Shingle Beaches Research Articles

The Restoration of Coastal Shingle Vegetation: Effects of Substrate Composition on the Establishment of Seedlings

1. Shingle beach vegetation at Sizewell, Suffolk, UK, was extensively damaged by the construction Qf a power station. We investigated the feasibility of restoring the vegetation by directly sowing seeds of species important in the existing plant communities, in field and glasshouse experiments. The species sown were: Crambe maritima, Eryngium maritimum, Glaucium flavum, Lathyrus japonicus and Rumex crispus. 2. The field experiment examined the effects of proximity to the sea, composition of the beach substrate, and its amendment with organic matter on seedling emergence and establishment. There was little emergence of seedlings during the first season and most occurred in the following spring, between February and April; G. flavum emergence was nearly confined to this period. A low percentage of the viable seeds of all five species had emerged even after two seasons. Greatest emergence was in the monocarpic G. flavum, whereas the relatively long-lived perennials showed lower emergence and slower growth. Only G. flavum produced reproductive plants, in the second year. 3. Seedling emergence was greater in organic matter treated plots for all species and most emerged better from sandy plots than shingle dominated plots. Although G. flavum emergence was greater in sandy plots, seedling survivorship and growth were much greater in shingle plots; mortality showed evidence of density dependence. 4. A glasshouse experiment examined the effects of sowing density and substrate texture on the survival of G. flarum. On shingle, survival was negatively density-dependent, but the much lower survival on sand was density-independent. Consequently, the higher mortality on sandy field plots was probably directly associated with substrate effects. 5. Direct sowing of seeds on the beach cannot be recommended as a general technique for the restoration of shingle beach vegetation, except for annual or monocarpic species. Amendment with organic matter provided little benefit that could not have been achieved more simply by the addition of beach sand to the coarsest shingle substrates.

Germination Characteristics of Shingle Beach Species, Effects of Seed Ageing and their Implications for Vegetation Restoration

1. Restoration of coastal-shingle vegetation at Sizewell, Suffolk, UK, after construction of a power station, was underpinned by an investigation into the germination ecology of six key species: Crambe maritima, Eryngium maritimum, Glaucium flavum, Honckenya peploides, Lathyrus japonicus and Rumex crispus. The use of indigenous seed, collected from the site before the 6-year construction project, necessitated long-term storage. The effects of seed ageing on viability and germination responses to temperature, light and salinity were examined to determine how any reduction in germination might be mitigated. 2. Innate seed dormancy was important in all species, except R. crispus. C. maritima and L. japonicus showed hard-seed dormancy. Stratification of E. maritimum, G. flavum and H. peploides effectively softened the pericarp or testa, and satisfied their varying requirements for low temperature to overcome physiological dormancy. 3. All species germinated well in diurnally alternating temperature regimes. Germination of H. peploides was promoted by light, but the other species were insensitive to light. Increasing salinity progressively reduced germination rate relative to that in distilled water, and sea water at concentrations of 50% or more completely inhibited germination. 4. Seed storage at low temperature and humidity for 7 years did not affect innate dormancy, except in H. peploides, where the requirement for stratification was lost. Storage reduced germination rate in all species, except R. crispus. Ageing resulted in considerably less germination at higher temperatures in some species. Salinity-enforced dormancy was significantly greater in aged seed for four of the species. The promotion of germination by light in H. peploides disappeared with age. These changes represented a narrowing of the environmental conditions that allow germination, even when viability only declined slightly. 5. Innate dormancy among shingle species and the use of stored seed, with high viability, but stringent germination requirements, are likely to result in poor and erratic germination. The use of appropriate pretreatments to overcome dormancy and optimal conditions for germination should allow the efficient use of seed for plant production in restoration projects.

Behaviour of an artificially replenished shingle beach at Hayling Island, UK

Abstract Many coastal areas throughout the world are suffering from erosion, so numerous attempts are made, by constructing various forms of sea defences, to stabilize a retreating beach or reduce its rate of erosion. In recent years, artificial beach replenishment has become an established method in helping to restore a deteriorating beach. However, there has been a relative lack of information regarding the post-replenishment behaviour of many artificially renourished beaches. Results of a study of a replenished beach at Hayling Island suggest that the apparent depositional and erosional trends measured along a typical beach profile can be due to the longshore movement of a single, trapezium-shaped, mass of shingle, at a constant rate, rather than variations in the longshore transport rate.

Recent shingle beach renourishment schemes in the UK: Some preliminary observations

Experience gained during shingle beach replenishment from offshore sources is described. Schemes undertaken along the Southern coastline of England reveal that the presence of fine-grained material in the sediments can lead to the formation of a more compact beach which has a lower permeability. This (generally) leads to the formation of a hard vertical face around high water mark as opposed to a mobile beach crest. Such features could reduce the sea defence and amenity values of beach replenishment schemes.

REBUILDING OF SEA DEFENCES, CENTRAL PARADE, HERNE BAY, KENT.

This paper reviews the investigation, the design and the construction of the new sea defences fronting the central area of Herne Bay on the North Kent coast. The existing defences consisted of a small shingle beach backed by a concrete wall. The paper describes the coastal morphology, computer and physical modelling and the design work carried out. It also sets out the reasons for the selection of a sea defence scheme comprising a linked offshore breakwater with a larger shingle beach. The paper reviews the importance of public consultation and the role that this played in the final form of the design proposal; finally it gives a brief description of the construction work. (A)

Genecological studies of groundsel (Senecio vulgaris L.). IV. Rate of development in plants from different habitat types

SUMMARYIn order to test the hypothesis that precocious variants might be at a selective advantage in well‐weeded sites, ripen pollinated achenes of Senecio vulgaris L. were collected in eastern Britain from three populations representative of each of live habitat types (botanic gardens, field margins, inland and coastal sandy areas and shingle beaches) Some subject to weeding and cithers not. Progenies of a number of seed‐parents (families) were grown in a garden trial, and life‐history and reproductive characteristics were recorded, in particular the rate of development from sowing, with synchronous germination, to first fruiting. Populations from botanic gardens were characterized by families exhibiting precocious reproduction, a finding which supports oru initial hypothesis. However, a degree of variation was detected in samples from all three botanic gardens ‐ Orford, Kew and Cambridge ‐ confirming the results of an earlier study of groundsel in the University Botanic Garden, Cambridge. In contrast, samples from maritime shingle beaches had a slower rate of development. There was no evidence of population variation, suggesting that genetic drift or founder effects might be important or that there may be selection for a narrow range of phenotypes, in such areas. Furthermore, at Shingle Street, Suffolk, there was evidence of sharp local differentation between plants from the single beach and from an arable field margin, 50m away, located behind sea defence. The characteristics of plants from other habitat types are discussed in relation to the apparent selection pressures imposed by different land use. Our results provide evidence of trade‐offs in life‐history evolution, e.g. the precocious variants were comparatively dwarf at first fruiting and shorter‐lived.

Beach Cleaning Trials: Newhaven 1989

ABSTRACT The aims of the work described here were to develop the most cost effective ways for mechanical removal of stranded oil from shingle beaches and to establish a basic set of procedures for responding to any future emergency. Previously, such a coherent response had been limited to firm sand. The experimental work was carried out at Tide Mills Beach, New-haven, England during February 1989. It comprised 28 experiments which involved flexible trackway, vehicle mobility testing, removal of oil emulsion by both scooping and scraping, beach material washing, demulsification, and aerial surveillance. Selective scooping with a large excavator bucket was the quickest and most economical removal method, achieving in excess of 0.25 cubic meters per minute. The beach material washing plant achieved efficiencies up to 99.9 percent and rates in excess of 30 metric tons per hour. A standard cleaning cycle has been specified which allows cleaned shingle to be returned to the beach.

Shingle-based wetlands at Dungeness

WATERS, S. J. P. & FERRY, B. W., 1989. Shingle-based wetlands at Dungeness. At Dungeness, a unique development of open water and natural wetland has occurred on the shingle beaches. Over 700–1000 years, low-lying areas have changed from saline lagoons into freshwater lakes which are now largely infilled by reedswamp and sallow carr. Since about 1970, the water-table has been lowered, by a combination of water abstraction and hydrological changes associated with gravel extraction. Water-table lowering has accelerated colonization by reedswamp and sallow carr, and has caused loss of sedge-rich marshland. Possible methods are suggested for promoting development of such marshland in artificial excavations.

Preface: Dungeness: the ecology of a shingle beach

Preface: Dungeness: the ecology of a shingle beach

The Seaford Sea Defence Scheme

ABSTRACTDuring THE LaST 100 years the shingle beach levels at Seaford have gradually declined, with the result that the 10‐m high sea wall, protecting low‐lying areas of the town against flooding, came under serious threat of collapse.Southern Water Authority assumed responsibility for the frontage in 1981, and the paper briefly describes the history of events leading into the problem, model studies, and the solution which was adopted. Details of behaviour of the beach during the months following completion, including the great storm of October 1987, are also given.

CHARACTERISTICS OF SHINGLE BEACHES WITH REFERENCE TO CHRISTCHURCH BAY, S. ENGLAND

The rapid recession of the shingle bank of Hurst Beach (up to 3.5m/yr) makes it an excellent natural laboratory for the study of the factors which influence the stability of shingle beaches. Studies have included: the significance of long period, high energy, swell waves - the classification and quantification of overwash processes - run-up and seepage characteristics - the effect of settlement of the underlying strata - and the implications for practices in shingle nourishment. The studies have revealed the distinctive character of shingle beaches as compared with the more fully researched sand beaches. More detailed research on shingle beaches is justified particularly in relation to (i) the run-up characteristics including its interaction with swash cusps and (ii) the influence of the subsidiary sand fraction on the beach characteristics.

THE DYNAMIC RESPONSE OF SHINGLE BEACHES TO RANDOM WAVES

An extensive laboratory investigation into the behaviour of shingle beaches has been undertaken using a large random wave flume. The study utilised a lightweight material scaled to reproduce the correct permeability of the beach, and the correct threshold and relative magnitude of the onshore/offshore movement. Results are presented describing both the wave reflection characteristics of the beach and the probabilistic distribution of wave run-up crests on the foreshore. Where possible the laboratory results are validated against field data.

Coastline changes and land management in East Sussex, Southern England

The stability of the shingle beaches at Eastbourne and Hastings is a prerequisite for the continued use of adjacent lowlying areas, and for the success of planned urban development schemes, which include the £200 million Eastbourne Harbour Village, Eastbourne Park and recreational facilities in the Combe Haven valley near Hastings. In the short term, beach monitoring data are at best ambiguous regarding stability, at worst they indicate falling beach volumes, especially at Eastbourne. However, over longer time scales, covering hundreds to thousands of years, there is unequivocal evidence for massive beach volume changes, radical alterations to the position of the shoreline; and, of great significance to land management, it is clear that the present shingle beaches represent an unusual coastal form of inherent instability. The atypical nature of the shingle beaches at Eastbourne and Hastings is confirmed by their absence before 800 bp. Furthermore, there is clear evidence for a substantial loss of sediment from the beaches over the last 300 years as a result of natural depletion of the shingle supply. Therefore, the viability of development projects at Eastbourne and Hastings relies on an understanding of shingle beach dynamics allied to a policy of detailed beach monitoring. The relationship between the development projects at Eastbourne and Hastings and the maintenance of the shingle is critical. Such policies are given greater urgency by the prediction of accelerated sealevel rise over the next century.

The Orford Shingles, Suffolk, UK—Classic conflicts in coastline management

The Orford Shingles consist of physiographically important, dynamic patterns of apposition shingle beaches, shingle spits and saltmarshes. The flora and fauna have many rare and local species, in communities that are unique to the unusual, vegetated, shingle habitat. The natural features of the system suffer from unsympathetic management as an integral part of regional coastal protection. Wide-ranging military uses have also degraded some areas. Development, gravel extraction and public pressure have damaged others. Yet the Orford Shingles form an internationally important Site of Special Scientific Interest, managed, in parts, by conservation bodies. This study examines aspects of the history and ecology of the area, in the context of these conflicting uses. In particular, it describes the natural processes of plant colonisation and succession on the beaches and illustrates how they are modified by man's activities. It shows how many such activities have been unnecessarily damaging, for example, when different government departments have conflicting management objectives. It concludes that a co-ordinated approach to coastline management can help achieve development and management objectives with minimum environmental impacts, reduced costs, maximum life expectancy for features under protection and improved safety to man and environment.

Vegetation Establishment on Shingle Beaches

Vegetation Establishment on Shingle Beaches

Plant Communities of the Shetland Islands

(1) The Shetland Islands lie between Scotland and Norway and this study describes the vegetation types found there with reference to both British/Continental and Scandinavian communities. (2) A conspectus of the main plant communities was obtained by recording vegetation plots from fifteen of the islands, from shingle beaches, sand-dunes, salt-marshes, wet meadows, grasslands, blanket peat and heaths. (3) Sixty-five noda were identified and their general characteristics described. These noda were assigned to both recognized and new taxa within seventeen phytosociological classes. (4) A new association of grazed low altitude blanket bogs, the EmpetrumRhytidiadelphus loreus Association is outlined. (5) The factors influencing plant and vegetation distribution in Shetland are discussed; geographical position and physical isolation from seed sources provide the historical basis. (6) While climatic and topographic interaction on the flora have determined the natural vegetation communities, the impact of land-use, particularly grazing, has been to confine these communities to areas inaccessible to sheep. The majority of Shetland's vegetation composition has been determined by grazing. (7) The absence of comparative taxonomic studies, the Islands' geographical position and climate, the influence of salt-spray and intensive land-use produce a merging of community boundaries and difficulties in delimiting discrete associations.

The coastal topography of the Moray Firth

SynopsisThe geology, glaciation, deglaciation and sea level history are summarised in relation to the evolution of the coastline. Deglaciation and sea level are established as particularly important factors responsible for the distribution of sand and shingle beach forelands. Forelands in the middle coastline of the southern shore of the firth are currently undergoing relatively severe coastal erosion. It is argued that this results from a diminution of nearshore sediment supplies combined with a unidirectional longshore movement of material along the beach face.

Coastal alluvial fans (fan deltas) of the Gulf of Aqaba (Gulf of Eilat), Red Sea

Coastal sediments of the Gulf of Aqaba are dominated by alluvial fans that prograde directly into the sea. The fans can be subdivided into four types: (1) largely inactive alluvial fans that merge into a braided fluvial system and pass seaward into sabkha flats, lagoons, mangroves and fringing reefs; (2) large alluvial fans that pass directly into the sea with one major entrenched channel and a fringing reef with a large incised canyon; both of these were formed during the Pleistocene, present fluvial activity is confined to the entrenched channels; (3) medium-sized (1–2 km long, 3–4 km wide) moderate to highly active alluvial fans with fringing reefs and backreef lagoons; and (4) small short-headed wadis that empty directly into the sea. The scale, overall sediment body geometry and facies associations of type (3) coastal alluvial fans (fan deltas) provide a close and useful modern analogue for many ancient fan-delta sedimentary sequences. On subaerial parts of the fan, disorganised cobbles and boulders, at the apex, deposited by debris flows pass downslope into longitudinal bars deposited during the high flood stage of periodic flash-flood events. The bars extend over the entire fan surface becoming progressively smaller and finer grained down fan. In general, the fans are characterised by a low proportion of floodplain deposits and extensive modification by aeolian processes, producing widespread gravel pavements and small dune fields over inactive areas of the lower fan. In the marine environment the fans are modified by a combination of wave action and longshore drift. Sand beaches are characterised by low-angle seaward-dipping lamination. On shingle beaches all gravel clasts have a strong preferred seaward dipping orientation. In areas where the fringing reefs are situated offshore from the fan, mixed quartz-bioclastic sand-filled lagoons develop. The nearshore lagoon areas are characterised by large sand bars orientated parallel to the shore. These pass seawards into the reef flat. Where the fringing reef lies adjacent to the foreshore, fluvial activity erodes and emphasises irregularities in the reef and redeposits coarse gravel onto and through the reef. Much of the coarse material is incorporated into the framework. Initial stabilisation is by a variety of encrusting organisms, mainly coralline algae. This organic cementation is followed by later recolonisation by corals.

Geology of Aves Island (Venezuela) and subsidence of Aves Ridge, Caribbean Sea

Aves Island, the only outcrop of Aves Ridge above sea level, is a calcareous sand island on a beach-rock platform surrounded by a fringing reef. The highest part (3.72 m a.s.l.) consists of a storm terrace. A comparison of geological maps of the island in 1968 and 1983, revealed the following changes: (1) the southern storm terrace, a prominent feature in 1968, has disappeared; (2) the northern storm terrace has been reduced in area; (3) beach rock crops out more extensively in 1983; (4) removal of beach sand in the northeastern part of the island has exposed probably older, weathered beach rock; and (5) shingle beaches, reported in 1957, absent in 1968, were again present in 1983; they may be a relict feature underneath the beach sand. These changes are attributed to erosion by hurricanes and storms; during the interval between hurricanes, normal beach and shore processes act on the island. Present-day sedimentary and erosional instability may also be in part due to extensive guano mining during the 19th century. A seismic survey of Aves Island platform has revealed two sedimentary units overlying the acoustic basement. These two units are interpreted as unconsolidated, water-saturated sand (Surficial Unit), and slightly compacted to compacted sediments (Middle Unit). The acoustic basement probably consists of consolidated sedimentary rocks. On the basis of dredged rocks, the rate of subsidence of Aves Ridge can be estimated as 3.8 or 6.0 × 10 −5 m yr −1. This rate is insufficient to explain historical changes in size and sedimentary distribution of Aves Island and platform. Using these rates, the acoustic basement cropped out above sea level 1.1–1.7 Ma ago; the last outcrop of this basement during an interglacial sea-level stand must have been between 0.25 and 0.40 Ma ago.

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