Summer and winter plankton fish assemblages around offshore oil and gas platforms in south-eastern Australia

The decommissioning of southern California offshore oil and gas platforms will create major economic, engineering, and environmental challenges in the next decade. Platform jackets, conductors, and shell mounds often host a diverse and productive marine community, and among the myriad considerations associated with decommissioning planning, platform operators and federal and state regulatory agencies will consider the ecological value of existing underwater structures as artificial reefs. In the event of partial removal of platform structure, fish assemblages on decommissioned platforms may remain unchanged in areas where structure is left intact. However, on the seafloor beneath the platforms, a mound of debris often called the shell mound will likely change over time if the supply of falling mussels and other organisms from the productive surface part of the structure is removed. In this study, we review shell mound research relevant to decommissioning, including mound formation, contaminant loads, associated biological communities, and transitions following the removal of platform structures at four sites. To address the gap in knowledge of shell mound fish community structure, we used manned submersible and remotely operated vehicle surveys from 1997 to 2013 to estimate the biomass, density, species composition and similarity between shell mounds at 22 southern California platforms. We found a wide range of variability in fish density and shell mound areal extent. Species composition also varied among sites, with three significant community clusters primarily distinguished by species depth preferences. These results will help inform a comprehensive net environmental benefit analysis of southern California offshore platform decommissioning alternatives.

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Temporal change in fish assemblages in the lower Goulburn River, south-eastern Australia: comment on Pollino et al. (2004)

Marine and Freshwater Research ◽

10.1071/mf05066 ◽

2006 ◽

Vol 57 (3) ◽

pp. 303 ◽

Cited By ~ 1

Author(s):

David A. Crook ◽

Wayne M. Koster

Keyword(s):

Survey Data ◽

Fish Assemblage ◽

Fish Assemblages ◽

Fish Fauna ◽

Recent Analysis ◽

Stressed Condition ◽

Fish Assemblage Structure ◽

South Eastern ◽

Eastern Australia ◽

South Eastern Australia

A recent analysis of fish assemblages in the Goulburn River, south-eastern Australia, used fish survey data collected between 1970 and 2002 to examine spatial patterns in the compositions and relative abundances of fish assemblages in the catchment. Based on this analysis, it was concluded that the native fish fauna of the Goulburn River is in a stressed condition and that introduced species dominate the fish assemblages. Fish survey data collected in 1982–1983 are compared with data collected in 2003–2004 to examine whether fish assemblages in the lower Goulburn River were stable at the temporal scale at which the data were aggregated in the previous analysis. The results show significant differences in fish assemblage composition between the two surveys, suggesting that fish assemblage structure in the lower Goulburn River did not remain stable between 1982–1983 and 2003–2004. The aggregation of data collected over several decades has the potential to confound analysis of spatial variations in fish assemblages and is unlikely to provide a reliable means of assessing their current condition.

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An analysis of the fish assemblages around 23 oil and gas platforms off California with comparisons with natural habitats

Bulletin of Marine Science ◽

10.5343/bms.2018.0061 ◽

2019 ◽

Vol 95 (4) ◽

pp. 477-514 ◽

Cited By ~ 4

Author(s):

Milton S Love ◽

Jeremy T Claisse ◽

Alexa Roeper

Keyword(s):

Oil And Gas ◽

Fish Assemblages ◽

Habitat Type ◽

Geographic Location ◽

Natural Habitats ◽

Central California ◽

Shell Mounds ◽

Young Of The Year ◽

Offshore Oil And Gas ◽

Offshore Oil

Between 1995 and 2013, we surveyed fishes living around 23 California offshore oil and gas platforms (midwaters, bases, and shell mounds) and 70 natural habitats. These platforms were distributed between about Point Arguello, central California, and Huntington Beach, southern California, had seafloor depths between 49 and 363 m, and were surveyed between one and 16 times. A total of 1,526,437 fishes were observed. Fish densities were highest around platform bases, followed by platform midwaters, shell mounds, and natural habitats. Of all fishes observed, 90.4% were in the genus Sebastes. Water depth was the strongest driver of the fish species assemblages, although habitat type and geographic location were also important. Most of the fishes living around platforms and natural habitats were relatively small, primarily ≤20 cm in length. Many of these individuals were the juveniles of larger taxa or the juveniles and adults of dwarf species. Larger fishes were less common and these were most often found around platform bases and on natural habitats. Most young-of-the-year (YOY) fishes occurred at water depths of ≤150 m at all four habitats. At platforms, YOY densities were highest in platform midwaters and bases. On average, densities of these young fishes were somewhat higher compared to natural habitats and it is likely that many, although not all, California platforms play a significant role as nursery grounds for a variety of fishes, particularly for a number of Sebastes species.

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