Biometrics of the Danube Delta ecosystem


What: Biological diversity is an essential preoccupation of modern science, becoming a basic concept, not only for specialists in biology or ecology, but also for other areas. Danube Delta is one of the world's largest wetlands, the largest compact area of reed thicket of the planet and a gene bank for the universal natural heritage. It also represents complex of ecosystems, characterized by a specific diversity. The uniqueness of the ecological characteristics of the Danube Delta, the only delta in the world declared a Biosphere Reservation, has imposed the necessity of long-term ecological studies.
Statistical graph
Why: Long-term measurements on planktonic communities in lakes Matita and Merhei, representative lakes for the lacustrine ecosystems of the Danube Delta, surprised three distinct phases in the diversity dynamics and abundance of phyto-and zooplankton in relation to trophic state. The dynamic of species, represented by the number of species and diversity as a function of habitat productivity (represented by the variable category) and habitat magnitude (represented by lake) was investigated using completely randomized design.
Unequally spaced and unbalanced measurements were performed from 1980 on two lakes from Danube delta. The study had consistent measurements for almost one decade and a half, but data recording was interrupted for more 12 years, which increased the complexity of the design analysis by introducing the repeated measures component. The model used to assess the species dynamics was a general linear model. To reduce the impact of the unbalanced –unequally spaced measurements on the estimates, the computations were performed using maximum likelihood estimation method.