15 research outputs found
Litter quality, stream characteristics and litter diversity influence decomposition rates and macroinvertebrates
Long-term trophic evolution of a northern reservoir following impoundment: different temporal response patterns of primary production and plankton biomass with a predictive model for future trends
Effects of sediment nutrients and depth on small-scale spatial heterogeneity of submersed macrophyte communities in Lake Pleasant, Pennsylvania
SPATIAL VARIATION AND DISTRIBUTION OF PHOSPHORUS FORMS IN BOTTOM SEDIMENTS OF TWO CANADIAN SHIELD LAKES
Myxomycetes occurring on Cecropia adenopus (Cecropiaceae) in fragments of Atlantic Rainforest Myxomycetes ocorrentes em Cecropia adenopus (Cecropiaceae) em fragmentos de Floresta Atlântica
Cecropia adenopus (Ambay pumpwood) is a frequent native species on the edges of woods and clearings and is considered a pioneer species in re-colonized areas. Despite its distribution from Mexico to Argentina, this substrate has never been examined in detail regarding the presence of Myxomycetes. In the present study, the myxobiota associated with leaf debris of C. adenopus was investigated in two Atlantic Rainforest conservation units located in the Brazilian state of Rio Grande do Norte. Five specimens and one plasmodium were obtained directly from the field and 87 were developed in 43.7% of 200 moist-chamber cultures set up separately with blades and petioles. Fifteen species were identified and illustrated. The two predominant groups were representatives of Trichiales and Physarales. Didymium columella-cavum was recorded for the second time in Brazil and in the world.<br>Cecropia adenopus (embaĂşba) Ă© uma espĂ©cie nativa, frequente em bordas de matas e clareiras e tida como espĂ©cie pioneira em áreas recolonizadas. Apesar de ocorrer desde o MĂ©xico atĂ© a Argentina este substrato nunca tinha sido examinado com detalhe quanto Ă presença de Myxomycetes. No presente estudo, a mixobiota associada a folhas mortas de C. adenopus foi investigada em duas Unidades de Conservação da Floresta Atlântica, situadas no estado do Rio Grande do Norte. Cinco espĂ©cimes e um plasmĂłdio foram obtidos diretamente no campo e 87 desenvolveram-se em 43,7% de 200 câmaras-Ăşmidas, montadas com lâminas foliares e pecĂolos separadamente. Quinze espĂ©cies de Myxomycetes foram identificadas e ilustradas. Os dois grupos predominantes pertencem Ă s ordens Trichiales e Physarales. Didymium columella-cavum foi encontrado pela segunda vez no Brasil e no mundo
The effect of aquatic plant chemistry and morphology on feeding selectivity by the crayfish, Orconectes virilis
Watercress and amphipods Potential chemical defense in a spring stream macrophyte
We investigated the potential role of defensive chemicals in the avoidance of watercress ( Nasturtium officinale ) by the cooccurring amphipod, Gammarus pseudolimnaeus at two spring brooks: Carp Creek, Michigan and Squabble Brook, Connecticut. We conducted observations and laboratory experiments on the consumption of watercress, the toxicity of damaged (frozen) watercress, and the toxicity of damage-released secondary chemicals. Field-collected yellowed watercress typically lacked the bite and odor characteristic of green watercress and was consumed by G. pseudolimnaeus. G. pseudolimnaeus strongly preferred yellowed watercress to green watercress despite the higher nitrogen content of the latter (2.7 vs 5.4%), and usually consumed five times more yellowed watercress (>50% of yellowed leaf area vs. <8% of green leaf area presented). Fresh green watercress contained seven times more phenylethyl glucosinolate than yellowed watercress (8.9 mg/g wet vs. 1.2 mg/g). Cell-damaged (frozen) watercress was toxic to G. pseudolimnaeus (48-hr LC 50 s: ca. 1 g wet/liter), and the primary volatile secondary chemicals released by damage were highly toxic. The predominant glucosinolate hydrolysis product, 2-phenylethyl isothiocyanate had 48-hr LC 50 s between 0.96 and 3.62 mg/liter, whereas 3-phenylpropionitrile was less toxic, with 48-hr LC 50 s between 130 and 211 mg/liter. These results suggest that live watercress is chemically defended against consumption. The glucosinolate-myrosinase system, recognized as the principle deterrent system of terrestrial crucifers, is also possessed by N. officinale and may contribute to defense from herbivory by aquatic crustaceans. This system may be just one of many examples of the use of defensive chemicals by stream and lake macrophytes.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44877/1/10886_2005_Article_BF01021282.pd