scholarly journals Finding the ‘lost years’ in green turtles: insights from ocean circulation models and genetic analysis

2013 ◽  
Vol 280 (1768) ◽  
pp. 20131468 ◽  
Author(s):  
Nathan F. Putman ◽  
Eugenia Naro-Maciel
Keyword(s):  
Genetic Analysis ◽  
Ocean Circulation ◽  
Circulation Model ◽  
Chelonia Mydas ◽  
Ecological Processes ◽  
Green Turtles ◽  
New Information ◽  
Basin Scale ◽  
Conservation Concern ◽  
Critical Developmental Period

Organismal movement is an essential component of ecological processes and connectivity among ecosystems. However, estimating connectivity and identifying corridors of movement are challenging in oceanic organisms such as young turtles that disperse into the open sea and remain largely unobserved during a period known as ‘the lost years’. Using predictions of transport within an ocean circulation model and data from published genetic analysis, we present to our knowledge, the first basin-scale hypothesis of distribution and connectivity among major rookeries and foraging grounds (FGs) of green turtles ( Chelonia mydas ) during their ‘lost years’. Simulations indicate that transatlantic dispersal is likely to be common and that recurrent connectivity between the southwestern Indian Ocean and the South Atlantic is possible. The predicted distribution of pelagic juvenile turtles suggests that many ‘lost years hotspots’ are presently unstudied and located outside protected areas. These models, therefore, provide new information on possible dispersal pathways that link nesting beaches with FGs. These pathways may be of exceptional conservation concern owing to their importance for sea turtles during a critical developmental period.

scholarly journals Predicting connectivity of green turtles at Palmyra Atoll, central Pacific: a focus on mtDNA and dispersal modelling

2014 ◽  
Vol 11 (93) ◽  
pp. 20130888 ◽  
Author(s):  
Eugenia Naro-Maciel ◽  
Stephen J. Gaughran ◽  
Nathan F. Putman ◽  
George Amato ◽  
Felicity Arengo ◽  
...  
Keyword(s):  
Genetic Analysis ◽  
Ocean Circulation ◽  
Circulation Model ◽  
Population Connectivity ◽  
Central Pacific ◽  
Green Turtles ◽  
South Central ◽  
The Pacific ◽  
Mitochondrial Sequences ◽  
Effective Conservation

Population connectivity and spatial distribution are fundamentally related to ecology, evolution and behaviour. Here, we combined powerful genetic analysis with simulations of particle dispersal in a high-resolution ocean circulation model to investigate the distribution of green turtles foraging at the remote Palmyra Atoll National Wildlife Refuge, central Pacific. We analysed mitochondrial sequences from turtles ( n = 349) collected there over 5 years (2008–2012). Genetic analysis assigned natal origins almost exclusively (approx. 97%) to the West Central and South Central Pacific combined Regional Management Units. Further, our modelling results indicated that turtles could potentially drift from rookeries to Palmyra Atoll via surface currents along a near-Equatorial swathe traversing the Pacific. Comparing findings from genetics and modelling highlighted the complex impacts of ocean currents and behaviour on natal origins. Although the Palmyra feeding ground was highly differentiated genetically from others in the Indo-Pacific, there was no significant differentiation among years, sexes or stage-classes at the Refuge. Understanding the distribution of this foraging population advances knowledge of green turtles and contributes to effective conservation planning for this threatened species.

scholarly journals Redescription of Charaxicephaloides polyorchis Groschaft and Tenora 1978 (Digenea: Pronocephalidae) from the green turtle Chelonia mydas in Costa Rica

2009 ◽  
Vol 46 (2) ◽  
pp. 97-99 ◽  
Author(s):  
M. Santoro ◽  
P. Brandmayr ◽  
E. Greiner ◽  
J. Morales ◽  
B. Rodríguez-Ortíz
Keyword(s):  
Costa Rica ◽  
Host Species ◽  
Green Turtle ◽  
Chelonia Mydas ◽  
Original Description ◽  
Northwest Coast ◽  
Green Turtles ◽  
New Information

AbstractCharaxicephaloides polyorchis Groschaft and Tenora, 1978 is redescribed on the basis of specimens collected from the stomach of green turtles Chelonia mydas in Costa Rica. Our specimens are consistent with the original description which was based on four flukes from the same host species from the northwest coast of Cuba. Our redescription provides a new range of variations and adds new information on this species. This represents only the second record of C. polyorchis in green turtles.

scholarly journals Effects of mesoscale eddies on behavior of an oil spill resulting from an accidental deepwater blowout in the Black Sea: an assessment of the environmental impacts

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5448
Author(s):  
Konstantin A. Korotenko
Keyword(s):  
Black Sea ◽  
Oil Spill ◽  
Marine Environment ◽  
Ocean Circulation ◽  
Coupled Model ◽  
Circulation Model ◽  
The Black Sea ◽  
Basin Scale ◽  
Near Shore ◽  
Oil Source

Because of the environmental sensitivity of the Black Sea, as a semi-enclosed sea, any subsea oil spill can cause destructive impacts on the marine environment and beaches. Employing numerical modeling as a prediction tool is one of the most efficient methods to understand oil spill behavior under various environmental forces. In this regard, a coupled circulation/deepsea oil spill model has been applied to the Black Sea to address the behavior of the oil plume resulting from a representative hypothetical deepwater blowout. With climatological forcing, the hydrodynamic module based on DieCAST ocean circulation model realistically reproduces seasonally-varying circulation from basin-scale dominant structures to meso- and sub-mesoscale elements. The oil spill model utilizes pre-calculated DieCAST thermo-hydrodynamic fields and uses a Lagrangian tracking algorithm for predicting the displacement of a large number of seeded oil droplets, the sum of which forms the rising oil plume resulting from a deepwater blowout. Basic processes affecting the transport, dispersal of oil and its fate in the water column are included in the coupled model. A hypothetical oil source was set at the bottom, at the northwestern edge of the Shatsky Ridge in the area east of the Crimea Peninsula where the oil exploration/development is likely to be planned. Goals of the study are to elucidate the behavior of the subsea oil plume and assess scales of contamination of marine environment and coastlines resulting from potential blowouts. The two 20-day scenarios with the oil released by a hypothetical blowout were examined to reveal combined effects of the basin-scale current, near-shore eddies, and winds on the behavior of the rising oil plume and its spreading on the surface. Special attention is paid to the Caucasian near-shore anticyclonic eddy which is able to trap surfacing oil, detain it and deliver it to shores. The length of contaminated coastlines of vulnerable Crimean and Caucasian coasts are assessed along with amounts of oil beached and deposited.

scholarly journals Southern Ocean controls of the vertical marine <i>δ</i><sup>13</sup>C gradient – a modelling study

2018 ◽  
Vol 15 (23) ◽  
pp. 7205-7223 ◽  
Author(s):  
Anne L. Morée ◽  
Jörg Schwinger ◽  
Christoph Heinze
Keyword(s):  
Gas Exchange ◽  
Southern Ocean ◽  
Ocean Circulation ◽  
General Circulation ◽  
Dissolved Inorganic Carbon ◽  
Circulation Model ◽  
Ocean Basin ◽  
Global Ocean ◽  
Basin Scale ◽  
Poc Export

Abstract. δ13C, the standardised 13C ∕ 12C ratio expressed in per mille, is a widely used ocean tracer to study changes in ocean circulation, water mass ventilation, atmospheric pCO2, and the biological carbon pump on timescales ranging from decades to tens of millions of years. δ13C data derived from ocean sediment core analysis provide information on δ13C of dissolved inorganic carbon and the vertical δ13C gradient (i.e. Δδ13C) in past oceans. In order to correctly interpret δ13C and Δδ13C variations, a good understanding is needed of the influence from ocean circulation, air–sea gas exchange and biological productivity on these variations. The Southern Ocean is a key region for these processes, and we show here that Δδ13C in all ocean basins is sensitive to changes in the biogeochemical state of the Southern Ocean. We conduct a set of idealised sensitivity experiments with the ocean biogeochemistry general circulation model HAMOCC2s to explore the effect of biogeochemical state changes of the Southern and Global Ocean on atmospheric δ13C, pCO2, and marine δ13C and Δδ13C. The experiments cover changes in air–sea gas exchange rates, particulate organic carbon sinking rates, sea ice cover, and nutrient uptake efficiency in an unchanged ocean circulation field. Our experiments show that global mean Δδ13C varies by up to about ±0.35 ‰ around the pre-industrial model reference (1.2 ‰) in response to biogeochemical change. The amplitude of this sensitivity can be larger at smaller scales, as seen from a maximum sensitivity of about −0.6 ‰ on ocean basin scale. The ocean's oldest water (North Pacific) responds most to biological changes, the young deep water (North Atlantic) responds strongly to air–sea gas exchange changes, and the vertically well-mixed water (SO) has a low or even reversed Δδ13C sensitivity compared to the other basins. This local Δδ13C sensitivity depends on the local thermodynamic disequilibrium and the Δδ13C sensitivity to local POC export production changes. The direction of both glacial (intensification of Δδ13C) and interglacial (weakening of Δδ13C) Δδ13C change matches the direction of the sensitivity of biogeochemical processes associated with these periods. This supports the idea that biogeochemistry likely explains part of the reconstructed variations in Δδ13C, in addition to changes in ocean circulation.

scholarly journals Tracking the long-distance dispersal of marine organisms: sensitivity to ocean model resolution

2013 ◽  
Vol 10 (81) ◽  
pp. 20120979 ◽  
Author(s):  
Nathan F. Putman ◽  
Ruoying He
Keyword(s):  
Ocean Circulation ◽  
Circulation Model ◽  
Ocean Model ◽  
Marine Organisms ◽  
Model Output ◽  
Ocean Circulation Model ◽  
Time Step ◽  
Long Distance ◽  
Near Surface ◽  
Basin Scale

Ocean circulation models are widely used to simulate organism transport in the open sea, where challenges of directly tracking organisms across vast spatial and temporal scales are daunting. Many recent studies tout the use of ‘high-resolution’ models, which are forced with atmospheric data on the scale of several hours and integrated with a time step of several minutes or seconds. However, in many cases, the model's outputs that are used to simulate organism movement have been averaged to considerably coarser resolutions (e.g. monthly mean velocity fields). To examine the sensitivity of tracking results to ocean circulation model output resolution, we took the native model output of one of the most sophisticated ocean circulation models available, the Global Hybrid Coordinate Ocean Model, and averaged it to commonly implemented spatial and temporal resolutions in studies of basin-scale dispersal. Comparisons between simulated particle trajectories and in situ near-surface drifter trajectories indicated that ‘over averaging’ model output yields predictions inconsistent with observations. Further analyses focused on the dispersal of juvenile sea turtles indicate that very different inferences regarding the pelagic ecology of these animals are obtained depending on the resolution of model output. We conclude that physical processes occurring at the scale of days and tens of kilometres should be preserved in ocean circulation model output to realistically depict the movement marine organisms and the resulting ecological and evolutionary processes.

Stock composition of green turtles Chelonia mydas foraging in the Ryukyu Archipelago differs with size class

2018 ◽  
Vol 600 ◽  
pp. 151-163 ◽  
Author(s):  
T Hamabata ◽  
H Nishizawa ◽  
I Kawazu ◽  
K Kameda ◽  
N Kamezaki ◽  
...  
Keyword(s):  
Chelonia Mydas ◽  
Size Class ◽  
Ryukyu Archipelago ◽  
Green Turtles

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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