Oil Spill Impacts on NGoM Fisheries and Food Webs: An Observational Study
Investigators:
Brian Fry (PI), Department of Oceanography and Coastal Sciences, Louisiana State University,
Baton Rouge LA 70803; tel. 225 578 9403, fax -6326; bfry@lsu.edu
Don Baltz (co-PI), Department of Oceanography and Coastal Sciences, Louisiana State
University, Baton Rouge LA 70803; tel. 225 578 6512, fax - 6513; dbaltz@lsu.edu
Dubravko Justic (co-PI), Department of Oceanography and Coastal Sciences, Louisiana State
University, Baton Rouge LA 70803; tel. 225 578 6394, fax - 6513; djusti1@lsu.edu
Nan Walker (co-PI), Department of Oceanography and Coastal Sciences, Louisiana State
University, Baton Rouge LA 70803; tel. 225 578 2520, fax - 6513; nwalker@lsu.edu
Ed Chesney, (co-PI), Louisiana Universities Marine Consortium Defelice Center, 8124 Highway
56, Chauvin, Louisiana 70344; tel 985-851-2800, fax – 2874; echesney@lumcon.edu.
A. Objectives
The Macondo 252 oil spill was long enough and large enough that managers and
scientists alike think that substantial ecosystem impacts are possible in the Northern Gulf of
Mexico. Our research team proposes a new project under the Phase II umbrella focused on
offshore fisheries that are routinely surveyed by the NOAA SEAMAP (Southeast Area
Monitoring and Assessment) program. We will work with this program to collect new samples
and compare them to historical collections to address the question, “Did the Macondo 252 Oil
Spill result in large scale perturbation of the NGoM ecosystem structure or function?”. We
seek to identify changes in the following four ways.
1. Spatial domain and chlorophyll (Justic and Walker). The spatial pattern of oil
spreading in the NGoM will be simulated and verified with existing hydrodynamic models and
remote sensing methods. The domain of the research is the Louisiana and Texas shelf system
adjacent to and to the west of the Macondo site. Spread of oil will be simulated under 2010
conditions, but also under longer-term average conditions that may move oil across the study
area in coming years. We will check the model output using images from remote sensing. We
will also use remote sensing to assess changes in pigments attributable to the oil spill and
compare 2010 estimates to those from previous years. This activity will generate maps of
potential primary productivity that can be compared across years for any large-scale
phytoplankton productivity changes due to the oil spill.
2. Fisheries Biomass and Species Composition (Baltz and Chesney). SEAMAP conducts
summer and fall trawl groundfish surveys for the Texas and Louisiana shelf ecosystems, systems
adjacent to and to the west of the Macondo site. SEAMAP collections were made this year
(2010), the year of the spill, and collections this year and the coming summer of 2011 will be
compared to data from previous years to test for oil-related changes in fisheries biomass and
species composition. This work with SEAMAP community patterns is a first step in assessing
fisheries dynamics and possible recruitment failures related to this large oil spill. Much
community-level data has been summarized for years prior to 2000 (Chesney et al. 2000,
Chesney and Baltz 2001) and we propose to update these summaries to see if there was a
detectable effect in 2010 possibly due to the oil spill.
3. Trophic structure (Baltz and Fry). New fisheries samples will be collected in summer
of 2011 for stable isotope analysis of common consumers in NGoM food webs, to test for
changes in trophic levels and oil incorporation into offshore food webs. Collections will be made
at 9 sites, 3 sites close to the oil spill site east of the Mississippi River (MR), 3 sites similarly
close to the MR but to the west on the Louisiana shelf and 3 in Texas waters that are expected to
be relatively unimpacted. Animals will be measured for stable CNS isotope composition (Fry
2008) and data used with fisheries biomass and species lists to examine large-scale changes that
could be related to the oil spill. Some samples will be analyzed for natural abundance 14C that
directly tracks oil incorporation into food webs, so that direct use of oil can be identified over
larger spatial scales in the NGoM. (Oil is a geologically old substance and lacks 14C that has
long-since decayed away, so that oil incorporation into food webs appears labels animals with
low 14C values; Spies and DesMarais 1983, Pearson et al. 2008).
4. Indicator Species and Maps (Fry and Chesney). Both brown shrimp (Farfantepenaeus
aztecus) and menhaden (Brevoortia patronus) are the basis of important commercial fisheries in
NGoM areas near the oil spill site. For both species, archival material is present for analyzing
stable isotopes to detect changes in food webs, with brown shrimp representing the demersal
benthic food web (Fry 2008) and menhaden representing the planktonic food web (Vaughan et
al. 2007). For menhaden, scales have been routinely collected by NOAA over the last several
decades and are archived at Beaufort NC (Joseph Smith and Bruce Vaughan, personal
communication). For brown shrimp, samples were collected extensively along the Louisiana
shelf in 2005 and 2006 (Fry, in review). These brown shrimp and menhaden samples can be
analyzed as historical reference points for pre-spill isotopes, for comparison to new collections
ongoing now and proposed here for summer 2011. Some 14C work will directly test for oil
incorporation into food webs for these indicator species, and some animals will be analyzed for
oil compounds (e.g. PAHs) where oil may be entering food webs. In addition to these indicator
species that are mobile, barnacles and stomach contents from shrimp also will be collected at
>30 sites to generate location-specific isotope maps to track spread of oil from the Macondo 252
block west across the Louisiana shelf. Oil entry into food webs and indicator species should be
detectable as low 14C, low 13C, and moderate-to-high 15N due to microbial links and
processing of oil (Spies and Desmarais 1983, Coffin et al. 1997, Slater et al. 2005, Pearson
2008)
Summary objectives. The proposed work encompasses large spatial and temporal scales
using decades of data and collections from the Louisiana and Texas shelves to test for “largescale perturbations” in fisheries and fisheries food webs. The work could seem correlative, but
the isotope and chemical PAH analyses provide an important additional tracer for isolating and
identifying specific effects due to oil. This project focused on Louisiana fisheries and food webs
will complement ongoing NGI work off the Florida panhandle conducted by FSU. The work is
expensive but involves a large team needed to do justice to the large spill – if we don’t look
broadly and carefully with interdisciplinary efforts, we may miss important offshore oil spill
impacts.
2
B. Methods
a) Modeling. We will use satellite imagery and an existing 3-dimensional
hydrodynamic model (Finite Volume Coastal Ocean Model, Justic and Wang, 2009,
Wang and Justic, 2009) to identify the regions most impacted by the oil spill.
b) Remote Sensing. The remote sensing will be performed by faculty, staff, and students
of the LSU Earth Scan Laboratory, a receiving station and image processing facility
for real-time and archival satellite data. Products (SST, true color, chlorophyll a) will
be generated in real-time as the data is acquired and the quicklooks and data files
(hdfs) will be made available on the ESL WEB in near real-time (www.esl.lsu.edu).
For this project, additional products will be developed to monitor pigments
(chlorophyll a) in the northern Gulf of Mexico from April 2010 through August 2011
(Walker and Rabalais 2006). We anticipate using the MODIS and MERIS sensors to
map pigments. Weekly and monthly compositing will be used to remove cloud
contamination. The remote sensing data will be used to interpret fisheries patterns as
well as to skill assess numerical modeling activities.
c) Fishery species and community composition. Multivariate techniques will be used
along with simple statistics to compare regions and years for oil impacts (Chesney
and Baltz 2001, Chesney et al. 2000, Roth and Baltz 2009).
d) Trophic structure, indicator species and isotopes. Isotope indicators of food webs will
be measured with standard techniques (Fry 2008) and interpreted in terms of basal
food resources, trophic level and oil inputs (Spies and DesMarais 1983, Fry 2006).
Isotopes in fish scales will be analyzed and interpreted following procedures used by
Trueman and Moore (2007). PAHs will be analyzed by the laboratory of Dr. Ed
Overton.
References:
Chesney, E.J. and D.M. Baltz. 2001. The effects of hypoxia on the northern Gulf of Mexico
coastal ecosystem: a fisheries perspective, pp. 321-354. In: N.N. Rabalais and R.E. Turner
(eds.), Coastal Hypoxia: Consequences for Living Resources and Ecosystems, Coastal and
Estuarine Studies v. 58. American Geophysical Union, Washington D.C.
Chesney, E.J., D.M. Baltz and R.G. Thomas. 2000. Louisiana estuarine and coastal fisheries and
habitats: perspectives from a fish’s eye view. Ecological Applications 10:350-366.
Coffin, R.B., L.A. Cifuentes, and P.H. Pritchard. 1997. Assimilation of oil-derived carbon and
remedial nitrogen applications by intertidal food chains on a contaminated beach in Prince
William Sound, Alaska. Marine Environmental Research 44: 27-39.
Fry, B. 2006. Stable isotope ecology. Springer, New York.
Fry, B. 2008. Importance of open bays as nurseries for Louisiana brown shrimp. Estuaries and
Coasts 31:776-789.
Justic, D., and L. Wang. 2009. Application of Unstructured-Grid Finite Volume Coastal Ocean
3
Model (FVCOM) to the Gulf of Mexico Hypoxic Zone. Proceedings of the 2009 MTS/IEEE
conference, Ocean Technology for Our Future: Global and Local Challenges, 26-29 October
2009, Biloxi, Mississippi, MTS, ISBN No. 978-0-933957-38-1.
Pearson, A., K.S. Kraunz, A.L. Sessions, A.E. Dekas, W.D. Leavitt and K.J. Edwards. 2008.
Quantifying microbial utilization of petroleum hydrocarbons in salt marsh sediments by using
the 13C content of bacterial rRNA. Applied and Environmental Microbiology 74:1157-1166.
Roth, A. F. and D. M. Baltz. 2009. Short-term effects of an oil spill on marsh-edge fishes and
decapod crustaceans. Estuaries and Coasts 32:565-572.
Slater, G.F., H.K. White, T.I. Eglinton and C.M. Reddy. 2005. Determination of microbial
carbon sources in petroleum contaminated sediments using molecular 14C analysis.
Environmental Science and Technology 39:2552-2558.
Spies, R.B. and D.J. DesMarais. 1983. Natural isotope study of trophic enrichment of marine
benthic communities by petroleum seepage. Marine Biology 73:67-71.
Trueman, C.N., and A. Moore. 2007. Use of stable isotope composition of fish scales for
monitoring aquatic ecosystems. Terrestrial Ecology 1:145-161.
Vaughan, D.S., K.W. Shertzer, and J.W. Smith. 2007. Gulf menhaden (Brevooria patronus) in
the U.S. Gulf of Mexico: Fishery characteristics and biological reference points for management.
Fisheries Research 83:263-275.
Walker, N.D. and N. N. Rabalais. 2006. Relationships among satellite chlorophyll a, river inputs
and hypoxia on the Louisiana continental shelf, Gulf of Mexico, Estuaries and Coasts 9:1-13.
Wang, L., and D. Justic. 2009. A modeling study of the physical processes affecting the
development of seasonal hypoxia over the inner Louisiana-Texas shelf: Circulation and
stratification. Continental Shelf Research 29: 1464-1476.
C. Costs
Budget Period: 1 year, January 01 –December 31, 2011. We have estimated a preliminary
budget of about 250k.
Budget Justification. One month of summer salary is requested for Fry, Baltz and Walker to
oversee the project. Funds are also requested 4 RAs and 2 student workers. This personnel will
work together to collect and analyze the samples, compare results to pre-spill conditions and
prepare reports and publications. Travel and operating funds are requested to cover collections
and presentations at meetings. Supplies are requested for isotope determinations and for
purchase of computers. Natural abundance radiocarbon analyses and oil contaminant analyses
needed to pinpoint oil contributions but these analyses are expensive (about $600/sample done at
specialized labs). Special funds (38k) are requested for these analyses.
4
.
Requested
Funds
A. Salaries and Wages
1.
2.
3.
4.
5.
6.
7.
B.
C.
D.
E.
F.
G.
H.
I.
J.
K.
L.
Fry
Baltz
Justic
Walker
1 month
1 month
0 months
0.5 month
Other Investigators (list on justification)
Postdoctoral Associates
Other
8.
Professionals 12 months RA
9.
Graduate Assistants
Student
10.
Workers
6 months
Subtotal Salaries and Wages
Fringe Benefits
@
35.0%
Total Salaries, Wages
and Fringe
Travel
Supplies
Operating Services
Professional Services
1. Subcontracts
2. Consultants
radiocarbon and oil chemical
3. Other Services
analyses
Other Charges
Equipment
Total Direct Costs
Facilities & Administrative Costs
@ 47.0%
M. Total Project Costs
*Base for
request = $148,949
5
$9,639
$9,820
$0
$4,287
$0
$0
$0
$40,290
$0
$6,000
$70,036
$22,413
$6,500
$10,500
$1,500
$21,000
$0
$38,000
$0
$169,949
$79,876
$249,824