Aquatic macroinvertebrates of Nee Soon 
99 
Fig. 18. Distribution and abundance of order Veneroida in the Nee Soon drainage. Solid 
circles indicate sites where representatives were collected and circle sizes are proportionate to 
abundance/numbers of individuals captured as reflected in the accompanying legend. 
Order Veneroida 
The order Veneroida is generally made up of marine bivalves, but with some freshwater 
representatives. In the Nee Soon drainage, two families (Corbiculidae and Sphaeriidae) 
from the order can be found, and both were recorded at site 32 in relatively high numbers 
(Fig. 18). At site 32, 125 Corbiculidae individuals and three Sphaeriidae individuals 
were recorded. Like the gastropods, bivalves are intolerant of acidic conditions, which 
could affect their survival, growth and shell integrity (Bressan et al., 2014). They are 
completely absent from the rest of the Nee Soon drainage, possibly due to the effects 
of low pH on their shells. 
