Graduation Year


Document Type




Degree Granting Department


Major Professor

John Lawrence, Ph.D.

Committee Member

James Garey, Ph.D.

Committee Member

Gordon Fox, Ph.D.


Sea grass, Algae, Pollution, Heavy metals, Toxicology


Small amounts of chromium (VI) are carcinogenic in mammals. Concentrations of Cr in marine algae and seagrasses range from 0.06-7.17 /g DW and 0.1-30.6 g/g DW respectively. To test for an effect of these concentrations, production (change in organic material), righting response, feeding rates, absorption efficiency and fecal production were measured in Lytechinus variegatus from Sarasota fed prepared diets containing 0, 4.1, and 32g Cr/ g DW and individuals from Ft. DeSoto fed diets containing 0, 41 and 82g Cr/ g DW. The urchins were fed for 4-5 weeks, with weekly measurements of their feeding rates, absorption efficiency and fecal production. At the end of the experiment the urchins were righted to note any changes in behavior. Their gonads, gut, lantern and test with spines were weighed and ashed to calculate gonadal and gut indices and inorganic and organic percentage and content. After five weeks individuals in all treatments from experiment one showed no significant results. Urchins in all treatments from experiment two showed a significant decrease Individuals in all treatments had a significant increase in wet (P<0.001) and dry (P=0.005) weights as well as total organic material (P<0.001) in the gut of the urchins recieveing 82µg Cr/ g DW. There was significant decrease in the feeding rate (P<0.001) and absorption efficiency (P<0.001), countered by a significant increase in fecal production. The righting times were significantly different between the 0µg Cr/ g dry weight, 82µg Cr/ g DW and initial (P=0.031), but not the 41µg Cr/ g DW. Chromium in the feed at the concentrations used in this experiment does not affect the production or absorption efficiency of Lytechinus variegatus, but it does affect feeding rates, fecal production and righting response.