MEPS 327:223-232 (2006)  -  doi:10.3354/meps327223

Toxic haptophyte Prymnesium parvum affects grazing, survival, egestion and egg production of the calanoid copepods Eurytemora affinis and Acartia bifilosa

Sanna Sopanen1,*, Marja Koski2, Pirjo Kuuppo1, Pauliina Uronen1,3, Catherine Legrand4, Timo Tamminen1

1Finnish Environment Institute (SYKE), PO Box 140, 00251 Helsinki, Finland
2Danish Institute for Fisheries Research, Kavalergården 6, 2920 Charlottenlund, Denmark
3Tvärminne Zoological Station, 10900 Hanko, Finland
4Marine Sciences Department, University of Kalmar, 39182 Kalmar, Sweden

ABSTRACT: Nitrogen- and phosphorus-depleted or NP-balanced toxic haptophyte Prymnesium parvum was fed to 2 dominant copepod species of the northern Baltic Sea (Eurytemora affinis and Acartia bifilosa), and their ingestion, egg and faecal pellet production rates and mortality were measured. The copepods were incubated in 5 different cell concentrations of P. parvum for 3 consecutive days; the cryptophyte Rhodomonas salina was used as a control for non-toxic, nutritionally high-quality food. Toxicity (haemolytic activity) of P. parvum was measured before and after the incubations. The haemolytic activity of P. parvum was the highest in cultures grown under nutrient deficiency. The toxicity decreased after 1 d incubation in all treatments, in both the presence and absence of copepods. Neither of the copepod species ingested P. parvum, irrespective of the nutrient treatment (toxicity) or cell concentration, and the pellet and egg production rates were correspondingly low. Although there was no significant increase in mortality in P. parvum treatments, copepods that were exposed to P. parvum in any concentration or nutrient treatment soon became inactive. It was evident that the toxicity of even nutrient-replete P. parvum had an indirect and sublethal influence on copepods, although this could not be measured as short-term increased mortality. Our results suggest a strong reduction in secondary production of copepods in an event of a P. parvum bloom.

KEY WORDS: Prymnesium parvum · Feeding · Toxicity · Food quality · Nutrient limitation · Acartia bifilosa · Eurytemora affinis · Copepods

Full text in pdf format