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October 2011 NATIONAL COOPERATIVE HIGHWAY RESEARCH PROGRAM Responsible Senior Program Officer: Christopher J. Hedges Research Results Digest 363 HYDROACOUSTIC IMPACTS ON FISH FROM PILE INSTALLATION Bridges, ferry terminals, and other structures commonly have driven-pile foundations, and pile driving can cause effects on fish ranging from altered behavior, hearing loss, and tissue injuries to immediate mortality. The objec- tive of NCHRP Project 25-28 was to develop guidelines for the prediction and mitigation of the negative impacts on fish from underwater sound pressure during pile and casing installation and removal. The research was con- ducted by a team comprised of researchers from the University of Mary- land and BattellePacific Northwest Division. The Principal Investigators were Michele B. Halvorsen, Thomas J. Carlson, and Arthur N. Popper, assisted by Brandon M. Casper and Christa M. Woodley. C O N T E N T S Summary, 1 SUMMARY a cumulative sound exposure level (SELcum) Chapter 1 Background, 4 of 187 dB re 1 Pa2s for fishes more than Introduction and Background Potential Effects of Pile Driving Sounds on Fish, 5 2 grams and 183 dB re 1 Pa2s for fishes Study Rationale, 5 Study Goal and Objectives, 7 As more pile driving activity occurs, less than 2 grams, and a single-strike peak Previous Studies Using Similar there is an increased concern about its level (SPLpeak) of 206 dB re 1 Pa for all Equipment, 7 potential effects on fishes and other aquatic sizes of fishes (Stadler and Woodbury, Chapter 2 Methods, 7 Study Fish, 7 organisms. The possibility of effects on 2009). If either the SELcum or SPLpeak are Fish Maintenance, 8 fishes rises as more offshore wind farms are exceeded, mitigation protocols should be Sound Exposure Apparatus and Methods, 8 installed around the United States and other applied. Sounds, 8 HICI-FT Sound Control Operation, 9 nations in addition to the ongoing infrastruc- Field research on effects of pile driving General Experimental Procedures, 10 ture and industrial maintenance and devel- is difficult to execute, and researchers have Barotrauma Analysis and Characterization, 10 opment activities, such as those performed not had control over the pile driving expo- Response Variable Derivation, 10 Statistical Analysis, 12 by transportation agencies throughout the sures (frequency of strikes, intensity, dura- United States. Effects on fishes potentially tion, and other parameters) nor, in many Chapter 3 Results, 12 Sound Exposures, 12 associated with pile driving include damage cases, the physiological state of test fishes Barotrauma, 12 to body tissues that could result in death, as during exposure. Thus, it was critical in Chapter 4 Discussion, 17 well as impacts on behavior that could cause this study to design an experiment in which Overview, 17 Rejection of the Equal Energy fishes to leave sites of biological importance researchers had control of all experimental Hypothesis for Pile Driving, 18 Relationship Between Pile Driving (e.g., feeding, spawning). parameters in order to investigate which Exposure and Biological The goal of this study was to provide variables play a role in tissue damage caused Response, 18 quantitative data that may be used to define by barotrauma. Barotrauma occurs when Chapter 5 Application to Pile Driving Projects, 19 criterion levels for tissue damage onset and there is a rapid change in pressure that Background, 19 Derivation of Exposure Criteria, 20 then use these criteria in design of future directly affects the body gases. Free gas in pile driving projects with options for pro- the swim bladder, blood, and tissue of fishes Chapter 6 Future Research, 21 tection of animals. Regulations for pile driv- along with gas in solution in blood and other References, 23 ing on the U.S. west coast currently utilize a fluids can respectively experience a change Acronyms, 24 dual interim criteria approach for onset of in volume and state (e.g. expansion and Appendices A Through H, 24 physiological effects. These criteria include contraction and/or bubble formation and

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absorption) during rapid pressure changes, which The distributions of results from experimental can lead to tissue damage, organ failure, and changes treatments of 1,920 and 960 pile driving strikes in behavior. showed a statistically significant correlation between RWI and SELcum. Additional statistical analysis showed that as SELcum increased, there was an Experimental Approach increase in RWI values. The increase in RWI was the To examine the effects of pile driving on fishes, result of the number of injuries each exposed fish a High Intensity Controlled Impedance Fluid-filled experienced as well as the physiological significance wave Tube (HICI-FT) was developed that enabled of those injuries. replication of aquatic far-field, plane-wave acoustic Results also showed that fish exposed to 960 conditions in the laboratory. The HICI-FT is con- strikes had a significantly higher RWI value (p = structed of a thick stainless steel tube that has a mov- 0.0145) than fish exposed to 1,920 strikes at the ing coil shaker at either end of the tube for sound same value of SELcum. In other words, for the same stimulation. The HICI-FT system enabled presenta- values of SELcum, higher levels of SELss resulted in tion of pile driving sounds in the laboratory and pro- increases in the number and severity of injuries vided control of the parameters that affect pile driving observed. These injury trends, when quantified signals. Juvenile Chinook salmon (Oncorhynchus using our assessment model, resulted in significantly tshawytscha), a federally protected species that is of higher RWI values for 960 vs. 1,920 strikes. This great concern around pile driving activities on the result is understandable if the energy in a strike and U.S. west coast, were exposed to pile driving signals the accumulated number of strikes are viewed as that had been recorded in the field during actual pile factors in producing the RWI. driving installations. One objective of the project was to prove a cor- relation between the SELcum with the response level Conclusions of barotrauma injury. Another objective was to test The findings of this study demonstrate that the the validity of the "equal energy" hypothesis that has equal energy hypothesis does not apply to effects of been implicitly accepted for management of activi- pile driving, thereby showing that a single metric of ties that generate impulsive sounds. The equal energy total energy, SELcum, is not sufficient to determine hypothesis states that the relevant metric for risk of criteria. Other metrics are necessary and should be injury to fish is the SELcum while other metrics are not taken into consideration. Those metrics include, but relevant [e.g., single-strike SEL (SELss) and/or the are not necessarily limited to, SELcum, SELss, and number of strikes]. In other words, the equal energy total number of strikes. hypothesis predicts that no matter how a damaging Interpreting the contour plot (Figure S-1) for SELcum is reached (e.g., a few strikes or many application, an RWI of 1 would be a single Mild strikes), the effects on fishes would be the same. To injury, and an RWI of 2 would be any two Mild test this hypothesis, experiments paired sound expo- injuries (see Table S-1 for injury descriptions). An sures such that there were two treatments with the RWI of 1 or 2 can only be achieved by 1 or 2 Mild same SELcum, while the SELss and number of strikes injuries. Because it is clear that there are no life- changed. threatening effects from these Mild injuries, an RWI of 2 is an acceptable level of effect and one that is sub-onset of injury. Findings In contrast, an RWI of 3 could be any three Examination of barotrauma injuries showed that Mild injuries or a single Moderate injury. The RWI not all injuries had the same physiological signifi- contours in Figure S-1 along with Table S-1 would cance for the fish following exposure. Table S-1 dis- first be used to determine an acceptable level of plays a rank, weight, and categorization for each injury; i.e., an RWI of 2. Second, the SELcum con- injury based on physiological effect. These data were tours and x axis would then be used to determine used in the computation of a response weighted index which SELss and SELcum, in combination with (RWI). Injuries were categorized as Mild, Moderate, number of strikes, define the acceptable limits for or Mortal. exposure. 2

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Table S-1 Observed barotrauma injuries by mathematical weight, category, injury, physiological rank, and brief biological significance statement. Trauma Physiol. Wt Category Injury Description Rank Biological Significance of Injury 5 Mortal Dead within 1 hr 1 Dead 5 Mortal Pericardial (heart) hemorrhage 2 Discrete organ, main body blood pump, bleeding from heart; decreased blood pressure 5 Mortal Hepatic (liver) hemorrhage 3 Discrete organ; bleeding from liver; decreased blood pressure 5 Mortal Renal (kidney) hemorrhage 4 Non-discrete spongy organ, held in place with membrane, bleeding; decreased blood pressure 5 Mortal Ruptured swim bladder 5 Lost ability to maintain buoyancy, sank to bottom; may affect hearing 3 Moderate Intestinal hemorrhage 6 Blood filling the abdominal cavity; decreasing blood pressure 3 Moderate Burst capillaries along body 7 Decreased ability to get blood to muscle; wall decreased blood pressure 3 Moderate Pericardial (heart) hematoma 8 Could decrease efficacy of heart 3 Moderate Intestinal hematoma 9 Major portal system, decreased amount of blood flow to the rest of body. 3 Moderate Renal (kidney) hematoma 10 Large amount of blood pooling in more severe cases 3 Moderate Body muscles hematoma 11 Could affect swimming ability 3 Moderate Swim bladder hematoma 12 Could affect ability to regulate buoyancy; could potentially affect hearing 3 Moderate Fat hematoma 13 Related to swim bladder, caused from swim bladder 3 Moderate Ovaries/testes hematoma 14 Potential short-term damage but potential long- term consequences for reproductive success 1 Mild Blood spots on vent 15 Dilated capillaries near skin, respiratory acidosis, stress with a predisposition, or severe damage 1 Mild Dorsal fin hematoma 16 Dilated capillaries near skin, respiratory acidosis, stress with a predisposition, or severe damage 1 Mild Caudal fin hematoma 17 Dilated capillaries near skin, respiratory acidosis, or stress with a predisposition, or severe damage 1 Mild Pelvic fin hematoma 18 Fin is near intestinal portal system 1 Mild Pectoral fin hematoma 19 Fin is near the heart portal system 1 Mild Anal fin hematoma 20 Dilated capillaries near skin, caused by respi- ratory acidosis, stress with a predisposition, or severe damage 1 Mild Fully deflated swim bladder 21 Negatively buoyant, which could be beneficial (no ruptures) for less barotrauma, quick recovery by surface air gulp 1 Mild Partially deflated swim bladder 22 Negatively buoyant, which could be beneficial (no ruptures) for less barotrauma, quick recovery by surface air gulp 3