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.

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 ◽  
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.

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 Contributions to Management Strategies in the NE Atlantic Regarding the Life History and Population Structure of a Key Deep-Sea Fish (Mora moro)

Biology ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 522
Author(s):  
Régis Santos ◽  
Wendell Medeiros-Leal ◽  
Osman Crespo ◽  
Ana Novoa-Pabon ◽  
Mário Pinho
Keyword(s):  
Population Structure ◽  
Life History ◽  
Deep Sea ◽  
Management Strategies ◽  
Size Composition ◽  
Large Size ◽  
The Common ◽  
Fishing Impacts ◽  
Sea Fish

With the commercial fishery expansion to deeper waters, some vulnerable deep-sea species have been increasingly captured. To reduce the fishing impacts on these species, exploitation and management must be based on detailed and precise information about their biology. The common mora Mora moro has become the main deep-sea species caught by longliners in the Northeast Atlantic at depths between 600 and 1200 m. In the Azores, landings have more than doubled from the early 2000s to recent years. Despite its growing importance, its life history and population structure are poorly understood, and the current stock status has not been assessed. To better determine its distribution, biology, and long-term changes in abundance and size composition, this study analyzed a fishery-dependent and survey time series from the Azores. M. moro was found on mud and rock bottoms at depths below 300 m. A larger–deeper trend was observed, and females were larger and more abundant than males. The reproductive season took place from August to February. Abundance indices and mean sizes in the catch were marked by changes in fishing fleet operational behavior. M. moro is considered vulnerable to overfishing because it exhibits a long life span, a large size, slow growth, and a low natural mortality.

scholarly journals Development of Resistance to Hymexazol Among Pythium Species in Cucumber Greenhouses in Oman

Plant Disease ◽  
2018 ◽  
Vol 102 (1) ◽  
pp. 202-208 ◽  
Author(s):  
Zainab M. Al-Balushi ◽  
Hesham Agrama ◽  
Issa H. Al-Mahmooli ◽  
Sajeewa S. N. Maharachchikumbura ◽  
Abdullah M. Al-Sadi
Keyword(s):  
Ribosomal Rna ◽  
Management Strategies ◽  
Soil Samples ◽  
Integrated Disease Management ◽  
Pythium Species ◽  
Internal Transcribed Spacer Region ◽  
Development Of Resistance ◽  
The Common ◽  
Cucumber Roots ◽  
Further Development

A study was conducted to characterize the common Pythium spp. in greenhouses in Oman and their level of resistance to hymexazol, a widely used fungicide in the country. Pythium isolates were obtained from soil samples, cocopeat bags, and cucumber roots collected from seven regions in the country. Identification of 80 Pythium isolates to the species level using sequences of the internal transcribed spacer region of the ribosomal RNA showed that they belong to four species: Pythium aphanidermatum (77 isolates), P. spinosum (1 isolate), P. myriotylum (1 isolate), and P. catenulatum (1 isolate). Investigating the aggressiveness of three Pythium spp. on cucumber showed that P. aphanidermatum, P. myriotylum, and P. spinosum are pathogenic. Phylogenetic analysis of P. aphanidermatum isolates showed that most of the isolates obtained from cocopeat clustered separately from isolates obtained from soil and roots. This may indicate a difference in the origin of the cocopeat isolates. Evaluating the resistance of 27 P. aphanidermatum isolates to hymexazol showed that most isolates were sensitive (0.9 to 31.2 mg liter−1) whereas one isolate was resistant (142.9 mg liter−1). This study is the first to report P. myriotylum and P. catenulatum in Oman. It is also the first to report the development of resistance to hymexazol among P. aphanidermatum populations from greenhouses. Growers should use integrated disease management strategies to avoid further development of resistance to hymexazol.

The Swimbladder and the Vertical Movement of Teleostean Fishes

1951 ◽  
Vol 28 (4) ◽  
pp. 553-566
Author(s):  
F. R. HARDEN JONES
Keyword(s):  
Body Wall ◽  
Bladder Wall ◽  
Relative Size ◽  
Perca Fluviatilis ◽  
Vertical Movement ◽  
Physical Factors ◽  
Vertical Movements ◽  
Perch Perca Fluviatilis ◽  
Percentage Volume ◽  
Two Factors

The vertical movements of a teleostean fish may be restricted by the presence of the swimbladder, which will increase or decrease in volume when the fish moves up or down in the water. It is shown that the restriction that the swimbladder imposes to vertical movements involving a reduction in pressure will depend on physical factors such as (1) The resistance that the bladder and body wall offer to the expansion of the bladder gas. (2) The percentage volume of the swimbladder and the density change of the fish when it is subjected to a reduction in pressure. (3) The pressure reduction that leads to the rupture of the bladder wall. A distinction is made between rapid and slow movements. In the former the compensatory ability of the fish must be considered and in the latter the speed with which the fish can accommodate itself to pressure changes. An equation is derived from which the minimum speed at which a physoclist can migrate from deep to shallow water can be calculated. To solve the equation two factors must be determined experimentally. Various experiments are described which were made on the perch, Perca fluviatilis, the wrasse, Crenilabrus melops, the rockling, Onos mustela and the dragonet, Callionymus lyra. The results showed that there was a relation between the relative size of the swimbladder and the change in the density of a fish when it is subjected to a reduction in pressure; that the bladder and body wall of the perch offer little resistance to the expansion of the bladder gas; and that the danger of the bladder wall rupturing might restrict the extent of rapid movements made by the perch. Experiments on the restriction that the swimbladder imposes to the rapid and slow vertical movements of the perch will be described in a following paper.

scholarly journals Horizontal-vertical movement relationships: Adélie penguins forage continuously throughout provisioning trips

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Javed Riaz ◽  
Sophie Bestley ◽  
Simon Wotherspoon ◽  
Louise Emmerson
Keyword(s):  
Environmental Conditions ◽  
Optimal Foraging ◽  
Three Dimensional ◽  
Spatial Location ◽  
Vertical Movement ◽  
Foraging Activity ◽  
Directed Movement ◽  
Vertical Movements ◽  
Movement Trajectories ◽  
Adélie Penguins

Abstract Background Diving marine predators forage in a three-dimensional environment, adjusting their horizontal and vertical movement behaviour in response to environmental conditions and the spatial distribution of prey. Expectations regarding horizontal-vertical movements are derived from optimal foraging theories, however, inconsistent empirical findings across a range of taxa suggests these behavioural assumptions are not universally applicable. Methods Here, we examined how changes in horizontal movement trajectories corresponded with diving behaviour and marine environmental conditions for a ubiquitous Southern Ocean predator, the Adélie penguin. Integrating extensive telemetry-based movement and environmental datasets for chick-rearing Adélie penguins at Béchervaise Island, we tested the relationships between horizontal move persistence (continuous scale indicating low [‘resident’] to high [‘directed’] movement autocorrelation), vertical dive effort and environmental variables. Results Penguins dived continuously over the course of their foraging trips and lower horizontal move persistence corresponded with less intense foraging activity, likely indicative of resting behaviour. This challenges the traditional interpretation of horizontal-vertical movement relationships based on optimal foraging models, which assumes increased residency within an area translates to increased foraging activity. Movement was also influenced by different environmental conditions during the two stages of chick-rearing: guard and crèche. These differences highlight the strong seasonality of foraging habitat for chick-rearing Adélie penguins at Béchervaise Island. Conclusions Our findings advance our understanding of the foraging behaviour for this marine predator and demonstrates the importance of integrating spatial location and behavioural data before inferring habitat use.

scholarly journals “Fiat Lux.” Navigating chaos through Sensing Leadership

2018 ◽  
Vol 4 (2) ◽  
Author(s):  
Johan Van der Merwe
Keyword(s):  
Change Management ◽  
Interpersonal Relationships ◽  
Leadership Style ◽  
Management Strategies ◽  
Sense Making ◽  
Leadership Attributes ◽  
Complex Interactions ◽  
Biblical Narratives ◽  
The Common ◽  
Response To Change

This article provides an overview of change management strategies described in business science. From the distinctions made, it becomes clear that change is all-pervasive and the result of complex interactions within and between the internal and external environments of organizations and communities. Complexity theory is subsequently considered as a better vantage point from where a response to change may be informed. The leadership style to correspond to this new reading of change needs to be that of “transcending leadership” where sensing and sense-making skills are honed to sense emerging meaning in organizations, in interpersonal relationships and through intrapersonal reflection. Instead of “making” change happen, the new leadership “lets” things happen, sensing the connections between emerging events in the context and creating a level of readiness to find the potential meaning in what may usually have been perceived as mere chaos. The creation narrative and a new reading of chaos as possibility provide Judeo-Christian sources of spirituality in this regard. Other Biblical narratives are cited to show in which way different change management frameworks can be applied to the respective narratives, but also how sensing and sense-making remain the common leadership attributes in successfully navigated change.

Two-Dimensional Records Of The Eyecup Movements Of The Crab Carcinus

1969 ◽  
Vol 50 (3) ◽  
pp. 673-682
Author(s):  
W. J. P. BARNES ◽  
G. A. HORRIDGE
Keyword(s):  
Carcinus Maenas ◽  
Two Dimensions ◽  
Shore Crab ◽  
Two Dimensional ◽  
Vertical Movements ◽  
Moving Stimulus ◽  
Light Stimuli ◽  
The Common

1. The eyecup movements of the common shore crab, Carcinus maenas L., have been recorded in two dimensions. 2. Saccades and eyecup drift occur in all directions. Eyecup tremor is a complex irregular movement although horizontal tremor predominates in most crabs. 3. Although the response to the movement of the light in a circle is usually an approximate circle or ellipse, rectangular responses are occasionally obtained and the eyecup often moves in a stepwise fashion in response to a smooth diagonal movement of the light. 4. The angle of response to a diagonal movement depends on the ratio of the response to horizontal and vertical movements alone. The eye is virtually stabilized in all planes by a contrasting object but never fixates upon a moving stimulus. 5. No torsional or twisting movements of the eyecups were obtained in response to light stimuli.

Microplastics from the Sources to Sinks: Assessment of Microplastics in the River Freshwater Environments and Wastewater Treatment Plants

2021 ◽  
Author(s):  
A H M Enamul Kabir ◽  
Masahiko Sekine ◽  
Tsuyoshi Imai ◽  
Koichi Yamamoto ◽  
Ariyo Kanno ◽  
...  
Keyword(s):  
Wastewater Treatment ◽  
Point Source ◽  
Pollution Control ◽  
Wastewater Treatment Plants ◽  
Management Strategies ◽  
Freshwater Ecosystems ◽  
Point Sources ◽  
Source To Sink ◽  
Comprehensive Knowledge ◽  
Marine Realm

<p>Freshwater microplastics pollution has been a recent focus. River freshwater microplastics pollution are vital towards freshwater ecosystems as well as have been the prominent source-to-sink conduits to export MPs into the marine realm. Wastewater treatment plants (WWTPs) have been identified as one of the major point-sources. To date, sources-to-sinks comprehensive knowledge are highly limited. This study explored sources-to-sinks microplastics pollution i.e., WWTPs-to-river-to-marine comprehensively. The two rivers i.e., Koya River (KR) and Nishiki River (NR) which are flowing to the Seto Inland Sea (SIS) and the WWTPs effluent samples were collected from selected (n=37) stations in the Yamaguchi prefecture, Japan. Filtration, wet peroxidation, and density separation methods were employed to extract microplastics particles. Polymers were identified via attenuated total reflectance-Fourier transform infrared spectroscopy. The average microplastics abundances were found KR—82.25±67.84 n/L and NR—38.73±24.13 n/L for the river water, and KRWWTPs—79.5±3.5 n/L and NRWWTPs—72.25±23.64 n/L for WWTPs effluents, respectively. The KR were found to be more polluted than the NR. WWTPs effluents were found posing higher abundances than rivers. Significantly higher microplastics concentration were found in the WWTPs downstream stations than other river stations. Characterization revealed that small MPs (<1000 µm) in size, fibers in shape, polymers— polyethylene, polypropylene, polyethylene terephthalate, vinylon were major in both of the WWTPs effluents and rivers. WWTPs influenced river environments by means both of the abundances and microplastics characteristics (shapes-size-polymers). The estimated source-to-sink emission demonstrated a substantial number of MPs discharge into the rivers by the WWTPs (0.007—0.086 billion/day) and rivers-to-SIS marine environments (1.15—7.951 billion/day). The emission represented that the WWTPs were the prominent point-source to cause river microplastics pollution. Rivers were the initial sinks of the Japan land-sourced microplastics and prominent pathways to emit microplastics to the ultimate marine sink i.e., SIS. Large amounts of MPs are being generated on land sources before the plastics wastes degrade into MPs secondarily. The pollution characteristics (shapes-sizes-polymers) indicated ecotoxicological threats to these rivers and the downstream environments. Overall, this study provided an insight of sources-to-sinks pollution, fulfilled the preliminary knowledge gaps of pollution occurring land-sources, fate and loadings. We recommended microplastics pollution control at source. This study will aid in developing microplastics pollution control and management strategies for environmental protection and sustainability in the regional Japan as well as global context upon “thinking globally and acting locally”.</p><p><strong>Keywords: </strong>Abundance, Point-source, Source-to-sink, Riverine microplastics pollution, Wastewater treatment plants</p>

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