scholarly journals Timing of juvenile fish settlement at offshore oil platforms coincides with water mass advection into the Santa Barbara Channel, California

2019 ◽  
Vol 95 (4) ◽  
pp. 559-582
Author(s):  
Mary M Nishimoto ◽  
Libe Washburn ◽  
Milton S Love ◽  
Donna M Schroeder ◽  
Brian M Emery ◽  
...  
Keyword(s):  
Water Mass ◽  
Juvenile Fish ◽  
Santa Barbara Channel ◽  
Santa Barbara ◽  
High Salinity Water ◽  
Oil Platforms ◽  
Offshore Oil Platforms ◽  
Salinity Water ◽  
Almost All ◽  
Offshore Oil

Recent pathways taken by pelagic juvenile fishes to offshore oil platforms were reconstructed from remotely sensed and in situ measurements of currents and hydrography. Juvenile fishes comprised 52.8% (16,952 of 23 species) of all individuals (32,080 juveniles and adults of 35 species) observed during scuba surveys conducted about twice per week at two platforms in the eastern Santa Barbara Channel from May to August 2004. Blacksmith, Chromis punctipinnis (Cooper, 1863), and rockfishes (genus Sebastes, at least 18 taxa) comprised 95.1% of the recruits. Almost all rockfishes recruited to the deepest part of the platforms surveyed (26 and 31 m), while most blacksmith recruited in shallower waters. The onset of the recruitment season for juvenile rockfishes (genus Sebastes, Scorpaenidae) coincided with the advection of a low salinity water mass into the channel from the Southern California Bight. Before arrival of this water mass, water at the platforms resembled upwelled, high salinity water around the Point Conception region at the western channel entrance. Settlement pulses of rockfishes and blacksmith were observed during advective events when salinity decreased in the upper 40 m and currents turned northwestward or intensified in that direction. Two abundant rockfish species [bocaccio, Sebastes paucispinis Ayres, 1854, and treefish, Sebastes serriceps (Jordan and Gilbert, 1880)] showed synchronous patterns of juvenile settlement between platforms separated by 7 km. Our findings indicate that currents from the bight, rather than from central California, supplied recruits to settlement habitat in the eastern channel and that the spatial scale of connectivity for some fish populations in this region is greater than the channel itself.

Fouling assemblages on offshore oil platforms: diverse vertical reefs in the Arabian Gulf

2018 ◽  
Author(s):  
Pedro Range ◽  
Rodrigo Riera ◽  
Mustafa Omerspahic ◽  
Jessica Bouwmeester ◽  
Steffen Sanvig Bach ◽  
...  
Keyword(s):  
Arabian Gulf ◽  
Oil Platforms ◽  
Offshore Oil Platforms ◽  
Fouling Assemblages ◽  
Offshore Oil

scholarly journals Distribution of Arctic and Pacific copepods and their habitat in the northern Bering Sea and Chukchi Sea

2015 ◽  
Vol 12 (22) ◽  
pp. 18661-18691 ◽  
Author(s):  
H. Sasaki ◽  
K. Matsuno ◽  
A. Fujiwara ◽  
M. Onuka ◽  
A. Yamaguchi ◽  
...  
Keyword(s):  
Sea Ice ◽  
Water Mass ◽  
High Salinity ◽  
Chukchi Sea ◽  
Bottom Layer ◽  
Sea Ice Extent ◽  
High Salinity Water ◽  
Explanatory Variables ◽  
Northern Bering Sea ◽  
Salinity Water

Abstract. The advection of warm Pacific water and the reduction of sea-ice extent in the western Arctic Ocean may influence the abundance and distribution of copepods, i.e., a key component in food webs. To understand the factors affecting abundance of copepods in the northern Bering Sea and Chukchi Sea, we constructed habitat models explaining the spatial patterns of the large and small Arctic copepods and the Pacific copepods, separately, using generalized additive models. Copepods were sampled by NORPAC net. Vertical profiles of density, temperature and salinity in the seawater were measured using CTD, and concentration of chlorophyll a in seawater was measured with a fluorometer. The timing of sea-ice retreat was determined using the satellite image. To quantify the structure of water masses, the magnitude of pycnocline and averaged density, temperature and salinity in upper and bottom layers were scored along three axes using principal component analysis (PCA). The structures of water masses indexed by the scores of PCAs were selected as explanatory variables in the best models. Large Arctic copepods were abundant in the water mass with high salinity water in bottom layer or with cold/low salinity water in upper layer and cold/high salinity water in bottom layer, and small Arctic copepods were abundant in the water mass with warm/saline water in upper layer and cold/high salinity water in bottom layers, while Pacific copepods were abundant in the water mass with warm/saline in upper layer and cold/high salinity water in bottom layer. All copepod groups were abundant in areas with deeper depth. Although chlorophyll a in upper and bottom layers were selected as explanatory variables in the best models, apparent trends were not observed. All copepod groups were abundant where the sea-ice retreated at earlier timing. Our study might indicate potential positive effects of the reduction of sea-ice extent on the distribution of all groups of copepods in the Arctic Ocean.

Observed features of the water masses in the Halmahera Sea in November 2016

2021 ◽  
Vol 26 (4) ◽  
pp. 225-236
Author(s):  
Mochamad Riza Iskandar ◽  
Adi Purwandana ◽  
Dewi Surinati ◽  
Wang Zheng
Keyword(s):  
Water Mass ◽  
Mixed Layer Depth ◽  
Strong Mixing ◽  
High Salinity Water ◽  
The North ◽  
Vertical Diffusivity ◽  
Water Mass Analysis ◽  
Salinity Water ◽  
Vertical Turbulence ◽  
Weak Wind

Halmahera Sea is one of the locations in the eastern route of Indonesian Throughflow (ITF), where high salinity water is mainly transported by the ITF. The description of water mass in the Halmahera Sea from the perspective of water mass, and related mixing is important. It is not only useful for understanding water mass features, but it can also be used to determine the strength of the turbulent mixing, and so allow how it relates to the water transformation. Here, we report the water mass properties and estimation of mixing quantities in the Halmahera Sea from the CTD profiles based on recent onboard observations during the IOCAS cruise in November 2016. The water mass analysis was done by examining the characteristics of water types in the Temperature-Salinity (T-S) diagram. The mixing estimation uses the density profile derived from temperature and salinity profiles and the quantification of vertical turbulence observed by density overturn. Halmahera Sea is to be found as the location where the thermocline salinity changes abruptly, it is shown from the erosion of salinity maximum in the density of 22-26σθ decreased from the north to the south of the basin. It is associated with strong mixing with spots of higher vertical diffusivity in the thermocline and intermediate layer. In the upper layer, the mixed layer depth in the Halmahera Sea is relatively shallow with an average of about 16.95 m and it is associated with weak wind stress during this month.

Modelling of methane emissions from offshore oil platforms in the Norwegian sea

2021 ◽  
Author(s):  
Ignacio Pisso ◽  
Amy Foulds ◽  
Grant Allen
Keyword(s):  
Radiative Forcing ◽  
Oil And Gas ◽  
Lagrangian Model ◽  
Model Parameters ◽  
Positive Contribution ◽  
Atmospheric Methane ◽  
Norwegian Sea ◽  
Oil Platforms ◽  
Offshore Oil Platforms ◽  
Offshore Oil

<p>Methane is a major greenhouse gas that has increased since the pre-industrial era and reducing its emissions is potentially an effective way of mitigating the radiative forcing in the short term. The oil & gas industry has a positive contribution to the global atmospheric methane budget with fugitive emissions from infrastructure installations such as offshore oil platforms. As part of the United Nations Climate and Clean Air Coalition (UN CCAC) objective to quantify global CH4 emissions from oil and gas facilities, a series of aircraft campaigns have been carried out in the Norwegian sea among other areas. We report on the Lagrangian modelling activity of the emissions and transport sensitivities used to support the flux assessment. Source identification has been carried out based on backward modelling and has proved useful to interpret observations form the in situ airborne platforms. In addition, forward modelling of the emission plume in high resolution has been applied to constraining the plume height for mass balance methods assessment. Dependency of the resulting uncertainty of the flux estimates on various factors such as the choice of the meteorology and the of the Lagrangian model parameters is also discussed.</p>

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