We conducted an enclosure/exclosure experiment in a forested, headwater stream to determine if crayfish acted as ecosystem engineers this community. Three sets of channels (4 per set) were placed separate pools. All contained cobble-filled baskets. Large (Cambarus bartonii) or 5 g chestnut oak (Quercus prinus) leaf pack added some channels. The 4 treatments the were: 1) no crayfish/no pack, 2) crayfish/leaf 3) and 4) pack. This design allowed us assess effects on benthic community adding It...

We have evaluated the potential of a North American aquatic weevil, Euhrychiopsis lecontei, to serve as an agent biological control for exotic weed, Eurasian watermilfoil (Myriophyllum spicatum), which is currently found throughout much United States and in some southern provinces Canada. this weevil on M. spicatum lakes where populations weed declined. introduced weevils into enclosures two dominated by spicatum. In both there was 50% less biomass with than without weevils. Also,...

Several studies have reported a positive relationship between species richness and ecosystem functioning. However, if much of particular function is performed by one (i.e. functionally dominant species) this also competitive that excludes other taxa from habitat, then it possible to obtain negative Results leaf pack breakdown experiment in small stream suggested the caddisfly Pycnopsyche gentilis , common detritivorous insect North American headwater streams, was both functional dominant. In...

Other| December 01 1975 The Meter and Melody of “Beowulf” Thomas Cable. Urbana, Chicago, London: University Illinois Press, Studies in Language Literature, 64, 1974. ix + 122 pp. $8.95. Robert P. Creed Search for other works by this author on: This Site Google Modern Quarterly (1975) 36 (4): 428–431. https://doi.org/10.1215/00267929-36-4-428 Cite Icon Share Facebook Twitter LinkedIn MailTo Permissions Citation Creed; “Beowulf”. 1 1975; doi: Download citation file: Zotero Reference Manager...

The Eurasian watermilfoil (Myriophyllum spicatum) population in Brownington Pond, Vermont, declined between 1986 and 1989. Watermilfoil covered ≈10‐11 ha of the littoral zone 1986. Less than 0.5 remained An herbivorous weevil (Euhrychiopsis lecontei), which is native to North America, was found associated with this we hypothesized that played a role decline. We monitored E. lecontei populations Pond from 1990 through 1992 by (1) mapping location extent beds pond, (2) determining biomass...

Astacoidean crayfishes serve as hosts to obligate ectosymbiotic annelids called branchiobdellidans. Branchiobdellidans can act either mutualistic cleaners or ectoparasites and have strong effects on crayfish growth survivorship. This potentially vital aspect of biology has gone largely unexplored until recently. We reviewed the current state knowledge regarding this symbiosis examined factors that contribute variability in branchiobdellidans crayfish. show affect various ways depending...

When the interests of mutualists are not perfectly aligned, control mechanisms that modulate interactions can maintain mutually beneficial outcomes and stabilize mutualisms over evolutionary time. However, costs benefits symbiosis often change with ontogeny whether adjusted to reflect ontogenetic changes is largely unknown. We examined recently described cleaning between crayfish Cambarus chaugaensis ectosymbiotic annelids ( Xironodrilus appalachius ) for evidence in symbiont control....

Symbiont community assembly is driven by host-symbiont and symbiont-symbiont interactions. The effects that symbionts exert on their hosts are often context-dependent, existing theoretical frameworks of symbiont do not consider the implications variable outcomes to processes. We hypothesized interactions become increasingly important along a parasitism/mutualism continuum because; (i) negative favour host resistance which in turn reduces colonization subsequently reduce interactions, whereas...

Crayfish can act as keystone species and ecosystem engineers in small streams, but their effects large rivers are not well known. Two of crayfish, Orconectes cristavarius Cambarus chasmodactylus, coexist the South Fork New River western North Carolina. We used gut-content analyses an enclosure–exclosure experiment to investigate influence both crayfish on sediment accumulation benthic invertebrates. guts contained mostly vegetative detritus. However, C. chasmodactylus significantly more...

The role of predators (particularly top such as fish) in structuring stream communities has been debated for 2 decades. Much the debate may have caused by lack a conceptual framework evaluating predator effects communities. First, I propose general model factors (abiotic, permanence and disturbance regime; biotic, predation) that can influence community structure, conditions which these various would be expected to important. Hydrologic transitions separate streams where abiotic are most...

Abstract Animal fitness is influenced by diverse assemblages of internal and external symbionts. These often change throughout host ontogeny, but the mechanisms that underlie these changes their consequences for are seldom revealed. Here we examine a cleaning symbiosis between crayfish an assemblage ectosymbiotic branchiobdellidan worms to uncover what drive in symbiont composition during ontogeny both In surveys North Carolina river, dominant worm species shifted from Cambarincola...

ABSTRACT Crayfish are keystone species and ecosystem engineers in aquatic ecosystems, many require conservation to support their continued persistence. Unfortunately, managers often lack basic data needed make effective decisions. This of is especially true within the New River catchment, United States, where there 12 known crayfish species, but it unclear which those native scant ecological life history available for species. Therefore, our objective was investigate coarse‐scale occurrence...

Recently, there has been an effort to view the study of symbiosis through lens community ecology. Hosts can be viewed as patches in a symbiont metacommunity, and host ontogenetic change alter properties occupied by symbionts. We used freshwater cleaning between population Conhaway crayfish Cambarus appalachiensis their ectosymbiotic branchiobdellidan worms explore how molting act disturbance assembly. Based on year‐long survey hosts communities, acted that reset process Crayfish had recently...

Mutualisms are reciprocal exploitations between 2 partner species in which both benefit. Partner regulation, i.e., reducing interaction duration or symbiont density, is generally performed by the larger host to prevent overexploitation its smaller associate and stabilize mutualism. Other mechanisms that may regulate abundance their negative effects symbioses have received less attention. We evaluated whether addition regulation occurred a symbiosis involving crayfish ectosymbiotic...