Habitats

Sussex District supports a wide range of marine habitats, ranging from soft sediments to rocky reefs. Much of the research undertaken by the Sussex IFCA aims to develop our knowledge of habitats found throughout our district, and to effectively manage them. Below are examples of key habitats found within Sussex.

Chalk Reef Habitat

Chalk reefs support a wide range of characteristic species, some of which are only found in this type of habitat. Fauna which are characteristic of chalk reefs include bivalves, piddock, polychaete worms and sponges. The biotope dominated by piddocks is the most widespread of the biotopes occurring on chalk reef habitats, despite being scarce throughout Britain in general. The chalk reefs in the eastern English Channel represents around 75% of all reefs found throughout Europe.

Rocky Habitats

Hard rocky habitats in the Sussex area are largely colonised by Keelworms and Balanus barnacle speices, as well as a range of mobile fauna such as netted dogwhelk, crabs and lobsters. Rock surfaces that feature foliose algal cover may also exhibit a greater diversity of mobile fauna.

Mixed Sediment Habitat

The mixed sediment habitats consist of variable amounts of sand, gravel, and cobble, often mixed with shell gravel. Mixed sediment habitats are known to harbour a rich variety of animal and plant species, particularly in stable conditions. In particular, anemones (Aneminia viridis, Urticina feline and Cerianthus lloydii) and slipper limpets (Crepidula fornicata) are typical of mixed sediment habitats.

Sand Sediment Habitat

Sand sediment habitats are typically found in regions of moderate to strong tidal currents. Areas of mobile sand tend to be characterised by robust and sometimes impoverished fauna such as venerid bivalves, amphipods, polychaete worms and heart urchins. Sand banks may also occur which provides nursey grounds for young commercial fish species such as plaice, cod and sole.

Kelp

The Sussex coast once held an extensive kelp habitat, with three species being regularly observed: Laminaria hyperborea , Laminaria digitata and Saccharina latissima . Divers in the 1980’s recorded the presence of kelp as abundant or common from Selsey to Eastbourne in over 50% of their dive sites. However, since the 1980’s Sussex has experienced a 95% loss in its kelp habitat, with the reasons implicated including changes in fisheries practices, storm damage, eutrophication, and a reduction in water quality. The decline of this important habitat is likely to have caused a concomitant decline in associated species and ecosystem function.

Looking at the extent and condition of the historic kelp forest and taking evidence from peer reviewed articles which document the benefits that kelp can provide, it is considered that the restoration of the Sussex kelp would be beneficial for commercial fisheries specifically and for the marine environment more broadly. Kelp provides a range of benefits such as the capture of carbon dioxide and the production of oxygen. Kelp has also been proven to support biodiversity and to act as key nursey grounds for many marine species including bass, cuttlefish, and lobster. Research indicates that macroalgae are an ecosystem component critical to the delivery of a broad range of ecosystem services, and therefore this habitat should be given special attention when considering management. It is also considered that the restoration of kelp could provide socio-economic benefits, such as increased tourism and increased catches for fishers.

As a partner of the Sussex Kelp Recovery Project (SKRP), the Sussex IFCA has assisted with several kelp specific research projects. The partnership was created following the establishment of the Nearshore Trawling Byelaw, which protects around 300km² of nearshore habitat from the damaging effects of trawl fishing. Currently SKRP is involved in various surveying work, including eDNA analysis, baited remote underwater video (BRUV) surveys, analysis of sedimentation in the Distract and investigation of how this will affect kelp recovery, as well as a population genetics analysis in conjunction with ZSL.

Since 2019, the Sussex IFCA undertook towed underwater video surveys between the areas of Selsey and Shoreham-by-Sea, in areas where the Nearshore Trawling Byelaw would be later implemented in March 2021. The data from this research was used to understand the condition of kelp before any changes in management were made. Any future kelp surveys can be compared to this project to understand the effectiveness of the Nearshore Trawling Byelaw and allow us to determine whether further management is required.

References

James, J W C, Pearce, B, Coggan, R A, Arnott, S H L, Clark, R, Plim, J F, Pinnion, J, Barrio Frójan, C, Gardiner, J P, Morando, A, Baggaley, P A, Scott, G, Bigourdan, N. 2010.

The South Coast Regional Environmental Characterisation. British Geological Survey Open Report OR/09/51. 249 pp.

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Habitats

Chalk Reef Habitat

Rocky Habitats

Mixed Sediment Habitat

Sand Sediment Habitat

Kelp

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