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The effect of environmental factors on filtration and the oxygen consumption rate of the rotifer Brachionus plicatilis:n a primary exploration of red tide control

Kang K.H., Seon S.C., Brzozowska R., Lee J.Y.

Oceanological and Hydrobiological Studies

2010

Vol. 39, No.1

3-9

To evaluate the potential to control red tides using the mass-cultured heterotrophic grazer, rotifer Brachionus plicatilis, the effects of environmental factors (water temperature and salinity) on physical activities (filtration and oxygen consumption rate) of B. plicatilis were estimated. Experiments were conducted at different water temperatures (15, 20, 25, 30 and 35°C) and salinities (20, 25, 30, 35 and 40 PSU), in 25 different combinations (5 temperatures × 5 salinities). Results showed that water temperature and salinity had significant effects on the filtration rate of B. plicatilis (F=41.66, P<0.05). The results of multiple regression analysis yielded the following functional dependence of filtration rate (F) on water temperature (T) and salinity (S): F=-1.658+0.917T+0.63S (R^2=0.769, P<0.001). The highest filtration rate (4.23 š0.74 μl rot-1 h-1) was obtained at 30°C and salinity 35 PSU, and the lowest one (0.869 š0.13 μl rot-1 h-1) was observed at 15°C and salinity 20 PSU. Both water temperature and salinity had significant effects on the oxygen consumption rate of B. plicatilis (F=34.08, P<0.05). The results of multiple regression analysis yielded the following functional dependence of oxygen consumption rate (O) on water temperature (T) and salinity (S): O=-3.133+0.165T+0.81S (R2=0.938, P<0.001). The highest oxygen consumption rate (5.38 š0.66 ng rot^-1 h-1) was observed at 35°C and salinity 40 PSU, and the lowest one (1.01 š0.15 μg rot^-1 h-1) was observed at 15°C and salinity 20 PSU. Results from this present study indicated that the filtration and oxygen consumption rate of the rotifer were significantly influenced by the water temperature and salinity. The utilization of rotifer for red tide control has to consider the influence of environmental factors.

Biogeochemical alteration of the benthic environment by the zebra mussel Dreissena polymorpha (Pallas)

Zaiko A., Paškauskas R., Krevš A.

Oceanologia

2010

No. 52 (4)

649-667

The aim of this study was to verify whether the biogeochemical features (e.g. concentration of nutrients, oxygen consumption, mineralization rate, Eh) of sediments changed by the zebra mussel or its shell deposits differ from those in the ambient soft bottom, and how these differences are related to the structure of benthic macroinvertebrates. In 2006 three sampling sessions were carried out in the Curonian Lagoon, SE Baltic Sea, at three pre-defined sites, corresponding to different bottom types: zebra mussel bed, zebra mussel shell deposits and bare soft sediments. Similarity analysis of biogeochemical parameters indicated that bottom sediments covered with zebra mussel shell deposits were rather distinct from the other bottom types because of the lowest total organic matter mineralization rate and highest organic carbon, total phosphorus and total nitrogen content. The parameters measured in the zebra mussel bed did not deviate conspicuously from the values observed in bare bottoms, except for the higher rate of oxygen consumption in the upper sediment layer. Unsuitable anoxic conditions on the one hand and the "attractive" shelters provided by zebra mussels on the other hand may promote the epifaunal life style in the habitats formed by dense zebra mussel clumps.