 |
| Titel |
Benthic macroinvertebrates and the use of stable isotopes (δ¹³C and δ¹⁵N) in the impact assessment of peatland use on boreal stream ecosystems |
| VerfasserIn |
Mika L. Nieminen, Emmanuela Daza Secco, Hannu Nykänen, Kristian Meissner |
| Konferenz |
EGU General Assembly 2013
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250075492
|
|
|
|
|
|
| Zusammenfassung |
| Stable isotope analysis (SIA) can provide insights into carbon flow dynamics and trophic
positions of consumers in food webs. SIA is used in this study, where we assess the possible
changes in the basal resources of Finnish boreal stream ecosystems and differences in the
impact of two forms of peatland use, forestry and peat mining. About 30% of the total land
area of Finland is classified as peatland, of which about 55% has been drained for forestry
and about 0.6% is in peat production. Unlike forestry, peat production is regionally less
scattered and can thus have measurable local impacts although the total area of peat
production is small.
Three watersheds were used as study areas. Within each watershed, one stream drains a
subcatchment affected only by peat mining, whereas the other stream flows through a
subcatchment affected by forestry. The two subcatchment streams merge to form a single
stream flowing into a lake. Studied watersheds were subject to no other forms of land use. In
addition to the impacted sites, we used two pristine natural mire and two natural forest
catchments as controls.
We analysed the stable isotopes of carbon (δ13C) and nitrogen (δ15N) from benthic
macroinvertebrates, stream bank soil, stream sediment, and dissolved organic carbon (DOC)
in stream water. Samples for stable isotope analyses were collected in the summer of
2011 and samples for invertebrate community analyses in the autumn of 2011.
Upon sampling we measured several physical parameters at each sampling site. In
addition, stream water samples collected in summer and autumn 2012 were analysed
for CH4 and CO2 gas concentrations and autumn gas samples also for their δ13C
values.
Our initial SIA results of invertebrates suggest some degree of discrimination between
different sources of OM and possible effects on feeding habits, presumably due to the quality
of the basal resources. We will explore this result further by examining not only taxonomical
structure, but also the role that functional feeding groups may have on results. Initial results
on invertebrate community structure in response to land use indicate the importance of
geographical site location over land use effects. We suggest that SIA results should be
interpreted together with benthic macroinvertebrate community analyses to get more insight
into ecological impacts of different peatland uses with respect to changed food quality.
Further, we will assess whether CH4 and CO2 could be used as an indicator of
basal resource change. In future studies, we will address the role of the quality
and quantity of the basal resources in more detail, which is likely to provide more
insight into the effects of different forms of peatland use on aquatic ecosystems. |
|
|
|
|
|
|