A Place of Uncertainty and Change: The Erme Estuary – by Philip Strange

The Land Lines Blog is pleased to share this unique look at the River Erme estuary by scientist and writer Philip Strange. In this piece, Philip compares two visits to the Erme estuary in 2019 and 2020 – and remarks upon the changes that have taken place over the course of the year.

The Devon countryside still looks fresh and green as I head towards the coast on this late spring morning. The narrow lanes are enclosed by steep grassy banks decorated red, white and blue with campion, cow parsley and bluebells, as if to celebrate the season.  I am on my way to the estuary of the river Erme, an isolated, unspoilt place that I love to visit. The last part of the journey takes me down a one-car’s width track that descends steadily for about a mile, winding gently from side to side as if it’s not quite sure which direction to take.  There’s mud on the lane in places, also running water and many potholes; this is Devon at its deepest.  In time, though, silvery gleams of water appear through the trees on the right.  

The Erme Estuary at low tide (Photo by Philip Strange)

I park by woodland near the end of the lane and walk down a rough stone slipway on to the sandy beach.  The tide is low and the estuary is spread out ahead, a vast tract of pale flat sand, sculpted into ripple patterns by the receding water and now mostly dry.  The river Erme, a snaking, shimmering, ribbon of water, flows across the sand in search of the sea.   There are a few people about enjoying the warmth and light of this sunny morning but there’s plenty of space and children help their parents build sandcastles on the beach while dog walkers saunter across the dry sand.  It is a peaceful, happy scene.  

But the mouth of the estuary is not far away and the sea is visible downstream, wave crests sparkling in the bright sunshine, reminding us of its power.  The proximity of the sea means that this part of the estuary is strongly tidal, a natural battleground where the sea and the river fight for supremacy.  At present, the sea is in retreat, but as the tide rises, the sea will take control, covering the sand and eventually filling the entire area between the tree-lined banks.  Waves then progress some way up the estuary and kayak surfers enjoy the watery surges of energy.

I walk upstream from the slipway along a strip of stony sand that borders the river.  As I make my way, the estuary gradually narrows into a corridor lined by bands of dense, dark green woodland and within this corridor, at low tide, the river flows in lazy meanders.  A snowy white egret prospects in the shallow water while ahead of me are the remains of one of several limekilns dotted around the estuary.  This one, still a substantial stone edifice, stands in the middle of an area of pale, dry sand stretching back to a row of sycamores covered with pendulous yellow flowers resembling miniature chandeliers.

A few years ago, my wife Hazel discovered two sand spits upstream from the lime kiln and took me to see them.  They fascinated me at the time and have since held my imagination.  The nearer of the two is a substantial tongue of raised sand protruding from the river bank, forcing the water to flow in a long curve.  In spring and summer, this spit is covered with rough grass accompanied around the edges by beach plants such as sea rocket and orache.  In winter, it is occasionally flooded and left with an untidy covering of woody debris; nature has no respect for appearances.  The sand is very loose, stabilised by the tangled matrix of grass and beach plants but its very existence seems precarious, changing, uncertain, adding an intriguing layer of mystery.  

The second sand spit lies a short distance upstream.  This is altogether more established and secure, attached firmly to the river bank and vegetated with thick grass and shrubs. It also stands higher above the water making it less likely to be inundated.   The locals seem to know this and leave their small boats littered around the spit turned upside down so that they resemble large beetles.  Today, the spit has good amounts of flowering hawkbits, mustards, radish and hawthorn and with all these flowers and the bright sunshine, there are many insects about.  Oddly, though, there are also many tall stands of a very spiny rose with large showy magenta or white flowers bearing a central fuzz of yellow stamens.  These are Rosa rugosa, originally a native of Eastern Asia that thrives along sandy coasts.   I am intrigued as to how it has come to be flourishing in this watery corner of Devon.  Was there habitation on the spit in the past or has a bird eaten one of the very large bright red hips, nicknamed beach tomatoes, and brought seed? 

As I walk along the sandy edge of the first spit that day, I am surprised to find many small bees darting about.  There are hundreds of the insects flying just above the surface of the loose sand in a seemingly random manner but moving incessantly, accompanied by their dark shadow doppelgängers.  The continuous movement of such a large group of these small creatures radiates an intense energy.

Female Sandpit Mining Bee carrying pollen (Photo by Philip Strange)

I am astonished, though, when one of the bees carrying a cargo of bright yellow pollen lands and quickly “swims” downwards in the sand to disappear from view, but I soon realise that this unusual behaviour is a regular occurrence.  Very occasionally, two of the bees struggle together briefly on the sand, most likely a male attempting to mate with a female. There are more of the same species on the second spit but only on areas of bare soft sand.  From their behaviour and their preference for a loose sandy habitat I work out that these are Sandpit Mining Bees (Andrena barbilabris), an exciting discovery as this is a new species for me and also because here are several large, thriving colonies.  I watch the bees for a while. They are slightly smaller than a honeybee and I think I can see bright chestnut hair on the thorax and a shiny black abdomen.  Time is running out, however, and I have to drag myself away to avoid being cut off by the tide.

Female Sandpit Mining Bee disappearing into the sand (Photo by Philip Strange)

That was the last week of May 2019 and, at the time, I made a mental note to return in 2020 to look more carefully at these bees and their unusual sand-swimming behaviour. In the meantime, though, the COVID-19 pandemic struck the UK and, once the lockdown had been imposed, my second visit became very unlikely. But then the travel restrictions were eased slightly and on a warm, sunny day towards the end of May, I made my way to the estuary once again.  This time, I travelled with the anticipation, exhilaration and trepidation that this sudden release from confinement held.  

When I reach the narrow lane leading to the slipway, it is littered with cars disgorging families dressed for the beach, their children thrilled to be carrying buckets and spades.  With the fine weather and with so many people off work and with schools closed, I am clearly not the only one to have had the idea of a trip to the Erme.  I can’t find anywhere to park, so I drive to a nearby village, leave the car and enjoy the scenic walk back.  When I finally reach the estuary, the tide is low and the view from the slipway across the flat sand is much the same as before.  The beaches are, though, noticeably busier and noisier with quite a few families scattered about.    

I make my way upstream past the limekiln towards the two sand spits, pausing to watch a group of seven swans pottering about on the water.  Crows gossip in the trees as if to warn me and when I reach the first sand spit, I am alarmed to find that it has virtually disappeared.  All that is left is a small tongue of sand with a perfunctory scattering of rough grass.  It isn’t just the spit that has gone, so have the bees and I am unable to find a single survivor from this once thriving colony. It is as though the river had finally tired of skirting round the spit and one day decided to take the direct route.

The second spit has survived and appears unchanged, its rough grass and shrubs are intact and it has the same selection of flowers and upturned boats.  I spend some time looking about the area.  A cockchafer lumbers through the rough grass, its reddish-brown and grey pattern echoing my earlier boat analogy.  Eventually, to my relief, I find two patches of loose sand together with the mining bees.  The colonies are very active in the warm sunshine; bees are returning regularly and when they arrive, they swing about the sand as if looking for something, emitting a low buzz.  Many have bright yellow pollen attached to their back legs as if they are wearing pantaloons.  Eventually they decide on a spot, land and “swim” into the sand using their fore legs for propulsion.  They disappear below the surface, the tip of their black abdomen pointing upwards as they dematerialise.  After a short time, bees reappear having deposited their pollen, swimming back up through the sand to fly off to collect more. I am, once again, astonished by their behaviour and manage to take some photos. These show that the insects have rich chestnut hairs on their thorax, a shiny black abdomen with white hoops and prominent bands of white hairs on the inside edge of their eyes, rather like hairy eyebrows.

The bees bringing the pollen back are mated females building nests in the firm sand below the loose surface. I don’t witness any mating attempts this time so the males must have already done their job.  The mated females lay eggs in their nests and equip them with pollen and nectar for the developing larvae that will become new bees ready to emerge next spring. Their ability to find their nests as they swim in the soft sand is very impressive. For us, it would be like trying to find our front door while blindfolded and I presume that the bees are using smell to navigate. It’s difficult to know the extent of the underground nests but, every time a bee lands and disappears it disturbs the soft surface leaving a mark, a small dip or hillock, and I notice these marks all over the loose sand suggesting that the area is well populated by nests.  

I suppose I shouldn’t be surprised by the destruction of the first sand spit and the loss of the bees.  A river estuary is a place of uncertainty and change where large bodies of water move backwards and forwards.  The Erme is also a spate river, responding rapidly to rainfall on Dartmoor where it rises about 14 miles away.  Between my two visits, there were major storms in Devon and flooding occurred along the course of the Erme.  Perhaps one of these storms created a torrent downstream bringing about the destruction of the first sand spit?  

The Erme estuary is a largely undeveloped place and appears to contain an unspoilt, natural environment, but does it really? I was made to reconsider this idea as I watched the Sandpit Mining Bees on my recent visit.  As they swam into the sand, I noticed a small, pale blue, cylindrical plastic pellet, about the size of a lentil, lying nearby.  This was a nurdle, one of the pellets used as a raw material in the plastics industry.  Unfortunately, these pellets are not handled carefully by plastics manufacturers and are allowed to escape to pollute our coasts and rivers.

Female Sandpit Mining Bee in flight (Photo by Philip Strange)

The presence of a nurdle on the second sand spit was of no consequence to the bees but it troubled me as these pellets are known to be eaten by seabirds and carry toxic trace metals. To me, this pale blue plastic pellet is a potent symbol of human intrusion into this seemingly unspoilt, natural environment. I then began to wonder whether human activity might also have played a part in the erosion of the sand spit. Global warming, driven by human actions, is leading to climate instability including increased intensity of rainfall during storms.  Perhaps the severe storms that hit Devon between my two visits and the loss of the first sand spit with its bee colony were due in part to human-driven climate instability?

As I walk back to the slipway, the tide is rising and I reflect on the day.  It is sad to see the loss of part of the colony of Sandpit Mining Bees, but they will survive here albeit on a reduced scale and may spread again in the future.  Much will depend on winter storms and downstream flooding but I’ll come back again next May to see what has happened.

A short video showing one of the Sandpit Mining Bees swimming in the sand can be viewed here:  https://www.youtube.com/watch?v=LiE_In6eFS4

About the Author

Philip Strange is a writer, scientist and naturalist who lives in south Devon.  His writing has been published in The Clearing, Resurgence and Ecologist Magazine, Zoomorphic and in Guardian blogs. He may be found searching for unusual plants on Chesil Beach, or looking for rare bees by the south west coast path, or chasing up a story about science in everyday life in the west country.  Or you can visit his blog: https://philipstrange.wordpress.com/

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