Increasing reliance on deep-water renewable energy has increased concerns about the effects of th... more Increasing reliance on deep-water renewable energy has increased concerns about the effects of the electromagnetic fields (EMFs) generated by submarine power cables on aquatic organisms. Off southern California, we conducted surveys of marine organisms living around energized and unenergized submarine power cables and nearby sea floor during 2012–2014 at depths between 76 and 213 m. In general, EMFs declined to background levels about one meter from the cable. We found no statistical difference in species composition between the fish assemblages along the energized and unenergized cables. The natural habitat community statistically differed from both energized and unenergized cable communities. Within species (or species groups), we found no differences in densities between energized and unenergized cables. Total fish densities were significantly higher around the cables than over the natural habitat. We found that invertebrate communities were structured by habitat type and depth a...
Bulletin, Southern California Academy of Sciences, 2021
Abstract. Worldwide, all oil and gas offshore platforms contain conductors, a series of closely s... more Abstract. Worldwide, all oil and gas offshore platforms contain conductors, a series of closely spaced vertical pipes, that carry oil and gas from the wells. During decommissioning, these conductors are usually removed. However, worldwide, there has been no research on the relationship between conductor arrays and fish densities. During summer and fall of 2017 and 2018, at Platforms Holly and A, in the Santa Barbara Channel, California, we conducted visual scuba surveys of the fish densities associated with 1) conductors, 2) crossbeams, and 3) blue (open) water under these platforms. A minimum of 14 species were observed at Platform Holly and 14 species at Platform A. Substantially more fishes, and higher densities, were observed at Holly (17,533, 636 per 100 m–2, respectively) than at A (1,185, 171 per 100 m2). Although there were similarities, the dominant species at the two platforms were distinct. Rockfishes (genus Sebastes), particularly Sebastes hopkinsi, dominated the Holly assemblage, while the damselfish, Chromis punctipinnis, was the most abundant at A. Overall, at both platforms, there was no statistical difference between fish densities at conductors and at crossbeams and fish densities were higher at both conductors and crossbeams when compared to those in blue water. The species assemblage among three habitats were similar, although there were two survey occasions where no fish were observed in blue water. Our research strongly suggests that, to the extent possible, retaining conductors during partial removal will likely have a positive influence on both fish diversity and fish abundance, during at least some years.
<p>After all wells are permanently sealed, decommissioning may encompass one of four altern... more <p>After all wells are permanently sealed, decommissioning may encompass one of four alternatives for the platform [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0135812#pone.0135812.ref002" target="_blank">2</a>–<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0135812#pone.0135812.ref004" target="_blank">4</a>]: (a. Complete Removal) explosives are detonated to sever the well conductors, pilings, and support legs 5 m below the seafloor and the structure is towed to shore and scrapped, (a. Tow-And-Place) the severed structure is towed to a designated reef location and placed on the seafloor, (b. Partial Removal) the well conductors, pilings, and support legs are mechanically cut off, often at 26 m depth, and then optionally placed back on the seafloor as additional reef habitat, (c. Toppling) explosives are detonated to sever the conductors in the middle and pilings and support legs on three sides of the platform at the seafloor and the whole structure is bent over to remain in a horizontal orientation on the seafloor.</p
<p>The values presented here are the product of the annual growth in weight and annual surv... more <p>The values presented here are the product of the annual growth in weight and annual survivorship (see reference [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0135812#pone.0135812.ref022" target="_blank">22</a>] for more detail) and plotted for each species that contributed at least 1% of Total Production on any platform (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0135812#pone.0135812.s002" target="_blank">S2 Table</a>). Values were plotted over the size classes that a species was observed and rockfishes, <i>Sebastes spp</i>. were plotted with dashed lines. We also identify the curves for the two species observed that have the highest individual production rates, and for <i>Sebastes hopkinsi</i> which was used as the proxy for unidentified rockfishes because it was the most common species and its relatively low annual production rate per individual would result in a relatively conservative production estimate. Note that while growth in length according to the von Bertalanffy growth equation is highest at the smallest size, production here is maximized at intermediate lengths due to the exponential increase with weight-at-length and low survival rates at small sizes. Also, production goes to 0 when fishes grow larger than the mean asymptotic length predicted by the von Bertalanffy growth function [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0135812#pone.0135812.ref022" target="_blank">22</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0135812#pone.0135812.ref030" target="_blank">30</a>].</p
When oil and gas platforms become obsolete they go through a decommissioning process. This may in... more When oil and gas platforms become obsolete they go through a decommissioning process. This may include partial removal (from the surface to 26 m depth) or complete removal of the platform structure. While complete removal would likely eliminate most of the existing fish biomass and associated secondary production, we find that the potential impacts of par-tial removal would likely be limited on all but one platform off the coast of California. On aver-age 80 % of fish biomass and 86 % of secondary fish production would be retained after partial removal, with above 90 % retention expected for both metrics on many platforms. Partial removal would likely result in the loss of fish biomass and production for species typi-cally found residing in the shallow portions of the platform structure. However, these fishes generally represent a small proportion of the fishes associated with these platforms. More characteristic of platform fauna are the primarily deeper-dwelling rockfishes (genus ...
Renewable energy in the U.S. remains a frontier industry on the Outer Continental Shelf (OCS). Th... more Renewable energy in the U.S. remains a frontier industry on the Outer Continental Shelf (OCS). This new activity in the marine environment requires an assessment of the potential environmental impacts to resources on the OCS and evaluation of technical issues related to proposed activities. The Bureau of Ocean Energy Management, Regulation and Enforcement (BOEMRE) has two distinct programs to conduct studies and research related to renewable energy: the Environmental Studies Program (ESP) and the Technology Assessment and Research Program (TA&R). Through ESP, BOEMRE collects a wide range of environmental information offshore the United States for environmental assessment. These studies are designed to provide an improved understanding of the ecosystem, a baseline for assessing cumulative effects, and the scientific basis for development of regulatory measures to mitigate adverse impacts. Each year, BOEMRE's ESP funds roughly $35M of research in a broad spectrum of biological, so...
Increasing reliance on deep-water renewable energy has increased concerns about the effects of th... more Increasing reliance on deep-water renewable energy has increased concerns about the effects of the electromagnetic fields (EMFs) generated by submarine power cables on aquatic organisms. Off southern California, we conducted surveys of marine organisms living around energized and unenergized submarine power cables and nearby sea floor during 2012–2014 at depths between 76 and 213 m. In general, EMFs declined to background levels about one meter from the cable. We found no statistical difference in species composition between the fish assemblages along the energized and unenergized cables. The natural habitat community statistically differed from both energized and unenergized cable communities. Within species (or species groups), we found no differences in densities between energized and unenergized cables. Total fish densities were significantly higher around the cables than over the natural habitat. We found that invertebrate communities were structured by habitat type and depth a...
Bulletin, Southern California Academy of Sciences, 2021
Abstract. Worldwide, all oil and gas offshore platforms contain conductors, a series of closely s... more Abstract. Worldwide, all oil and gas offshore platforms contain conductors, a series of closely spaced vertical pipes, that carry oil and gas from the wells. During decommissioning, these conductors are usually removed. However, worldwide, there has been no research on the relationship between conductor arrays and fish densities. During summer and fall of 2017 and 2018, at Platforms Holly and A, in the Santa Barbara Channel, California, we conducted visual scuba surveys of the fish densities associated with 1) conductors, 2) crossbeams, and 3) blue (open) water under these platforms. A minimum of 14 species were observed at Platform Holly and 14 species at Platform A. Substantially more fishes, and higher densities, were observed at Holly (17,533, 636 per 100 m–2, respectively) than at A (1,185, 171 per 100 m2). Although there were similarities, the dominant species at the two platforms were distinct. Rockfishes (genus Sebastes), particularly Sebastes hopkinsi, dominated the Holly assemblage, while the damselfish, Chromis punctipinnis, was the most abundant at A. Overall, at both platforms, there was no statistical difference between fish densities at conductors and at crossbeams and fish densities were higher at both conductors and crossbeams when compared to those in blue water. The species assemblage among three habitats were similar, although there were two survey occasions where no fish were observed in blue water. Our research strongly suggests that, to the extent possible, retaining conductors during partial removal will likely have a positive influence on both fish diversity and fish abundance, during at least some years.
<p>After all wells are permanently sealed, decommissioning may encompass one of four altern... more <p>After all wells are permanently sealed, decommissioning may encompass one of four alternatives for the platform [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0135812#pone.0135812.ref002" target="_blank">2</a>–<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0135812#pone.0135812.ref004" target="_blank">4</a>]: (a. Complete Removal) explosives are detonated to sever the well conductors, pilings, and support legs 5 m below the seafloor and the structure is towed to shore and scrapped, (a. Tow-And-Place) the severed structure is towed to a designated reef location and placed on the seafloor, (b. Partial Removal) the well conductors, pilings, and support legs are mechanically cut off, often at 26 m depth, and then optionally placed back on the seafloor as additional reef habitat, (c. Toppling) explosives are detonated to sever the conductors in the middle and pilings and support legs on three sides of the platform at the seafloor and the whole structure is bent over to remain in a horizontal orientation on the seafloor.</p
<p>The values presented here are the product of the annual growth in weight and annual surv... more <p>The values presented here are the product of the annual growth in weight and annual survivorship (see reference [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0135812#pone.0135812.ref022" target="_blank">22</a>] for more detail) and plotted for each species that contributed at least 1% of Total Production on any platform (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0135812#pone.0135812.s002" target="_blank">S2 Table</a>). Values were plotted over the size classes that a species was observed and rockfishes, <i>Sebastes spp</i>. were plotted with dashed lines. We also identify the curves for the two species observed that have the highest individual production rates, and for <i>Sebastes hopkinsi</i> which was used as the proxy for unidentified rockfishes because it was the most common species and its relatively low annual production rate per individual would result in a relatively conservative production estimate. Note that while growth in length according to the von Bertalanffy growth equation is highest at the smallest size, production here is maximized at intermediate lengths due to the exponential increase with weight-at-length and low survival rates at small sizes. Also, production goes to 0 when fishes grow larger than the mean asymptotic length predicted by the von Bertalanffy growth function [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0135812#pone.0135812.ref022" target="_blank">22</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0135812#pone.0135812.ref030" target="_blank">30</a>].</p
When oil and gas platforms become obsolete they go through a decommissioning process. This may in... more When oil and gas platforms become obsolete they go through a decommissioning process. This may include partial removal (from the surface to 26 m depth) or complete removal of the platform structure. While complete removal would likely eliminate most of the existing fish biomass and associated secondary production, we find that the potential impacts of par-tial removal would likely be limited on all but one platform off the coast of California. On aver-age 80 % of fish biomass and 86 % of secondary fish production would be retained after partial removal, with above 90 % retention expected for both metrics on many platforms. Partial removal would likely result in the loss of fish biomass and production for species typi-cally found residing in the shallow portions of the platform structure. However, these fishes generally represent a small proportion of the fishes associated with these platforms. More characteristic of platform fauna are the primarily deeper-dwelling rockfishes (genus ...
Renewable energy in the U.S. remains a frontier industry on the Outer Continental Shelf (OCS). Th... more Renewable energy in the U.S. remains a frontier industry on the Outer Continental Shelf (OCS). This new activity in the marine environment requires an assessment of the potential environmental impacts to resources on the OCS and evaluation of technical issues related to proposed activities. The Bureau of Ocean Energy Management, Regulation and Enforcement (BOEMRE) has two distinct programs to conduct studies and research related to renewable energy: the Environmental Studies Program (ESP) and the Technology Assessment and Research Program (TA&R). Through ESP, BOEMRE collects a wide range of environmental information offshore the United States for environmental assessment. These studies are designed to provide an improved understanding of the ecosystem, a baseline for assessing cumulative effects, and the scientific basis for development of regulatory measures to mitigate adverse impacts. Each year, BOEMRE's ESP funds roughly $35M of research in a broad spectrum of biological, so...
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