Biogeochemical value of intertidal areas - A case study of the Humber estuary

We present results from the Humber estuary in England to illustrate that loss of intertidal habitat to reclamation over the last 300 years has dramatically reduced the capacity of the estuary to store and remove carbon nitrate and phosphorus inputs. This, coupled to large increases in riverine nitrate and phosphorus concentrations, means the estuary is now a major input of nitrate and phosphorus to the North Sea. This general pattern of change is common to many estuaries. We argue that management realignment offers an opportunity to restore the capacity of the estuary to store and trap carbon, nitrogen and phosphorus. It is possible already to make preliminary estimates of the likely extent of storage and this provides a basis to include these biogeochemical functions in cost-benefit analysis, although further work is required to improve these estimates and extend them to other estuarine biogeochemical functions.