Memorandum by University College London
TAXONOMY AND AQUATIC ENVIRONMENTAL CHANGE
Taxonomy is fundamental to environmental change
science in two principal ways, (i) using organisms as biological
indicators; and (ii) more directly in biodiversity studies
At UCL we have been especially interested in
the use of diatoms as indicators of water quality.
DIATOMS
Diatoms are a very distinctive group of algae.
They occur in all kinds of aquatic environment in great abundance
and diversity and they are especially sensitive to changes in
water chemistry. Because they have a resistant siliceous cell
wall, they are preserved in lake sediments and can be used, not
only to track contemporary water quality changes, but also to
reconstruct past water quality over previous decades and centuries.
In this context we have been and are concerned
especially with problems of;
1.
eutrophication of surface
waters through waste-water discharge and fertiliser runoff from
agricultural land;
SURFACE WATER
ACIDIFICATION: AN
EXAMPLE
Taking the example of surface water acidification
we were able to show from diatom analysis of lake sediments that
acidification in Britain began in the mid 19th century and was
indeed caused by acid deposition from the combustion of fossil
fuels. Our results helped to persuade the Thatcher government
that Britain needed to sign up to the various UNECE and EU protocols
and directives and agree to reduce emissions of sulphur and nitrogen
gases.
For the last 20 years on behalf of Defra we
have been monitoring lakes and streams across the UK to assess
the extent to which surface waters in the UK are recovering from
acidification (but see below). We are now especially interested
in whether climate change may influence the recovery process.
This work has depended on (i) establishing a
rigorous high resolution taxonomy for diatoms found in upland
waters of the UK; and (ii) matching the distribution of diatoms
across the UK (and adjacent parts of North-west Europe) with associated
environmental data to define the indicator value of individual
species.
THE ROLE
OF TAXONOMY
The taxonomic work involves:
3.
Identification of unknown species using reference
literature and type material in museums, especially the NHM
4.
Harmonisation of taxonomies between research groups
using taxonomic quality control techniques ("blind"
counting, microscope workshops).
6.
Developing statistical models to describe the relationship
between species distribution and environmental variables (eg pH,
phosphorus).
DEVELOPMENT IN
DIATOM TAXONOMY
Considerable progress has been made over the
last 30 years, in particular:
2.
We have built large databases, some available on
the internet, that describe the distribution (mainly with respect
to water chemistry) of most taxa
3.
European scale research projects (eg EDDI, European
Diatom Database Information System) have been successful in harmonising
taxonomy (but not nomenclature) between national research communities
4.
Diatoms are now used routinely by environment agencies
across Europe as environmental (mainly water quality) indicators,
facilitated by electronically available identification keys
5.
The NHM has been able to maintain staffing in the
diatom section, despite threats of closure in the 1980s. It sustains
it's own research programme and curates the worlds largest collection
of diatom slides
6.
We (UCL) have maintained an international diatom
analysis training programme for over 20 years and conduct workshops
in the UK for Environment Agency staff.
FUTURE CONCERNS
Despite the progress there are also worrying
trends. In particular there has been an overall decline in the
training of freshwater biologists and a related decrease
in the taxonomic competence of staff employed by environment agencies
and related bodies. This applies not just to diatom analysis but
also to other aspects of freshwater biology.
Assessing the ecological status of surface waters
using biological indicators (diatoms, phytoplankton, aquatic macro-invertebrates,
aquatic plants) is central to the EU Water Framework Directive,
and the need for taxonomic skills in these biological groups is
growing at a time when supply is decreasing. High quality phytoplankton
identification skills are in especially short supply.
Moreover, there is increasing concern about
global biodiversity loss (especially acute in freshwaters) and
the future role of climate change in modifiying the structure
and functioning of aquatic ecosystems. Taxonomic skills underpin
both the research and surveillance needed to assess the
impact of climate change in future, both in the use of organisms
as indicators of climate change and conversely in assessments
of biodiversity loss. Ironically, and as an aside, Defra have
this year decided to make massive reductions to the national programme
(noted above) for monitoring the ecology of upland waters in the
UK. The programme has now been running for 20 years and the cuts
have been made at a time when the network is arguably most needed.
We coordinate a major 36 partner EU project
on "The impact of climate change on European freshwater ecosystems".
As part of the project a German team is leading a major initiative
to develop a new system of freshwater biological indicators for
monitoring the impacts of climate change. In due course
this system and related results from the project will be built
into the Water Framework Directive allowing Environment Agencies
across Europe to improve their monitoring methods. Implementation,
however, will depend on the ability of staff in the field and
laboratory to identify organisms correctly.
17 March 2008
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