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 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.

Climatological Annual Cycle of the Salinity Budgets of the Subtropical Maxima

2016 ◽  
Vol 46 (10) ◽  
pp. 2981-2994 ◽  
Author(s):  
Benjamin K. Johnson ◽  
Frank O. Bryan ◽  
Semyon A. Grodsky ◽  
James A. Carton
Keyword(s):  
Ocean Circulation ◽  
Mixed Layer ◽  
Annual Cycle ◽  
Salinity Gradient ◽  
Circulation Model ◽  
Open Ocean ◽  
Surface Cooling ◽  
The North ◽  
The Pacific ◽  
Diffusive Fluxes

AbstractSix subtropical salinity maxima (Smax) exist: two each in the Pacific, Atlantic, and Indian Ocean basins. The north Indian (NI) Smax lies in the Arabian Sea while the remaining five lie in the open ocean. The annual cycle of evaporation minus precipitation (E − P) flux over the Smax is asymmetric about the equator. Over the Northern Hemisphere Smax, the semiannual harmonic is dominant (peaking in local summer and winter), while over the Southern Hemisphere Smax, the annual harmonic is dominant (peaking in local winter). Regardless, the surface layer salinity for all six Smax reaches a maximum in local fall and minimum in local spring. This study uses a multidecade integration of an eddy-resolving ocean circulation model to compute salinity budgets for each of the six Smax. The NI Smax budget is dominated by eddy advection related to the evolution of the seasonal monsoon. The five open-ocean Smax budgets reveal a common annual cycle of vertical diffusive fluxes that peak in winter. These Smax have regions on their eastward and poleward edges in which the vertical salinity gradient is destabilizing. These destabilizing gradients, in conjunction with wintertime surface cooling, generate a gradually deepening wintertime mixed layer. The vertical salinity gradient sharpens at the base of the mixed layer, making the water column susceptible to salt finger convection and enhancing vertical diffusive salinity fluxes out of the Smax into the ocean interior. This process is also observed in Argo float profiles and is related to the formation regions of subtropical mode waters.

Recent Changes in the Pacific Subtropical Cells Inferred from an Eddy-Resolving Ocean Circulation Model*

2007 ◽  
Vol 37 (5) ◽  
pp. 1340-1356 ◽  
Author(s):  
Wei Cheng ◽  
Michael J. McPhaden ◽  
Dongxiao Zhang ◽  
E. Joseph Metzger
Keyword(s):  
Ocean Circulation ◽  
General Circulation ◽  
Control Volume ◽  
Circulation Model ◽  
Ocean General Circulation Model ◽  
Volume Transport ◽  
Western Boundary ◽  
Equatorial Undercurrent ◽  
Model Driven ◽  
The Pacific

Abstract In this study the subtropical cells (STC) in the Pacific Ocean are analyzed using an eddy-resolving ocean general circulation model driven by atmospheric forcing for the years 1992–2003. In particular, the authors seek to identify decadal changes in the STCs in the model and to compare them with observations in order to understand the consequences of such changes for the equatorial ocean heat and mass budgets. The simulation shows a trend toward increasing pycnocline volume transport at 9°N and 9°S across the basin from 1992 to 2003. This increase [4.9 ± 1.0 Sv (Sv ≡ 106 m3 s−1)] is in qualitative agreement with observations and is attributed primarily to changes in the interior ocean transport, which are partially compensated by opposing western boundary transports. The subtropical meridional volume transport convergence anomalies in the model pycnocline are found to be consistent with anomalous volume transports in both the observed and modeled Equatorial Undercurrent, as well as with the magnitude of simulated anomalous upwelling transport at the base of the mixed layer in the eastern Pacific. As a result of the increased circulation intensity, heat transport divergence through the lateral boundaries of the tropical control volume (defined as the region between 9°N and 9°S, and from the surface to σθ = 25.3 isopycnal) increases, leading to a cooling of the tropical upper ocean despite the fact that net surface heat flux into the control volume has increased in the same time. As such, these results suggest that wind-driven changes in ocean transports associated with the subtropical cells play a central role in regulating tropical Pacific climate variability on decadal time scales.

Molecular and morphological evolution in the south-central Pacific skink Emoia tongana (Reptilia : Squamata): uniformity and human-mediated dispersal

1999 ◽  
Vol 47 (5) ◽  
pp. 425 ◽  
Author(s):  
Christopher C. Austin ◽  
George R. Zug
Keyword(s):  
Pacific Islands ◽  
Morphological Evolution ◽  
Research Effort ◽  
Tropical Pacific ◽  
The South ◽  
Central Pacific ◽  
South Central ◽  
The Poor ◽  
The Pacific ◽  
Minimal Research

Human-mediated and waif dispersal are both responsible for the distribution of lizards on tropical Pacific islands. The component of each of these dispersal modes to the Pacific herpetofauna, however, is unclear. Morphological conservatism of Pacific lizards, the poor paleontological record on tropical Pacific islands, and minimal research effort in the Pacific (compared with other island systems) has hampered our understanding of waif versus human-mediated patterns. We examine morphological and genetic variation of Emoia concolor and E. tongana (formerly E. murphyi), two scincid lizards, from the south-central Pacific, to assess modes of dispersal and population structure. Emoia tongana from Tonga and Samoa is genetically uniform, suggesting that these are synanthropic populations recently introduced, presumably from Fiji. Relatively large genetic divergence is evident for populations of E. concolor within the Fijian archipelago, suggesting prehuman intra-archipelago dispersal and isolation.

scholarly journals Stable isotopes in barnacles as a tool to understand green sea turtle (<i>Chelonia mydas</i>) regional movement patterns

2015 ◽  
Vol 12 (23) ◽  
pp. 7081-7086 ◽  
Author(s):  
M. Detjen ◽  
E. Sterling ◽  
A. Gómez
Keyword(s):  
Oxygen Isotope ◽  
Movement Patterns ◽  
Chelonia Mydas ◽  
Sea Turtle ◽  
Central Pacific ◽  
Green Sea Turtle ◽  
Use Patterns ◽  
Green Turtles ◽  
The Pacific ◽  
Breeding Grounds

Abstract. Sea turtles are migratory animals that travel long distances between their feeding and breeding grounds. Traditional methods for researching sea turtle migratory behavior have important disadvantages, and the development of alternatives would enhance our ability to monitor and manage these globally endangered species. Here we report on the isotope signatures in green sea-turtle (Chelonia mydas) barnacles (Platylepas sp.) and discuss their potential relevance as tools with which to study green sea turtle migration and habitat use patterns. We analyzed oxygen (δ18O) and carbon (δ13C) isotope ratios in barnacle calcite layers from specimens collected from green turtles captured at the Palmyra Atoll National Wildlife Refuge (PANWR) in the central Pacific. Carbon isotopes were not informative in this study. However, the oxygen isotope results suggest likely regional movement patterns when mapped onto a predictive oxygen isotope map of the Pacific. Barnacle proxies could therefore complement other methods in understanding regional movement patterns, informing more effective conservation policy that takes into account connectivity between populations.

scholarly journals The Global Ocean Mass Budget in 1993–2003 Estimated from Sea Level Change

2007 ◽  
Vol 37 (2) ◽  
pp. 203-213 ◽  
Author(s):  
Manfred Wenzel ◽  
Jens Schröter
Keyword(s):  
Atlantic Ocean ◽  
Sea Level ◽  
Ocean Circulation ◽  
General Circulation ◽  
Circulation Model ◽  
Ocean Model ◽  
Global Ocean ◽  
Mass Budget ◽  
Ocean Mass ◽  
The Pacific

Abstract The mass budget of the ocean in the period 1993–2003 is studied with a general circulation model. The model has a free surface and conserves mass rather than volume; that is, freshwater is exchanged with the atmosphere via precipitation and evaporation and inflow from land is taken into account. The mass is redistributed by the ocean circulation. Furthermore, the ocean’s volume changes by steric expansion with changing temperature and salinity. To estimate the mass changes, the ocean model is constrained by sea level measurements from the Ocean Topography Experiment (TOPEX)/Poseidon mission as well as by hydrographic data. The modeled ocean mass change within the years 2002–03 compares favorably to measurements from the Gravity Recovery and Climate Experiment (GRACE), and the evolution of the global mean sea level for the period 1993–2003 with annual and interannual variations can be reproduced to a 0.15-cm rms difference. Its trend has been measured as 3.37 mm yr−1 while the constrained model gives 3.34 mm yr−1 considering only the area covered by measurements (3.25 mm yr−1 for the total ocean). A steric rise of 2.50 mm yr−1 is estimated in this period, as is a gain in the ocean mass that is equivalent to an eustatic rise of 0.74 mm yr−1. The amplitude and phase (day of maximum value since 1 January) of the superimposed eustatic annual cycle are also estimated to be 4.6 mm and 278°, respectively. The corresponding values for the semiannual cycle are 0.42 mm and 120°. The trends in the eustatic sea level are not equally distributed. In the Atlantic Ocean (80°S–67°N) the eustatic sea level rises by 1.8 mm yr−1 and in the Indian Ocean (80°S–30°N) it rises by 1.4 mm yr−1, but it falls by −0.20 mm yr−1 in the Pacific Ocean (80°S–67°N). The latter is mainly caused by a loss of mass through transport divergence in the Pacific sector of the Antarctic Circumpolar Current (−0.42 Sv; Sv ≡ 109 kg s−1) that is not balanced by the net surface water supply. The consequence of this uneven eustatic rise is a shift of the oceanic center of mass toward the Atlantic Ocean and to the north.

scholarly journals Evolution of atmospheric connectivity in the 20th century

2014 ◽  
Vol 21 (4) ◽  
pp. 825-839 ◽  
Author(s):  
F. Arizmendi ◽  
A. C. Martí ◽  
M. Barreiro
Keyword(s):  
20Th Century ◽  
General Circulation ◽  
Circulation Model ◽  
Internal Variability ◽  
Western Pacific ◽  
Positive Trend ◽  
Central Pacific ◽  
Nonlinear Networks ◽  
The Pacific ◽  
Linear And Nonlinear

Abstract. We aim to study the evolution of the upper atmosphere connectivity over the 20th century as well as to distinguish the oceanically forced component from the atmospheric internal variability. For this purpose we build networks from two different reanalysis data sets using both linear and nonlinear statistical similarity measures to determine the existence of links between different regions of the world in the two halves of the last century. We furthermore use symbolic analysis to emphasize intra-seasonal, intra-annual and inter-annual timescales. Both linear and nonlinear networks have similar structures and evolution, showing that the most connected regions are in the tropics over the Pacific Ocean. Also, the Southern Hemisphere extratropics have more connectivity in the first half of the 20th century, particularly on intra-annual and intra-seasonal timescales. Changes over the Pacific main connectivity regions are analyzed in more detail. Both linear and nonlinear networks show that the central and western Pacific regions have decreasing connectivity from early 1900 up to about 1940, when it starts increasing again until the present. The inter-annual network shows a similar behavior. However, this is not true of other timescales. On intra-annual timescales the minimum connectivity is around 1956, with a negative (positive) trend before (after) that date for both the central and western Pacific. While this is also true of the central Pacific on intra-seasonal timescales, the western Pacific shows a positive trend during the entire 20th century. In order to separate the internal and forced connectivity networks and to study their evolution through time, an ensemble of atmospheric general circulation model outputs is used. The results suggest that the main connectivity patterns captured in the reanalysis networks are due to the oceanically forced component, particularly on inter-annual timescales. Moreover, the atmospheric internal variability seems to play an important role in determining the intra-seasonal timescale networks.

scholarly journals Contrasting global, regional and local patterns of genetic structure in gray reef shark populations from the Indo-Pacific region

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
E. Boissin ◽  
S. R. Thorrold ◽  
C. D. Braun ◽  
Y. Zhou ◽  
E. E. Clua ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Population Structure ◽  
Genetic Differentiation ◽  
Spatial Scales ◽  
Biological Information ◽  
Shark Species ◽  
Central Pacific ◽  
South Central ◽  
The Pacific ◽  
Reef Sharks

Abstract Human activities have resulted in the loss of over 90% of sharks in most ocean basins and one in four species of elasmobranch are now listed at risk of extinction by the IUCN. How this collapse will affect the ability of populations to recover in the face of continued exploitation and global climate change remains unknown. Indeed, important ecological and biological information are lacking for most shark species, particularly estimates of genetic diversity and population structure over a range of spatial scales. Using 15 microsatellite markers, we investigated genetic diversity and population structure in gray reef sharks over their Indo-Pacific range (407 specimens from 9 localities). Clear genetic differentiation was observed between the Indian and the Pacific Ocean specimens (FST = 0.145***). Further differentiation within the Pacific included a West and East cleavage as well as North-Central and South-Central Pacific clusters. No genetic differentiation was detected within archipelagos. These results highlight the legacy of past climate changes and the effects of large ocean expanses and circulation patterns on contrasting levels of connectivity at global, regional and local scales. Our results indicate a need for regional conservation units for gray reef sharks and pinpoint the isolation and vulnerability of their French Polynesian population.

scholarly journals Stable isotopes in barnacles as a tool to understand green sea turtle (<i>Chelonia mydas</i>) regional movement patterns

2015 ◽  
Vol 12 (6) ◽  
pp. 4655-4669 ◽  
Author(s):  
M. Detjen ◽  
E. Sterling ◽  
A. Gómez
Keyword(s):  
Oxygen Isotope ◽  
Movement Patterns ◽  
Chelonia Mydas ◽  
Sea Turtle ◽  
Central Pacific ◽  
Green Sea Turtle ◽  
Use Patterns ◽  
Green Turtles ◽  
The Pacific ◽  
Breeding Grounds

Abstract. Sea turtles are migratory animals that travel long distances between their feeding and breeding grounds. Traditional methods for researching sea turtle migratory behavior have important disadvantages, and the development of alternatives would enhance our ability to monitor and manage these globally endangered species. Here we report on the isotope signatures in green sea turtle (Chelonia mydas) barnacles (Platylepas sp.) and discuss their potential relevance as tools with which to study green sea turtle migration and habitat use patterns. We analyzed oxygen (δ18O) and carbon (δ13C) isotope ratios in barnacle calcite layers from specimens collected from green turtles captured at the Palmyra Atoll National Wildlife Refuge (PANWR) in the Central Pacific. Carbon isotopes were not informative in this study. However, the oxygen isotope results suggest likely regional movement patterns when mapped onto a predictive oxygen isotope map of the Pacific. Barnacle proxies could therefore complement other methods in understanding regional movement patterns, informing more effective conservation policy that takes into account connectivity between populations.

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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