ISSN:
1365-2427
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Biology
Notes:
1. Benthivorous fish may play an important role in internal nutrient loading. Ruffe are highly specialised, feeding exclusively on bottom animals; thus all nutrients released via their feeding are derived from the bottom and are new to the water column. The fish can also release nutrients from the sediment through resuspension while searching for food.2. The aim of this study was to estimate experimentally in the laboratory the effect on water quality of resuspension and nutrient release by ruffe and bottom animals (chironomids).3. Ruffe released nutrients during 8 h experiments as follows: total P 1.4, dissolved PO4 0.6, total N 24.0 and NH4-N 15.9 μg g−1 WW h−1. A decreasing trend in mass-specific release was observed over time, probably because of starvation. The mass-specific release of total N and NH4-N decreased as the mean weight of fish increased. The mean ratio of excreted N : P was 32.4. In 26 h experiments with sediment and both ruffe and chironomids, ruffe increased nutrient concentrations and turbidity values significantly but chironomids had an effect only on turbidity. Neither ruffe nor chironomids affected the ratio of inorganic N : P concentrations. An interaction between ruffe and chironomids was found for turbidity.5. According to these results, benthivorous fish may increase nutrient concentrations in the water column and need to be taken into account when estimating internal loading.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1365-2427.2005.01331.x
Permalink