Benthic Macroinvertebrates of Temperate, Sub-Antarctic Streams: The Effects of Altitudinal Zoning and Temperature on the Phenology of Aquatic Insects Associated to the Robalo River, Navarino Island (55°S), Chile Page: 89
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from 2006-2011 at site V (120 m.a.s.1) in the R6balo river watershed. Furthermore, historical
hatching and emergence dates for Meridialaris chiloeense at site V (120 m.a.s.1) from 2006 to
2011 were estimated. As noted in Fig. 28, CDD vary in approximately 160 CDD between 2006
and 2009, while there is a variation of 208 CDD with 2010. This variation has a direct effect on
the emergence dates of Meridialaris chiloeense: in years with a higher accumulation of degree-
days (2006, 2008, 2010), emergence begins in early January, while during years with a lower
accumulation of degree-days (2007, 2009), emergence begins in late January and early February.
Discussion
Meridialaris chiloeense Life Cycle in South American Sub-Antarctic Streams
Although life history studies have been carried out for many years in the Northern
Hemisphere and other countries of the Southern Hemisphere (i.e. New Zealand), little is known
about the life histories of aquatic insects in Patagonia (Beltran and Miserendino 2011) and the
Sub-Antarctic ecoregion of southern Chile. This is study is one of the few report on the life
history of any freshwater insect inhabiting Sub-Antarctic South American streams. Our results
indicate that Meridialaris chiloeense (Ephemeroptera: Leptophlebiidae) has a life history, which
varies from merovoltine to univoltine, from the headwaters to the mouth of the sharp altitudinal
gradient of the R6balo River Watershed. These results are similar to other studies carried out in
Northern Patagonian streams (Hollman et al. 2006) but contrasting in the fact that Meridialaris
chiloeense presents a bivoltine life cycle at 420S. Most aquatic insects of high latitudes and
altitudes exhibit a seasonal emergence pattern, as the interaction of temperature, photoperiod,
and local climate conditions helps to determine aquatic insect seasonal phenology in temperate
regions (Weathers et al. 2000). Generally, where climates are cold, rapid development is89
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Contador Mejías, Tamara Andrea. Benthic Macroinvertebrates of Temperate, Sub-Antarctic Streams: The Effects of Altitudinal Zoning and Temperature on the Phenology of Aquatic Insects Associated to the Robalo River, Navarino Island (55°S), Chile, dissertation, December 2011; Denton, Texas. (https://digital.library.unt.edu/ark:/67531/metadc103303/m1/103/: accessed April 28, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; .