scholarly journals Active dispersal in loggerhead sea turtles ( Caretta caretta ) during the ‘lost years’

2016 ◽  
Vol 283 (1832) ◽  
pp. 20160690 ◽  
Author(s):  
D. K. Briscoe ◽  
D. M. Parker ◽  
G. H. Balazs ◽  
M. Kurita ◽  
T. Saito ◽  
...  
Keyword(s):  
Ocean Circulation ◽  
Numerical Models ◽  
Sea Turtles ◽  
Circulation Model ◽  
Marine Species ◽  
Geographical Information ◽  
Foraging Strategies ◽  
Loggerhead Sea Turtles ◽  
Physical Forcing ◽  
Active Dispersal

Highly migratory marine species can travel long distances and across entire ocean basins to reach foraging and breeding grounds, yet gaps persist in our knowledge of oceanic dispersal and habitat use. This is especially true for sea turtles, whose complex life history and lengthy pelagic stage present unique conservation challenges. Few studies have explored how these young at-sea turtles navigate their environment, but advancements in satellite technology and numerical models have shown that active and passive movements are used in relation to open ocean features. Here, we provide the first study, to the best of our knowledge, to simultaneously combine a high-resolution physical forcing ocean circulation model with long-term multi-year tracking data of young, trans-oceanic North Pacific loggerhead sea turtles during their ‘lost years’ at sea. From 2010 to 2014, we compare simulated trajectories of passive transport with empirical data of 1–3 year old turtles released off Japan (29.7–37.5 straight carapace length cm). After several years, the at-sea distribution of simulated current-driven trajectories significantly differed from that of the observed turtle tracks. These results underscore current theories on active dispersal by young oceanic-stage sea turtles and give further weight to hypotheses of juvenile foraging strategies for this species. Such information can also provide critical geographical information for spatially explicit conservation approaches to this endangered population.

scholarly journals A coarse resolution North Atlantic ocean circulation model: an intercomparison study with a paleoceanographic example

1996 ◽  
Vol 14 (2) ◽  
pp. 246-257 ◽  
Author(s):  
Dan Seidov ◽  
Ralf Prien
Keyword(s):  
Ocean Circulation ◽  
North Atlantic ◽  
Numerical Models ◽  
Bottom Topography ◽  
Circulation Model ◽  
Deep Ocean ◽  
Return Flow ◽  
Freshwater Flux ◽  
Surface Boundary

Abstract. Paleoreconstructions suggest that during the Last Glacial Maximum (LGM) the North Atlantic circulation was noticeably different from its present state. However, the glacial salt conveyor belt is believed to be similar to the present-day's conveyor, albeit weaker and shallower because of an increased freshwater flux in high-latitudes. We present here the investigation of the conveyor operation based on ocean circulation modelling using two numerical models in parallel. The GFDL primitive equation model and a planetary geostrophic model are employed to address the problem of the paleocirculation modelling in cases of uncertain and sparse data comprising the glacial surface boundary conditions. The role of different simplifications that may be used in the ocean climate studies, including the role of grid resolution, bottom topography, coast-line, etc., versus glacial-interglacial changes of the ocean surface climatology is considered. The LGM reverse conveyor gyre appeared to be the most noticeable feature of the glacial-to-interglacial alteration of the ocean circulation. The reversed upper-ocean conveyor, weaker and subducting 'normal' conveyor in the intermediate depths, and the change of the deep-ocean return flow route are robust signatures of the glacial North Atlantic climate. The results are found to be 'model-independent' and fairly insensitive to all factors other than the onset of the glacial surface conditions.

scholarly journals Deepwater Horizon oil spill impacts on sea turtles could span the Atlantic

2015 ◽  
Vol 11 (12) ◽  
pp. 20150596 ◽  
Author(s):  
Nathan F. Putman ◽  
F. Alberto Abreu-Grobois ◽  
Iñaky Iturbe-Darkistade ◽  
Emily M. Putman ◽  
Paul M. Richards ◽  
...  
Keyword(s):  
Gulf Of Mexico ◽  
Oil Spill ◽  
Ocean Circulation ◽  
Sea Turtles ◽  
Circulation Model ◽  
Deepwater Horizon ◽  
The United States ◽  
Deepwater Horizon Oil Spill ◽  
Spill Site ◽  
Kemp's Ridley

We investigated the extent that the 2010 Deepwater Horizon oil spill potentially affected oceanic-stage sea turtles from populations across the Atlantic. Within an ocean-circulation model, particles were backtracked from the Gulf of Mexico spill site to determine the probability of young turtles arriving in this area from major nesting beaches. The abundance of turtles in the vicinity of the oil spill was derived by forward-tracking particles from focal beaches and integrating population size, oceanic-stage duration and stage-specific survival rates. Simulations indicated that 321 401 (66 199–397 864) green ( Chelonia mydas ), loggerhead ( Caretta caretta ) and Kemp's ridley ( Lepidochelys kempii ) turtles were likely within the spill site. These predictions compared favourably with estimates from in-water observations recently made available to the public (though our initial predictions for Kemp's ridley were substantially lower than in-water estimates, better agreement was obtained with modifications to mimic behaviour of young Kemp's ridley turtles in the northern Gulf). Simulations predicted 75.2% (71.9–76.3%) of turtles came from Mexico, 14.8% (11–18%) from Costa Rica, 5.9% (4.8–7.9%) from countries in northern South America, 3.4% (2.4–3.5%) from the United States and 1.6% (0.6–2.0%) from West African countries. Thus, the spill's impacts may extend far beyond the current focus on the northern Gulf of Mexico.

scholarly journals Simulating stable carbon isotopes in the ocean component of the FAMOUS General Circulation Model with MOSES1 (XOAVI)

2020 ◽  
Author(s):  
Jennifer E. Dentith ◽  
Ruza F. Ivanovic ◽  
Lauren J. Gregoire ◽  
Julia C. Tindall ◽  
Laura F. Robinson
Keyword(s):  
General Circulation Model ◽  
Ocean Circulation ◽  
General Circulation ◽  
Large Scale ◽  
Stable Carbon Isotopes ◽  
Numerical Models ◽  
Circulation Model ◽  
Ocean General Circulation Model ◽  
Fossil Fuel Burning ◽  
Isotope Distributions

Abstract. Isotopic ratios are often utilised as proxies for ocean circulation and the marine carbon cycle. However, interpreting these records is non-trivial because they reflect a complex interplay between physical and biogeochemical processes. By directly simulating multiple isotopic tracer fields within numerical models, we can improve our understanding of the processes that control large-scale isotope distributions and interpolate the spatiotemporal gaps in both modern and palaeo datasets. We have added the stable isotope 13C to the ocean component of the FAMOUS coupled atmosphere-ocean General Circulation Model, which is a valuable tool for simulating complex feedbacks between different Earth System processes on decadal to multi-millennial timescales. We tested three different biological fractionation parameterisations to account for the uncertainty associated with equilibrium fractionation during photosynthesis and used sensitivity experiments to quantify the effects of fractionation during air-sea gas exchange and primary productivity on the simulated δ13CDIC distributions. Following a 10,000 year pre-industrial spin-up, we simulated the Suess effect (the isotopic imprint of anthropogenic fossil fuel burning) to assess the performance of the model in replicating modern observations. Our implementation captures the large-scale structure and range of δ13CDIC observations in the surface ocean, but the simulated values are too high at all depths, which we infer is due to biases in the biological pump. In the first instance, the new 13C tracer will therefore be useful for recalibrating both the physical and biogeochemical components of FAMOUS.

scholarly journals Sea turtle strandings, sightings and accidental catch along the Croatian Adriatic coast

2020 ◽  
Author(s):  
FEITOUMATT LEMATT HAMA ◽  
DEAN KARAICA ◽  
BOJAN KARAICA ◽  
PETRA RODIĆ ◽  
KATJA JELIĆ ◽  
...  
Keyword(s):  
Adriatic Sea ◽  
Sea Turtles ◽  
Marine Species ◽  
Sea Turtle ◽  
Northern Adriatic Sea ◽  
Loggerhead Sea Turtles ◽  
Northern Adriatic ◽  
Northern Areas ◽  
Adriatic Coast ◽  
Mortality Causes

The northern Adriatic Sea has long been known as the foraging and developmental habitat of loggerhead sea turtles. Previous literature on stranded, floating, sighted, and accidentally caught sea turtles is fragmentary and mainly obtained from this shallower northern part. This work presents data on 272 records of stranded, floating, sighted and accidentally captured turtles within the entire Croatian Adriatic. The data was collected through the national stranding network for strictly protected marine species run by the Croatian Agency for the Environment and Nature during a six-year period (2010-2015). We focused on analysing spatial and temporal observations, age structure, and reporting sources. The collected morphometric data revealed that most measured C. caretta (85%) were immature individuals found stranded and floating at sea. These observations were location-dependent with a tendency towards the shallow northern areas (≤200 m). Most of the stranded individuals were severely decomposed preventing the determination of possible mortality causes. Most non-decomposed individuals had fishery- or boat-inflicted mechanical injuries confirming fishing activities and boat collisions as threats to young C. caretta individuals in the Croatian Adriatic Sea. Results also revealed an important contribution of local people in reporting the C. caretta strandings and sightings whereas most accidentally caught individuals were reported by unknown sources. Altogether, the data presented in this paper indicate possibilities for improving the ongoing sea turtle monitoring and conservation activities along the entire Croatian Adriatic coast.

scholarly journals Simulating stable carbon isotopes in the ocean component of the FAMOUS general circulation model with MOSES1 (XOAVI)

2020 ◽  
Vol 13 (8) ◽  
pp. 3529-3552
Author(s):  
Jennifer E. Dentith ◽  
Ruza F. Ivanovic ◽  
Lauren J. Gregoire ◽  
Julia C. Tindall ◽  
Laura F. Robinson
Keyword(s):  
General Circulation Model ◽  
Ocean Circulation ◽  
General Circulation ◽  
Large Scale ◽  
Stable Carbon Isotopes ◽  
Numerical Models ◽  
Circulation Model ◽  
Ocean General Circulation Model ◽  
Fossil Fuel Burning ◽  
Isotope Distributions

Abstract. Ocean circulation and the marine carbon cycle can be indirectly inferred from stable and radiogenic carbon isotope ratios (δ13C and Δ14C, respectively), measured directly in the water column, or recorded in geological archives such as sedimentary microfossils and corals. However, interpreting these records is non-trivial because they reflect a complex interplay between physical and biogeochemical processes. By directly simulating multiple isotopic tracer fields within numerical models, we can improve our understanding of the processes that control large-scale isotope distributions and interpolate the spatiotemporal gaps in both modern and palaeo datasets. We have added the stable isotope 13C to the ocean component of the FAMOUS coupled atmosphere–ocean general circulation model, which is a valuable tool for simulating complex feedbacks between different Earth system processes on decadal to multi-millennial timescales. We tested three different biological fractionation parameterisations to account for the uncertainty associated with equilibrium fractionation during photosynthesis and used sensitivity experiments to quantify the effects of fractionation during air–sea gas exchange and primary productivity on the simulated δ13CDIC distributions. Following a 10 000-year pre-industrial spin-up, we simulated the Suess effect (the isotopic imprint of anthropogenic fossil fuel burning) to assess the performance of the model in replicating modern observations. Our implementation captures the large-scale structure and range of δ13CDIC observations in the surface ocean, but the simulated values are too high at all depths, which we infer is due to biases in the biological pump. In the first instance, the new 13C tracer will therefore be useful for recalibrating both the physical and biogeochemical components of FAMOUS.

Juvenile recruitment in loggerhead sea turtles linked to decadal changes in ocean circulation

2016 ◽  
Vol 22 (11) ◽  
pp. 3529-3538 ◽  
Author(s):  
François Ascani ◽  
Kyle S. Van Houtan ◽  
Emanuele Di Lorenzo ◽  
Jeffrey J. Polovina ◽  
T. Todd Jones
Keyword(s):  
Ocean Circulation ◽  
Sea Turtles ◽  
Loggerhead Sea Turtles ◽  
Juvenile Recruitment

scholarly journals A Global Assessment of the Potential for Ocean-Driven Transport in Hatchling Sea Turtles

Water ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 757
Author(s):  
Morgan J. DuBois ◽  
Nathan F. Putman ◽  
Susan E. Piacenza
Keyword(s):  
Ocean Circulation ◽  
Sea Turtles ◽  
Circulation Model ◽  
Sea Turtle ◽  
Physical Factors ◽  
Theoretic Approach ◽  
Turtle Species ◽  
Essential Tool ◽  
The World ◽  
Nesting Sites

Ocean circulation models are an essential tool for use in estimating the movements of drifting marine species. Across the world, hatchling sea turtle transport to the pelagic ocean is facilitated by the local currents off their natal beaches. It is difficult, if not impossible, to observe this transport reliably for any lengthy period, and, as such, ocean circulation models are an essential tool for studying sea turtles during this vulnerable time. Here, we use the ocean circulation model HYCOM and the particle simulator Ichthyop to model the first month of hatchling transport across all sea turtle species from nesting sites across the world from 25 cohorts of hatchlings at 67 nesting sites. We evaluated transport as a function of spatiotemporal factors that could influence turtle movement, using generalized linear models and the information theoretic approach to model selection. We found that multiple physical factors influence transport across the first month of movement and that annual variability is an important factor in hatchling transport. Our findings suggest that the beaches turtles hatch from and the year in which they hatch may shape their early life and the speed of transport into the relative safety of the open ocean. An increased understanding of the likely survival of a cohort may aid in designating funds and planning conservation strategies for individual beaches to either compensate for or take advantage of the local currents.

On the impact of sea ice in a global ocean circulation model

1997 ◽  
Vol 25 ◽  
pp. 111-115 ◽  
Author(s):  
Achim Stössel
Keyword(s):  
Southern Ocean ◽  
Sea Ice ◽  
Ocean Circulation ◽  
General Circulation ◽  
Thermohaline Circulation ◽  
Circulation Model ◽  
Deep Ocean ◽  
Global Ocean ◽  
Convective Activity ◽  
The Impact

This paper investigates the long-term impact of sea ice on global climate using a global sea-ice–ocean general circulation model (OGCM). The sea-ice component involves state-of-the-art dynamics; the ocean component consists of a 3.5° × 3.5° × 11 layer primitive-equation model. Depending on the physical description of sea ice, significant changes are detected in the convective activity, in the hydrographic properties and in the thermohaline circulation of the ocean model. Most of these changes originate in the Southern Ocean, emphasizing the crucial role of sea ice in this marginally stably stratified region of the world's oceans. Specifically, if the effect of brine release is neglected, the deep layers of the Southern Ocean warm up considerably; this is associated with a weakening of the Southern Hemisphere overturning cell. The removal of the commonly used “salinity enhancement” leads to a similar effect. The deep-ocean salinity is almost unaffected in both experiments. Introducing explicit new-ice thickness growth in partially ice-covered gridcells leads to a substantial increase in convective activity, especially in the Southern Ocean, with a concomitant significant cooling and salinification of the deep ocean. Possible mechanisms for the resulting interactions between sea-ice processes and deep-ocean characteristics are suggested.

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