Marine Bioassay Endpoint Pictures
The EPA1 and the California State Water Resources Control Board2 each have methods for conducting purple sea urchin, Strongylocentrotus purpuratus, larval development tests that were adapted from methods developed at SCCWRP. Lacking from these manuals are pictures of the larval endpoints, both normal and abnormal, after 72 hours of development. Located below are links to annotated pictures of normal embryos, as well as some of the categories of abnormalities. Watch this site for additional pictures as they become available.
1 “Short-term Methods for Estimating the Chronic Toxicity of Effluents and Receiving Waters to West Coast Marine and Estuarine Organisms”
2 “Procedures Manual for Conducting Toxicity Tests Developed by the Marine Bioassay Project”
Normal embryo.
This picture is of a lateral view of a normal embryo, with major structures annotated. Note the well formed gut, arm buds and skeletal rods that extend the length of the embryo.
Two normal embryos
.
Similar view to above, only with two embryos and no annotation.
Pathological post-hatch abnormality.
Note the beginning of gut formation, lack of fertilization membrane (denoted “hatching”) and the proliferation of necrotic cells at the posterior end. This is a very common abnormality in toxic samples.
Skeletal abnormality.
This picture has both a normal embryo and one with a skeletal abnormality. In the abnormal embryo, note the extra skeletal rod that is perpendicular to the usual rods and located at the apex of the embryo. This is a relatively rare abnormality.