Geoscience Reference
In-Depth Information
Table 17.1
Coleoptera and Trichoptera taxa recorded
from palaeo-sediments and the contemporary channel of
the River Eye, Leicestershire.
(
Brachycentrus subnubilus
and
Athripsodes aterrimus
)
present in the palaeo-sample were notably absent
from the river today. These taxa are typically
associated with coarse-grained substrates and
instream vegetation, suggesting that there has
been an increase in the volume of fine sediment
input and a reduction in aquatic macrophyte
growth (Gunn, 1985; Dietrich and Waringer, 1999;
Wallace
et al
., 2003; Smith and Howard, 2004).
In addition, the overall reduction of riffle habitat
availability due to ponding means that availability
of habitat for the historic 'benchmark community'
may be confined to a relatively small number of
localities on the River Eye today. However, given
the similarities between the contemporary and
historic Coleoptera and Trichoptera communities,
it suggests that appropriate restoration measures,
addressing the availability of riffle habitat and
fine sediment input, may assist the recovery and
expansion
Species
Palaeo
Contemporary
COLEOPTERA
Haliplus ruficollis
group
√
x
√
√
Nebrioporus depressus
(F.)
√
√
Helophorus brevipalpis
Bedel
√
Helophorus
sp.
x
√
√
Elmis aenea
(M uller)
√
Limnius volckmari
(Panzer)
x
√
√
Oulimnius tuberculatus
(M uller)
√
Riolus subviolaceus
(M uller)
x
TRICHOPTERA
Agapetus fuscipes
(Curtis)
√
x
√
Tinodes waeneri
(L.)
x
√
Polycentropus flavomaculatus
(Pictet)
x
√
√
Hydropsyche pellucidula
(Curtis)
of
the
benchmark
community
type
recorded.
√
√
Hydropsyche siltalai
(D ohler)
√
Hydropsyche instabilis
x
√
Hydropsyche
sp.
x
√
Future prospects
Brachycentrus subnubilus
(Curtis)
x
√
Lepidostoma hirtum
(F.)
x
The results of the pilot study suggest that the
proposed method enables the identification of a
benchmark community, including details of the
taxa that may have been extirpated historically
and more recent colonizers. This information will
help those agencies engaged in managing the
contemporary system, and for planning future
conservation and restoration activities, by directly
supporting research and management efforts
centred on the physical and ecological restoration
of river SSSIs in England being undertaken by
Natural England. In addition, the results generated
from this research will support the work of the
Environment Agency in implementing the WFD.
However, further analysis of other historic localities
(palaeo-sediments) on the River Eye is essential
to characterize the communities associated with
historic pools, backwaters and 'run' habitats
(Amoros
et al
., 1987). On the River Eye, this will
allow historic instream biodiversity to be more
fully quantified. Research at present is examining
lateral sediment deposits and those associated with
√
Halesus radiatus
(Curtis)
x
√
Limnephilus lunatus
Curtis
x
√
√
Goera pilosa
(F.)
√
Athripsodes aterrimus
(Stephens)
x
√
√
Athripsodes bilineatus
(L.)
√
√
Hydroptila
sp.
aterrimus
) were unique to the palaeo-samples
(Table 17.1). Most of the gastropods recorded in
the contemporary samples were recorded from
macrophytes in slow-flowing and marginal areas
(with the exception of
Theodoxus fluviatilis
and
Ancylus fluviatilus
), and as a result they are not
considered further here.
The results indicate that broadly similar faunal
communities occur within the riffle habitats of
the River Eye circa 1962 and contemporaneously.
However, two riffle beetle taxa (
Limnius volckmari
and
Riolus subviolaceus
) and two Trichoptera taxa
