9.2. The Jump to Band 6

Sea walls built only as smooth concrete leave little habitat when the tide drops. In the last decade, engineers have begun to cast shallow pools into new walls so that water and small animals remain between tides. A 2019 survey of 18 walls on the south-west coast of England found that species counts were about 40 per cent higher in the pooled sections than on matched stretches of bare concrete. Pools next to a slipway were used most by children and by people collecting seaweed; pools behind a locked gate were barely visited. A 2022 follow-up counted people rather than species. Just over 60 per cent of recorded visits were at weekends. About a fifth were school groups booked in advance. The researchers argue that a pool only adds public value if it can be reached without a key. City authorities sometimes treat these findings as a request to cut every new wall with pools. The researchers do not. They recommend pools where the public can walk at low tide, and plain concrete where waves would empty a pool on every tide. The open question is scale. All six harbours in the study already had a wildlife group that recorded species. The team cannot say that a first pool in a harbour with no such group would produce the same 40 per cent rise.