1. 4. Sand Dunes and Sandy Shores
Coastal Ecology
4. Sand Dunes and Sandy Shores

2. Druridge Bay, Northumberland

3. Cape Coast, Ghana

4. Development of sand dunes
Sand dunes are an example of succession: if one progresses inland from the beach one is, essentially, seeing all the stages through which a community develops.
Really, the only way to appreciate the extent to which the habitat changes on a small scale with time is to make regular visits at different times of the year.
Ultimately dependent upon one grass species: Ammophila arenaria (Marram grass).

5. Marram grass
Tolerates – and, indeed, thrives – on being buried by sand.
Sand accumulates in the wind shadow behind plants.
Because plants take a long time to decay the old parts of plants add a fibrous mass to the sand.
Xerophytic: fibrous rolled leaves with stomata on inside.

6. Marram grass (continued)

7. Leaf of marram grass

8. Leaf of marram grass (SEM)

9. Leymus arenarius: Sea Lyme grass
Larger, broad blue-green leaves.

10. Early stages of sand dune system (mobile dunes)
Soil essentially just pure sand: well drained, mobile, lacking in nutrients.
Very few plant species present: at first, just Marram Grass and then a few tap-rooted species start to appear. For example, Dandelion, Coltsfoot. (Tap roots supposedly seek for the water table, which may be many feet below).

11. Taraxacum officinale: Dandelion

12. Tussilago farfara: Coltsfoot

13. Further development of first dunes
Arrival of leguminous plants such as Bird’s foot trefoil (Lotus corniculatus) and Rest harrow (Ononis repens).
These have root nodules which contain bacteria responsible for fixing atmospheric nitrogen (useless) into nitrates (usable by plants).
Thus, the ‘soil’ is starting to become enriched.

14. Lotus corniculatus: Bird’s foot trefoil

15. Bird’s foot trefoil (in fruit)

16. Ononis repens (Rest harrow)

17. Continuing development
Further plant growth stabilises the soil.
Break down of dead plants (and the occasional buried dead seagull) adds to the nutrients in the soil and improves its water holding capacity.
Mosses growing across the surface of the sand further stabilise the surface.
Many new plant species appear causing the vegetation community to become more complex and diverse.

18. Sand dune mosses
Tortula ruralis

19. Sand dune mosses
Hypnum cupressiforme

20. Geranium sanguineum: Bloody Cranesbill

21. Calystegia soldanella: Sea bindweed

22. Tropical species of bindweed: Ipomoea pes-caprae

23. Rosa pimpinellifolia: Burnet Rose

24. Galium verum: Lady’s bedstraw

25. Dune slacks
Behind the dune ridges, and representing a later stage in development, the dune slacks are produced when there is a stable cover of vegetation and the soil has water holding capacity (partially as a result of humus and decaying plant remains) and nutrients (from the decay of generations of plants.
Number of plant species continues to increase.

26. Salix repens: Creeping willow

27. Epipactis palustris: Marsh Helleborine

28. Epipactis dunensis: Dune Helleborine

29. Corallorhiza trifida: Coralroot Orchid

30. Dactylorhiza incarnata: Early Marsh Orchid

31. Dactylorhiza fuchsii: Common Spotted Orchid

32. Dactylorhiza purpurella: Northern Marsh Orchid

33. Later stages in development
The continuing development of the succession depends on soil types (and inland land usage to a certain extent – farmers often encroach onto dunes).
Acidic soils may develop into dune heath.
Shrub/tree species cause the development of dune scrub.

34. Problems with sand dunes
Very fragile habitat.
Fore-dunes susceptible to winter storms.
Dune system in its entirety is a thin skin of vegetation – as a result, any damage to the surface exposes the sand underneath and wind very rapidly scours this out so that large areas of uncolonised sand exposed.
Problems range from rabbits to mountain bikers.

35. Management techniques
Variety of strategies are used in the management of sand dunes:
Manually replant with marram grass.
Cover exposed areas with chicken wire.
Bury old Christmas trees (or, in some instances, e.g. in Jutland, plant pine trees).
Discourage damaging behaviour – includes fires, camping, bicycles, etc.

36. Blyth Beach

37. Common Jellyfish: Aurelia aurita

38. Common Jellyfish: Aurelia aurita

39. Common Jellyfish: Aurelia aurita

40. Compass Jellyfish: Chrysaora hyoscella

41. Compass Jellyfish: Chrysaora hyoscella

42. Blue Jellyfish: Cyanea lamarkii

43. Blue Jellyfish: Cyanea lamarkii

44. Sea Potato: Echinocardium cordatum

45. Ensis minor: Razor Shell

46. Ensis siliqua: Razor Shell

47. Ensis siliqua: Razor Shell

48. Scallop

49. Scallop for the artistically minded

50. Sea Mouse: Aphrodite aculeata

51. Sea Mouse: Aphrodite aculeata

52. Lugworm: Arenicola marina

53. Lugworm: Arenicola marina

54. What you cannot see: Diatoms

55. …and a couple of things to look out for on tropical beaches