SUSSEX MARINE SITES OF NATURE CONSERVATION IMPORTANCE

Site: 'Outer' Mulberry Harbour unit						Ref. No. 4
Location: 4 km SE of Pagham village					Other conservation designation?: Just outside proposed Solent SAC boundary
Lat./Long. position of centre of site: 50° 4' 6"   0° 0' 0"			OS grid ref. of centre of site: SZ 915 949			Author: Robert Irving
Sea bed type: Wreckage of concrete and rusted steel. Surrounding sea bed of pebbles, gravel & silty sand.			Depth range (below chart datum): 4-11 m			Date identified: November 1995

Summary

The 'Outer' Mulberry Harbour unit (sometimes referred to as the 'Far' Mulberry) is the most popular wreck dive site in the Pagham box area, if not off the West Sussex coast. It was one of 80 'caissons' temporarily parked off the Selsey-Bognor coast in the early summer of 1944, but broke its back when being raised from the sea bed. It now lies in relatively shallow water, providing a hard and stable substratum as an artificial reef, which rises above the surrounding flat sea bed of gravel, sand, shells and pebbles. The wreck provides a variety of inclined surfaces well as sheltered and exposed locations. Surveys of the wreck were undertaken by members of the Marine Conservation Society and the Nautical Archaeological Society in 1995 & 1996.

Biological Description

The wreckage consists of concrete slabs and rusting steel rods. It remains partially intact, with horizontal, vertical and overhanging surfaces being present. The uppermost kelp-covered surfaces of the main (highest) part of the wreck may be visible from the surface at low tide. All three species of kelp (Laminaria digitata, L. hyperborea and L. saccharina) are present, with foliose red algae dominating horizontal, unshaded surfaces. Brown algae (including Halidrys siliqua) and some green algae (e.g. Ulva lactuca) also occur. Vertical and shaded surfaces are usually heavily colonised (~70-80% cover) by a low faunal turf of hydroids and bryozoans. Occasional discrete sponges, such as Dysidea fragilis and Esperiopsis fucorum, and the white anemone Actinothoe sphyrodeta are present in amongst the turf. There is less cover on some of the inward-facing walls, which are silty and virtually bare, though certain organisms such as the sponge Polymastia boletiforme, are found here. The overhanging wall at the northern end is dominated by plumose anemones Metridium senile (absent from naturally-occurring hard substrata in the vicinity), together with dead man's fingers Alcyonium digitatum. In 1983, the jewel anemone Corynactis viridis was recorded as being on this wall, though there was no sign of it in 1993. Devonshire cup corals Caryophyllia smithii make a rare appearance here too.

McDonald (1985) reports this wreck as being one of the best sites along the Sussex coast for those who want to see fish. Large shoals of bib Trisopterus luscus, numbering several hundred individuals, gather in amongst the superstructure, while pollack Pollachius pollachius and bass Dicentrarchus labrax hover above it. Other commonly seen fish include tompot blennies Parablennius gattorugine, goldsinny wrasse Ctenolabrus rupestris, two-spotted gobies Gobiusculus flavescens and butterfish Pholis gunnellus.

References: 1994. Diver magazine June 1994, 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, C. (ed) 1984. Sussex Sublittoral Survey: Selsey Bill to Beachy Head Marine Conservation Society, SE Branch

Sussex SEASEARCH dive nos.: 93/31, 32a&b, 33; 94/122

Sussex Sublittoral Survey site no.: 6

Site Location

Diagrammatic representation of site: 'Outer' Mulberry Harbour unit