The effects of ultraviolet radiation on the covering behavior of the sea urchin Tripneustes ventricosus
Recent studies have indicated that levels of solar ultraviolet radiation (UVR) are increasing globally as ozone is depleted. Ultraviolet radiation often has negative effects on organism survival; in sea urchins, UVR has been found to reduce sperm motility (reducing fertilization success) and to increase the occurrence of abnormal embryonic development (decreasing embryonic survival). Several species of sea urchins cover themselves with rubble; this study examined how this behavior was affected by UVR in situ. Three types of treatment boxes were placed over Tripneustes ventricosus specimens: a control box, a UVR-blocking box, and an opaque box. Specimens were photographed before and after treatment and percent change in rubble cover was calculated for each individual. The mean change in percent rubble cover presented significant reduction under opaque conditions relative to other treatment conditions (p = 0.005, p = 0.010). There was no significant difference between the latter two treatment groups (p = 0.980). The data suggest that covering behavior in T. ventricosus is not a response specific to UVR, but is a response to light. Further studies of how UVR affects T. ventricosus and as well as how other species cover themselves in response to sunlight and UVR are needed to understand the benefits of covering behavior in elevated UVR climate conditions. Further study on the costs and benefits of covering behavior as well as studies on the covering and sheltering behaviors of other sea urchins is needed to gain a full understanding of how increasing UVR will affect sea urchins.
This student research was retrieved from Physis: Journal of Marine Science XVIII (Fall 2015)19: 27-33 from CIEE Bonaire.