The mussel Perna viridisis used in the Philippine saxitoxin monitoring program as an indicator organism
for the presence of saxitoxin in shellfish in an effort to assess concentration beyond a level considered safe
for public consumption. Saxitoxin bioaccumulates in mussels through ingestion of saxitoxin-producing
algae Pyrodinium bahamense var. compressum(Pbc). This study focuses on the relationship between mussel
length and mussel toxicity in mussels exposed to a natural bloom of Pbc. Mussel toxicity was assessed
weekly in a 134-day sampling period using Receptor Binding Assay (RBA). Smaller mussels are more toxic
than larger mussels at low Pbc cell density (≈ 102
cells/L) and the reverse is true at higher Pbc cell density
(≈ 5×103
cells/L). These results can be useful in developing strategies for the collection of mussel samples
in a toxic algal bloom monitoring program