The rocky intertidal plankton trap RIPT2: A modified device

The paper describes a modification (RIPT2) of an earlier described, passive Rocky Intertidal Plankton Trap (RIPT1) to be used in exposed rocky shores. The trap is light, simple to build, easy to install, and inexpensive. It a ims to evaluate and integrate over time the mero- and holoplankton arriving to the rocky shore. A set of 3 RIPT2 and 3 RIPT1 traps were tested, over a period of 3 days, on an exposed horizontal rocky platform at El Eden, Anto fagasta, Chile. RIPT-flowmeters permitted an approximation of the rate of w ater filtering, which was about 3 rimes greater (ranging from 1.48 to 1.69 m(3) 24 h(-1)) through the RIPT2 trap than the RIPT1 trap. Maximum water ve locities on the intertidal platforms, determined with the use of an interti dal dynamometer, ranged between 1.64 and 3.25 m s(-1). The RIPTs collected a total of 21-22 major plankton items belonging to 7-8 phyla. The individua ls ranged between approximately 100 mum (bivalve larvae) and 2720 mum (Isop oda). The cumulative (over 72 h) number of planktonic organisms collected b y RIPT2 was significantly greater than those collected by RIPT1 traps.