Country diary: sandhoppers are nature’s refuse workers

Langstone Harbour, Hampshire: As they break down rubbish on the strandline, the tiny crustaceans may however be contributing to the spread of secondary microplastics

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 high-tide 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 the distribution and abundance of 14 indicator seaweeds.

The seaweed was growing in an uninterrupted three-metre-wide band that arced around the bay. Long skeins of pea-green gutweed were interwoven with flattened, tawny-coloured fronds of bladderwrack and spiralwrack, and an unfamiliar species that had tiny, spherical air bladders clustered along its wiry branches. According to my field guide, it was Japanese wireweed, an invasive alien.