Grantee Research Project Results
Final Report: Uptake and Effects of Dispersed Oil Droplets and Emulsified Oil by Estuarine Crustaceans in the Gulf of Mexico
EPA Grant Number: R835184Title: Uptake and Effects of Dispersed Oil Droplets and Emulsified Oil by Estuarine Crustaceans in the Gulf of Mexico
Investigators: Lee, Richard F , Chung, J Sook , Snyder, Christopher , Perry, Harriet
Institution: Skidaway Institute of Oceanography , University of Maryland Center for Environmental Science , University of Southern Mississippi
EPA Project Officer: Aja, Hayley
Project Period: May 1, 2012 through April 30, 2015
Project Amount: $476,553
RFA: Environmental Impact and Mitigation of Oil Spills (2011) RFA Text | Recipients Lists
Research Category: Ecological Indicators/Assessment/Restoration , Aquatic Ecosystems
Objective:
- To determine the uptake of petroleum hydrocarbons and dispersants by blue crab and grass shrimp embryos and larvae exposed to dispersed oil droplets in seawater.
- To determine the uptake of petroleum hydrocarbons by juvenile blue crabs and grass shrimp exposed to sediments containing emulsified oil.
- The effects on molting, molting hormones, genes mediating molting, embryogenesis and DNA strand breaks of blue crab and grass shrimp exposed to dispersed and emulsified oil.
- The establishment and implementation of a Community Outreach for Accurate Science Translation teams in 4 communities in the north central Gulf of Mexico coastline. These teams will be part of proposed project and will develop public presentations on the project and its results.
Summary/Accomplishments (Outputs/Outcomes):
Introduction
This project had research and community outreach components with a focus on commercial shellfish affected by the Deepwater Horizon spill in the Gulf of Mexico. The following two research projects were completed: (1) The fate of water-in-oil emulsions in estuaries and the effects of these emulsions on grass shrimp and blue crabs; (2) Effects of dispersed oil droplets on molting processes (molting, ecdysteroids, EcR/RXR complexes) on grass shrimp embryogenesis. The co-operative research was carried out by investigators at the Skidaway Institute of Oceanography University of Georgia (R. Lee), Gulf Coast Research Laboratory at the University of Southern Mississippi (H. Perry), and the Institute of Marine and Environmental Technology at University of Maryland Center for Environmental Sciences (J.S. Chung). The community outreach phase of the project was carried out at the Marine Education Center of the Gulf Coast Research Laboratory at the University of Southern Mississippi (C. Snyder and K. Kastler) and involved members of Gulf of Mexico coastal communities. This outreach included several events and training sessions that linked ongoing oil spill research to concerns of the community about the effects of the oil spill on Gulf of Mexico shellfish.
Fate and Effects of Emulsions Produced after Oil Spills
A. Stable water-in-oil emulsions, often formed after oil spills, contribute to the difficulties of cleanup due to their persistence and high viscosity (Fig. 1). Our objectives were to determine the fate and effects of these emulsions on grass shrimp (Palaemonetes pugio) and blue crabs (Callinectes sapidus) after the entrance of emulsions into estuaries. Reproductive parameters (ovary development, embryo production) of adult grass shrimp were assessed after exposure of juveniles to mesocosm sediments with emulsified oil, sediments with non-emulsifed oil and reference sediments. There was a significant reduction in grass shrimp embryo production after exposure to sediments with emulsified oil compared to shrimp exposed to reference or non-emulsifed oiled sediments (Table 1). Grass shrimp embryos exposed to pore water from emulsified oiled sediments resulted in significantly more DNA strand breaks (comet assay) and reduced embryo hatching rates compared to embryos exposed to reference or non-emulsifed oiled sediments (Table 2).
B. In addition to work with oiled sediments, a histological study was conducted on juvenile blue crabs from the Gulf of Mexico (provided by H. Perry) fed food containing emulsified oil. The most notable effect was distended hemocytes with large amounts of glycoproteins in the hepatopancreas (Fig. 2). It is speculated that crabs with these distended hemocytes are less able to deal with invading microbes, since crab hemocytes are an important part of crabs immune system.
C. Changes in polycyclic aromatic hydrocarbons (PAHs) concentrations were followed in cores taken from mesocosms containing emulsified oiled sediments, non-emulsifed oiled sediments and reference sediments. PAH concentrations in emulsified oiled sediments decreased from 284 to 7 µg/g sediment in 56 days, while in the mesocosm with non-emulsifed oil the PAHs decreased from 271 to 0.2 µg/g sediment over the same time period (Fig. 3). Oiled sediments showed a typical petrogenic PAH profile with high concentrations of lower molecular weight alkylated PAHs, e.g. methylnaphthalenes and phenanthrenes. Control sediment had a low concentration of total PAHs (0.1 µg/g sediment) composed of high molecular weight pyrogenic type PAHs (4-5 ringed nonalkylated PAHs).
Effects of Dispersed Oil Droplets on Molting Processes (Molting/Hatching, Ecdysteroids, EcR/RXR Complex) during Grass Shrimp Embryogenesis
A. Dispersed Oil Droplets
Subsurface plumes of small, stable dispersed oil droplets have been observed when oil spills are treated with dispersants (Fig. 4) (Lichenthaler and Daling, 1985; McAuliffe et al., 1981). Exposure of crustaceans to oil components, particularly polycyclic aromatic hydrocarbons (PAHs) can cause molting problems. (Cantelmo et al., 1982; Karinen and Rice, 1975; Mothershead and Hale, 1992; Weis et al., 1992) and the effects of dispersed oil droplets on the molting process was the focus of present study.
B. Effects of Oil Droplets on Hatching/Molting on Embryos
1. Introduction
Developing embryos attached to the female grass shrimp, pass through 10 developmental stages with a prezoeal molt taking place before hatching with nutrients and energy provided by the yolk (Fig. 5) (Broad, 1957; Glas et al., 1997; Lee et al., 2013, Nazari et al., 2000). During late embryogenesis the embryo wall/membrane becomes very permeable, as seawater is taken up to facilitate hatching from the egg sac, and at this time there can be uptake of large macromolecules (Davis, 1965; Glas et al., 1997.
2. Uptake and effects of dispersed oil droplet exposure on hatching/molting of different embryo stages.
When early embryo stages (stages 1-6) were exposed to various concentrations of oil droplets (800 to 8000 droplets/ml), droplets were not observed within the embryos. However, late embryo stages (stages 7-10) ingested oil droplets (80 to 220 droplets/ embryo) after oil droplet exposure. Droplet concentrations were converted to oil concentrations using the density of the oil, diameter of the mean oil droplets and number of droplets per ml.
Hatching/molting success was significantly reduced after stages 7 and 8 were exposed to different oil droplet concentrations. However, stage 9 hatching/molting success was only reduced at the highest concentration. One explanation for the different results with different embryo stages may be that by stage 9 the hatching/molting process is far enough along that only the highest droplet number disrupts this process.
Fig. 6 reports the hatching/molting success rates of stages 7-10 exposed to various oil droplet concentrations. While between 85 and 100% of the controls hatched and molted into the swimming zoea stage, hatching success was significantly reduced in stages 7-9 after exposure to droplet concentrations >4080 droplets/ml. Stage 10 embryos hatching/molting success was only effected at a 8300 droplets/ml concentration. EC50 values, where oil droplets reduced hatching/molting success by 50%, ranged from 4200 droplets/ml (stage 7) to 8300 droplets/m (stage 10).
C. Effects of Oil Droplets on Ecdysteroid Concentrations and on Expression of the Ecdysone Receptor/Retinoic Acid receptors.
1. Introduction
Molting in crustaceans is regulated by hormones (ecdysteroids) and the action of these hormones is mediated by the ecdysone receptor (EcR)/retinoic acid receptor (RXR) complex (Mykles, 2011; Zou, 2005). Changes in the edcysteroid titers were observed in grass shrimp exposed to xenobiotics, including PAHs, and it has been suggested that PAHs affect expression of the EcR/RXR complex (Oberdorster et al. 1999, 2000; Tuberty and McKenney, 2005). We determined changes in ecdysteroid concentrations and the EcR/RXR gene expression during grass shrimp, Palamonetes pugio, embryogenesis after oil droplet exposures.
2. Changes in Ecdysteroid Levels during Embryogenesis and Effects of Oil Droplet Exposure
Total ecdysteroid concentrations were relatively low in stages 1 through 8 (8 to 12 pg/embryo) followed by dramatic increase from stage 8 to 9 (12 to 50 pg/embryo), remaining high in stage 10, and then decreased to 25 pg/embryo in the stage 11 swimming zoea stage (Fig. 7). Ecdysteroid concentrations in stages 7-8, 8-9 and 9-10 were determined after embryos were exposed to 3 different oil droplet concentrations (4080,6100 and 8250 droplets/ml). Since early embryo stages (stages 1-6) did not show evidence of oil uptake these stages were not exposed to oil for this aspect of the study. Only stage 7-8 embryos exposed to 6100 and 8250 droplets/ml showed a significant drop in ecdysteroid levels compared to controls (12 TO 5 pg/embryo) (Fig. 8)
3. Changes in PapEcR and RXR Expression During Embryogenesis
Changes in PapEcR and RXR expression (copies/µg of total RNA) during embryogenesis are shown in Fig. 9 & 10. PapEcR expression was low in stages 1 to 3 (700 copies/µg of total RNA), increased to 2100 and 6000 copies/µg of total RNA in stages 4 and 7, respectively, followed by a decrease to 5000 and 2000 copies/ µg of total RNA in stages 9 and 10, respectively (Fig. 9). In contrast, RXR expression values during embryogenesis were highly variable and showed no consistent increase or decrease.
4. Changes in PapEcR Expression After Oil Droplet Exposure
When stages 7-8 and 8-9 were exposed to 3 different concentrations of oil droplets, there were significant increases in EcR expression in oil exposed embryos compared with controls (Fig 10). Stage 7-8 embryos showed the most pronounced effect of oil drop exposure on EcR expression. RXR expression in the different embryo stages were not significantly effects by oil droplet exposure (data not presented).
D. Discussion of Results
Filter feeding crustacean zooplankton can ingest dispersed oil droplets (Conover, 1971) but few studies have examined the effects on crustacean embryos as a result of dispersed oil uptake. We observed little or no oil uptake during early embryogenesis (Stages1-6), but droplet ingestion occurred in late embryogenesis (stages 7-9). Egg sac membranes become more permeable to seawater and associated particles during late embryogenesis (Davis, 1965; Glas et al., 1997).
1. Ecdysteroids
Since embryo development in grass shrimp ends with a prezoeal molt followed by hatching into a swimming zoeal stage (Broad, 1957), our oil droplet effect studies focused on ecdysteroids and molting gene expression during late embryogenesis. In our studies with grass shrimp embryos the ecdysteroid levels increased dramatically in late embryogenesis (from 8 to 50 pg/embryo) followed by a decrease to 25 pg/embryo in the zoea stage (Fig. 7). Spindler et al, (1987) noted a continuous increase in total ecdysteroids during embryogenesis of Palaemon erratus with concentrations reaching 25 pg/embryo in late embryo stages. Similar studies Techa et al. (2015) found ecdysteroid increased during blue crab embryogenesis with a peak at 20 pg/embryo in late stages. The low concentrations of ecdysteroids found in early embryo stages is these studies were likely maternally derived while the large increases in ecdysteroid concentrations in late embryo stages were due to synthesis in the Y-organ. The Y-organ has been shown to be an important tissue in crustacean ecdysteroid synthesis and large increase in ecdysteroid levels in late embryo stages were associated with the appearance of Y-organs (McCarthy and Skinner, 1979; Spindler et al, 1987). Juvenile crabs during a molt cycle show similar changes in ecdysteroid levels, i.e. large increases before molting begins followed by decreases after molting is completed (Chung, 2010; Techa and Chung, 2013). In addition to the Y-organ, the X-organ in the eyestalk play an important role in regulating crustacean ecdysteroids levels (Chang, 1993). In the present studies with grass shrimp the peak of ecdysteroid occurred at the stage when the embryonic eye appeared (stage 9).
After oil droplet exposure, ecdysteroid decreases were observed in late embryo stages compared to controls. A number of studies have shown that environmental chemicals, including polycyclic aromatic hydrocarbons, can affect crustacean ecdysteroid levels (Mu and LeBlanc, 2002; Rodriguez et al., 2007; Tuberty and McKinney, 2005; Zou, 2005). The ecdysone 20-monoxygenase, a cytochrome P450 system found in crustacean Y-organs plays an important role in ecdysteroid synthesis. We speculate that effects of oil droplets on ecdysteroids levels are due to effects of PAHs on cytochrome P450 systems in the Y- and/or the X-organs. The binding of PAHs to cytochrome P450, known to occur in crustaceans and other animals (Brouwer and Lee, 2007; Szklar and Paulsen, 2002) could decrease the levels of ecdysteroids by inhibiting synthesis or stimulating metabolism of ecdysteroids.
2. Ecdysone receptor
Ecdysteroids are regulated by binding to the ecdysteroid receptor, EcR. EcR binds to various ecdysone response elements as a heterodimer to transactivate several target genes. At present, the gene regulation model for some receptors assumes that the unliganded receptor is bound to hormone response elements and silences activity by an associating with a corepressor (Mykles, 2011; Nakagawa and Henrich, 2009) Thus, binding of an environmental chemical like PAHs to EcR could affect expression of EcR and ecdysteroid signaling.
EcR expression in grass shrimp was low during early embryogenesis, increased in middle embryogenesis and decreased in late embryo stages (Fig. 9). Similar changes in EcR expression were observed during embryogenesis of blue crabs (Techa et al., 2015). Thus the peak of EcR expression occurs before the ecdysteroid peak in embryos of both grass shrimp and blue crabs. The Y-organ and X-organ are important sites for the expression of EcR in crustaceans (Techa and Chung, 1983) and presumably are the site for EcR expression during embryo development.
In grass shrimp embryos dispersed oil droplet uptake results in a decrease in ecdysteroid concentrations but a stimulation of EcR expression. Both stimulation and repression of EcR expression has been observed in crustaceans. Tarrant et al. (2012) found elevated EcR in lobsters with epizootic shell disease, while EcR expression was repressed in copepods exposed to bisphenol A (Hwang et al., 2010). Zou (2005) suggested that xenobiotic exposure in crustaceans can interfere with ecdysteroid signaling by direct binding of the xenobiotic to EcR. Clearly, more studies are necessary to understand how environmental chemicals interact with EcR expression and how this interaction may affect the molting process.
Outreach
Community outreach was an important component of this EPA grant, and took place from March through June 2013, when grant-funded research was just beginning to yield results in Georgia and Maryland. Agencies that sponsored related research as part of the Natural Resources Damage Assessment (conducted by Co-Investigator Perry) were unwilling to allow outreach to share specific details of this research being conducted in Mississippi, which further limited opportunities to engage members of the public directly in research activities. However, members of the public on the Gulf Coast who were the intended audience for outreach were still struggling to understand how science was contributing to oil spill activities and identify real news and credible sources of information among the many contributions to the public body of spill-related information. An outreach project was developed to 1) conduct training in the role of science during such an emergency, 2) discuss how to judge the credibility of diverse info sources related to the oil spill and 3) introduce ways research is carrying out these roles using the specific example of the funded project. The research component of this EPA grant was on the effects of dispersed and emulsified oil on estuarine crustaceans in the Gulf of Mexico and the outreach activities presented early results of this research to the Gulf community. Twenty five citizen scientist volunteers were selected to be the Community Outreach for Accurate Science Translation (COAST), which received 48 hours of training, including lectures, lab exercises, field studies and interaction with researchers at the University of Southern Mississippi Gulf Coast Research Laboratory. Sessions were facilitated by staff of the Marine Education Center and products included an outreach event attended by more than 300 members of the public, a web page describing COAST team activities, a video of COAST team training, fact sheets concerning oil effects, and a poster describing activities of the COAST team.
Community Outreach for Accurate Science Translation: COAST Team
Recruitment: Members of Gulf coast communities were invited to apply be members of the COAST team. Presentations in various coastal communities, posters, television, radio and newspaper articles were used to advertise this outreach activity. From 50 applications, MEC staff selected 25 team members based on interviews. The team was highly diverse and included recreational fishermen, commercial shrimpers, a member of the US Coast Guard, members of the Vietnamese American Fisher Folks and Families (MSCVAFF), fisheries biologists, graduate students, a Girl Scout leader, the owner of eco tour company, naturalists, a writer, primary and secondary school teachers, a national park ranger, a librarian, an oil spill first responder, scuba instructors, newspaper reporter, and retirees. Two of them were closely associated with GCRL and were designated as advisors rather than volunteers (Abrams, Shaw). Additional team members included project investigators (Lee and Perry, research; Snyder, outreach) and two MEC staff (Kastler, outreach leader, and Lamey, project coordinator). Very short biographies of team members are included in the Appendix. Additional people who worked with the COAST team in limited ways include Lynn Rabren of New Point Media, who produced a video documenting the project and the crew of the RV McIlwain.
Retention: Twenty two of the COAST Team citizen scientists attended meetings and participated in the culminating outreach event. One was forced to terminate his participation because of the unanticipated health crisis of a family member. A second stopped attending after Session 4 when it was time for team members to develop their outreach products. The third, who had been a first responder at the oil spill site, told the outreach leader after several meetings that he was uncomfortable with comments made by some in the class that BP had not worked adequately to prevent or respond to the spill. He contended that BP is a stand-up company by comparison with others that had caused spills (to which he responded) that had just declared bankruptcy and left the cleanup to others. Recognizing the difficulty of listening to enduring anger from others while he retained a different perspective, the outreach leader (Kastler) worked with him to voice his opinions. He remained uncomfortable and did not return after Session 3. This was a disappointment because his opinion, while rare among the volunteers, was respectable, represented many residents employed in industry and their families and worthy of sharing broadly.
Products Our Coast Three Years Later: Oil Spills and Gulf Ecology
An outreach event for the general public was held at the Mary C. OKeefe Cultural Center for Arts and Education (the Mary C) on June 1, 2013. COAST Team citizen scientists set up booths including oil and dispersant demonstrations, plankton observation, oral presentations and sharing of the four fact sheet they developed. This activity was conducted in collaboration with Mississippi Alabama Sea Grant Consortium, which sponsored the purchase of Gulf shrimp that the chef of the Mary C cooked into shrimp tacos for a tasting booth. The Mary C also engaged two artists to work during the event. One conducted an activity that allowed children to create a painting using an emulsion containing marine algae. The other painted her interpretation of oil spill experiences shared by members of the public who attended the event. Attendance was estimated at more than 300 people.
An outreach event for the general public was held at the Mary C. OKeefe Cultural Center for Arts and Education (the Mary C) on June 1, 2013. COAST Team citizen scientists set up booths including oil and dispersant demonstrations, plankton observation, oral presentations and sharing of the four fact sheet they developed. This activity was conducted in collaboration with Mississippi Alabama Sea Grant Consortium, which sponsored the purchase of Gulf shrimp that the chef of the Mary C cooked into shrimp tacos for a tasting booth. The Mary C also engaged two artists to work during the event. One conducted an activity that allowed children to create a painting using an emulsion containing marine algae. The other painted her interpretation of oil spill experiences shared by members of the public who attended the event. Attendance was estimated at more than 300 people.
The website features COAST team members, describes both research and outreach activities, and provides links to products. The video documents COAST team training.
Outreach Evaluation
The evaluation component of this project focused on gauging the experiences and knowledge of COAST team members. Because the goal of this project was to train citizen scientists to share what they learned in their training, evaluation was designed to explore volunteers understanding of oil spill science and comfort level communicating it. Specific instruments included: 1) A test of four multiple-choice and fill-in-the-blank questions designed for each session, administered before and after Sessions 1, 2, 3 and 4 to assess changes in volunteer content knowledge related to each session. 2) A Likert-type scale-assessment of volunteer perceptions of their ability to share specific content addressed during training. This survey was administered before and after Session 1 and after Sessions 2, 3, 4 and 6 to explore how volunteer perceptions changed during training. 3) A survey of three questions asking how volunteers understood the role of science in the oil spill. The same three questions were asked before and after Session 1 and after Session 6. In order to maintain confidentiality while following progress on individual responses, volunteers provided their initials on assessment materials then the outreach coordinator coded materials with a number for each participant and removed name identifiers before materials were graded, transcribed and analyzed.
Conclusions:
Twenty three volunteers and two GCRL staff members were selected as COAST team members and advisors, respectively. This group of citizen scientists was trained to 1) explore the role science has played in the oil spill, 2) learn background information and practice research skills related to the funded research project assessing how oil and oil-dispersant mixtures affect early life stages of estuarine invertebrates, and 3) develop confidence and products to share what they learned with a wide range of public audiences. Through grant sponsorship and in partnership with the Mississippi-Alabama Sea Grant Consortium and the Mary C. OKeefe Cultural Center for the Arts and Education, they hosted an event attended by more than 300 people using the products they developed to help attendees understand the science related to significant oil spill issues. Evaluation of volunteer experiences showed increases in content knowledge, recognition of the roles science plays during an emergency and sophistication in knowledge related to specific oil spill issues. In addition, volunteers became more adept at separating science related oil spill questions from those associated with financial, legal and political concerns. In the year since the outreach program ended, volunteers have not been formally tracked. However COAST team members formally presented this project in a variety of formats and venues. Periodic communications suggest they continue to share their experiences informally with colleagues, family, students and friends.
References:
Broad, A.C., 1957. Larval development of Palaemonetes pugio. Biological Bulletin 112:144-161.
Brouwer, M., Lee, R.F., 2005. Responses to toxic chemicals at the molecular, cellular, tissue, and organismal level, in: Kennedy, V.S., Cronin, L.E. (Eds), The Blue Crab Callinectes sapidus. Maryland Sea Grant Book, College Park, MD, pp. 485-512.
Cantelmo, A., Mantel, L., Lazell, R., Hospod, F., Flynn, E., Goldberg, S., Katz, M., 1982. The effects of benzene and dimethylnaphthalene on physiological processes in juveniles of the blue crab, Callinectes sapidus. in: Vernberg, W.B., Calabrese, A., Thurberg, F.P., Vernberg, F.J. (Eds.). Academic Press, New York, pp. 349-389.
Chang, E.S., 1993. Comparative endocrinology of molting and reproduction: insects and crustaceans. Annual Reviews of Entomology 38:161-180.
Chung, J.S., 2010. Hemolymph ecdysteroids during the last three molt cycles of the blue crab, Callinecyes sapidus: quantitative and qualitative analyses and regulation. Archives of Insect Biochemistry and Physiology 73:1-13.
Conover, R.J. 1971. Some relations between zooplankton and Bunker C oil in Chedacucto Bay following the wreck of the tanker Arrow. J. Fish. Bd. Canada 28:1327-1339.
Davis, C.C., 1965. A study of the hatching process in aquatic invertebrates. XIV. An examination of hatching in Palaemonetes vulgaris (Say).Crustaceana 8:233-238.
Glas, P.A., Courtney, L.A., J.R. Rayburn, Fisher, W.S., 1997. Embryonic coat of the grass shrimp Palaemonetes pugio. Biological Bulletin 192:231-242.
Hwang, D.-S., Lee, J.-S., Lee, K.-W., Rhee, J.-S., Han, J., Lee, J., Park, G.S., Lee, Y.-M., Lee, J.-S., 2010. Cloning and expression of ecdysone receptor (EcR0 from the intertidal copepod, Tigriopus japonicus. Comparative Biochemistry and Physiology 151C:303-312.
Karinem, J.F., Rice, S.D., 1974. Effects of Prudhoe Bay crude oil on molting Tanner Crabs, Chionectes bairdi. Marine Fisheries Review 36:31-37.
Lee, R.F., Köster, M. Paffenhöfer, G.A., 2012. Ingestion and defecation of dispersed oil droplets by pelagic tunicates. Journal of Plankton Research 34: 1058-1063.
Lichenthaler, R.G., Daling, P.S., 1985. Aerial application of dispersants comparison of slick behavior of chemically treated versus non-treated slicks, in: Proceedings 1985 Oil Spill Conference. American Petroleum Institute, Washington, DC, pp. 471-478.
McAuliffe, D., Steeleman,B.L., Leek, W.R., Fitzgerald, D.E., Ray, J.P., Barker, C.D., 1981. The 1979 Southern California dispersant treated research oil spills, in: Proceedings 1981 Oil Spill Conference. American Petroleum Institute, Washington, DC, pp. 269-282.
McCarthy, J.F., Skinner, D.M., 1979.Changes in ecdysteroids during embryogenesis of the blue crab, Callinectes sapidus. Developmental Biology 69:627-633.
Mothershead, R.F., Hale, R.C., 1962. Influence of ecdysis on the accumulation of polycyclic aromatic hydrocarbons in field exposed blue crab (Callinectes sapidus). Marine Environmental Research 33:145-156.
Mu, X., LeBlanc, G.A., 2002. Environmental anti-ecdysteroids alter embryo development in the crustacean Daphnia magna. Journal of Experimental Zoology 292:287-292.
Mykles, D.L., 2011. Ecdysteroid metabolism in crustaceans. Journal of Steroid and Molecular Biology 127:196-202.
Nakagawa, Y., Henrich, V.C., 2009. Arthropod nuclear receptors and their role in molting. FEBS Journal 276:6128-6157.
Nazari, E.M., Müller, Y.M.R., Ammar, D., 2000. Embryonic development of Palaemonetes argentinus Nobili, 1901 (Decapoda, Palaemonidae), reared in the laboratory. Crustaceana 73:143-152.
Oberdörster, E., Cottam, D.M., Wilmot, F.A., Milner, M.J., McLachlan, J.A., 1999. Interactions of PAHs and PCBs with ecdysone-dependent gene expression and cell proliferation. Toxicology and Applied Pharmacology 160:101-108.
Oberdörster, E., Brouwer, M., Hoexum-Brouwer, T., Manning, S., McLachlan, J.A., 2000. Long-term pyrene exposure of grass shrimp, Palaemonetes pugio, affects molting and reproduction exposed males and offspring of exposed females. Environmental Health Perspectives 108:641-646.
Rodriguez, E.Z, Medasani, D.A., Fingerman, M., 2007. Endocrine disruption in crustaceans due to pollutants: A review. Comparative Biochemistry and Physiology 146A:661-671.
Spindler, K.D., Van Wormhoudt, A., Sellos, D., Spindler-Bath, M., 1987. Ecdysteroid levels during embryogenesis in the shrimp, Palaemon serratus (Crustacea Decapoda). Quantitative and qualitative changes. General and Comparative Endocrinology 66:116-122.
Szklarz, G.D., Pausen, M.D., 2002. Molecular modeling of cytochrome P450 1A1: enzyme-substrate interactions and substrate binding affinities. Journal of Biomolecular Structural Dynamics 20:155-162.
Tarrant, A.M., Granks, D.G., Verslycke, T., 2012. Gene expression in American lobster (Homarus americanus) with epizootic shell disease. Journal of Shellfish Research 31:505-513.
Techa, S., Chung, J.S., 2013. Ecdysone and retinoid-X receptors of the blue crab, Callinectes sapidus: cloning and their expression patterns in eyestalks and Y-organs during the molt cycle. Gene 527:139-153.
Techa, S., Alvarez, J.V., Chung, J.S., 2015. Changes in ecdysteroid levels and expression patterns of ecdysteroid-responsive factors and neuropeptide hormones during the embryogenesis of the blue crab, Callinectes sapidus. General and Comparative Endocrinology 214:157-166.
Tuberty, S.R., McKinney, C.L., 2005. Ecdysteroid responses of estuarine crustaceans exposed through complete larval development to juvenile hormone agonist insecticides. Integrative and Comparative Biology 45:106-117.
Weis, J.S., Cristini, A., Rao, K.R., 1992. Effects of pollutants on molting and regeneration in crustaceans. American Zoologist 32:495-500.
Zou, E., 2005. Impacts of xenobiotics on crustacean molting: the invisible endocrine disruption. Integrative and Comparative Biology 45:33-38.
Journal Articles:
No journal articles submitted with this report: View all 8 publications for this projectRelevant Websites:
Deepwater Horizon Oil Spill: Five Years Later, Vigorous Research Continues ExitTeens hit Maryland beach to study crabs Exit
Crabs’ birds and bees: Effects of crab sex life on Maryland industry Exit
Progress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.