Sediment-induced reduction in the pumping rate of the tropical sponge Verongia lacunosa

The pumping rate of Verongia lacunosa (Lamarck), a tropical marine sponge, varied between 1 and 6 l h^-1 in clear seawater for sponges with a volume of about 500 ml. Sponges were exposed to seawater containing suspensions of clay maintained at a constant level for 4 h; concentrations of 11 mg l^-1 or greater significantly reduced the pumping rate, while concentrations of 3 mg l^-1 did not. Other sponges were exposed to suspensions of clay for 4 days; a concentration of 95 mg l^-1 caused a continuing decline in the pumping rate. These sponges were more sensitive to sediment than some other suspension-feeding organisms. Such sensitivity may limit the distribution of V. lacunosa and other sponge species.Please address requests for reprints to A.O. Flechsig at the address shown above.