Seasonal fluctuation of planktonic rotifers in Azibo reservoir (Portugal)

Abstract

The rotifers of the recently-commissioned Azibo reservoir were studied during two years. The community was similar to that of other Portuguese reservoirs with Keratella cochlearis, Polyarthra spp., Asplanchna priodonta and Collotheca pelagica dominant, although densities varied strongly. Maximum rotifer density was 640 ind 1-' in 1987 and 315 ind I-' in 1988. During the first year two density peaks were observed, while in the second year fluctuations were irregular. Phytoplankton availability was considered the main reason for the fluctuation of rotifer density, although temperature, dissolved oxygen and cladoceran interference may also have played a role. A high density of AnabaenaJlos-aquae might have facilitated the dominance of K. cochlearis in 1988.

Environmental Impact Assessment of Aquaculture Practices Using Zooplankton in Lake Mariout, Alexandria, Egypt

“…Rotifera formed 91.82% of the total zooplankton density; its maximum density was recorded during spring, and this is due to the increasing trophic status. Similar observation was reported in the studies of Vasconcelos (1994) and Abdel Aziz and Aboul Ezz (2004) who mentioned that, the availability of phytoplankton is considered to be the main reason for the fluctuation of rotifer density. Moreover, the current finding coincides with the report of Paturej (2008) who showed that the density of rotifers increases significantly with increasing trophic state elsewhere.…”

The impact of agricultural drains on water quality and Phyto- zooplankton communities in fish farms, Egypt.

“…Increasing densities in ponds may be attributed to high density of phytoplankton. This complied with Vasconcelos (1994), who concluded that the phytoplankton availability was considered the main reason for fluctuation of zooplankton density, although temperature and dissolved oxygen interference may also have played a role. But the low number of zooplankton in drains may be related to the decrease in nutrients concentration, where it covered with macrophytes and hence depriving the water from its nutrient and suppressing the phytoplankton growth and decreasing zooplankton.…”

Seasonal development of planktonic rotifers in Slapy Reservoir (Czech Republic)

“…The 38 species found is a relatively low number in comparison with natural lakes (Virro 1996), but is common in deep reservoirs (De Manuel & Armengol 1993;Vasconcelos 1994;Devetter 1998bDevetter , 2004. Fluctuation of the diversity index does not show any strong trend apart from a regular decrease around the end of the year.…”

“…The seasonal fluctuation of individual species generally corresponds to their common habits (Vasconcelos 1994). However, typical population phases in many species, such as the start of population development or maxima, were synchronized through the years.…”

“…A number of studies dealing with species composition and seasonal fluctuation of rotifer communities in reservoirs were conducted during the last few years in the Czech Republic (Kubíček 1959(Kubíček , 1968Kubíček et al 1965;Devetter 1998a, b;Seďa & Devetter 2000;Devetter & Seďa 2003) as well as other European countries (Manuel & Armengol 1993;Vasconcelos 1994;Dohet & Hoffmann 1995;Hudec 2000).…”