RÉSUMÉ
En esta investigación se muestra diferentes métodos de desmontes para evitar el desgaste del suelo.
Sujet(s)
Sol , Zone TropicaleRÉSUMÉ
Muestra los aspectos técnicos que se debe tener en cuenta para instalar una cortina rompevientos y así reducir la velocidad del viento y evitar daños en los cultivos.
Sujet(s)
Énergie Éolienne , Érosion , Sol , VentRÉSUMÉ
Variation in mitochondrial DNA (mtDNA) was examined among 86 red snapper (Lutjanus campechanus) from three geographic localities in the northern Gulf of Mexico (Gulf). A total of 29 composite mtDNA genotypes (haplotypes) was found; one haplotype occurred in 39 of 86 (45.3%) individuals assayed, and 20 haplotypes occurred in only one individual each. Tests of heterogeneity in mtDNA haplotype frequencies among localities were not significant, and there was little evidence of phylogeographic structuring of mtDNA haplotypes. These findings are consistent with the hypothesis that red snapper in the northern Gulf comprise a single, panmictic population. The observed genetic homogeneity also indicates considerable gene flow (migration) among red snapper in the northern Gulf. Significant differences in levels of intrapopulational mtDNA variation were found among localities. Levels of intrapopulational mtDNA diversity in red snapper are low relative to other marine fish species studied to date.
Sujet(s)
ADN mitochondrial/composition chimique , Poissons/génétique , Variation génétique , Animaux , Séquence nucléotidique , Analyse de regroupements , ADN mitochondrial/isolement et purification , Floride , Fréquence d'allèle , Haplotypes , Louisiane , Données de séquences moléculaires , Phylogenèse , Polymorphisme de restriction , Eau de mer , TexasRÉSUMÉ
During February and March 1985, nitrite levels along the northern (approximately 7 degrees to 10 degrees S) Peruvian coast were unusually high. These accumulations occurred in oxygen-deficient waters, suggesting intensified denitrification. In a shallow offshore nitrite maximum, concentrations were as high as 23 micromoles per liter (a record high). Causes for the unusual conditions may include a cold anomaly that followed the 1982-83 El Niño. The removal of combined nitrogen (approximately 3 to 10 trillion grams of nitrogen per year) within zones of new or enhanced denitrification observed between 7 degrees to 16 degrees S suggests a significant increase in oceanic denitrification.