Dinner on the Don: aquatic insects and the foodweb

In this blog we hear from DCRT Director, Ed Shaw, on how emerging aquatic insects feed the wider terrestrial foodweb…

CC BY-SA 3.0, Low creek by Fir0002, 2005

The beds of most streams and rivers are jam packed with the nymphs of various kinds of insects. This includes (relatively) well-loved insect groups such as mayflies, caddisflies and stoneflies, as well as less appreciated groups such as midges and blackfly. Most of these insects share a similar approach to life. They spend the majority of their life as aquatic larvae, slowly growing in the cold water, before they emerge out of the water as adults to find a mate and reproduce, often en masse. Different species tend to emerge at different times in the year, so regardless of when you visit your local river, you will often notice insects ‘dancing’ above water or resting on foliage.

An adult Mayfly resting

This is why the riverbank is a favoured haunt of the insectivore (animals that mainly feed on invertebrates and insects). Not only is there often an abundance of freshly emerged potential snacks, but many of these snacks, winged and mobile as they are, are actually pretty poor flyers and easily caught. These insects are also often single-mindedly focussed on reproduction that they obligingly neglect their personal safety.

An adult stonefly

So plentiful and reliable can emergent aquatic insects be that rivers be that some terrestrial predators specialise in catching them. Sand martins make their nests in river cliffs (or in riverside walls in Sheffield) and can be seen swooping across the Don, while grey wagtails bob on rocks or at the water’s edge, snatching up morsels that catch their eye. At night, another aerial predator emerges, Daubenton’s bat, which feast on midges, and can even trawl for prey on the surface of water using their feet.

CC-BY-SA, Sand martin (Riparia riparia), Guidel-Plage, Brittany, France by Frank Vassen, 2015

Invertebrate predators are also drawn to rivers and streams. Well known are the dragonflies and damselflies that patrol back and forth before darting to seize a passing insect. Less well known are the long-jawed orb-weaver spiders that like to set up home near water, building their webs in riparian vegetation, even tilting them over rivers and streams to increase their chances of ensnaring an unlucky emerging insect.

CC BY-SA 3.0, Tetragnatha striata by James Lindsey at Ecology of Commanster , 2005 

An important quality of emergent aquatic insects as prey is that some species emerge during the colder months, when there are very few other insects around. For example, the common and widespread mayfly species, the Large Dark Olive, can emerge throughout winter. This can make aquatic insects a relatively important source of food when other insect life is scarce. Researchers in a part of Japan with harsh winters observed that wrens (the same species as our own) tended to preferentially forage along streams in search of aquatic insects. Although British winters are comparatively mild, it seems quite conceivable that British insectivorous birds may do the same.

With winter setting in, do look out for those clouds of dancing insects, and if by a river or stream keep an eye out for a mayfly or stonefly. They might end up an important meal for a goldcrest or wren, or against the odds, they might find a mate and start a new generation. 

Snaps from a river survey

This photo diary documents our Autumn freshwater invertebrate survey of the river Rother. We now have three years of data from this stretch of river, creating a picture of underwater life in the recovering Rother (once considered the most polluted river in Europe!).

With all our protective and life-saving equipment on, we can start our survey. We have 7 sites to survey on this stretch of the river, collecting 21 riverbed samples in total! The samples and data reveal insights into the health of the river.

For each site we record information about the habitat and collect data on the flow, width and depth of the river. We look to see if there’s any evidence of pollution, litter or sewage by recording what we can see (and smell!).

We then start our kick-samples. This sampling method involves positioning the net on the river floor and kicking upstream of it. Kicking dislodges the tiny insects and creatures living on the riverbed, which are then pushed by the river’s current into the net. With the help of volunteers, we then analyse the invertebrates we’ve found.

The diversity and abundance of invertebrates found in the river can reveal important secrets about the river’s health

The 5 Ways to Wellbeing

At DCRT we believe that time spent in nature can be incredibly restorative. In fact there is plenty of scientific evidence that being better connected with nature makes us both healthier and happier people. Being physically active in nature relaxes our nervous system, releases mood-lifting hormones and increases our energy-levels. But, it’s not just positive for our physical health, exposure to nature can help us to manage existing mental health issues and prevent them from occurring in the future – a green prescription for our minds and bodies.

At DCRT we follow the 5 ways to wellbeing, five simple strategies that when incorporated into our lives can improve our health and wellbeing. Here’s some of our favourite wellbeing-focused activities that can bring more nature into our lives during lockdown.

Connect

Volunteering provides a space to meet like-minded people and share experiences with people from all walks of life. Our online volunteer tea-breaks and online activities are a great way to stay in touch during lockdown.

Be Active

Swap the gym for green exercise, like running, walking, swimming or cycling outdoors and feel the benefit. Explore some of the incredible landmarks in the Don Catchment.

Keep Learning

Feel the benefit of connecting with nature by finding more about the wild world around you. Join an online wildife identification training course and then practise your new skills.

Did you know that diving beetles are the scuba-divers of the animal world, trapping bubbles of air under their wings which they carry with them underwater to breathe. Or with two pairs of eyes, the surface-dwelling whirligig beetle can see both above and below the water’s surface at the same time? Join Katy Potts, Biodiversity Officer at the Natural History Museum, for an introductory online training course on ‘Beetles of the Riverbank’ and find out how beetles are adapted to life on the water’s edge. Click here to register for a free place.

Give

Take positive action in your community for nature. Try some Nature DIY and create a bug hotel, bird house or bat box from found materials. If you have a garden implement some Natural Flood Management – make a green roof on your shed or create a rain-planter.

A major contributor to increased flood risk is the amount of hard surfaces across our urban areas. Storm water rushes off our roofs, onto paved gardens, down pavements and roads and into drains that often struggle to cope with the volume and speed of water pouring into them. Slowing this water down and capturing it in our gardens is a great way to do your bit to help reduce flood risk. Here’s how to try it: Take a good look at any outside space you have – front and back gardens or yards, driveways, balconies or even that little space by your front/back door. Look for where the hard surfaces are and start to think about how you might make these areas better able to capture rainwater. Turning grey to green is a great way to do this. Remove concrete/slabs where you can and fill them with plants, or add pots and planters.

Take Notice

Be mindful of nature and our place in it. Try an activity to help you better observe nature, such as nature art or forest-bathing.

Shinrin yoku, or forest bathing, has been practised in Japan since the 1980s, prescribed to city-dwellers with hectic lives as a form of eco-therapy. Studies show forest bathing de-stresses and improves sleep, mood and focus. Here’s how to try it: When you go for your next walk, head to the local woods and tune into the nature around you. Hear the bird song, become mindful of the sun’s warmth on your face and feel the cool breeze. Breathe in the clean air and tune into your senses. Practise being still and calm amongst the trees. These top tips from Forestry England show you how it can form part of your daily exercise, just keep in mind social-distancing rules and limits.

Nature Art online events

Want more ideas how to incorporate both the 5 ways to wellbeing and more nature into your life? Sign up to our monthly newsletter here or go to our News and Activities webpage to read our previous issues.

Matt’s Mushroom Meanderings

Let me take you on a walk through some of the mushrooms I have seen over the last few months. Some of them have been on volunteer days and others whilst I’ve just been out and about.

I already knew a few from previous fungi foray’s I’ve been on but I used the FREE app ‘Shroomify’ (https://shroomify-mushroom-id.en.aptoide.com/app) to ID a few of these – it has a really useful key you can use to determine what you’re looking at.

iSpot is also very good for getting an ID on alll things naturey – https://www.ispotnature.org/

This is the first one I found of the year in Ecclesall Woods – a Common Earthball (Scleroderma citrinum). These next few were also found there.

Sulphur Tuft (Hypholoma fasciculare)

Amethyst deceiver (Laccaria amethystina)

• 

• 

The classic Fly Agaric (Amanita muscaria), these were found near Grindleford.

A common conecap (Conocybe tenera) found at the Rother Rec in Chesterfield on a volunteer day. These next ones were also found on the same day.

Shaggy Scaly Cap (Pholiota squarrosa)

Jelly Ear (Auricularia auricula-judae)

Fairies Bonnets (Coprinellus disseminatus)

We think this might be Butter Cap (Rhodocollybia butyraceae)

Tawny Funnel Cap (Lepista flaccida)

Collared Earth Stars (Geastrum triplex) in the woodland next to where the Rivers Hipper and Rother confluence

Small staghorn (Calocera cornea) at Blackamoor

Oyster mushroom (Pleurotus ostreatus) found at Crookes Valley Park

From oyster mushrooms to osyterlings (Crepidotus variabilis)

Shaggy Inkcaps (Coprinus comatus)

Shaggy Inkcap Linguine

Inspired by a squid ink pasta dish i had in Madrid a few years ago, I decided to make these Shaggy Inkcaps into a linguine. I would only reccomend eating mushrooms if you’re certain you know what they are. These grow on the grass out the back of where I live every year.

I also left one of the inkcaps in a bowl over night and they dissolve into ink – hense their name. Here’s a few paintings I did with them…

• 

• 

• 

Elfin Saddles (Helvella crispa). There were lots of these found along Sheffield canal

These are witch’s hat (Hygrocybe conica), found on Anthony’s lawn!

Golden Spindles (Clavulinopsis fusiformis) found near High Bradfield

Weir’s the Weir gone?

Here at Don Catchment Rivers Trust we have a mission of protecting and restoring rivers in the Don Catchment – this not only includes the Don, but the Dearne and Rother too.

Over the last ten years, we have had a focus on restoring the rivers as a habitat for fish, particularly migrating fish such as salmon. Historically, dozens of weirs were built across rivers to divert water to mills and factories, but this created an ‘obstacle course’ for fish that were unable to swim up and across the weirs. The weirs also fragmented habitats, prevented fish from reaching their spawning grounds, and altered the natural processes a river should have.

Image shows Kelham Island Weir, Sheffield (centre of image, left of the bridge) diverting water from the River Don into an artificial channel called a ‘goit’ above it. This water would have originally powered a water wheel.

Since the trust formed, we have built seven fish pass solutions on weirs along the Don. But we have never had an opportunity to actually remove a weir until recently.

Fish passes can be built on weirs that cannot be removed, such as here at Masbrough Weir in Rotherham. © DCRT

That opportunity arose as part of our Hidden Heritage Secret Streams project at Slitting Mill Weir on the river Rother. The river around Staveley has been altered a lot over the decades to meet the needs of industry – it has been straightened and de-meandered. The original Slitting Mill Weir was several hundred years old, and as the name suggests fed water to the nearby slitting mill, which slit metal bars into rods, to be passed on to other local mills making nails. We know that the Weir was heavily altered, possibly rebuilt using original stones, around the 1950s for the nearby chemical works. Since the works closed the weir has had no use, but remained in the river as a barrier to fish and other wildlife.

Slitting Mill Weir – this weir was once used to divert water to power the nearby mill, but now does not have a function. Weirs such as this are too steep for migrating fish to jump and swim across, so they prevent access to spawning grounds making it impossible for populations to sustain themselves in the river. © DCRT

So, in October, after about two years preparation to get the appropriate permits and planning permission the weir was removed. We understand that this can be quite a sad sight for people who appreciate built heritage, as do we, but the weir was not listed and ultimately we need to right some historical wrongs – all the weirs in the catchment were man-made structures that led to the decimation of the natural environment.

To remove the weir, a small section is first removed to allow the water on either side to level up. At Slitting Mill Weir the impoundment was so large this took 3 hours! After this excavators can remove the rest of the material and even out the bed levels. © DCRT

The weir was removed by using an excavator and the beautiful local cut stone from the crest was salvaged for use by the estate. We opted to leave the stones acting as bank protection in place to serve as a reminder of where the weir used to be. Now, the water level upstream of the weir has returned to a more natural level, and given time the river should start to heal from it’s impoundment.

The river after Slitting Mill Weir was removed, looking upstream. You can see from the banks how far the water levels have dropped – nature will soon repair the bare banks. © DCRT

So, what’s next? Well the team and our citizen science volunteers have been carrying out base line monitoring of the invertebrates in this stretch of the river, so that we can see what impact removing the weir has. We’ll carry on with the post-removal sampling, and will produce our first comparison report in about a years time.

Out team of citizen scientists at work checking on a sample for invertebrates. Currently our samples are consistent with still water or ponds, but now that the weir is gone and the river can flow more naturally we hope to see a change for the better in future samples. © DCRT

Also, now that the water level has dropped, quite a lot of abandoned tyres have revealed themselves! We’ll organise some clean up days once the spring arrives with some dryer weather, and the Covid-19 restrictions allow larger groups to gather.

There’s always a job to do! We’ll make a plan for getting these unsightly tyres removed. Where do they all come from?! © DCRT

There are still more barriers to tackle and habitats to improve on the Rother to allow fish to move up and down the river. Other organisations are working on improvements through the ‘River Rother Restoration’ project, so we hope to see more action soon!

This plan of the River Rother shows the major barriers (red dots) that need a fish passage solution. [to be updated shortly with a green dot for Slitting Mill and Masbrough in Rotherham.] © DCRT