Shoaling behaviour enhances risk of predation from multiple predator guilds in a marine fish
John Ford and Stephen Swearer (2012)
Fig. S1 An artificial reef unit, composed of 10 milk crates arranged 2-high in an X shape and covered with
a 1.2m x 1.6m PVC sheet. Each crate was filled with bricks, either solid or with small holes, for a total of
192 holes per reef unit. Total volume, including spaces between crates, was 0.75m3, and the volume of
crates only was 0.41m3. Reefs were fouled before the experiment commenced and supported a diverse
community of encrusting invertebrates and algae, most prominently ascidians, polychaetes, bryozoans
and sponges. In the main experiment, 50 juveniles of the southern hulafish, Trachinops caudimaculatus,
were placed on each of twelve artificial reefs manipulated in a crossed factorial design of either the
presence or absence of the benthic and pelagic predator guilds. Benthic predators were removed
manually by divers on SCUBA, before reefs were dismantled to remove remaining cryptic predators, and
the reefs then rebuilt. Pelagic predators were excluded using 6mm diamond stretch mesh nets covering
the reef. Subsequent colonisation of all reefs by benthic predators resulted in variable abundances
amongst reefs in later weeks.