Fertilized eggs were exposed to 0.1, 10 and 100 mg/l of benzene, naphthalene and Aroclor 1254 individually and in combination in seawater at temperatures and salinities of 20 and 25. Toxicity was measured as frequencies of: (1) meiotic and mitotic abnormalities in 3-hour embryos; (2) total development to the 48-hour straight-hinge larval stage; (3) mortality and abnormality at the 48-hour larval stage; (4) mean size of larvae at 48 hours; and (5) cytogenetic and cytological abnormalities in 48-hour larvae. Dose-dependent responses were observed. Most cytogenetic aberrations were the result of abnormalities of the spindle apparatus, such as anaphase bridges and laggard chromosomes, multipolar spindles, polyploidy, aneuploidy and chromosomally mosaic embryos with different numbers of chromosomes in different embryo sectors. Micronuclei and clumped, pycnotic and deteriorating nuclei were observed in moribund larvae. Overall, naphthalene and aroclor at 100 mg/l had few embryos that survived to the stage where they could be examined and scored for cytogenetic and cytological abnormality even by 3-hours post-fertilization. Abnormality of the few embryos available for examination was somewhat higher for aroclor but was significantly higher for naphthalene than for control embryos and those exposed to 0.1 mg/l. At the highest concentration of 100 mg/l, mortality was 100% by the larval stage for naphthalene and aroclor. Though total development and survival of embryos to the larval stage at the 10 mg/l dose were high, many of the larvae were dead or abnormal in the aroclor-exposed cultures. This mean incidence was significantly higher than for all other groups. Larvae developing in these cultures with 10 mg/l were also significantly smaller and cytological condition of the larvae was significantly worse. Higher temperature appeared to increase the frequency of deleterious effects, particularly for naphthalene and aroclor. Results with salinity were more variable. Naphthalene and aroclor were more toxic than benzene. Furthermore, benzene was antagonistic in interactions with naphthalene and with aroclor. Naphthalene was acutely toxic. However, benzene was also toxic, but demonstrated more sublethal than direct effects. The PCB, aroclor, appeared to be both acutely and sublethally toxic at the doses tested. High temperature was synergistic with naphthalene and with aroclor, probably by increasing solubility and uptake. Benzene and naphthalene together in high temperature-high salinity water were more toxic than in low temperature-low salinity water. Overall, results showed that petroleum aromatic hydrocarbons and PCBs can have toxic effects on the development and survival of early life stages of oysters, as well as sublethal effects on growth and cytological condition, depending on dose and interactions with other compounds and with environmental variables. (Abstract shortened by UMI.)
| Identifer | oai:union.ndltd.org:UMASS/oai:scholarworks.umass.edu:dissertations-2713 |
| Date | 01 January 1994 |
| Creators | Stiles-Jewell, Sheila |
| Publisher | ScholarWorks@UMass Amherst |
| Source Sets | University of Massachusetts, Amherst |
| Language | English |
| Detected Language | English |
| Type | text |
| Source | Doctoral Dissertations Available from Proquest |
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