scholarly journals Vertical movements of a pelagic thresher shark (Alopias pelagicus): insights into the species’ physiological limitations and trophic ecology in the Red Sea

2020 ◽  
Vol 43 ◽  
pp. 387-394
Author(s):  
MC Arostegui ◽  
P Gaube ◽  
ML Berumen ◽  
A DiGiulian ◽  
BH Jones ◽  
...  
Keyword(s):  
Red Sea ◽  
Trophic Ecology ◽  
Movement Ecology ◽  
Vertical Movements ◽  
Acoustic Backscattering ◽  
Hypoxic Conditions ◽  
Mesopelagic Zone ◽  
First Results ◽  
Epipelagic Zone ◽  
Thresher Shark

The pelagic thresher shark Alopias pelagicus is an understudied elasmobranch harvested in commercial fisheries of the tropical Indo-Pacific. The species is endangered, overexploited throughout much of its range, and has a decreasing population trend. Relatively little is known about its movement ecology, precluding an informed recovery strategy. Here, we report the first results from an individual pelagic thresher shark outfitted with a pop-up satellite archival transmitting (PSAT) tag to assess its movement with respect to the species’ physiology and trophic ecology. A 19 d deployment in the Red Sea revealed that the shark conducted normal diel vertical migration, spending the majority of the day at 200-300 m in the mesopelagic zone and the majority of the night at 50-150 m in the epipelagic zone, with the extent of these movements seemingly not constrained by temperature. In contrast, the depth distribution of the shark relative to the vertical distribution of oxygen suggested that it was avoiding hypoxic conditions below 300 m even though that is where the daytime peak of acoustic backscattering occurs in the Red Sea. Telemetry data also indicated crepuscular and daytime overlap of the shark’s vertical habitat use with distinct scattering layers of small mesopelagic fishes and nighttime overlap with nearly all mesopelagic organisms in the Red Sea as these similarly undergo nightly ascents into epipelagic waters. We identify potential depths and diel periods in which pelagic thresher sharks may be most susceptible to fishery interactions, but more expansive research efforts are needed to inform effective management.

scholarly journals Novel use of pop-up satellite archival telemetry in sawsharks: insights into the movement of the common sawshark Pristiophorus cirratus (Pristiophoridae)

2020 ◽  
Author(s):  
Patrick J Burke ◽  
Johann Mourier ◽  
Troy F Gaston ◽  
Jane E Williamson
Keyword(s):  
Trophic Ecology ◽  
Management Strategies ◽  
Movement Ecology ◽  
Vertical Movement ◽  
Unexpected Result ◽  
Vertical Movements ◽  
Archival Tags ◽  
Marine Realm ◽  
Elasmobranch Species ◽  
The Common

Abstract Background Understanding movement patterns of a species is vital for optimising conservation and management strategies. This information is often difficult to obtain in the marine realm for species that regularly occur at depth. The common sawshark (Pristiophorus cirratus) is a small, benthic associated elasmobranch species that occurs from shallow to deep-sea environments. No information is known regarding its movement ecology. Despite this, P. cirrata are still regularly landed as nontargeted catch in the south eastern Australian trawl fisheries. Three individuals were tagged with pop-up satellite archival tags (PSATs) off the coast of Tasmania, Australia, to test the viability of satellite tagging on these small elasmobranchs and to provide novel insights into their movement. Results Tags were successfully retained for up to three weeks, but movement results differed on an individual basis. All three individuals displayed a post-release response to tagging and limited vertical movement was observed for up to 5–7 days post-tagging. Temperature loggers on the tags suggest the animals were not stationary but moved horizontally during this time, presumably in a flight response. After this response, continuous wavelet transformations identified diel vertical movements in one individual at cyclical intervals of 12- and 24-hour periods, however, two others did not display as clear a pattern. Temperature was not significantly correlated with movement in the study period. The deepest depths recorded during the deployments for all individuals was approximately 120 meters and the shallowest was 5 meters. Conclusions This study demonstrates that sawsharks can be successfully tagged by pop-up satellite archival tags. The data presented here show that sawsharks regularly move both horizontally and vertically in the water column, which was an unexpected result for this small benthic species. Additional research aimed at resolving the trophic ecology will help identify the drivers of these movements and help to better define the ecological, behavioural and physiological roles of these sharks in their ecosystems. These data describe a substantial ability to move in the common sawshark that was previously unknown and provides the first account of movement ecology on the family of sawsharks: Pristiophoridae.

scholarly journals Novel use of pop-up satellite archival telemetry in sawsharks: insights into the movement of the common sawshark Pristiophorus cirratus (Pristiophoridae)

2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Patrick J. Burke ◽  
Johann Mourier ◽  
Troy F. Gaston ◽  
Jane E. Williamson
Keyword(s):  
Trophic Ecology ◽  
Management Strategies ◽  
Movement Ecology ◽  
Vertical Movement ◽  
Unexpected Result ◽  
Vertical Movements ◽  
Archival Tags ◽  
Marine Realm ◽  
Elasmobranch Species ◽  
The Common

Abstract Background Understanding movement patterns of a species is vital for optimising conservation and management strategies. This information is often difficult to obtain in the marine realm for species that regularly occur at depth. The common sawshark (Pristiophorus cirratus) is a small, benthic-associated elasmobranch species that occurs from shallow to deep-sea environments. No information is known regarding its movement ecology. Despite this, P. cirrata are still regularly landed as nontargeted catch in the south eastern Australian fisheries. Three individuals were tagged with pop-up satellite archival tags (PSATs) off the coast of Tasmania, Australia, to test the viability of satellite tagging on these small elasmobranchs and to provide novel insights into their movement. Results Tags were successfully retained for up to 3 weeks, but movement differed on an individual basis. All three individuals displayed a post-release response to tagging and limited vertical movement was observed for up to 5–7 days post-tagging. Temperature loggers on the tags suggest the animals were not stationary but moved horizontally during this time, presumably in a flight response. After this response, continuous wavelet transformations identified diel vertical movements in one individual at cyclical intervals of 12- and 24-hour periods; however, two others did not display as clear a pattern. Temperature was not significantly correlated with movement in the study period. The deepest depths recorded during the deployments for all individuals was approximately 120 m and the shallowest was 5 m. Conclusions This study demonstrates that sawsharks can be successfully tagged by pop-up satellite archival tags. The data presented here show that sawsharks regularly move both horizontally and vertically in the water column, which was an unexpected result for this small benthic species. Additional research aimed at resolving the trophic ecology will help identify the drivers of these movements and help to better define the ecological, behavioural and physiological roles of these sharks in their ecosystems. These data describe a substantial ability to move in the common sawshark that was previously unknown and provides the first account of movement ecology on the family of sawsharks: Pristiophoridae.

Feeding patterns of transforming and juvenile myctophids that migrate into neustonic layers

2020 ◽  
Vol 650 ◽  
pp. 239-252 ◽  
Author(s):  
T Contreras ◽  
MP Olivar ◽  
JI González-Gordillo ◽  
PA Hulley
Keyword(s):  
Carbon Content ◽  
Trophic Ecology ◽  
Feeding Patterns ◽  
Early Stages ◽  
Mesopelagic Zone ◽  
Night Feeding ◽  
Increasing Trend ◽  
Epipelagic Zone ◽  
Juvenile Stages ◽  
The Relationship

Adult and juvenile myctophids feed at night in the epipelagic zone (<200 m) and are more dispersed in the mesopelagic zone (200-1000 m) during the daylight hours. In contrast, larvae inhabit the upper 200 m throughout a 24 h period and have daylight feeding patterns. Transforming stages occur both at the surface and in the mesopelagic zone and show less-defined feeding patterns. In this study, we analysed the trophic ecology of transforming and juvenile stages of 4 myctophids that occupy the neustonic layers (first 0-20 cm of the water column) during their nightly vertical migrations: Dasyscopelus asper, Gonichthys cocco, Myctophum affine, and M. nitidulum. Day and night neuston samples were collected across the equatorial and tropical Atlantic in April 2015. Transforming and juvenile stages occurred at night in the neuston, where they fed, but were absent from this layer during the day. The highest prey ingestion was observed between 01:00 and 04:00 h (UTC). Feeding incidence and the number of prey ingested increased from transformation stages to juvenile stages. Although the maximum prey size increased with fish body length, there was no significant increasing trend in mean prey sizes, but a great variability in the sizes of consumed prey. Diets of the 4 species mainly comprised a variety of copepod genera, usually dominated by Oncaea species. There was no evidence of resource partitioning among the 4 myctophid species. Estimates of daily feeding rations, based on the relationship between carbon content per gut and carbon content of fish body, throughout the night feeding period, showed that these species in these early stages ingested between 0.43 and 5.78% of their body carbon weight daily. We suggest that the occurrence and feeding of these early stages in the neuston may contribute to reducing trophic competition between migrating myctophids by space segregation.

scholarly journals Novel use of pop-up satellite archival telemetry in sawsharks: insights into the movement of the common sawshark Pristiophorus cirratus (Pristiophoridae)

2020 ◽  
Author(s):  
Patrick J Burke ◽  
Johann Mourier ◽  
Troy F Gaston ◽  
Jane E Williamson
Keyword(s):  
Trophic Ecology ◽  
Management Strategies ◽  
Movement Ecology ◽  
Vertical Movement ◽  
Unexpected Result ◽  
Vertical Movements ◽  
Archival Tags ◽  
Marine Realm ◽  
Elasmobranch Species ◽  
The Common

Abstract BackgroundUnderstanding movement patterns of a species is vital for optimising conservation and management strategies. This information is often difficult to obtain in the marine realm for species that regularly occur at depth. The common sawshark (Pristiophorus cirratus) is a small, benthic associated elasmobranch species that occurs from shallow to deep-sea environments. No information is known regarding its movement ecology. Despite this, P. cirrata are still regularly landed as nontargeted catch in the south eastern Australian fisheries. Three individuals were tagged with pop-up satellite archival tags (PSATs) off the coast of Tasmania, Australia, to test the viability of satellite tagging on these small elasmobranchs and to provide novel insights into their movement.ResultsTags were successfully retained for up to three weeks, but movement differed on an individual basis. All three individuals displayed a post-release response to tagging and limited vertical movement was observed for up to 5 – 7 days post-tagging. Temperature loggers on the tags suggest the animals were not stationary but moved horizontally during this time, presumably in a flight response. After this response, continuous wavelet transformations identified diel vertical movements in one individual at cyclical intervals of 12- and 24-hour periods, however, two others did not display as clear a pattern. Temperature was not significantly correlated with movement in the study period. The deepest depths recorded during the deployments for all individuals was approximately 120 meters and the shallowest was 5 meters.ConclusionsThis study demonstrates that sawsharks can be successfully tagged by pop-up satellite archival tags. The data presented here show that sawsharks regularly move both horizontally and vertically in the water column, which was an unexpected result for this small benthic species. Additional research aimed at resolving the trophic ecology will help identify the drivers of these movements and help to better define the ecological, behavioural and physiological roles of these sharks in their ecosystems. These data describe a substantial ability to move in the common sawshark that was previously unknown and provides the first account of movement ecology on the family of sawsharks: Pristiophoridae.

Hypoxic conditions induce centrum defects in red sea bream Pagrus major (Temminck and Schlegel)

2006 ◽  
Vol 37 (8) ◽  
pp. 805-812 ◽  
Author(s):  
Yoshifumi Sawada ◽  
Manabu Hattori ◽  
Naoko Sudo ◽  
Keitaro Kato ◽  
Yasuaki Takagi ◽  
...  
Keyword(s):  
Red Sea ◽  
Sea Bream ◽  
Red Sea Bream ◽  
Pagrus Major ◽  
Hypoxic Conditions

Inherited discontinuities and Neogene structure: the Gulf of Suez and the northwestern edge of the Red Sea

1986 ◽  
Vol 317 (1539) ◽  
pp. 129-139 ◽  
Keyword(s):  
Red Sea ◽  
Strike Slip ◽  
Stress System ◽  
Gulf Of Suez ◽  
Vertical Movements ◽  
Tectonic Events ◽  
Zigzag Pattern ◽  
Vertical Displacements ◽  
Intracontinental Deformation ◽  
Extensional Model

The Gulf of Suez and the northern Red Sea rifts are the result of intracontinental deformation during Neogene times. The initiation and the development of the rift are controlled by (i) four main trends of faults: N140°-N150°; NS to N 20°; sub E -W ; and N40°-60°; (ii) a zigzag faulting pattern; (iii) two main tectonic events. The first is characterized by strike-slip displacements inducing the formation of antithetic tilted blocks. The geometry of the blocks changes according to their orientation. Complex structures can result from the com bination of several trends. Vertical movements are weak. The second is characterized by synthetic normal movements forming a horst and graben pattern. Vertical displacements are important and induce the generation of the axial trough and uplift of the shoulders of the rift. The zigzag pattern of the faults that govern the Rift and the initial strike-slip displacements cannot result from a simple extensional model but imply a reactivation of inherited discontinuities in the Miocene stress system induced by the northern convergent boundaries of the African and Arabic plates. The major trends of faults that control the Neogene structure have been active in this area since Palaeozoic or even Proterozoic times.

scholarly journals Distribution and diel vertical movements of mesopelagic scattering layers in the Red Sea

2012 ◽  
Vol 159 (8) ◽  
pp. 1833-1841 ◽  
Author(s):  
Thor A. Klevjer ◽  
Daniel J. Torres ◽  
Stein Kaartvedt
Keyword(s):  
Red Sea ◽  
Vertical Movements

scholarly journals Environmental properties of the southern Gulf of Aqaba, Red Sea, Egypt

2012 ◽  
Vol 13 (2) ◽  
pp. 179 ◽  
Author(s):  
M.M. DORGHAM ◽  
M.M. EL-SHERBINY ◽  
M.H. HANAFI
Keyword(s):  
Dissolved Oxygen ◽  
Water Column ◽  
Chlorophyll A ◽  
Red Sea ◽  
Environmental Parameters ◽  
Gulf Of Aqaba ◽  
High Concentration ◽  
Environmental Properties ◽  
Epipelagic Zone ◽  
Deep Layers

Environmental properties (temperature, dissolved oxygen, nutrients and chlorophyll a) of the epipelagic zone off SharmEl-Sheikh, Red Sea, Egypt were studied seasonally throughout a year from March 1995 to March 1996. Water samples werecollected from five water depths (0, 25, 50, 75 & 100 m). The studied parameters exhibited clear seasonal variability along the water column. The vertical distribution of water temperature showed thermal homogeneity during most seasons, and thermal stratification in summer. Dissolved oxygen attained slightly high concentrations (5.3-7.8 mg l-1) in the whole water column, with slight seasonal variation. The concentrations of nutrients reflected dominant oligotrophic conditions in the epipelagic zone and occasional mesotrophic status at some depths. Phosphate fluctuated between 0-0.7 μM, ammonium (0-2.27 μM), nitrite (0-0.72 μM), nitrate (0-1.49 μM) and silicate (0-6.48 M). Phytoplankton biomass was generally low in the epipelagic zone throughout the study, whereas chlorophyll a was less than 0.5 μg l-1, except relatively high concentration (0.7-1.12 μg l-1) in deep layers in spring. In comparison with previous studies on the Gulf of Aqaba all environmental parameters during present study showed pronouncedlydifferent values.

Movements of thick evaporites on the flanks of a mid-ocean ridge: the central Red Sea Miocene evaporites

2020 ◽  
Author(s):  
Neil Mitchell ◽  
Wen Shi ◽  
Ay Izzeldin ◽  
Ian Stewart
Keyword(s):  
Red Sea ◽  
North Atlantic ◽  
Ocean Basin ◽  
Vertical Movements ◽  
Oceanic Spreading ◽  
Mid Ocean Ridge ◽  
History Of ◽  
Global Sea Level ◽  
Ocean Ridge ◽  
Thermal Subsidence

&lt;p&gt;Thick evaporites (&quot;salt&quot;) were deposited in the South and North Atlantic, and Gulf of Mexico basins, in some parts deposited onto the flanks of nascent oceanic spreading centres.&amp;#160; Unfortunately, knowledge of the history of evaporite movements is complicated in such places by their inaccessibility and subsequent diapirism.&amp;#160; This is less of a problem in the Red Sea, a young rift basin that is transitioning to an ocean basin and where the evaporites are less affected by diapirism.&amp;#160; In this study, we explore the vertical movements of the evaporite surface imaged with deep seismic profiling.&amp;#160; The evaporites have moved towards the spreading axis of the basin during and after their deposition, which ended at the 5.3 Ma Miocene-Pliocene boundary.&amp;#160; We quantify the evaporite surface deflation needed to balance the volume of evaporites overflowing oceanic crust of 5.3 Ma age, thermal subsidence of the lithosphere and loss of halite through pore water diffusion, allowing for isostatic effects.&amp;#160; The reconstructed evaporite surface lies within the range of estimated global sea level towards the end of the Miocene.&amp;#160; Therefore, the evaporites appear to have filled the basin almost completely at the end of the Miocene.&amp;#160; Effects of shunting by terrigenous sediments and carbonates near the coast and contributions of hydrothermal salt are too small to be resolved by this reconstruction.&lt;/p&gt;

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