Morphometric changes in the cultured starry flounder, Platichthys stellatus, in open marine ranching areas.

Hatchery seeds released into open coasts for wildstock enhancement are often a biological pollutant and affect the recipient ecosystem integrity. We studied morphological changes in two hatchery populations of the starry flounder Platichthys stellatus; one released into the open coast from the hatchery (released population) and the other kept in the hatchery (captive population). The released population differed significantly from the captive population 3-36 months after release from the hatchery. Two-way ANOVA comparison revealed that 11 of 15 starry flounders differed significantly in morphological measurements, 10 of 15 differed in pigmentation, and 5 of 15 differed in morphometric ratios between the two populations. Pigmentation on the blind side (a representative sign of captive flounders) also differed between the two populations with an occurrence rate of 22.7% for the former and 39.5% for the latter groups. The released population was more similar to wild populations than to captive populations in terms of morphology; namely, longer and broader heads, a narrower body shape, longer fins, and a shorter and narrower peduncle.

Live algae as a vector candidate for hydrophobic polychlorinated biphenyls translocation to bivalve filter feeders for laboratory toxicity test.

Live algae carrying hydrophobic xenobiotics can be an effective vector candidate for the chemical translocation to filter feeders in the laboratory toxicity test, but information on their application is lacking. Time-course uptake and elimination of polychlorinated biphenyls (PCBs) (0, 50, 100, and 500 ng g-1) by two key algal foods, Isochrysis galbana and Tetraselmis suecica, were measured. Both of the algae achieved maximum concentration in an hour after PCBs exposure regardless the chemical concentrations in our time-course measurements (0, 1, 5, 10, 24, 48 and 72 hrs). Once achieved the maximum concentration, the algae shortly exhibited elimination or eliminating tendency depending on the chemical concentrations. Algae exposed to the chemical for 1 and 24 hrs (hereafter 1 and 24 hr vectors, respectively) were then evaluated as a chemical translocation vector by feeding test to larval and spat Crassostrea gigas. In the feeding test the 24 hr vector, which contained lower chemicals than the 1-hr vector, appeared to be more damaging the early lives of the oyster. This was particularly significant for vectors of higher PCBs (p<0.05), probably due to algal reduction in food value by the prolonged chemical stress. These findings imply that 1 hr exposure is long enough for a generation of algal vector for laboratory toxicity test, minimizing data error resulted from reduction in food value by longer chemical stress.