Thomas F. Lytle

Hydrocarbons in 60 northeast Gulf of Mexico shelf sediments: a preliminary survey

Hydrocarbon results from gas chromatography of 60 recent sediment and 10 benthic algae samples delineate two distinct shelf environments in the northeastern Gulf of Mexico. Sediments off Florida (shell hashes and sands) have moderate amounts of lipids/total sediment (average 113ppm ± 80%) but low hydrocarbon levels (average 3.06 ppm ± 41%). Aliphatic hydrocarbons are dominated by a series of branched or cyclic, unsaturated C25 isomers. The major n-alkane is n-C17. The n-alkane and isoprenoid patterns are consistent with a marine hydrocarbon source. Sediments closer to the Mississippi River (silts and clays) contain large amounts of lipids (average 232 ppm ± 53%) and hydrocarbons (average 11.7 ppm ± 55%) to total sediment. Aliphatic hydrocarbons are mainly odd carbon number high molecular weight n-alkanes, indicating a terrigenous hydrocarbon source. Isoprenoids are present in greater abundance than in sediments off Florida (n-C17/ pristane and n-C18/phytane ratios ~2to 3). Relatively large amounts of n-C16, together with an even distribution of n-alkanes in the range C14–C20 and a substantial unresolved envelope all point to a fossil fuel input to the Mississippi samples. Samples off the Alabama coast show intermediate characteristics.

Decreased resistance of eastern oysters (Crassostrea virginica) to a protozoan pathogen (Perkinsus marinus) after sublethal exposure to tributyltin oxide

Abstract Anthropogenic environmental stress is a likely contributor to outbreaks of disease due to immunosuppression or increased host vulnerability. Estuarine organisms are exposed to variable concentrations of marine antifouling agents, such as tributyltin (TBT), with higher exposures existing near ports and marinas. Eastern oysters ( Crassostrea virginica ), inhabiting the northern Gulf of Mexico and the Atlantic coast of North America, are susceptible to a protozoan pathogen, Perkinsus marinus , which has devastated oyster populations and depleted oyster fisheries throughout its range. This study examined the effects of exposure to environmental levels of TBT on susceptibility and survival of oysters when subsequently challenged with P. marinus . Oysters were exposed to TBT (0, 30 and 80 ng/L) in flow-through aquaria for 9 weeks, then moved to static aquaria, where they were challenged with parasites and monitored for an additional 8 weeks for mortality and disease. Results indicated increased infection intensity and oyster mortality in the TBT-exposed treatments relative to unexposed controls. It is hypothesized that TBT exacerbates the infectious disease process and that exposed oysters succumb at lower levels of infection.

Carcinogenic effects of some polycyclic aromatic hydrocarbons on the Japanese medaka and guppy in waterborne exposures

In this paper, we review studies on the carcinogenic effects of two polycyclic aromatic hydrocarbons (PAHs), benzo(a)pyrene (BaP) and 7,12-dimethylbenz(a)anthracene (DMBA), on the Japanese medaka (Oryzias latipes) and the guppy (Poecilia reticulata). Exposure media were prepared by adding PAHs to water, with and without dimethylformamide (DMF) as a carrier, and passing this solution through various sized filters. The low exposure medium was a 0.45 micron filtrate without DMF that contained less than 5 micrograms L-1 PAH. The intermediate medium was a DMF-mediated 0.45 micron filtrate which contained 30-50 micrograms L-1 of PAH. The high medium was a DMF-mediated glass-fibre filtrate which contained 150-250 micrograms L-1 of PAH. Young fish specimens (6-10 d old) were given a 6 h exposure once weekly for 2 to 4 wk. Both BaP and DMBA induced hepatic neoplasms in the two species, with the medaka being more sensitive than the guppy, and DMBA being a stronger carcinogen than BaP. Liver neoplasms almost exclusively developed after exposure to BaP and the neoplasms were limited to the high concentration exposure, whereas DMBA caused a substantial number of extrahepatic neoplasms as well as hepatic ones, especially in the medaka. Furthermore, all three concentrations of DMBA induced hepatic neoplasms in the medaka and all but the low concentration induced neoplasms in the guppy. These studies demonstrate the carcinogenic effects of two waterborne PAHs on two small fish species following brief exposures to very low concentrations, and support the contention that environmental PAHs can contribute to the occurrence of cancer in wild fishes.

Polyunsaturated fatty acid profiles as a comparative tool in assessing maturation diets of Penaeus vannamei

Abstract The polyunsaturated fatty acids (PUFA) in the Maine bloodworm, Glycera dibranchiata , are compared to the PUFA in other live feed sources as well as commercial feeds to determine what other feed sources have fatty acid profiles most like those of the bloodworm. Bloodworms have been used successfully as a feed source to produce maturation in reared Penaeus vannamei . It has been suggested that certain PUFA in bloodworms may help trigger maturation. PUFA are comprised primarily of two families: omega-6 ( n −6) and omega-3 ( n −3). Analytical results indicate that oysters, squid, and certain marine worms have fatty acid profiles similar to that of the bloodworm. Commercial feeds have high absolute concentrations of n −3 fatty acids, but the ratios of n −3 to n −6 fatty acids are dissimilar to those of bloodworms. The balance between these two omega fatty acid families may be an important factor to consider when providing a maturation diet for P. vannamei .

Dose-related carcinogenic effects of water-borne benzo [a] pyrene on livers of two small fish species

Benzo[a]pyrene (BaP) administered by water-borne exposures caused dose-related carcinogenic effects in livers of two small fish species, the Japanese medaka (Oryzias latipes) and the guppy (Poecilia reticulata). Medaka and guppies each were given two 6-h exposures. The first exposure was conducted on 6- to 10-day-old specimens. The second exposure was given 7 days later. The tests incorporated five treatment groups: (1) control, (2) carrier (dimethylformamide) control, (3) low BaP dose (not detectable--4 ppb), (4) intermediate BaP dose (about 8-47 ppb BaP), and (5) high BaP dose (200-270 ppb). Following the high-dose exposure, hepatocellular lesions classified as foci of cellular alteration (altered foci), adenomas, and hepatocellular carcinomas occurred in both species. In medaka, the lesions appeared to develop sequentially with the appearance of altered foci followed by adenomas and then hepatocellular carcinomas. Most lesions in guppies, however, were classified as altered foci although a few adenomas occurred in the early (24-week) sample and hepatocellular carcinomas occurred in the late (52-week) sample. When total lesions were combined, medaka had an 11% incidence at 24 weeks after the initial exposure and 36% incidence at 36 weeks. In guppies, 8% had liver lesions at 24 weeks, 19% at 36 weeks, and 20% at 52 weeks. A single extrahepatic neoplasm, a capillary hemangioma in a gill filament, occurred in a medaka from the 36-week high-dose sample. The results suggest that the medaka and guppy are capable of metabolizing water-borne BaP to carcinogenic metabolites which initiate hepatic tumor development.

Carcinogenic effects of 7,12-dimethylbenz[a]anthracene on the guppy (Poecilia reticulata)

Abstract The carcinogenic effects of 7,12-dimethylbenz[a]anthracene (DMBA) on the king cobra strain of guppy (Poecilia reticulata) were examined. Specimens were exposed for 6 h once weekly for 4 wk to DMBA. Guppies were 6–11 days old at the initial exposure. Treatment groups included the following: (1) untreated control; (2) dimethylformamide (DMF) carrier control; (3) low, water-mediated DMBA concentration (about 1–3 μg/l or ppb DMBA); (4) intermediate, DMF-mediated DMBA concentration (about 20 ppb DMBA); and (5) high, DMF-mediated DMBA concentration (about 35 ppb DMBA). Hepatic neoplasms developed in guppies exposed to the intermediate and high concentrations. Both of these exposure media contained the same concentrations of soluble DMBA. The high exposure medium, however, also contained an insoluble, particulate fraction of DMBA. Hepatic neoplasm incidences in fish exposed to the intermediate concentrations were 10% at 24 wk and 19% at 37 weeks after the initial exposure. In samples from the high concentration group, 47% had hepatic neoplasms at 24 weeks and 46% at 37 wk. Histologically, the hepatic lesions were categorized as altered foci, hepatocellular adenomas, and hepatocellular carcinomas. In addition to liver neoplasms, several other types of lesions developed in DMBA-exposed guppies. These included two undifferentiated sarcomas, a rhabdomyosarcoma, a renal adenocarcinoma, and a neurilemmoma. Only one control specimen (representing 0.38% of all controls) had a neoplastic lesion, a small hepatocellular adenoma in a 37-wk specimen. This study demonstrates that the guppy develops hepatic and extrahepatic neoplasms rapidly following brief water-borne exposures to those rather low levels of DMBA. Furthermore, the study showed that the particulate fraction of DMBA contributes to the carcinogenicity of the compound.

Sediment hydrocarbons near an oil rig

Abstract Sediment samples were collected from 25 strategic locations at a site on the Texas shelf before emplacement of an exploratory oil rig, during drilling and after the rig had been in place for 2 months. These sediments were analysed for aliphatic and aromatic hydrocarbons, and thirteen gas Chromatographic parameters, used in assessing pollution, were calculated. Graphic cluster analysis, analysis of variance and discriminant analysis were applied to these parameters to view changes as well as to evaluate the effectiveness of gas Chromatographic data in monitoring sediment hydrocarbons. Changes discernible by these techniques were slight but more noticeable at stations close to the rig. Hydrocarbons in the C14 to C20 region of the aliphatic chromatograms were in low abundance in all samples but consisted mostly of n-C17 and C25 branched-chain olefins. The high molecular weight region contained high concentrations of the odd carbon numbered n-alkanes with a predominance of n-C29. This similarity to terrestrial hydrocarbons was further confirmed by a mean δC13 value vs. PDB of −28·0‰ for the aliphatic hydrocarbons.

Stability of a commercially prepared fish oil (omega‐3 fatty acid) laboratory rodent diet

There is evidence that highly unsaturated omega-3 fatty acids present in fish oils can provide a cancer-protective effect; however, when added to laboratory rodent formulations, these fatty acids are subject to rapid and/or extensive oxidation and other chemical changes by exposure to air, light, or heat during processing of pellets or when stored for various lengths of time. An animal diet with 16% refined fish oil and 4% corn oil was commercially prepared with antioxidants (butylated hydroxytoluene and butylated hydroxyquinone in addition to alpha-tocopherol) present, and precautions were taken to prevent oxidation at all stages of production and handling. Fatty acid composition of dried powdered diet as well as freshly processed dried pellets was analyzed from four lots at the beginning and end of a 45-day feeding period. Additionally, fatty acid analyses were carried out on pellets dried by both vacuum and air techniques, and pellets were left exposed to air at room temperature for 96 hours. No statistical difference in overall fatty acid composition was observed among lots due to pelletization or drying procedures. Moreover, 4 days of exposure of pellets to air at ambient temperatures and 45 days of freezer storage had no significant effect on their fatty acid composition. It would appear that rodent diets containing omega-3 fatty acids can be reliably prepared commercially and safely substituted for diets prepared manually and in bulk on a weekly basis.

SEDIMENT HYDROCARBONS AS ENVIRONMENTAL INDICATORS IN THE NORTHEAST GULF OF MEXICO

Abstract Surface sediment samples were collected in 1975-76 from forty-five locations in the Gulf of Mexico along the continental shelf from Pascagoula, Mississippi to Fort Myers, Florida. Hydrocarbons were analyzed in the sediments for the Bureau of Land Management in an effort to survey hydrocarbons in the northeast Gulf and detect man-induced and seasonal effects in hydrocarbon profiles. Clearly, there are three zones in this area as distinguished by their aliphatic hydrocarbon distributions. The Florida shelf contains aliphatics which consist primarily of a branched-cyclic-unsaturated complex at Kovats Index 2-75-2150, with lesser components at 1640-2500 and 3400 on FFAP. The small, n -alkane fraction is dominated by C-17 and resembles algal hydrocarbons. The sediments from the Mississippi-west Alabama shelf and from the outermost edge of the Florida shelf are characterized by an abundance of high molecular weight n -alkanes of pronounced odd/even preference typical of terrestrial hydrocarbons. Occurring in lesser amounts, is a suite of low molecular weight n -alkanes with a uniform distribution characteristic of degraded crude oil. The west Florida and east Alabama shelf contain hydrocarbons intermediate in nature between these two extremes. These characteristics have remained virtually unchanged through several seasons and suggest that seasonal effects upon hydrocarbons are minimal in this area.

Lignin residues as tracers of organic waste transport

Abstract Lignin residues from a paper mill have been used as chemical tracers of organic pollutant transport in a river emptying into Mississippi Sound. Paper mill wastes, having vanillyl and no syringyl lignins, can be detected in sediments at the river mouth 17 km downstream, but most deposition occurs very near the source. No evidence of effective transport beyond the river mouth into the Sound or Gulf of Mexico was observed.