Langstone Harbour, Hampshire
With my back to the sea, I paced out a five-metre-wide transect and began methodically surveying the shore, working my way up the exposed shingle towards the hightide mark. I was taking part in the Big Seaweed Search – a citizen science project that aims to investigate whether sea temperature rise, ocean acidification and the spread of non-native species is affecting 14 indicator seaweeds.
The seaweed was growing in a three-metre-wide band that arced around the bay. Long skeins of peagreen gutweed were interwoven with flattened, tawny fronds of bladderwrack and spiralwrack, and an unfamiliar species with tiny, spherical air bladders clustered along its wiry branches. According to my field guide, it was Japanese wireweed, an invasive alien.
The weed deposited along the strandline was sun-bleached and studded with marine detritus – dead crabs, cuttlebones, spongy balls of common whelk egg-cases and the ubiquitous litter of singleuse plastics. Peeling back the vegetation, I exposed a pulsing mass of sheltering sandhoppers
( Orchestia gammarellus ). With their semi-translucent segmented bodies and oversized hind legs, they looked like composite creatures – part shrimp, part woodlouse, part flea. They can jump up to 30cm by flexing and releasing their abdomen and flap-like tail, and I could feel them ricocheting off my shins as they leapt for cover.
Omnivorous scavengers, sandhoppers are nature’s refuse workers, helping to break down the vast quantities of dead and decaying material washed up on our shores. However, these amphipods may actually be contributing to the spread of secondary microplastics. Scientists at the University of Plymouth discovered that they could shred a single plastic carrier bag into 1.75m microscopic fragments, and found microplastics in their faecal matter.
By the time I reached the top of the beach, I had picked up a takeaway cup lid, a supermarket bag, a sandwich wrapper, two deflated balloons, three drinks bottles, a shotgun cartridge case and a sheaf of straws and cotton-bud sticks. Claire Stares