SUSSEX MARINE SITES OF NATURE CONSERVATION IMPORTANCE

Site: The Bracklesham Balls (i)						Ref. No. 1i
Location: Bracklesham Bay: 1.5 km SW of end of Bracklesham Road					Other conservation designation?: Within proposed Solent SAC
Lat./Long. position of centre of site: 50° 44' 90" N  0° 52' 10" W			OS grid ref. of centre of site: SZ 798 949			Author: Robert Irving
Sea bed type: Boulder-sized concretions embedded in level, mixed sediment.			Depth range (below chart datum): 5-7 m			Date identified: November 1995

Summary

The 'Bracklesham Balls', as they are popularly known, are spherical and hemispherical boulders up to 1.5 m in diameter, which are located in two areas close to the shore within Bracklesham Bay in approximately 6 m depth. Several of the boulders appear to have had their tops 'sliced off', though others are intact and entirely spherical. Some have even been found joined in a manner resembling Siamese twins. Wood (1992) reports that Hume Wallace believes these to be concretions of the Myocardia Bed (consisting of fine shelly sand, sandstone nodules and many bivalve molluscs including Veniella (Myocardia) and resembling 'shells embedded in clay') standing proud of the sea bed. The balls provide a most unusual, though not unique, geological feature: similar boulders have been reported from Southampton Water (H. Wallace, pers. comm.).

Biological Description

The tops of the shallowest boulders may have occasional kelp plants Laminaria sp. growing on them, together with an assortment of red foliose algae (Calliblepharis ciliata and Griffithsia flusculosa being found frequently). In deeper water, growths of the hydroid Nemertesia antennina and of the leafy bryozoan Flustra foliacea may be present. The sides of the boulders are dominated by a hydroid-bryozoan turf (dominated by Bugula spp.) with occasional white anemones Actinothoe sphyrodeta, dead man's fingers Alcyonium digitatum and small patches of the grey colonial sea squirt Diplosoma listerianum. A rich encrusting sponge fauna has been recorded from the boulders, including the 'shredded carrot' sponge Esperiopsis fucorum, the 'goose bump' sponge Dysidea fragilis, Hymeniacedon perleve and Halichondria bowerbanki. Less common are the sponges Tethya aurantium, Suberites domuncula and Polymastia mamilaris. The boulders tend to have a covering of fine silt. There are signs of scouring around their bases.

The surrounding sea bed is of muddy sand, gravel and shells (mostly of slipper limpets Crepidula fornicata and oysters Ostrea edulis). Marine life here is relatively sparse, with occasional dahlia anemones Urticina felina, netted dogwhelks Hinia reticulata, sandmason worms Lanice conchilega, the finger bryozoan Alcyonidium diaphanum and juvenile gobies. Mobile marine life recorded from the locality includes bib Trisopterus luscus, bass Dicentrarchus labrax, plaice Pleuronectes platessa and small edible crab Cancer pagurus.

References: Irving, R. A. 1994. Report of the West Sussex Seasearch Project, 1992-1993: Chichester Harbour to Littlehampton Unpublished Report, Coldwaltham, West Sussex McDonald, K. 1985. Dive Sussex - A Diver Guide Underwater World Publications, London Wood, E.M. 1992. Coastal zone planning: information review and survey proposals for the sublittoral zone between Arun and Chichester A report for English Nature, West Sussex County Council, National Rivers Authority, Arun District Council and the Chichester Harbour Conservancy

Sussex SEASEARCH dive nos.: 93/52 & 79; 94/157

Site Location

Diagrammatic representation of site: The Bracklesham Balls (i)