The Use of Palaeoecological Techniques to Identify Reference Conditions for River Conservation Management - River Conservation and Management - page 202

reconstruction techniques, in the form of transfer
functions for nutrients, pH and salinity over
varying time-scales (Bennion et al ., 2001; Anderson
et al ., 2006; Battarbee et al ., 2011). Recent research,
centred on the palaeochannel sediments of former
active river channels, has demonstrated that it
is possible to reconstruct in-channel habitat and
floral and faunal community characteristics based
on the sub-fossil remains of aquatic invertebrates
from the late-glacial through to the modern
period (Greenwood et al ., 2003; Davis et al .,
2007). When this information is combined with
historic data in the form of maps, archival
records and aerial photographs it allows the
exploration of the recent fluvial geomorphological
and biological change and the identification
of features (habitats or organisms) that have
suffered from historic management operations or
environmental degradation, to be identified.
Such evaluations have direct relevance to
the scientific underpinning and generation of
strategic physical restoration plans for rivers,
working alongside strategic plans for addressing
other human impacts, such as pollution and
unsustainable water use. Results can potentially be
used to identify appropriate restoration measures,
based on a knowledge of lost or disadvantaged
habitats and species, and to provide a transparent
ecological and biodiversity justification for those
measures when seeking to secure operational
resources for their future restoration and
conservation. Strategic physical restoration
plans are being developed for riverine Sites of
Special Scientific Interest (SSSIs) across England,
including those designated as Special Areas of
Conservation under the EC Habitats Directive
(Mainstone and Holmes, 2010). These plans have
long-term objectives and accommodate natural
and assisted natural recovery processes, and can
benefit in the short, medium and long term from
the results of palaeoecological evaluations. More
widely, the WFD is emerging as a potentially
powerful driver for the physical restoration of
river habitats, and over time should lead to the
development of further river restoration plans that
would benefit potentially from palaeoecological
information of historic instream conditions and
community composition.

A range of potential proxies exist within
palaeochannel sediments including diatoms,
pollen, plant macrofossils, aquatic insects and
gastropods (Greenwood et al ., 2003; Davis et al .,
2007) which have been used to characterize
instream habitats and conditions over historic
timescales (Gandouin et al ., 2005; Greenwood
et al, 2006; Howard et al ., 2010). Some proxies,
particularly diatoms, are widely used in lentic
and lotic ecosystems to reveal contemporary and
palaeolimnological change (Gell et al. , 2005; Kelly
et al ., 2008). They are increasingly used to help
support decision making in river management
(Kelly et al ., 2008) and in conjunction with
transfer functions can be used to infer past/palaeo
conditions for a number of ecological and water
quality parameters and for nutrient levels (Reavie
and Smol, 1997; Gell et al ., 2005, 2007). However,
within the current investigation, the use of four
aquatic invertebrate proxies (aquatic Coleoptera,
Trichoptera, Chironomidae and Gastropoda)
are examined in detail. All four proxies display
long-term

genetic stability with morphological

consistency seen in their exoskeleton and

shell features (Lowe and Walker, 1997). This

enables direct cross-referencing of fossils with

contemporary samples.

Coleoptera
The use of sub-fossilized insect remains recorded
in river sediments as proxies has historically
centred on the elytra (wing cases) and pro-notal
plates of aquatic and terrestrial Coleoptera (beetles)
(Coope, 1986) which have been widely used
in palaeoenvironmental investigations of rivers
(Coope et al ., 2002; Elias, 2006). Many taxa
display adaptations to specific instream habitats
and preferences for substratum, flow velocity
and thermal ranges (Coope, 1986; Greenwood
et al ., 2006). The sub-fossil remains are easily
extracted from river sediments and can provide
comprehensive palaeoenvironmental information
(Coope, 1986). Smith and Howard (2004) for
instance, used groups of aquatic beetles to
characterize the palaeodischarge rates of streams.
More recently the preferences set out in the Lotic
Invertebrate Index for Flow Evaluation (LIFE)
have been applied successfully to palaeochannel