3.4.5 Troubleshooting

Cultures will fail to grow, will become overly contaminated with competing micro organisms or will crash even in the best-run hatcheries. Below are some pointers to check to determine the source of such failures.

1. Air supply. Is there adequate air entering the cultures? Are the cells sedimenting to the bottom of the culture vessel? This may happen when culturing certain diatoms, in which case the air flow rate should be increased. It should not happen in the case of commonly cultured flagellates. If it does, then the problem lies elsewhere.
2. Temperature. Check min/max thermometer. Were there any increases or decreases in the temperature of the algal culture facility over the past 24 hours? Most of the commonly cultured algal species cannot tolerate temperatures above 26oC for extended periods – or temperatures below 12oC. Temperatures in the range 18 to 22oC are ideal.
3. pH. Check CO2 supply. Is the CO2 cylinder empty? Check pH of the algal cultures using a pH probe. Is the pH too high (above 8.5)? Is the pH too low (below 7.5)? Adjust the CO2 supply accordingly.
4. Nutrients. Check records for the last time the cultures received nutrients. This is particularly important for semi-continuous cultures.

5. Contamination. Are the walls of the culture container, particularly at the water/air interface, visibly foaming or fouled with what appears to be detritus? If so, the culture is at the end of its useful life and needs to be replaced. If this is a continuing problem in the early stages of the culture cycle with a particular species, then check the starter cultures for signs of contaminating organisms and replace them as necessary.
Not all species can be cultured successfully during the entire season. Some have particular “windows of opportunity” when they can be grown reliably. However, there is no consistency between hatcheries as to when a named species will grow well or will not. This has to be learned through on-site experience and highlights the importance of maintaining thorough records.