Effects of Produced Water on Complex Behavior Traits of Invertebrate Larvae 

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FINAL TECHNICAL SUMMARY 

STUDY TITLE: Effects of Produced Water on Complex Behavior Traits of Invertebrate 

Larvae

REPORT TITLE: Effects of Produced Water on Complex Behavior Traits of Invertebrate 

Larvae

CONTRACT NUMBER: 14-35-0001-30758 

SPONSORING OCS REGION: Pacific

APPLICABLE PLANNING AREA: Southern California

FISCAL YEAR(S) OF PROJECT FUNDING: FY 96, FY 97, FY 98 

COMPLETION DATE OF THE REPORT: December 2001 

COST(S): FY 96 - $25,000; FY 97 - $33,910; FY 98 - 63,819, FY 99 – no cost 

CUMULATIVE PROJECT COST: $122,729 

PROJECT MANAGER: Peter Raimondi

AFFILIATION: University of California, Santa Cruz

ADDRESS: Department of Biology, University of California, Santa Cruz, CA 95460 

PRINCIPAL INVESTIGATOR: 

1

Peter Raimondi 

POST DOCTORAL RESEARCHER: 1,2Anthony Boxshall

ADDRESSES: 1

Department of Biology, University of California, Santa Cruz, CA 95460; 

2

Marine Sciences Unit, EPA Victoria, Ernest Jones Drive, Macleod VIC, Australia, 3085 

KEY WORDS: ecotoxicology, produced water, oil drilling, invertebrate larvae, bryozoan, 

Watersipora spp, Bugula neritina, Haliotis rufescens, Schizoporella unicornis, sub-lethal impact, 

pulsed exposure, carry-over effects. 

BACKGROUND: Produced Water (PW) is a by-product of oil drilling and in the Southern 

California region a common form of disposal of PW is by direct discharge into the ocean from a 

platform-based diffuser. Many compounds and elements in PW are known to have toxic effects 
Final Technical Summary – Raimondi and Boxshall 

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on a number of organisms however these toxic effects are not always lethal, even in static 

conditions. 

Short, spiked exposure sees larvae exposed to a pulse of PW for a short period of time and is 

unlikely to produce lethal effects, however it may result in a series of important sub-lethal effects 

for organisms in various stages of their lifecycles. It is now generally believed that the discharge 

of produced water can cause severe, generally sub-lethal, effects to organisms over distances well 

beyond that predicted by plume dilution models. Plume measurement and modeling has shown 

that it is more than possible for larvae in the water column 1km away from a diffusion source to 

contact PW at 1% of it’s original concentration. 

The early life history stages of invertebrate larvae are very important developmental phases. 

Some invertebrates and algae have been shown to be particularly susceptible to any negative 

effects of contaminants during these developmental phases. The impacts seen on larval behavior 

have included swimming behavior, cue-recognition, settlement and larval survival. Little work 

has been published that follows the sub-lethal impacts on larvae through to their adult phase. 

The ecological consequence of carrying-over impacts to the adult phase from sub-lethal impacts 

on larvae have been rarely tested. 

OBJECTIVES: One of the major aims of this project was to test the assumption that sub-lethal 

impacts on larvae can, and do, carry-over into the adult phase of the invertebrate life-cycle. By 

exposing invertebrate larvae at an early developmental stage and following their development 

through to adulthood and beyond, it is possible track the impact of early exposure to PW. 

Other aims were more broad: to expand the number of larvae exposed to, and types of sub-lethal 

impacts assessed from exposure to PW. 

DESCRIPTION: By exposing different types of larvae to PW at various stages of their 

development, we had a number of outcomes: 

3⁄4 First, we expanded the number and type of larvae tested for sub-impacts from pulsed 

exposure to PW. 

3⁄4 Second, we tested the types of sub-lethal impacts that can occur on invertebrate larvae from 

exposure to PW. By doing so, we tested for the impact of PW on a number of sub-lethal 

endpoints, including swimming behavior, cue-recognition, attachment and metamorphosis. 

3⁄4 Finally, we followed some species of larvae through their development into adults and tested 

for any carry-over impacts for a range of endpoints, including growth, competitive ability, 

reproduction and survival. 

The project tested a wide range of invertebrate larvae, including the bryozoans Watersipora spp, 

Bugula neritina, Schizoporella unicornis, the red abalone Haliotis rufescens, the sea star Asterina 

miniata and the ascidian Botrylloides spp. for carry-over effects from the sub-lethal impact of 

exposure to produced water as larvae. This broad range represents four different phyla of both 
Effects of Produced Water on Complex Behavior Traits of Invertebrate Larvae 

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introduced and local species as well as a broad range of types of larval development. All 

exposures were short-term, spiked exposure in still water conditions in the lab. 

SIGNIFICANT CONCLUSIONS: 

• All exposures were short-term, spiked exposure in still water conditions in the lab. 

• Not all experiments on all invertebrate larvae were successful. 

• Those experiments that were successful showed, in broad terms, that there was little evidence 

for strong sub-lethal effects on the growth, competitive ability or reproductive output of those 

invertebrates successfully studied. However sub-lethal impacts did occur. 

• Where mortality occurred, it tended to be larger in colonies of bryozoans in treatments 

exposed to concentrations of 10% PW. 

• Many and varied sub-lethal impacts were found from exposing larvae to a range of PW 

concentrations (with 10 % PW having the greatest and most consistent impact). 

• Sub-lethal impacts include decreases in swimming capacity, slowed metamorphosis, altered 

attachment and settlement behaviors, and delayed opercula development. 

• Not all invertebrate larvae showed all impacts, nor were tested for the full range of endpoints. 

• There was little evidence for strong carry-over effects to adulthood of larval PW exposure, 

with some caveats. 

STUDY RESULTS: The results of this study are fully contained within the Report “Effects of 

Produced Water on Complex Behavioral Traits of Invertebrate Larvae” presented to MMS.

STUDY PRODUCTS: A number of presentations (6) were given during this work as both 

invited and conference seminars. Three posters were also given at a range of conferences. The 

details of all these were contained in the annual reports written for MMS. 

There are three manuscripts in preparation from work down during this project: 

Boxshall, AJ and PT Raimondi, The sub-lethal impact on Watersipora subtorquata adults 

from exposing larvae to a toxicant. In prep. A 

Boxshall, AJ, and PT Raimondi, Carry-over effects on adults from exposing Bugula 

neritina and Schizoporella unicornis larvae to sub-lethal toxicant. In prep. B 

Boxshall, AJ and PT Raimondi, Impacts on adult Phragmatapoma californica of 

exposing larvae to a sub-lethal toxicant. In prep. C