Distribuzione ed ecologia di Copepodi Arpacticoidi in torrenti d’alta quota italiani
Author(s)
Raschioni, Roberta
Date Issued
January 8, 2009
Type
Doctoral Thesis
Abstract
This project deals with the results of ecological researches, carried out in the Conca
(Adamello-Brenta Natural Park) and Val de La Mare river systems (Stelvio National Park)
from 2001 to 2005, and it aims at studying the ecological and biological distribution of
Copepods harpacticoids in Italian high altitude streams.
Samples were collected in different fluvial typologies: stations were dominated either by
glacial (kryal), spring (krenal), snowmelt and rain (rhithral) or mixed (kreno-rhithral,
kryal-rhithral) contribution. We analyzed 5 streams, as a total of 21 work stations located
between 2703 and 1200 metres above sea level.
We tested different several techniques: both in benthonic areas, such as the drift nets (3
nets of 100μ mesh, opening 10 cm, length 1 m, along a transect perpendicular to the
current, collecting for 15 minutes), the kick sampling (collecting 5 samples per station with
a 100μ mesh pond net, disturbing for one minute a 1 m2 area) and surface pipes; and in
hyporheic areas, such as hyporheic bottles, hyporheic pipes and Bou-Rouch pump.
Therefore, this project also shows the medium and small scale distribution of different
bentonic and interstitial taxa by focusing its attention on both different fluvial systems and
the interface between river and groundwater ecosystem which is one the most important
ecological ecotone among all the current waters. We gathered a total of 16,000
harpacticoids: 2,867 copepods at their initial stages and 13,733 adult and late staged
copepods assigned to 15 taxa, belonging to 5 genus of Canthocamptide family.
As a conclusion of this research, the most predominant specie is Bryocamptus (A.)
cuspidatus which has a wide ecological importance and is able to colonize habitats marked
by environmental border conditions such as glacial water paths. The analyzed hyporheic
areas were ecotones and lacking in species. In fact, we did not find any typical species of
subterranean water given that stygoxene, stygophiles and stigobionts species lack entirely.
The lack in stygobiont species is presumably due to the impoverishment of the quaternary
glaciations. Furthermore, the following re-colonization of these glacial areas by the
stygobiont species was not possible because of their limited capacity of dispersion and
their difficulty in adapting to not much deep subterranean waters such as the hyporheic
areas.
Moreover, thanks to the study of copepods harpacticoids distribution during the whole
year, we observed that some species accommodated themselves to very restrictive
environmental conditions also in winter periods, when water paths are completely frozen
and snowy.
Additional information
Dottorato di ricerca in Evoluzione biologica e biochimica
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