CAPE LOOKOUT Barrier Island Ecology of Cape Lookout National Seashore and Vicinity, North Carolina NPS Scientific Monograph No. 9

Most people think of the National Park Service as the guardian of the spectacular West, plus a handful of outstanding eastern sites. In recent years, however, the service has expanded rapidly into the management of coastal lands in the form of National Seashores. These ventures are quite different from the traditional objectives of the National Park Service since the seashores are classed as "recreation areas"; recreation is the main concern, with preservation of natural features a secondary objective.

Cape Hatteras was the pioneer National Seashore, followed on the East Coast by Cape Cod, Fire Island, Assateague, Cape Lookout, Padre Island, and most recently Gulf Islands, with further projects underway. Altogether, the National Park Service will control about 400 miles of Atlantic and Gulf shoreline and 425,500 acres of beaches, dunes, dramatic sea cliffs, maritime forests, fresh ponds and marshes, and estuaries. Since the seashores range from Cape Cod in the north to Padre Island near the Texas-Mexico border, these critical coastal habitats can be found in fascinating variety.

One main impetus for the National Seashore program has been the need to preserve some unspoiled shoreline within easy reach of the urban public with its increasing appetite for recreation. Another principal motive has been the specter of beach erosion. Political pressure from groups interested in these two aspects has a great influence on the direction that National Seashore development takes. As examples, the building of roads and bridges for easy access has often been stipulated in the seashores' enabling legislation; and when seashores are set up, the National Park Service is almost always given a mandate to control erosion and flood damage through cooperative efforts with the U.S. Army Corps of Engineers. Even though the National Seashores are protected from Coney Island-type development, they still face other, almost as dramatic, alterations in the name of recreation and erosion control.

The seashore program has grown more rapidly than has our knowledge of how to reconcile the guidelines of the seashores' establishment with broader National Park Service ideals of natural resource preservation. Planners find coastal data spotty at best. The scientific information that has been built into seashore management plans has often been that of the U.S. Army Corps of Engineers, which concerns itself almost solely with controlling beach erosion and storm flooding. Sometimes the plans have been drawn up so quickly that planners have had no time to search the literature for better information, and in altogether too many cases the scientific community has simply failed to make adequate data available. Coastal scientists obviously have an important responsibility to meet in advising seashore managers. Fortunately, recent years have seen an improvement in both the quantity and quality of coastal research, with biologists and geologists learning to see the maritime environment as an integrated whole. Nearly every seashore now has in progress at least one study designed to come up with the information so badly needed by managers.

Even when the manager is supplied with data, his troubles are not over; more and more, the patterns of natural change which emerge are at variance with political and economic interests. When a restless ocean rearranges a shoreline that cottage and motel owners expect to remain static, the National Park Service, which frequently has ownership of the beachfront such as at Cape Hatteras, finds itself quite literally trapped "between the devil and the deep blue sea."

TRADITIONAL MANAGEMENT APPROACHES

The basic geological and ecological research that has been done at the land-sea interface has often simply been ignored, or else it has not been applicable to management problems. Geologists have tended to think mainly about sand movement. Coastal botanists have been content just to list species; ecologists have usually been interested in the adaptations of biological systems to maritime influences such as salt spray, moving sand, and tidal flooding. Most studies have been so compartmentalized that the interrelationships of the total coastal ecosystem have been obscured. Much has been made of what the "natural ecology" of the shoreline, particularly barrier islands, is supposed to be. Many have assumed that maritime woodland represents this "natural ecology;" an island lacking such a woodland has been "damaged" and must be restored to its "original, pristine" condition by engineering works. Such an approach to "conservation" has actually led to projects that involve pumping sand out of estuaries and salt marshes for dune lines and beach fill. This leaves us with the ultimate absurdity of destroying an existing ""natural ecology" in order to restore a "natural ecology" that could not possibly survive under prevailing conditions and indeed may never have existed at all.

The main goal of a considerable part of past coastal research has been to find mechanical or biological ways to combat beach erosion. Vast sums have been spent on engineering studies, and on sea walls, dikes, man-made dunes, jetties, groins, beach fill, and even plastic bags full of sand, in the vain hope of holding down the retreating beaches. Most of these efforts were demanded by commercial interests trying to protect businesses, private landowners whose cottages were about to fall into the sea, and even by National Seashores in danger of losing visitor-use facilities and roads. There is a widespread myth that the barrier islands are in grave danger of disappearing unless something is done. The U.S. Army Corps of Engineers (1971) has just completed an erosion study of United States shorelines and has called for $1.8 billion to combat recession along 2700 miles of coast. Ironically, these projects often either make natural erosion worse or even start new erosion; ways must then be found to undo the damage.

Whether a stable dune line is built with sand fences and beach grass, or by dredges, bulldozers, and beach grass, the results are the same: a wall against the sea. The idea is to get that dune line up as high as possible, and not to allow any messy natural processes such as the wind blowing the sand around, the ocean overtopping dunes, or the beach continuing to retreat. In other words, total artificial control of the coastline is attempted. The trouble is, it doesn't work.

PRESENT RESEARCH

Soon after Cape Lookout National Seashore in North Carolina was authorized, the National Park Service instituted a research project designed to find ways to avoid some of the management problems experienced at nearby Cape Hatteras National Seashore. These two seashores are on the same barrier-island chain but are separated by Ocracoke Inlet (Fig. 1). The separation has given us an opportunity to compare a heavily developed seashore with one which has hardly been touched. The Cape Lookout islands have only a few fishing camps, while the Cape Hatteras area has paved roads, bridges, towns, visitors' facilities, and commercial operations, plus all the engineering works designed to protect such things.

Fig. 1. Apollo 9 photograph of North Carolina Outer Banks, showing Cape Lookout and Cape Hatteras National Seashores, taken from an altitude of 120 miles on 12 March 1969. The linear distance from the top of the photograph to Cape Lookout is about 150 miles (241 km). (Photo by NASA) (click on image for an enlargement in a new window)

Our ecological work at Cape Lookout began in 1968, and we will report here some of the ways in which we observed that barrier islands and their ecosystems seem to be adapted to the sea. We have tried to tie together some of the factors which influence the whole island system, from beach to estuary. As yet we have only scratched the surface, but we look forward to being able to fill some of the gaps.

A partial listing of other research projects underway on the Outer Banks follows. Dr. Robert Dolan of the University of Virginia is doing geological research at Cape Hatteras and Cape Lookout, and various projects are underway at other seashores. Recent geological studies on the Outer Banks led to dissertations for Dr. J. W. Pierce (1964) and Dr. J. J. Fisher (1967). Fisher also studied relic inlets on the Outer Banks for a Masters thesis (1962). Doctors Riggs and O'Connor of East Carolina University have been conducting geological and biological studies of the northern Outer Banks. Paul Hosier of Duke University is now completing a Ph.D. dissertation on the ecological effects of overwash at Cape Lookout National Seashore; his work expands some of our preliminary observations described here. Au (1969) described the vegetation of Shackleford Banks within Cape Lookout National Seashore. Scientists from North Carolina State University (Doctors A. W. Cooper, W. W. Woodhouse, E. Seneca, J. Langfelder) are working on various projects along the Outer Banks such as dune stabilization, the ecology of dune strand plants, stabilizing dredge spoil with marsh grass, rates of beach recession, and so forth.

GENERAL FEATURES OF THE COASTAL ENVIRONMENT

We will restrict our observations to the patterns we see on the Outer Banks, but these patterns repeat themselves, at least in general, all along the East Coast. Few environments are in such a state of flux as a coast line which is constantly being reworked by sea, wind, and water. Only a few remarkable terrestrial organisms can stand up to the rigors of salt spray, sea-water flooding, water stress, and moving sand. Where the ecological hazards are most severe, species diversity is very low; sometimes a whole community is dominated by one or two hardy vascular plants.

The controlling environmental force, of course, is the ocean; its storms and its changing level have combined over time to determine the seashore's primary characteristics. Hurricanes and winter northeasters can be expected to drive high water over the beach annually. The storms seem to come in cycles, with relatively calm periods followed by a great deal of storm activity. At least 149 hurricanes affected the North Carolina coast between 1585 and 1966 (Carney and Hardy 1967). Figure 2 shows the storm tracks of September hurricanes in the western Atlantic over a 60-year period (Cry 1965).

Fig. 2. (A) Hurricane tracks during the first 10 days of September (time of maximum storm activity) for a 62-year period. (B) Total annual frequency of North Atlantic tropical cyclones (1871-1963) and hurricanes (1886-1963). Note the general pattern of movement westward, then recurving north and northeastward up the U.S. East Coast. The Outer Banks are an area of storm concentration, almost a focal point. (From Cry 1965) (click on image for an enlargement in a new window)

All through the history of the earth the land-sea interface has been in a state of change. Our present shorelines are the result of the post-Pleistocene sea-level rise, which covered much of what was once land. Isostatic variations have been superimposed upon the general eustatic sea-level change, so that the apparent effect of the increasing amount of water in the sea varies along the coast depending on whether the local land is rising or subsiding. Although coastal geologists argue about the exact pattern of sea-level changes since the last Ice Age, most agree that the ocean level reached a low of about -130 m from its present position at the height of the Wisconsin glaciation, and has risen ever since. Evidence also shows that the sea rose faster prior to about 5000 or 6000 years ago than it is rising now (Fig. 3). Today, along the southeastern coast of the United States, this rise relative to the land surface has been about 25 cm per century. Recent estimates suggest a rise of 8 cm in the past decade (Hicks 1971). The rate also varies along the East Coast; in some places the sea level seems to be at a relative standstill. However, the worldwide trend of rising sea level has resulted in general erosion and retreat of shorelines (Hoyt 1967).

Fig. 3. Sea level curve for the past 35,000 years. showing a low stand about 15,000 years B.P., with a rapid rise until about 5000 years B.P. and a more gradual rise since then. (From Milliman and Emery 1968) (click on image for an enlargement in a new window)