Environmental Engineering Reference
In-Depth Information
The lower part of the estuary is one of the few places in Britain where the polychaete worm Ophelia bi-
cornis is found. On the whole, however, there is a lack of knowledge about the marine invertebrate com-
munities, which will have to be addressed if serious decisions about the conservation of the area need
to be taken. We probably know, to the nearest 10 individuals, how many oystercatchers there are in and
around the Burry at any one time, but almost nothing is known about the vast majority of the invertebrate
species the birds depend on, or their abundance. Nearly all the research to date has been a by-product of
studies concerned with cockles.
Lugwormareusedbyseaanglersasbait,andasanglinghasincreasedinpopularitysohasthedemand
for lugworm. In addition anglers are now much more prepared to purchase supplies of bait from tackle
dealers where prices can be very high when demand outstrips supply, especially in the autumn and winter
when cod and whiting are in season. This has led to large numbers of bait diggers visiting the inlet and
estuary, some of whom are employed on a commercial basis. Commercial lug diggers and experienced
anglersdigalargetrenchwithastandardgardenfork,turningthesedimentoverandreturningthespoilto
the trench, but some bait diggers dig a trench two orthree forks wide and place the spoil in mounds either
side of the trench. The latter approach obviously affects a wider area. Due to a concern about the effects
on the cockle beds bye-laws were initially introduced by the Sea Fisheries Committee in 1987. Subse-
quentlystudiesbyCardiffUniversityshowedthatbothmethodskilledsubstantialnumbersofcockles,and
additional bye-laws were introduced in 1992. These prohibited bait digging in the lower three-quarters of
the inlet, to protect the cockles, and therefore indirectly created a conservation area for lugworm. There
is no mechanism, however, for a Sea Fisheries Committee to directly restrict the harvesting of a marine
organism unless it is classified as a 'sea fish'.
Although no detailed account of the vegetation of the salt marshes in the inlet and estuary has ever
beenpublished,saltmarshesingeneralhavebeenclassicareasforthestudyofplantecology.Researchers
have been attracted by the extreme nature of the habitat, the relatively small number of species involved,
the clear zonation and the effects of easily measured environmental factors. In contrast to the great quant-
ity of published work on saltmarsh vegetation, the ecology of the associated terrestrial invertebrates has
beenlittle studied,althoughexcellent studiesofparticular groupshavebeenmade.Locally workwascar-
ried out in the 1960s and 1970s on the ecology of spiders and saltmarsh mites, and on the influence of ant
colonies on saltmarsh vegetation, but more research is needed to properly understand the community as a
whole.
An interest in the spider fauna of the Gower salt marshes began in July 1964 when, during the course
ofanecologicalsurveyofthespidersandotherarthropodsofthesanddunesatWhitefordNationalNature
Reserve,asinglefemaleofanunknownbutdistinctivemoneyspiderwasfoundbyG.H.Locket.Thiswas
subsequently described as a species new to science under the name of Lasiargus gowerensis . At the time
there was considerable discussion as to whether the new species should be included in the genus Lasi-
argus or that of Baryphyma , as it had characters similar to both. It was eventually concluded, however,
that it was a member of the second genus and it is now known as Baryphyma gowerense , the only species
to be named after the peninsula (Fig. 104). The original animal is now preserved in the Natural History
Museumasthespeciesholotype.Aholotypeistheparticularspecimenwhichisfirstdescribedandwhich
carries the name of the species. Holotypes are used because concepts of a species may change over time
andbiologistsmusthavecriteriaforassigningtheoriginalname.Havingtheoriginalspecimentogoback
to is essential.
The female animal varies in length from 2.7 to 3.3 millimetres, while the male is slightly smaller at
2.6 to 3.1 millimetres. The head is elevated into a distinctive lobe with long curved hairs at the front. The
abdomen isblack, rather elongate andtapering, covered with widely spaced hairs, andhasfourimpressed
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