Memorial University DAI: The ecology of net-spinning caddisflies in a Newfoundland lake outlet

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Title	The ecology of net-spinning caddisflies in a Newfoundland lake outlet
Author	Genge, Peter D.
Description	Thesis (M.Sc.)--Memorial University of Newfoundland, 1985. Biology
Date	1985
Pagination	xiii, 128 leaves : ill.
Subject	Caddisflies--Newfoundland and Labrador; Stream ecology--Newfoundland and Labrador
Degree	M.Sc.
Degree Grantor	Memorial University of Newfoundland. Dept. of Biology
Discipline	Biology
Language	Eng
Spatial Coverage	Canada--Newfoundland and Labrador
Notes	Bibliography: leaves 109-120.
Abstract	The community of dominant species of net-spinning caddisflies found in the Axes Pond outlet - an oligotrophic lake-stream system near Torbay, Newfoundland was investigated. The dominant species in the system included: Cheumatopsyche pettiti, Hydropsyche betteni, Hydropsyche slossonae, Hydropsyche sparna, Neureclipsis crepuscularis and Chimarra aterrima. Zonation existed in the abundance and distribution of these species along the stream within short distances from the lake outlet. H. betteni, C. pettiti and N. crepuscularis were predominant at the immediate lake outlet while 60 meters downstream H. slossonae and H. sparna were predominant with large numbers of C. pettiti and N. crepuscularis present. Downstream from this point, C. aterrima was predominant. Biomass of net-spinning caddisfly larvae varied throughout the year and between stations. Highest values were generally reached at the immediate outlet during late spring or late fall and winter. Lowest values were observed at the sampling station furthest from the outlet during mid summer. -- It is strongly suspected that density dependent drift resulted in a developmental gradient within the densest populations at the outlet. For any one generation, the modal instar number for a species population decreased with distance below the outlet. - Life history patterns of the net-spinning caddisflies studied at Axes Pond were not necessarily comparable with those described for the same species on the mainland. Larvae of most species of hydropsychids studied at Axes Pond were larger at a given larval instar and overwintered in earlier larval instars than the same species studied on the mainland. With the exception of H. slossonae, which had a univoltine life cycle, all species studied had univoltine and/or semivoltine life cycles. This is the first report of a semivoltine life history in net-spinning caddisflies. -- Large particles of lake-derived seston disappeared from the stream faster than smaller particles. This reduction in mean food particle size over distance downstream from the outlet corresponded with the feeding habits and zonation of the net-spinning caddisflies. In addition to differences in feeding habits it is postulated that these species may be able to exist together as a result of several other factors including temporal variation in life history and differences in habitat preference. These factors permit the existence of a complex guild of net-spinning caddisflies at a lake outlet.
Type	Text
Resource Type	Electronic thesis or dissertation
Format	Image/jpeg; Application/pdf
Source	Paper copy kept in the Centre for Newfoundland Studies, Memorial University Libraries
Local Identifier	75352497
Rights	The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission.
Collection	Electronic Theses and Dissertations
Scanning Status	Completed
PDF File	(22.90 MB) -- http://collections.mun.ca.qe2a-proxy-mun.ca/PDFs/theses/Genge_PeterD.pdf
CONTENTdm file name	70224.cpd