科研之友
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摘要
AIM: To establish the dynamics of C. furcoides in horizontal and temporal scales; and to determine the main ecological factors related to its dynamics. METHODS: Samples were taken in five stations between July 2002 and July 2003. Physical and chemical variables were sampled monthly. Density was evaluated by sampling carried out within the photic zone. Growth rate (r), Turnover rate (T), Generation Time (gt), Niche Width (NW), Taylor%26apos;s Power Law, and the rate of population change (考s), were used. Canonical Correspondence Analysis (CCA) was used too. RESULTS: Total density was 264163.4 cel.L-1, the highest was found in Up R赤o Chico and the lowest in Dam. The species was more clustered in space than in time. r ranged between 0.29 and 0.3 cel.d-1, gt between 1.8 and 2.4 days, T between 0.55 and 0.42 divisions per day, NW between 0.58 and 0.72, and 考s between 0.3 d-1 and 2.3 d-1. The first three components of CCA explained 92.2% of the variation. Density was positively associated with chlorophyll a, NH4+, RWCS and wind direction. Light attenuation, NO3-, SiO2 and O2 were negatively associated with C. furcoides. DISCUSSION: C. furcoides is a S strategist; it increases its density in the warmest periods under eutrophic conditions, low light penetration and high thermal stability; it is independent of the temperature but dependent of changes in rainfall and nutrients, - especially nitrogen - and not soluble phosphorus. Up R赤o Chico presented the best conditions for the increase of C. furcoides, since this station presented the highest levels of total nitrogen, and the highest relative stability. CONCLUSION: C. furcoides has a very similar ecology to that of C. hirundinella. It is an organism highly variable in temporal and spatial scales, with a wide niche and a clustered distribution. It belongs to the Morpho-funtional Group V and to Lo and L M Assotiations. OBJETIVO: determinar a dinamica de C. furcoides em escalas horizontal e temporal, e determinar os principais fatores ecol車gicos relacionados com sua dinamica. M谷TODOS: As amostras foram coletadas em cinco esta es entre julho de 2002 e julho de 2003. As vari芍veis f赤sicas e qu赤micas foram amostrados mensalmente e a densidade foi estimada a trav谷s de coletas realizadas dentro da zona f車tica, a taxa de crescimento (r), taxa de rotatividade (T), Tempo de Gera o (GT), Largura do nicho (NW), Power Taylor%26apos;s Law, e a taxa de mudan a da popula o (考s) foram utilizados. An芍lise de Correspond那ncia Can nica (CCA) foi usado tamb谷m. RESULTADOS: A densidade total foi 264.163,4 cel.L-1, a maior foi encontrada em Up R赤o Ch
