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Thames Estuary and Marshes Conservation Objectives

The conservation objectives for the site are detailed in the Regulation 33 advice for the Thames Estuary and Marshes Marine Site 2001. The conservation objectives for the nationally and internationally important populations of the regularly occurring migratory species are:

Subject to natural change, maintain in favourable condition the habitats for the internationally important population of the regularly occurring Annex 1 bird species, under the Birds Directive, in particular:

  • Saltmarsh;
  • Intertidal Mudflats; and
  • Intertidal shingle.

And;

Subject to natural change, maintain in favourable condition the habitats for the internationally important assemblage of waterfowl, under the Birds Directive, in particular:

  • Saltmarsh;
  • Intertidal Mudflats; and
  • Intertidal shingle.

Numbers of bird species using these habitats within the Benfleet and Southend Marshes SPA are shown below (average peak counts for the five year period 1986/87 to 1990/91).

Internationally important populations of regularly occurring Annex 1 species

Species

Population (5yr Peak mean)

Avocet

283 birds (28.3% Great Britain)

Internationally important populations of regularly occurring migratory species

Species

Population (5yr Peak mean)

Ringed Plover

1,324 birds (2.6% Europe/North Africa)

Grey Plover

2,593 birds (1.7% Eastern Atlantic)

Dunlin

29,646 birds (2.1% Northern Siberia;/Europe/West Africa)

Knot

4,848 birds (1.4% North West Europe)

Black-tailed Godwit

1,699 birds (2.4% Iceland)

Redshank

3,251 birds (2.2% Eastern Atlantic)

An internationally important assemblage of waterfowl

Importance

Population (5yr Peak mean)

Thames Estuary supports large populations of wintering waterfowl

75,019 individual birds

Nationally important bird populations within internationally important assemblages of waterfowl

Species

Shelduck (Tadorna tadorna), Teal (Anas crecca) and Pintail (Anas acuta).

The Regulation 33 advice provides favourable condition tables for the Thames Estuary and Marshes European Marine Sites.  The relevant favourable condition targets for the Thames Estuary and Marshes SPA are presented below.

Favourable Condition Table for the Thames Estuary European Marine Site

Feature

Sub-Feature

Attribute

Measure

Target

Comments

Internationally important populations of regularly occurring Annex 1 bird species (Avocet)

All sub-features

Disturbance in feeding and roosting areas

Reduction or displacement of wintering birds, measured periodically (frequency to be determined).

No significant reduction in numbers or displacement of wintering birds attributable to disturbance, subject to natural change.

Significant disturbance attributable to human activities can result in reduced food intake and/or increased energy expenditure. Five year peak mean information on populations will be used as the basis for assessing whether disturbance is damaging.

Absence of obstructions to view lines

Openness of terrain unrestricted by obstructions, measured periodically (frequency to be determined).

No increase in obstructions to existing bird view lines, subject to natural change.

Avocet ideally require unrestricted views >200 m to allow early detection of predators when feeding and roosting.

Intertidal mudflats

Extent and distribution of habitat

Area (ha) measured once per reporting cycle.

No decrease in extent form an established baseline (established during first reporting cycle), subject to natural change.

Intertidal sediment and their communities provide both habitat and feeding area for the Annex 1 bird populations.

Food availability

Diversity and abundance of fish and intertidal invertebrates including e.g. Gammarus, Corophium, flies, beetles, Nereis, Hydrobia, Cardium, gobies. Measured periodically. Frequency to be determined

Diversity and abundance of prey species should not deviate significantly from the established baseline (established during first reporting cycle), subject to natural change.

Marine insects, crustaceans, mollusc

Internationally important populations of regularly occurring Annex 1 bird species (Avocet)

Saltmarsh

Extent and distribution of habitat

Area (ha) measured once per reporting cycle.

No decrease in extent from an established baseline (established during first reporting cycle), subject to natural change.

Saltmarsh provides roosting areas, and shallow water within saltings may be used for feeding.

Vegetation characters

Open, short vegetation or bare ground predominating (roosting), measured periodically (frequency to be determined).

Vegetation height throughout areas used for roosting should not deviate significantly from an established baseline (established during first reporting cycle), subject to natural change.

Vegetation of <10 cm is required throughout areas used by roosting avocet.

Internationally important assemblage including internationally and nationally important populations of migratory species

All sub-features

Disturbance in feeding and roosting areas

Reduction or displacement of wintering birds, measure periodically(frequency to be determined)

No significant reduction in numbers or displacement of wintering birds attributable to disturbance, subject to natural change.

Significant disturbance attributable to human activities can result in reduced food intake and/or increased energy expenditure. Five year peak mean information on populations will be used as the basis for assessing whether disturbance is damaging.

Absence of obstructions to view lines

Openness of terrain unrestricted by obstructions, measured periodically (frequency to be determined

No increase in obstructions to existing bird view lines, subject to natural change

Some waders require unrestricted views >200 m to allow early detection of predators when feeding and roosting.

Internationally important assemblage including internationally and nationally important populations of migratory species

Intertidal mudflats

Extent and distribution of habitat

Area (ha) measured once per reporting cycle

No decrease in extent form an established baseline (established during first reporting cycle), subject to natural change.

Intertidal mudflats and their communities provide both roosting and feeding areas for the migratory species of birds.

Food availability

Diversity and abundance of intertidal invertebrates. Measured periodically (frequency to be determined)

Diversity and abundance of prey species should not deviate significantly from the established baseline (established during first reporting cycle), subject to natural change.

Marine insects, crustaceans, molluscs and worms are important food sources for the migratory species of birds: Gammarus and Posidium for ringed plover. Nereis, Arinicola and Notomastus for grey plover. Nereis, Macoma, Hydrobia, Crangon and Carcinus for dunlin. Macoma, Mytilus/Cerastoderma spat and Hydrobia for knot. Macoma, Cardium and Nereis for black-tailed godwit. Hydrobia, Macoma, Corophium and Hydrobia for shelduck. Hydrobia for teal and pintail.

Saltmarsh

Extent and distribution of habitat

Area (ha) measured once per reporting cycle

No decrease in extent form an established baseline (established during first reporting cycle), subject to natural change.

Water fowl feed and roost within the saltmarsh areas of the Thames Estuary European marine site.

Internationally important assemblage including internationally and nationally important populations of migratory species

Saltmarsh

Food availability

Presence and abundance of soft leaved and seed bearing plants. Measured periodically (frequency to be determined.

Presence and abundance of food species should not deviate from an established baseline (established during first reporting cycle), subject to natural change.

Salicornia and Atriplex are important for teal.

Vegetation characteristics

Open, short vegetation or bare ground predominating (roosting), measured periodically (frequency to be determined).

Vegetation height throughout areas used for roosting should not deviate significantly from an established baseline (established during first reporting cycle), subject to natural change.

Vegetation of <10 cm is required throughout areas used by roosting waders.

Intertidal shingle/ cobble beach

Extent and distribution of habitat

Area (ha) measured once per reporting cycle

No decrease in extent form an established baseline (established during first reporting cycle), subject to natural change.

Areas of intertidal shingle/cobble beach provide high tide roots for the migratory species of waterfowl which use the Thames Estuary European marine site.

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