanting trees where we have totally slaughtered them.

Very much agree with you on this, unfortunately, I don't think that we are going to accept that until it's hopeless.

 

[Matt_S]

Thank you for all your comments and suggestions on this idea. Dosing would work if it was a localised issue, but the catchment area is large ('The Wye catchment covers 4,285km2 spanning two countries and five counties. The River Wye stretches for over 200 kilometres from its source at Plynlimon in mid-Wales to the Severn estuary making it the fifth longest river in the UK.'). Some improvements such as planting more trees along the river to give shading will reduce peak summer time water temperatures, and buffer strips either side of the water way to reduce surface and sub-surface runoff from agricultural land. But it's not enough.
The idea is to install artificial weed beds at regular intervals where high nitrate & phosphate levels are recorded. The weed beds hold a continuous natural fibre rope (wool) that is looped along the length and left to float freely in the flow (but not allowed to float away). Think of a wide upside-down garden rake with maybe 100 loops of rope trailing 3 metres in the downstream flow. The rope is wound with seeded twine in a similar way to kelp farming. The seeding uses filamentous algae species that are local to the ecology of the river. The rope can be removed from the river, the algae harvested and the rope put back (semi-automated process similar to kelp harvesting).
I'd like to find out more about filamentous algae species that grow in the Wye, or that can be introduced and not create a new ecological problem. Any Ecologists out there that can help please?

 

[Matt_S]

Somewhat tangential to this. In our community we have had great success with Alum treatment of the lake we are living on (aluminum sulphate that removes phosphates through precipitation). In addition, the city put in a large stormwater infiltration basin a couple of years ago - essentially a huge rain garden to alleviate yard and agricultural run-off etc. from entering the lake. Last summer the lake was in great condition; crystal clear water, more natural vegetation than seen in years, plenty of fish, insects and amphibian wildlife (turtles and frogs). It's really been a great success. I am still a little worried about the long term effect of the Alum treatment and we may have to do the treatment again in a couple of years.... time will tell. Judging from the amount of ice fishing that's been going on this winter I would say the fish stock is in very good condition and it bodes well for the coming summer.

I know it's not directly applicable to situations on rivers, but still, things can be done.

Cheers,
Michael

thanks Michael, that's one method to use. Ferric sulphate also works, and is used by the waste water treatment industry. These methods are costly and not environmentally acceptable though (at least not on a large scale). Hopefully a lower cost and natural method can be found.

 

[Matt_S]

It's always possible.

I see it the same as what we try and do in our tanks, encourage an easy-to-manage nutrient hog to outcompete a pest species. It is done more in saltwater with things like chaetomorpha and Caulerpa algae.

thank you Nick, nicely put! This is exactly the plan -fight fire with fire, the Red Adair way.