Coastal Conservation And Management

The coastal zone, defined in 1.4, stretches from the land to the sea and includes a series of habitats which occur either as individual units or in combination. This book concentrates on the conservation of those coastal habitats which cross the land — sea interface or form part an integral coastal unit. Following a general introduction to the principles of management and conservation, attention switches to individual coastal habitats (sea cliffs, saltmarshes, sand dunes and shingle structures), considering management issues specifically related to them and their associated biota. Discussion of the wider conservation issues associated with more complex systems such as estuaries and deltas are considered under a general heading of coastal wetlands.

The massive changes in land-use and habitat loss described in Chapter 1 have resulted in the remaining areas of unspoilt coastal landscapes being considered to be particularly precious. As a result nature conservation organisations world-wide have expended considerable time and money in an attempt to prevent the worst excesses of human destruction. Despite this, loss of habitat and degradation of the environment continues. This chapter reviews some of the general principles of habitat, species and site conservation management as they apply to coast.

Sea cliffs create some of the most attractive and spectacular coastal landscapes in the World. Their distinctive nature is defined by the extent to which the material forming it is consolidated (‘hard’ rock cliffs), developing in resistant bedrock and unconsolidated (‘soft’ rock cliffs), developing in easily-eroded materials. The former are stable though they may be steep and inaccessible, the latter unstable and highly erodable. These attributes help maintain freedom from intensive human use, which is an important element in the survival of sometimes considerable nature conservation interest. The rock types ‘hard’ and ‘soft’ lie at the two ends of a spectrum which support very different nature conservation interests.

The previous chapter dealt with the conservation of sea cliffs and sea cliff vegetation. This chapter briefly considers the conservation of a variety of mobile species (notably seabirds) inhabiting sea cliffs and islands. Historically, many island bird and mammal populations have provided a source of food for indigenous populations. Larger flightless birds such as geese were particularly vulnerable to human predation and in Hawaii Polynesian settlers are estimated to have exterminated 39 species (including 7 species of geese) over the last 1,000 years. A further 14 have been lost in the last 200 years as European colonisers continued the extermination of native species (Schreiber et al. 1987). The introduction of ground predators, notably black rat (Rattus rattus) and in Europe American mink (Mustela vison), caused further losses and in many areas today populations are considerably reduced or extinct.

Saltmarshes can be defined by habitats containing halophytic plant communities and associated animals which are tolerant of sea water. Typically they are regularly inundated by the tide, have sometimes rapid accumulations of sediment and, in the absence of enclosure, include transitions to non-tidal vegetation. They are at their most extensive in the northern hemisphere in areas subject to high tidal range (macro-meso tidal) where flat tidal plains develop in the shelter of estuaries and on open coasts protected by offshore sand bars and other structures. A key to their sometimes extensive formation is the presence of an abundant supply of fine sediment which settles out from the water column as tidal movement and wave action are reduced. Pioneer salt tolerant plants such as Salicornia spp., Suaeda spp. and Spartina spp. are among the most frequent colonists in northern latitudes.

In the United States of America the Federal Fish and Wildlife Service estimate that there are approximately 6,300 non-native invasive plants and animals which pose a threat to wildlife. This chapter describes one of these species which has had a profound impact on coastal tidal areas in many parts of the world. It highlights some of the questions posed for wildlife conservation managers and amenity interests.

Sand dunes border long stretches of the World’s coastline and are best developed in temperate and arid zones (Bird 1984). They are formed when sandy shores dry out and sand grains are blown inland. Accumulations a few centimetres to 40m or more thick are formed by the combined action of wind and the stabilising effects of vegetation. Whilst most dunes show contemporary contact with the sea, on rising shorelines or where sand accumulation is extensive this contact may be discontinuous or absent. In Queensland, Australia, dunes exceeding 275m in height have developed through episodic migration (Bird 1984) and in Scandinavia land uplift has resulted in dunes occurring today far removed from the coast (Aartolahti 1973, Heikkinen & Tikkanen 1987). This chapter is concerned largely with dunes which are derived from sediments driven onshore by the action of the sea and subsequently moved inland by wind. Throughout reference is made to geomorphological issues though this is not dealt with in detail, but see Pye & Tsoar (1990), Nordstrom et al. (1990) and Bakker et al. (1990). The extensive barrier island coast of the eastern USA is mentioned only in relation to considering sea defence issues.

Shingle beaches are widely distributed around the world. They are composed of deposits of pebbles lying at or above mean high water. These most often occur as fringing beaches which are subject to periodic displacement or overtopping by high tides and storms. Waves determine the position of the sediment on the beach. Deposits may be reworked in front of the shore or moved in parallel to it by longshore drift, before being thrown up onto the beach by storm waves. Small foreshore ridges are deposited at the limit of high tide and form the fringing beaches which may occur on their own or as precursors to more permanent ridges.

Dungeness (Figure 9.69) is one of the largest shingle cuspate foreland structures in the world, and is a worthy subject for more detailed discussion of the relationship between biodiversity and integrated coastal management. A well-studied geomorphological system with extensive and intensive human activity affecting the surface shingle, its future is largely determined by local approaches to planning and shoreline management. Despite the adverse treatment it has received, touched upon in Chapter 8, it also remains one of the most important nature conservation sites in Europe and has been the subject of detailed scientific study (Ferry & Waters 1985, Ferry et al. 1989, Ferry in Press).

The term ‘coastal wetlands’ can be used to embrace estuaries, deltas and lagoons which are here taken together as integrated, complex and dynamic systems. The interactions between the component habitats and species concentrations often mean that one part of the system is dependent upon another. Thus the enclosing sand dune or shingle barrier may help create sheltered conditions for the development of mud flats and saltmarshes to form a ‘bar built estuary’. Each component habitat has its own importance which is discussed in the relevant chapters above. This chapter is concerned with those systems which occur in temperate regions and does not include coastal wetlands in tropical and sub-tropical areas (including mangroves).

Few, if any, coastal habitats are truly natural, but the two principal habitats in this chapter have a special conservation significance because they have largely been created through human intervention. In nature conservation terms the habitats lie between those which are (or are considered to be) entirely natural and those which are intensively used, with little or no conservation interest. The former include inaccessible sea cliffs and newly formed sand dunes, the latter intensively cultivated grasslands and cereal crops. These ‘secondary’ wildlife habitats (as defined in Chapter 5) are dealt with separately below and their key attributes discussed.

Mobile species may rely on one or more habitats during the course of their life cycle and these may be spatially separated by a few metres or several thousand kilometres. Previous chapters have described the important spatial and temporal relationships between and within coastal habitats. These include sometimes complex ecological and geomorphological links where external forces may force rapid change. The management of an individual site can also fundamentally alter the nature of the component habitats and all these factors can influence the value of the area to visiting species. When considering the conservation of a mobile species it is important, therefore, to understand the individual habitat and feeding requirements at the different stages in its life cycle. This is particularly important for those species with special needs when breeding (e.g. sea cliffs for sea birds, shallow dune slacks for natterjack toad or saltmarsh with a good structural diversity for redshank), or feeding habitat (e.g. estuary mudflats for wintering waders or saline lagoons for the flamingo). Those species which are more catholic in their tastes are less dependent on specific habitats and therefore more resistant to change.

Traditionally the cornerstone of the nature conservation is the protection of the best examples of particular habitats and species concentrations. Many precious wildlife areas have been destroyed or reduced considerably in size, others survive only as small ‘islands’ in a landscape used for intensive agriculture or otherwise highly modified. In the face of the continuing attrition of wildlife and their habitats, it is perhaps not surprising that the conservation movement continues to promote the protection of those places with special habitats and species.

This final chapter examines the successes and failures in protecting coastal habitats and sites. It reviews the role of change as a natural component of coastal systems and examines the way in which this is viewed by the conservationist, the developer, and those concerned with sea defence and coast protection.