Swimming in the rain

Posted on May 26, 2009

Small terrestrial arthropods, such as springtails, beetles, ants and flies, that drop into streams are an important food source for fish.  In a tropical (Hong Kong) study, terrestrial arthropods contributed up to 43% (by volume) of the diet of a local species of cyprinid fish (Parazacco spilurus ).   

Arthropod “rain” into forest streams was estimated at about 20 grams dry weight per square metre per year.  The corresponding estimate for shrubland streams was about 25% lower (c. 15 grams).   These estimates were higher than those made in previous studies on temperate streams inJapanandOregon(9-14 grams).  

Reference:  Eric K. W. Chan, Yixin Zhang and David Dudgeon.  2008.   Arthropod ‘rain’ into tropical streams: the importance of intact riparian forest and influences on fish diets.  Marine and Freshwater Research  59, 653-660.