scholarly journals The role of jacket complexity in structuring fish assemblages in the midwaters of two California oil and gas platforms

2019 ◽  
Vol 95 (4) ◽  
pp. 597-616 ◽  
Author(s):  
Milton S Love ◽  
Li Kui ◽  
Jeremy T Claisse
Keyword(s):  
Species Richness ◽  
Southern California ◽  
Oil And Gas ◽  
Fish Assemblages ◽  
Habitat Requirements ◽  
Rocky Reefs

Between 2005 and 2011, using manned research submersibles, we compared the fish assemblages associated with the midwater platform structures (at depths between 40 and 195 m) of two southern California oil and gas platforms, Gail and Eureka. Gail is a typical California platform, with rounded crossbeams and pilings, while the midwater jacket of Eureka, studded with bowl-shaped piling guides, is more complex. While the assemblages of both platforms were dominated by rockfishes (Sebastes spp.), there were also significant differences. Compared to Gail, Eureka: (1) exhibited higher densities of all species combined and of most species in common, (2) had more mature individuals of most species, (3) exhibited greater species richness, and (4) had higher densities of species typical of complex high relief. We propose that the complex midwater jacket of Eureka, with its many sheltering sites, resembles rugose natural rocky reefs. This research both reinforces the conclusion that many reef species have quite specific habitat requirements and that the platform decommissioning process must consider each platform individually.

scholarly journals Fish densities associated with structural elements of oil and gas platforms in southern California

2019 ◽  
Vol 95 (4) ◽  
pp. 639-656 ◽  
Author(s):  
Erin L Meyer-Gutbrod ◽  
Li Kui ◽  
Mary M Nishimoto ◽  
Milton S Love ◽  
Donna M Schroeder ◽  
...  
Keyword(s):  
Habitat Use ◽  
Southern California ◽  
Oil And Gas ◽  
Fish Assemblages ◽  
Fish Habitat ◽  
Artificial Reef ◽  
Offshore Structures ◽  
Structural Elements ◽  
Structural Element ◽  
Young Of The Year

There are thousands of offshore oil and gas platforms worldwide that will eventually become obsolete, and one popular decommissioning alternative is the "rigs to reefs" conversion that designates all or a portion of the underwater infrastructure as an artificial reef, thereby reducing the burden of infrastructure removal. The unique architecture of each platform may influence the size and structure of the associated fish assemblage if different structural elements form distinct habitats for fishes. Using scuba survey data from 11 southern California platforms from 1995 to 2000, we examined fish assemblages associated with structural elements of the structure, including the major horizontal crossbeams outside of the jacket, vertical jacket legs, and horizontal crossbeams that span the jacket interior. Patterns of habitat association were examined among three depth zones: shallow (<16.8 m), midwater (16.8–26 m), and deep (>26 m); and between two life stages: young- of-the-year and non-young-of-the-year. Fish densities tended to be greatest along horizontal beams spanning the jacket interior, relative to either horizontal or vertical beams along the jacket exterior, indicating that the position of the habitat within the overall structure is an important characteristic affecting fish habitat use. Fish densities were also higher in transects centered directly over a vertical or horizontal beam relative to transects that did not contain a structural element. These results contribute to the understanding of fish habitat use on existing artificial reefs, and can inform platform decommissioning decisions as well as the design of new offshore structures intended to increase fish production.

scholarly journals Taking a deeper look: Quantifying the differences in fish assemblages between shallow and mesophotic temperate rocky reefs

2018 ◽  
Author(s):  
Joel Williams ◽  
Alan Jordan ◽  
David Harasti ◽  
Peter Davies ◽  
Tim Ingleton
Keyword(s):  
Species Richness ◽  
Linear Models ◽  
Fish Assemblages ◽  
Habitat Type ◽  
Rocky Reefs ◽  
Temperate Reefs ◽  
Video Systems ◽  
Parsimonious Model ◽  
Using Data ◽  
Species Richness And Abundance

AbstractThe spatial distribution of a species assemblage is often determined by habitat and climate. In the marine environment, depth can become an important factor as degrading light leads to changes in the biological habitat structure. To date, much of the focus of ecological fish research has been based on reefs in less than 40 m with little research on the ecological role of mesophotic reefs. We deployed baited remote underwater stereo video systems (stereo-BRUVS) on temperate reefs in two depth categories: shallow (20-40m) and mesophotic (80-120m), off Port Stephens, Australia. Sites were selected using data collected by swath acoustic sounder to ensure stereo-BRUVS were deployed on reef. The sounder also provided rugosity, slope and relief data for each stereo-BRUVS deployment. Multivariate analysis indicates that there are significant differences in the fish assemblages between shallow and mesophotic reefs, primarily driven by Ophthalmolepis lineolatus and Notolabrus gymnogenis only occurring on shallow reefs and schooling species of fish that were unique to each depth category: Atypichthys strigatus on shallow reefs and Centroberyx affinis on mesophotic reefs. While shallow reefs had a greater species richness and abundance of fish when compared to mesophotic reefs, mesophotic reefs hosted the same species richness of fishery targeted species. Chrysophrys auratus (pink snapper) and Nemodactylus douglassii (grey morwong) are two highly targeted species in this region. While C. auratus was numerically more abundant on shallow reefs, mesophotic reefs provide habitat for larger fish. In comparison, N. douglassii were evenly distributed across all sites sampled. Generalized linear models revealed that depth and habitat type provided the most parsimonious model for predicting the distribution of C. auratus, while habitat type alone best predicted the distribution of N. douglassii. These results demonstrate the importance of mesophotic reefs to fishery targeted species and therefore have implications for informing the management of these fishery resources on shelf rocky reefs.

scholarly journals Seascape connectivity exerts differing effects for fish assemblages in distinct habitats of the surf zones of ocean beaches

2020 ◽  
Vol 77 (3) ◽  
pp. 1033-1042
Author(s):  
Jesse D Mosman ◽  
Christopher J Henderson ◽  
Andrew D Olds ◽  
Ben L Gilby ◽  
Thomas A Schlacher
Keyword(s):  
Species Richness ◽  
Indicator Species ◽  
Surf Zone ◽  
Fish Assemblages ◽  
Spatial Configuration ◽  
Spatial Scales ◽  
Coastal Habitat ◽  
Rocky Reefs ◽  
Eastern Australia ◽  
Management Approaches

Abstract Animals move throughout coastal seascapes to disperse, feed, and spawn, including the surf zones of ocean beaches. Yet, the influences of seascape context on surf-zone fish are largely unquantified. We sampled surf-zone fish assemblages with baited remote underwater video deployments at 25 beaches across 50 km of coastline in eastern Australia to determine if variation in the spatial configuration of broader coastal seascapes shapes fish assemblages in different surf-zone habitats. We show that surf zones are not homogenous fish habitats, with offshore bars and nearshore troughs having distinct fish assemblages, shaped by different environmental variables. Fish assemblages of offshore bars were characterized by greater species richness and a higher abundance of indicator species (as identified by Dufrene–Legendre indicator species analysis) when close to rocky reefs and estuaries. In contrast, fish assemblages of nearshore troughs were characterized by greater species richness and a higher abundance of indicator species when far from estuaries, and off wider beaches. Our results highlight the importance of seascape connectivity in structuring surf-zone fish assemblages. Consequently, management approaches need to more thoroughly quantify the effects of seascape connectivity over smaller spatial scales and consider surf zones as key components of broader coastal habitat mosaics.

scholarly journals Decommissioning impacts on biotic assemblages associated with shell mounds beneath southern California offshore oil and gas platforms

2019 ◽  
Vol 95 (4) ◽  
pp. 683-702 ◽  
Author(s):  
Erin L Meyer-Gutbrod ◽  
Milton S Love ◽  
Jeremy T Claisse ◽  
Henry M Page ◽  
Donna M Schroeder ◽  
...  
Keyword(s):  
Species Composition ◽  
Southern California ◽  
Oil And Gas ◽  
Fish Assemblages ◽  
Ecological Value ◽  
Remotely Operated Vehicle ◽  
Wide Range ◽  
Shell Mounds ◽  
Offshore Oil And Gas ◽  
Offshore Oil

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.

The Role of Oil and Gas Conductors as Fish Habitat at Two Southern California Offshore Platforms

2021 ◽  
Vol 119 (3) ◽  
Author(s):  
Milton S. Love ◽  
Scott Clark ◽  
Merit McCrea ◽  
Katelin Seeto ◽  
Conner Jainese ◽  
...  
Keyword(s):  
Southern California ◽  
Oil And Gas ◽  
Fish Habitat ◽  
Offshore Platforms

scholarly journals Fish assemblages of tropical floodplain lagoons: exploring the role of connectivity in a dry year

2003 ◽  
Vol 1 (2) ◽  
pp. 111-119 ◽  
Author(s):  
Ana Cristina Petry ◽  
Angelo Antonio Agostinho ◽  
Luiz Carlos Gomes
Keyword(s):  
Species Richness ◽  
Fish Assemblage ◽  
Fish Assemblages ◽  
Hydrological Connectivity ◽  
Spatial And Temporal Patterns ◽  
Marginal Areas ◽  
Upper Paraná River Floodplain ◽  
Density And Biomass ◽  
Year 2000

Irregular rainfall and pronounced reductions of the hydrometric level in the year 2000 resulted in drastically altered hydrological connectivity of lentic environments in the upper Paraná River floodplain. The objective of the present work was to examine spatial and temporal patterns of fish assemblage attributes and structure in relation to limnological variables associated with hydrological connectivity. Fish were collected quarterly by seining in the marginal areas of 15 lagoons belonging to two biotopic categories (connected and disconnected). Variation in assemblage composition reflected the degree of hydrological connectivity. Values of assemblage attributes (species richness, density and biomass) were significantly lower in connected lagoons than in disconnected lagoons. Significantly higher values of species richness and biomass were recorded in November than in August. Rare species had the greatest effect on observed patterns in fish assemblage ordination (DCA). Observed patterns of variation in assemblage attributes were directly correlated with factors related to hydrological connectivity, such as depth, resources (zooplankton and chlorophyll a) and nutrients (total phosphorus).

Protection effects on Mediterranean fish assemblages associated with different rocky habitats

2012 ◽  
Vol 93 (2) ◽  
pp. 425-435 ◽  
Author(s):  
Rita Sahyoun ◽  
Simona Bussotti ◽  
Antonio Di Franco ◽  
Augusto Navone ◽  
Pieraugusto Panzalis ◽  
...  
Keyword(s):  
Fish Assemblages ◽  
Marine Protected Area ◽  
Economic Value ◽  
Economic Role ◽  
North East ◽  
Rocky Reefs ◽  
Sea Bottom ◽  
Total Fish ◽  
Rocky Habitats

Rocky banks (i.e. sea mountain-like structures rising from the sea bottom) are hard substrate habitats of high socio-economic value (e.g. for fishermen and divers) and ecological relevance as they often host unusually high density of fish. Here we tested whether the response of fish assemblages to protection (i.e. related to the presence of a Marine Protected Area (MPA)) in rocky banks is comparable with the response of rocky reefs dropping from the coast (hereafter called ‘coastal rocky substrates’), and whether there are differences between fish assemblages associated with protected and unprotected rocky banks. Fish assemblages were assessed in shallow and deep coastal rocky substrates, and in rocky banks, in unprotected and protected conditions at a Mediterranean MPA in north-east Sardinia in August 2007 and 2008. Whole fish assemblage structures (in terms of biomass) differed between protected and unprotected conditions in both study years. Fish assemblages at rocky banks, in addition, differed from those associated with coastal rocky substrates. Total fish biomass (summing contribution of all species) was higher under protected than unprotected condition in 2007, while species richness and total fish density did not demonstrate any significant change related to protection. The responses to protection displayed by the target species Epinephelus marginatus and Diplodus sargus were clear especially in terms of greater frequency of large-sized specimens in both study years. Biomass of E. marginatus in 2007 and density of D. sargus in 2007 and 2008 were significantly higher in protected than unprotected conditions, especially in protected rocky banks. This study emphasizes the ecological and socio-economic role of protection and the potential role of rocky banks within management/conservation programmes in the Mediterranean Sea.

The Role of Migration in the Formation of Regional Labour Markets Amidst the Second Wave of Depopulation in Modern Russia

2020 ◽  
Vol 27 (6) ◽  
pp. 26-36
Author(s):  
A. V. Topilin ◽  
A. S. Maksimova
Keyword(s):  
Labour Market ◽  
Oil And Gas ◽  
Labour Markets ◽  
Labour Migration ◽  
Sample Surveys ◽  
Balance Sheets ◽  
Permanent Migration ◽  
Regional Labour Markets ◽  
The Impact

The article reflects the results of a study of the impact of migration on regional labour markets amidst a decline in the working-age population in Russia. After substantiating the relevance of the issues under consideration, the authors propose a methodological analysis toolkit, the author’s own methodology for calculating the coefficients of permanent long-term external and internal labour migration in regional labour markets, and the coefficient of total migration burden. In addition, the authors provide an overview of the information and statistical base of the study. According to current migration records, data of Rosstat sample surveys on Russian labour migrants leaving for employment in other regions, regional labour resources balance sheets based on the calculated coefficients of labour market pressures, the authors analyzed the impact of migration on the Russian regional labour markets over the past decade. It revealed an increasing role of internal labour migration in many regions, primarily in the largest economic agglomerations and oil and gas territories. At the same time, the role of external labour migration remains stable and minimum indicators of the contribution of permanent migration to the formation of regional labour markets continue to decrease. It has been established that irrational counter flows of external and internal labour migration have developed, which indicates not only an imbalance in labour demand and supply but also a discrepancy between the qualitative composition of migrants and the needs of the economy. It is concluded that the state does not effectively regulate certain types of migration, considering its impact on the labour market. The authors justified the need for conducting regular household sample surveys according to specific programs to collect information about labour migrants and the conditions for using their labour. In addition to the current migration records, using interregional analysis, this information allows making more informed decisions at the federal and regional levels to correct the negative situation that has developed in the regional labour markets even before the coronavirus pandemic had struck.

The Role of Oil and Gas in the Economic Development of the Global Economy

2018 ◽  
Author(s):  
Paul Stevens
Keyword(s):  
Economic Development ◽  
Global Economy ◽  
Oil And Gas ◽  
Primary Energy ◽  
Oil And Gas Producers ◽  
The Future ◽  
History Of ◽  
Factor Inputs ◽  
The Impact

This chapter is concerned with the role of oil and gas in the economic development of the global economy. It focuses on the context in which established and newer oil and gas producers in developing countries must frame their policies to optimize the benefits of such resources. It outlines a history of the issue over the last twenty-five years. It considers oil and gas as factor inputs, their role in global trade, the role of oil prices in the macroeconomy and the impact of the geopolitics of oil and gas. It then considers various conventional views of the future of oil and gas in the primary energy mix. Finally, it challenges the drivers behind these conventional views of the future with an emphasis on why they may prove to be different from what is expected and how this may change the context in which producers must frame their policy responses.

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