Figure 1

Map of the river mouth locations for rivers included in the project. Key to catchments analysed: (1 - 15, Scotland) 1: Blackwater; 2: Creed; 3: Laxford; 4: Gruinard; 5: Ewe; 6: Loch Lochy; 7: Awe; 8: Loch Lomond; 9: Clyde; 10: Ayr; 11: Doon; 12: Cree; 13: Fleet; 14: Nith; 15: Annan; (16 - 36, England and Wales) 16: Esk; 17: Eden; 18: Derwent; 19: Kent; 20: Lune; 21: Ribble; 22: Dee; 23: Teifi; 24: Usk; 25: Wye; 26: Severn; 27: Taw; 28: Torridge; 29: Camal; 30: Fowey; 31: Tamar; 32: Dart; 33: Exe; 34: Avon; 35: Itchen; 36: Test; (37 - 45, France) 37: Sée; 38: Sélune; 39: Léguer; 40: Élorn; 41: Aulne; 42: Ellé; 43: Scorff; 44: Blavet; 45: Nivelle; (46 - 49, Spain) 46: Asón; 47: Cares; 48: Sella; 49: Narcea; 50: Eo; 51: Ulla; (52 - 57, Ireland) 52: Moy; 53: Laune; 54: Cork Blackwater; 55: Barrow; 56: Suir; 57: Boyne. Full details of catchments studied are given in Additional File 1.