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H1160 - Large shallow inlets and bays

General

Description habitat

General occurrence

The current Oosterschelde is the only example of this habitat type in The Netherlands. This area has lost most of its original character after the construction of dams, both inland as well as seaward. After construction of the Hellegatsdam near Willemstad, the influence of the river diminished. After completion of the storm surge barrier, the Oosterschelde was partly cut off from the sea. This showpiece of the Deltaworks resulted in lower flow velocities and less tidal influence. It thus deeply affected the geomorphology of the Oosterschelde. The area has developed from an estuary with plates and trenches into a less differentiated shallow bay #1.

Environmental boundary conditions

This habitat type includes large indentations (creeks and bays) of the coast where, in contrast to estuaries, the influence of freshwater is generally limited. These shallow indentations are generally sheltered from wave action and contain a great diversity of sediments and substrates with a well-developed zonation of benthic communities. Several physiographic types may be included under this category providing the water is shallow over a major part of the area: Eelgrass (Zostera marina and Zostera noltii) or Ruppia (Ruppia cirrhosa and_Ruppia maritima_). Just as habitat type H1130 - Estuaries, this habitat type is defined on landscape scale and it includes only the aquatic habitats. The adjoining salt marshes are described in the individual habitat types (H1320 - Spartina swards, H1320 - Spartina swards and H1330 - Atlantic salt meadows) and are not included in 'creeks and bays'. #1.

Control and growth opportunities

This habitat type is mainly sensitive to changes in velocity and flooding frequency. Mechanical damage makes this habitat unsuitable for eelgrass species #1.

Dose-effect relations

Large shallow inlets and bays are landscape elements that are difficult to capture with habitat factors. However, the occurrence of eelgrass can be predicted with the aid of habitat factors. Therefore, it has been included as an extra dose-effect relation.

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Flowchart

Dose-effect relations

influence	HSI
no fresh water	1
not much fresh water	0.5
much fresh water	0

Reference: #1

Occurrence characteristic species

Common eelgrass and Dwarf eelgrass are a main food source for many organisms. The occurrence of eelgrass is thus beneficial for this habitat type. Therefore, Common eelgrass and Dwarf eelgrass are included as an additional dose-effect relation. You can find the dose-effect relations of both types of eelgrass on macrophyte pages (Common eelgrass - Zostera marina and Dwarf eelgrass - Zostera noltii) only available in Dutch.

Common eelgrass or dwarf eelgrass(HSI)	HSI
0	0
1.0	1.0

Reference: #2

Uncertainty and validation

These dose-effect relations have not been validated.

Applicability

To describe a landscape element according to habitat factors is very difficult. Therefore, it is more informative to determine if an area that is classified as large shallow inlets and bays is suitable for, for instance, eelgrass. This will give an indication of the quality of the area, as eelgrass is a main food source for many fish, birds, mammals and it provides shelter for fish. The occurrence of eelgrass is thus beneficial for the habitat.

Example project

At present, there is no example project available.

References

1 http://www.minlnv.nl/natura2000
2 Haasnoot, M. en K.E. van de Wolfshaar (ed). Habitat analyse in het kader van de Planstudie/MER voor Krammer, Volkerak en Zoommeer. WL report Q4015. 2006