 |
| Titel |
Detecting phenology change in the mayfly Ephemera danica in response to water temperature variations |
| VerfasserIn |
Matthew Johnson, Nicholas Everall, Robert Wilby |
| Konferenz |
EGU General Assembly 2014
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250091457
|
| Publikation (Nr.) |
 EGU/EGU2014-5752.pdf |
|
|
|
|
|
| Zusammenfassung |
| Water temperature is critical to aquatic life. Rising river temperatures under climate change
are expected to affect the phenology (i.e.timing of life events) of aquatic insects, including
Ephemera danica which is a large burrowing mayfly that is widespread throughout
Europe.
To assess the temporal and spatial variability in mayfly emergence, E. danica were monitored
at two reaches in the River Dove, English Peak District over the period 2007 to 2013.
Inter-annual variations in Growing Degree Days (GDDs) were modelled for an upstream site
with intermittent spring flows supplementing main channel flow (Beresford Dale)
and a downstream site dominated by near constant discharges of cool groundwater
(Dovedale).
The emergence cycle of E. danica was strongly related to GDDs at each site. E. danica
usually remains in an aquatic larval stage for two years before emerging in its adult,
terrestrial form. However, after particularly warm summers in Beresford Dale, E.
danica was recorded to emerge after only one year in its aquatic form. Following the
particularly wet/cold year of 2012, E. danica began to revert back to a bi-annual cycle.
In Dovedale, an average of 374 fewer GDDs were accumulated in comparison to
Beresford Dale. As a result, E. danica maintained a two-year growth cycle throughout
the monitoring period despite the phenology changes observed 8 km upstream at
Beresford.
Changes to insect phenology are significant because populations with a one-year cycle are
potentially more vulnerable to adverse weather when the majority of the population is in
terrestrial form. Also, altering the growth, development and size of insects affects
reproductive success with implications for population dynamics.
Conventional monitoring of both water temperature and invertebrates as used by regulatory
authorities in the UK, did not identify the changes in insect phenology or the association
between phenology and water temperature. Data from the present study suggest that habitats
near cool groundwater may provide important refugia for populations of insects, potentially
delaying permanent shifts in phenology under climate change. However, the ability to detect
changes in thermal triggers and phenological response may be hindered by conventional spot
sampling protocols. |
|
|
|
|
|
|