Zooplankton Carcasses Research Articles

Simple staining method for differentiating live and dead marine zooplankton in field samples

We describe and evaluate a method for the use of neutral red staining to differentiate live and dead zooplankton in marine field samples. The protocol can be easily incorporated into shipboard zooplankton sampling. The use of neutral red in laboratory studies is common, but its application for quantifying natural live/dead zooplankton composition under field conditions has not been evaluated in detail. We tested the accuracy and precision of the method for a range of salinities and temperatures, and for common estuarine zooplankton groups. Detailed descriptions of staining intensities and patterns are provided. In addition, we evaluated potential artifact mortality due to collection and sample handling. The method produced accurate results under conditions tested, and artifact mortality was negligible using the recommended protocol. Neutral red staining is ideal for quantification of zooplankton carcasses in field samples, which will allow for more systematic study of in situ zooplankton mortality and related processes.

Use of aniline blue to distinguish live and dead crustacean zooplankton composition in freshwaters

Summary1. Traditional zooplankton sampling methods do not account for the presence of zooplankton carcasses, which could lead to a biased understanding of the ecological role of zooplankton.2. The aniline blue staining method for the differentiation between live and dead freshwater crustacean zooplankton was adapted for field application and the accuracy of the new protocol was tested in the laboratory. Detailed descriptions of the characteristic staining patterns of individuals are provided. The adapted staining method was subsequently applied in a field study to assess the live–dead zooplankton composition in the oligotrophic Lake Stechlin and the eutrophic Lake Dagow in Germany.3. The modified aniline blue staining method accurately identified percentages of mixed live and dead crustacean zooplankton, making it suitable for quantifying live–dead compositions of copepods and cladocerans in freshwater samples.4. On average 6% and 8% of the zooplankton were identified as dead in Lake Stechlin and Lake Dagow, respectively. Within each lake there were no significant spatial variations in the horizontal or vertical distribution of zooplankton carcasses. Nor did the percentage of dead zooplankton differ between day and night.5. The aniline blue staining method provides an effective, simple and economical means for more systematic study of the occurrence and fate of crustacean zooplankton carcasses in freshwaters.

Preliminary observations on californium-252 behaviour in sea water, sediments and zooplankton.

We carried out radiotracer experiments on the behaviour of 252Cf in the marine environment. The particulate fraction of californium in sea water approached 45% after four days. Californium rapidly adsorbed onto marine coastal and deep-sea sediments with Kd values from 1.4 X 10(4) to greater than or equal to 1 X 10(5). The concentration of 252Cf in euphausiids reached near-equilibrium factors of 3 X 10(2) in water after one week; in contrast, the assimilation from food was very low. Excreted fecal pellets, molts and zooplankton carcasses are potentially important vectors for californium re-distribution in the oceans.