Detecting Chronic EffectsOf Oil Development

In Caddo Lake

Charles W. RamcharanDept. Biological Sciences

Louisiana State UniversityBaton Rouge, LA

Louisiana Oil Spill ResearchAnd Development Program

(OSRADP)

Caddo Lake Map

Texas Louisiana

Oil Cit y

Shreveport

Caddo Lake

Red River

Lake ‘O t he Pines

Big Cypress Bayou

10 km6.3 miles

Ramsar areaOil development areaMunitions dump

NW-Basin near RAMSAR

North-west basin of Caddo Lake in Ramsar watershed area.

Main Basin

Main basin of Caddo Lake.

Oil head in North Arm

Active oil head found in the North Arm of Caddo Lake.

Historical Marker – First over-water oil well

Historical Marker for first oil well in Caddo Lake.

Early wells on Pine Island?

Some of the first wells in Caddo Lake.

Early wells in main basin

Extensive oil field in Caddo Lake.

• Chronic effects of oil development in freshwater lakesare not well understood

• Chronic effects may be difficult to identify because manydisturbed ecosystems face multiple stressors

• Usually there are available few long-term, pre- and post-perturbation data

The Problem

Lake Food Web Reconstruction

Lake Sediment

BenthicInvertebrates

Game Fish

PlanktivorousFish

InvertebratePredators

LargeZooplankton

SmallZooplankton

Edible Algae

InedibleAlgae

Lake Coring

Core from Caddo Lake showing about 70 years of accumulation. (Army Corps of Engineers)

Purge valveHandle

PVC coupling

NosepieceCore catcher

Transparent core tubeTransparent liner

1 m

Applications Of Paleo-Limnology

• Impacts of agriculture,urbanization, and forestry• Long-term estimates of fish production• Effects of acid precipitation• Determining frequency and intensity of droughts• Studies of climate change• Fish stock degradation due to overfishing• Effects of different types of fish predation

Expt. Design

Texas Louisiana

Oil Cit y

Shreveport

Caddo Lake

Red River

Lake ‘O t he Pines

Big Cypress Bayou

10 km6.3 miles

Oil contamination site

Metal contamination site

Reference site

Metal Contamination In LOP And Caddo Lake

Met

al C

once

ntra

tion

(mg

L-1 )

150

100

50

0

Org.

Car

bon

Arse

nic

Mer

cury

Cadm

ium

Lead

*Iron Zinc

Copp

er

Chro

miu

m

(406 + 66.0)

Lake O’ the PinesCaddo Lake

(*Iron levels are g L-1)

Variables

PAH’s- some residues of creosote are

refractory- detectable with HPLCMetals- metal contamination can be detected using AA

Dating- 210Pb and 137Cs using a gamma-ray counter

Foodweb- various degradation products of phytoplankton

phytopigments are detectable with HPLC- lignins produced by rooted plants are also

detectablewith HPLC

- invertebrate hard-parts can be studied by lightmicroscopy

• Use sediment records to re-create long-term data.• Compare sediment profiles before and after

perturbation• Compare sediment profiles in impacted and

reference systems

A Solution

Statistical Analyses – Randomized Intervention Analysis

0 20 40 60 800

200

400

600

800

p<0.001

Dobserved= 61

Freq

uenc

y

Drandom

Cesium Dating Results

-30

-20

-10

0

0.0 0.5 1.0 1.5 2.0 2.5

1840

1860

1880

1900

1920

1940

1960

1980

2000

Cesium Level (pCi g-1 dry wt.)

Sedi

men

t Dep

th (

cm)

Core A Core B

Year

Sedimentation Rates

0.0 0.1 0.2 0.3 0.4 0.5 0.6

Our Value(0.18)

Sedimentation Rate (cm yr-1)

James Bayou Profile

Original James Bayou

Flooded James Bayou

Summary

• Acute effects of oil development in Caddo Lake occurred (1920-19• Chronic effects may continue today due to creosote• Lake history can be re-constructed using paleo-limnology.

• Cores can be dated successfully.• Sedimentation rates low and variable.

• Now underway: 210Pb dating, phytopigments, invertebrate hard pa• Bottom features will be revealed using geo-referenced, side-scan

Charles W. RamcharanDept. Biological SciencesLouisiana State University

Baton Rouge, LA

cramcha@LSU.edu

Louisiana Oil Spill ResearchAnd Development Program

(OSRADP)

Lake History

Before 1850• Caddo Lake exists as an ephemeral water body.• The lake area was always at the least a wet marsh.• A lake would form whenever a log-jam blocked the outflow river.

1850-1910• Lake was formed by a large log jam.• Army Corps of Engineers replaced the log jam in 1910 with

an earthen dam.• Dam served to raise the water level enough to float barges

carrying drilling machinery.

1920 – 1970’s• Hundreds of oil platforms installed in the lake, then decommissione• Oil rigs constructed of creosote-soaked timbers.• Decommissioned rigs were cut down and the timbers were left

on the lake bottom.

Summary

• Caddo Lake is the first freshwater lake to have beensubjected to oil development.

• Chronic effects of oil development may be caused by leachingof creosote from oil rig support timbers.

• Chronic effects are now only detectable by searching for cluesin the lake’s sediments.

• Cores from contaminated and reference sites will be dated.determinations of levels of phytopigments, metals, and invertebratehard-parts will be performed.

• Differences in time-series between the two sites will be attributedto effects of oil development.

• A second comparison will be made between the creosote-contaminatedsite (Caddo Lake) and a metal-contaminate site (LOP)

Historical Marker for Caddo-Pine Island Oil Field.

Historical Marker –Caddo-Pine oil field

Another oil head in North Arm

A typical oil head located in the North Arm of Caddo Lak