Dynamics, threats and management of biogenic reefs

UNDER CONSTRUCTION

PROCESSES AND MECHANISMS DRIVING NATURAL DYNAMICS & ECOSYSTEM DEVELOPMENT

In this section, the processes and mechanisms driving natural dynamics and ecosystem development of biogenic reefs are discussed for each group in turn: Sabellaria spinulosa, Sabellaria alveolata, Mytilus spp. and Modiolus modiolus.

Sabellaria spinulosa

Environmental Requirements

S.spinulosa is thought to require stable foundations on which to settle and establish a tube (Jackson, 1977; Wood, 1999; Chisholm and Kelley, 2001) and is thus likely to favour substrata which include bedrock; boulders, cobbles, mixed substrata; and mixed sediment (Connor et al., 1997). Although it is assumed that a firm substratum is required for colony establishment, it has been suggested that a reef can increase in extent without the need for hard substratum (Holt et al., 1997). Many studies have reported extensive colonies in predominantly sandy areas (Warren & Sheldon 1967; Schäfer, 1972; Warren, 1973; Limpenny et al., 2010). Recent observations from The Wash, England show that S. spinulosa had ‘seeded’ on shell fragments predominantly from blue or horse mussels (Ian Reach, Natural England, pers. comm.).

As S. spinulosa is a sedentary species, it relies on wave and current action to supply food and wash away waste products (Kirtley, 1992). Strong water movement is required for food provisions, but is perhaps more important to raise sediment into suspension for tube building (Jones, 1999). As a result, S. spinulosa colonies are typically located in areas of weak to moderately strong water flow (Jones et al., 2000). It also appears to favour locations around the edges of sand banks or areas with sand waves (Foster‐Smith, 2001a). S. spinulosa typically occurs subtidally in depths of a few meters to up to 40 m depth (Caspers, 1950; George & Warwick, 1985; Connor et al., 1997; Jessop & Stoutt, 2006), but can occur in depths up to 600 m (Hartmann-Schröder, 1971). S. spinulosa occasionally occurs in the lower intertidal zone (Jessop & Stoutt, 2006).

Reproduction and Development

Sabellaria alveolata

Environmental Requirements

Reproduction and Development

Mytilus spp.

Environmental Requirements

Reproduction and Development

Modiolus modiolus

Environmental Requirements

Reproduction and Development

VULNERABILITY & THREATS

GENERAL SUMMARY

Sabellaria spinulosa

Sabellaria alveolata

Modiolus modiolus

Mytilus spp.

NATURAL AND ANTHROPOGENIC THREAT

Sabellaria spinulosa

Physical threats

Chemical threats

Biological threats

Sabellaria alveolata

Physical threats

Chemical threats

Biological threats

Mytilus spp.

Physical threats

Chemical threats

Biological threats

Modiolus modiolus

Physical threats

Chemical threats

Biological threats

KEY PROCESSES TO FOCUS ON FOR MAINTAINING ECOSYSTEMS INTEGRITY

CURRENT MANAGEMENT PRACTICES

Sabellaria spinulosa

Sabellaria alveolata

Mytilus spp.

Modiolus modiolus

SEE ALSO

Theseus Official Deliverable 3.3-Natural habitats for coastal protection and relevant multi-stressor coastal risks. Report and European Scale overview.

REFERENCES

The main authors of this article are Firth, Louise, Davies, Andrew, Hawkins, Stephan, Airoldi, Laura and Colangelo, Marina Antonia Please note that others may also have edited the contents of this article. For other articles by this author see Category:Articles by Firth, Louise