ACCESS NUMBER: 30582

STUDY TITLE: Gulf of Mexico Offshore Monitoring Experiment (GOOMEX), Phase I: 

Sublethal Response to Contaminant Exposure 

REPORT TITLE: Gulf of Mexico Offshore Monitoring Experiment (GOOMEX), Phase I: 

Sublethal Response to Contaminant Exposure, Final Report 

CONTRACT NUMBER: 14-35-0001-30582 

SPONSORING OCS REGION: Gulf of Mexico 

APPLICABLE PLANNING AREAS: Central and Western 

FISCAL YEARS OF PROJECT FUNDING: 1992, 1994, and 1995 

COMPLETION DATE OF REPORT: September 1995 

COSTS: FY 1992: $2,361,611; FY 1994: $1,675,693; FY 1995: $142,617 

CUMULATIVE PROJECT COST: $4,444,921 

PROGRAM MANAGER: Mahlon C. Kennicutt II 

AFFILIATION: Geochemical and Environmental Research Group (GERG), Texas A&M 

University (TAMU) 

ADDRESS: 833 Graham Road, College Station, Texas 77845 (409/690-0095, Fax 

409/690-0059) 

PRINCIPAL INVESTIGATORS*: J.M. Brooks, S. Carr, R. Darnell, R.R. Fay, R.H. 

Green, D. Harper, J. McEachran, P. Montagna, B.J. Presley, R. Rezak, S. Safe, J.W. 

Fournie, S.J. McDonald, D.A. Wiesenburg, F.J. Kelly, T. Wade, and G.A. Wolff 

KEY WORDS: Offshore oil and gas production, oil platforms, sublethal chronic effects, 

detoxification responses, community structure analysis, histopathology, pore water 

toxicity, reproductive effort, contaminant analyses, hydrocarbons, and trace metals 

BACKGROUND: The most significant unanswered questions related to environmental 

impacts of offshore oil and gas development and production are those concerning 

chronic, low-level stresses on ecosystems that result from discharges, spills, leaks, and 

disruptions caused by long-term development of energy resources. A mandate to 

conduct studies to predict, assess, and manage the effects of Outer Continental Shelf 

(OCS) oil and gas development activities on the marine environment is provided to the 

MMS under the OCS Lands Act Amendments. 

OBJECTIVES: (1) To document any fundamental detoxification responses in the 

resident fauna of long-term OCS production sites, which have resulted from exposure to 
ACCESS NUMBER: 30582

contaminants associated with OCS activities; and (2) To document the impacts of any 

contaminant exposure at the organism, population, or community level. 

DESCRIPTION: The "Gulf of Mexico Offshore Operations Monitoring Experiment 

(GOOMEX)" is a three-phase study to test and evaluate a range of biological, 

biochemical, and chemical methodologies to detect and assess chronic sublethal effects 

of offshore oil and gas production. Study results will be used to formulate and 

recommend techniques for monitoring offshore activities to assess the importance of the 

associated environmental changes. A closely coordinated series of investigations is 

being used to test for biological impacts in the vicinity of long duration activities 

associated with oil and gas exploration and production. A chronic impact is defined as 

an effect on the biota that is caused by exposure to the long-term accumulation of 

chemicals in the environment. Study components are linked by a common design and 

analytical approach. The basic program included four field activities over a two year 

period. The sampling was designed to detect nearfield impacts and contaminant 

gradients extending out from each site. The study evaluated five test sites and 

narrowed the long-term study to the three most appropriate sites: MU-A85, MAI-686, 

and HI-389. The sampling design included a radial pattern with stations at 30-50, 100, 

200, 500, and 3000 m distance. The radial design employed a dose-response model to 

test the hypothesis that biological, chemical and biochemical variations are due to 

platform derived contaminants. Study components included contaminant (trace metals 

and hydrocarbons) analysis in sediments, pore waters, and biological tissues; 

assemblage analysis of benthic meiofauna, infauna, and epifauna; assessment of 

community health based on life history and reproduction studies; and the induction of 

detoxification responses. 

SIGNIFICANT CONCLUSIONS: The biological patterns around platforms are the result 

of the complex interactions of variations in sediment grain size, organic matter 

enrichments, and toxic response to contaminant exposure. Contaminant levels 

associated with these three study sites only exceed levels thought to produce 

deleterious biological effects at a few stations close to the platform. In general the 

levels of contamination were low. While further study is needed, the results of 

GOOMEX Phase I suggest that benthic environments around platforms were disturbed 

as a result of the presence of the platform and discharges derived from exploration and 

production activities. Observed shifts in populations and other sublethal effects can 

only be more fully understood based on directed studies in the field and the laboratory. 

STUDY RESULTS: Several important observations have come from Phase I of the 

GOOMEX project. First, we found sediments under platforms were highly enriched in 

sand and the texture o sediment is strongly correlated with distance from the platform. 

Visual examination and chemical analysis showed that the sand was primarily related to 

disposal of cuttings during drilling activities. Hydrocarbons and metals are common 

contaminants near platforms. As a direct result of the disposal of drill mud and cuttings, 

contaminants were restricted to sediments close to the platforms (100's of meters). 

Polycyclic aromatic hydrocarbon (PAH) levels in sediments were well below levels 

known to be associated with toxic biological effects (<4,000 ppb) and no significant 
ACCESS NUMBER: 30582

enhancement of bioaccumulation of hydrocarbons was observed in megafaunal 

invertebrates or fish near platforms. Two of the three study sites (HI-A389 and MUA85) exhibited strong gradients in the concentrations of barium, silver, cadmium, 

mercury, lead, antimony and zinc in sediments. Still, no significant enhancement in 

bioaccumulation of metals in invertebrates or fish in close proximity of platforms was 

observed. A comparison with contaminant levels in continental-shelf organisms 

suggested that metal levels in invertebrate tissues are higher in general at the study 

sites. 

Meiofaunal communities in sediments provided sensitive indications of stress and 

exposure including decreased abundances for some species. This pattern is consistent 

with previous studies showing the sensitivity of some species to toxic chemicals. As a 

consequence of a differential response to toxin exposure, the ratio of the resistant of the 

sensitive meiofaunal species (i.e., nematode/harpacticoid) provided a good indicator of 

changes in community structure. 

For macroinfauna, some species were enhanced while others were depressed in 

abundance near platforms confirming a shirt in community structure near the platforms. 

Some species of macroinfauna (i.e., ploychaetes) were enhanced within 100-meter of 

the platforms. In contrast, a reduction in some species of meiofauna was observed. 

Enhancements in the abundance of macroinfauna are attributable to an increase in just 

a few species. Reductions in abundance are consistent with a toxic response while 

increases in abundance are consistent with the increased food (carbon; i.e., 

ploychaetes/amphipods). 

Few effects were detectable in invertebrates that lived primarily on top of the sediments. 

Each platform appeared to affect these animals in unique ways and there did not 

appear to be an over-riding influence on patterns attributable to the presence of the 

platform. Histopathological evaluations of fish found no contaminant-related liver 

lesions. 

When exposed to chemical contaminants many organisms have systems to eliminate 

damaging toxicants. No increase in the activity of these protective systems was 

apparent when comparing results between near and far stations. This suggests little or 

no increased exposure was being experienced by bottom dwelling animals near 

platforms. 

Another method of assessing the potential for toxic effects is to expose test organisms 

to the suspected contaminants in the laboratory and monitor for indications of 

deleterious effects. Utilizing several test organisms, a detrimental effect was observed 

when the organisms were exposed to sedimentary interstitial waters collected within 

100 m of HI-A389. Laboratory induced toxic effects and high concentrations of trace 

metals in sediments seemed to correlate providing circumstantial evidence of cause and 

effect. 
ACCESS NUMBER: 30582

STUDY PRODUCTS: Kennicutt, M.C., II, ed. 1995. Gulf of Mexico offshore operations 

monitoring experiment, phase I: sublethal responses to contaminant exposure, final 

report. U.S. Dept. of the Interior, Minerals Management Service, Gulf of Mexico OCS 

Region, New Orleans, Louisiana. OCS Study MMS 95-0045. 748 pp. 

Kennicutt, M.C., II, ed. 1995. Gulf of Mexico Offshore Operations Monitoring 

Experiment, Phase I: Sublethal Responses to Contaminant Exposure. Interim Report: 

Year 1. OCS Study MMS 95-0005. U.S. Department of the Interior, Minerals 

Management Service, Gulf of Mexico OCS Region, New Orleans, Louisiana. 304 pp. 

Carr, R.S. and D.C. Chapman. 1993. Toxicity of sediment pore water associated with 

offshore oil and gas platforms in the Gulf of Mexico. Pater to be presented at the 14th 

Annual Meeting of the Society of Environmental Toxicology and Chemistry, Houston, 

Texas. November 14-18. 

McDonald, S., T.R. Narasimhan, K. Connor, K. Willett, S. Safe, and M.C. Kennicutt II. 

1994. CYP1A1 Induction in Marine Fish Species from the Gulf of Mexico. Society of 

Toxicology 1994 Annual Meeting, abstract. 

Rosicigno, P.F., and M.C. Kennicutt II. 1993. Marine Ecosystems: Assessing the 

Impacts of Chronic Contamination from Offshore Platforms. Marine Technology Society 

Journal. 27:66-71. 

*P.I.'s affiliation may be different than that listed for Program Managers.