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21.
We assessed the influence of ice-storm-derived debris dams on aquatic macroinvertebrates and stream substrates in a high-gradient
watershed in the eastern Adirondack Mountains of New York State. Using a modification of electrofishing techniques, invertebrates
were collected once before (June 2000) and once after (June 2001) wood removal from the downstream reach in each of six pairs
of reaches (second and third-order streams). Stream substrates were also mapped in 2000 and 2001 to evaluate shifts in dominant
substrates within a reach following wood removal. The following metrics were used to compare the invertebrate communities
before and after wood removal: genera similarity, Shannon–Weiner equitability, taxa richness, dominant taxon, percent dominance
and functional feeding group relative abundance. The changes in removal reaches were evaluated relative to changes in upstream
reference reaches using a Before-After Control-Impact (BACI) design and analysis. Stream substrates did not change significantly
in response to wood removal, although a trend toward coarser substrates was observed following removal. Following wood removal,
the relative proportion of grazers increased upstream and downstream from removed dams in all streams; however, comparisons
of other metrics indicated no significant response to removal. Invertebrate responses to wood removal were lower than expected,
perhaps due to the presence of abundant boulder-formed pools in this high gradient system.
Electronic supplementary material Electronic supplementary material is available for this article at
and accessible for authorised users. 相似文献
22.
Macrophyte communities in unimpacted European streams: variability in assemblage patterns, abundance and diversity 总被引:5,自引:5,他引:0
Annette Baattrup-Pedersen Krzysztof Szoszkiewicz Rebi Nijboer Mattie O’Hare Teresa Ferreira 《Hydrobiologia》2006,566(1):179-196
Macrophytes are an important component of aquatic ecosystems and are used widely within the Water Framework Directive (WFD)
to establish ecological quality. In the present paper we investigated macrophyte community structure, i.e., composition, richness
and diversity measures in 60 unimpacted stream and river sites throughout Europe. The objectives were to describe assemblage
patterns in different types of streams and to assess the variability in various structural and ecological metrics within these
types to provide a basis for an evaluation of their suitability in ecological quality assessment. Macrophyte assemblage patterns
varied considerably among the main stream types. Moving from small-sized, shallow mountain streams to medium-sized, lowland
streams there was a clear transition in species richness, diversity and community structure. There was especially a shift
from a predominance of species-poor mosses and communities dominated by liverwort in the small-sized, shallow mountain streams
to more species-rich communities dominated by vascular plants in the medium-sized, lowland streams. The macrophyte communities
responded to most of the features underlying the typological framework defined in WFD. The present interpretation of the WFD
typology may not, however, be adequate for an evaluation of stream quality based on macrophytes. First and most important,
by using this typology we may overlook an important community type, which is characteristic of small-sized, relatively steep-gradient
streams that are an intermediate type between the small-sized, shallow mountain streams and the medium-sized, lowland streams.
Second, the variability in most of the calculated metrics was slightly higher when using the pre-defined typology. The consistency
of these results should be investigated by analysing a larger number of sites. Particularly the need of re-defining the typology
to improve the ability to detect impacts on streams and rivers from macrophyte assemblage patterns should be investigated.
Electronic supplementary material Electronic supplementary material is available for this article at
and accessible for authorised users. 相似文献
23.
24.
Mattie T. O’Hare Annette Baattrup-Pedersen Rebi Nijboer Krzysztof Szoszkiewicz Teresa Ferreira 《Hydrobiologia》2006,566(1):197-210
The impact of altering hydro-morphology on three macrophyte community types was investigated at 107 European stream sites.
Sites were surveyed using standard macrophyte and habitat survey techniques (Mean Trophic Rank Methodology and River Habitat
Survey respectively). Principal Components Analysis shows the macrophyte community of upland streams live in a more structurally
diverse physical habitat than lowland communities. Variables representing the homogeneity and diversity of the physical environment
were used to successfully separate un-impacted from impacted sites, e.g. homogeneity of depth and substrate increased with
decreasing quality class for lowland sites (ANOVA p < 0.05). Macrophyte attribute groups and structural metrics such as species richness were successfully linked to hydro-morphological
variables indicative of impact. Most links were specific to each macrophyte community type, e.g., the attribute group liverworts,
mosses and lichens decreased in abundance with increasing homogeneity of depth and decreasing substrate size at lowland sites
but not at upland sites. Elodea canadensis, Sparganium emersum and Potamogeton crispus were indicative of impacted lowland sites. Many of the indicator species are also known to be tolerant to other forms of
impact. The potential for a macrophyte tool indicative of hydro-morphological impact is discussed. It is concluded one could
be constructed by combining indicator species and metrics such as species richness and evenness. 相似文献
25.
26.
Miguel Archangelsky 《Studies on Neotropical Fauna and Environment》2013,48(3):199-204
Spercheus halophilus n. sp. is described together with its egg case and larval stages. This is the second Neotropical species for the genus. Comparative notes with adults of related species are included: S. halophilus seems closely related to S. fimbriicollis Bruch, 1915 and S. spangleri Hebauer, 1990. Larvae of S. halophilus show several important differences when compared with those of S. emarginatus (Schaller, 1783) and S. cerisyi Guérin-Meneville, 1842, most of them related to the mouthparts. This species lives in temporary pools of water gathered along the margins of roads running through a large salt flat in Central Argentina. Notes on the biology of this species are also included. 相似文献
27.
Wm. J. Woelkerling 《欧洲藻类学杂志》2013,48(3):209-225
Mastophoropsis canaliculata (Harvey in Hooker) gen. et comb. nov. (Corallinaceae, Rhodophyta) is restricted to south-eastern Australian waters. It is unique among Corallinaceae in possessing an erect, tenacular, branched, taeniform, non-geniculate thallus which produces multiporate tetrasporangial conceptacles. Based on a detailed morphological and anatomical study, including an examination of the designated lectotype, this taxon is referred to the tribe Phymatolitheae in the subfamily Melobesioideae and its relationships to other non-geniculate Corallinaceae are discussed. A simplified microtechnique procedure involving decalcification with nitric acid, resin embedding and staining serially mounted sections with KMnO4 also is outlined. X-ray microanalysis of surface tissues indicates that calcification occurs largely as CaCO3 and that various structures contain substantially differing amounts of Ca. 相似文献
28.
29.
Rodney A. Rountree Joachim P. Gröger David Martins 《Marine and Freshwater Behaviour and Physiology》2013,45(1):73-78
The extensive periodic vertical movements of up to 14 h and 209 m observed in this study for an individual goosefish, Lophius americanus, challenges previous assumptions about the benthic and highly sedentary behavior of the species as well as of other lophiids. Researchers should consider conducting similar data storage tagging studies with other benthic fishes to test assumptions of sedentary behavior. 相似文献
30.