IADIZA   20886
INSTITUTO ARGENTINO DE INVESTIGACIONES DE LAS ZONAS ARIDAS
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Does elevation modify aquatic export to riparian habitats?
Autor/es:
CASTRO BURGOS, GUSTAVO; JESÚS, GÓMEZ; FERNÁNDEZ CAMPÓN, M.F.; SCHEIBLER, ERICA; SCHOEN, JOHN; SNOBL, ZACHARY R. ; WOJAN, CHRISTOPHER M. ; XIONG, ONG ; WELLNITZ, TODD
Lugar:
Portland
Reunión:
Congreso; ESA Annual Meeting; 2012
Institución organizadora:
Ecological Society of America
Resumen:
Background/Question/Methods
Stream ecosystems
traverse gradients of elevation and are tightly linked to adjacent
riparian habitats through reciprocal subsides. Aquatic insect emergence
is an important component of this linkage and is generally assumed to
reflect benthic production. However, elevation-specific environmental
conditions may also influence exchange rates and modify connectivity
across the gradient. To examine how elevation and concomitant
environmental variables affected lotic-riparian connectivity, we studied
two reaches of the Rio Tambillos in the Andes Mountains of Argentina.
The study reaches were 20 m, extended 4 m into the riparian habitat, and
were located at 2470 and 2630 m elevation. We assessed aquatic,
terrestrial and emergent arthropod assemblages at each site by
collecting 12 Surber samples, 18 pitfall traps and 9 sticky traps.
Stream depth and near-bed current were measured for each Surber sample.
Pitfall and sticky traps were arranged along 3, 4-m transects that
extended away from the stream and were left in place 5-d prior to
collection. Aquatic and terrestrial temperature was logged over 72-h in
the stream and 10 cm above the ground on the shore. Riparian plants
were identified and their density was measured across each transect.
Data were analyzed using ANOVA and multiple regression.
Results/Conclusions
Temperature, riparian vegetation, terrestrial arthropod abundance
and, to a lesser extent, the aquatic macroinvertebrate community
changed with elevation. However, effects on aquatic emergence were
inconclusive. The upper reach was cooler than the lower, with
respective maximum temperatures of 16.2° and19.2° C for the stream and
44.1° and 49.6°C for the riparian zone. Both reaches had fewer
terrestrial arthropods near the stream and the upper reach had less
overall, averaging 39 vs. 62 individuals/trap (P < 0.01). Benthic
macroinvertebrate diversity and total abundance in the stream did not
differ between reaches; however, Ephemeroptera were twice as numerous at
the upper site, averaging 1333 vs. 646 individuals/m2 (P
< 0.01). Benthic assemblages showed unique responses to local
physical conditions. Macroinvertebrate numbers declined with velocity
at lower reach (P = 0.005), but showed no relationship to current at the
upper. Similarly, macroinvertebrate diversity was inversely related to
depth at in the lower reach, but not at the upper (P = 0.005). No
clear pattern was seen for aquatic emergence. Although both riparian
and terrestrial systems changed with elevation, we could not find a link
through aquatic export. This suggests that longer-term study is needed
to distinguish the connection.