Inlet and Estuary - Gower - page 184

better, even though it breaks down more slowly than straw. Two striking and rather uncommon saltmarsh
plants are locally abundant in the highest grazed marsh, marsh mallow Althaea officianalis , which has
attractive pink flowers in July (Fig. 103), and sea wormwood Serphidium maritima with its aromatic pin-
nately divided leaves. This plant community, avoided by grazing animals, is a distinctive feature of the
area. Much of this upper salt marsh is now managed as part of the Tir Cymen agri-environment scheme
runbytheCountrysideCouncilforWales,thelocalfarmershavingenteredinto10-yearagreementsbased
on continuing current farming practices.
FIG 103. Marsh mallow, an uncommon saltmarsh plant, which is abundant on the marshes. (David Painter)
Further upstream the limit of salt water is characterised by extensive areas of brackish swamp domin-
ated by common reed and sea club-rush Bolboschoenus maritimus , and at Llangennech this merges into
reedmarsh and invading willow scrub, with abundant common club-rush Schoenoplectus lacustris . Di-
verse upper marsh swamps with tall stands of yellow iris Iris pseudacorus are present especially at the
western end of the inlet in and around Cwm Ivy Marsh, which is of particular interest as a lowland fen
meadow.
MARINE AND TERRESTRIAL INVERTEBRATES
The marine invertebrate community appears to be typical of saline, muddy sand environments. In areas
of fine sand cockles are abundant along with lugworm, amphipods and worms. In muddier sediments the
sand-gaper Mya arenaria , peppery furrow-snail Scrobicularia plana and mud-snail Hydrobia ulvae are
foundinextremelylargenumbersalongsidethepolychaeteworms Spio filicornis and Spiophanes bombyx
and the common ragworm Nereis diversicolor . Predators in the community include the snail Retusa ob-
tuse , which feeds on mud-snails, the polychaete Eteone longa , which eats other polychaete worms, and
general crustacean scavengers such as the common shore crab and the brown shrimp Crangon crangon .