Allometric relationships in the filtration rates of the Asian clam Corbicula fluminea fed two phytoplankton species

Filtration rates (FRs) of the invasive Asian clam C. fluminea of various sizes ranging from 0.5 to 4.5 g whole-body weight were experimentally assessed under controlled laboratory conditions using two phytoplankton species of different sizes and biovolumes (Chlamydomonas reinhardtii and Pseudokirchneriella subcapitata) as food. Overall, the FRs ranged from 0 to 347 mL g⁻¹ h⁻¹ (median value: 52 mL g⁻¹ h⁻¹). We found no statistical difference (p > 0.05) between the two phytoplankton species used, nor did we find a significant relationship between individual FRs (mL individual⁻¹ h⁻¹) and wet weight (WW) or shell length (SL). However, we did find a significant negative relationship between FRs (mL g⁻¹ h⁻¹) and WW in clams fed on C. reinhardtii and P. subcapitata (FR = 131 WW^−1.05 and FR = 203 WW^−1.28, respectively), indicating that smaller (younger) individuals had a higher FR than larger (older) individuals in the tested range of particle size (i.e., 4–6 µm diameter). Such results highlight the strong influence of size/age on the filtration rate of C. fluminea and provide new insights to better understand the invasive capacity of this species.