Oceanic fronts in the Sargasso Sea control the early life and drift of Atlantic eels

Munk, Peter; Hansen, Michael Møller; Maes, Grégory E.; Nielsen, Torkel Gissel; Castonguay, Martin; Riemann, Lasse; Sparholt, Henrik; Als, Thomas Damm; Aarestrup, Kim; Andersen, Niels Gerner; Bachler, Mirjam

doi:10.1098/rspb.2010.0900

Cited by 90 publications

(136 citation statements)

References 24 publications

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“…1). Additional data on currents and the frontal hydrography of the sampled STCZ region have been presented elsewhere (Munk et al 2010).…”

Section: Methodsmentioning

confidence: 99%

Distribution and production of plankton communities in the subtropical convergence zone of the Sargasso Sea. I. Phytoplankton and bacterioplankton

Riemann¹,

Nielsen²,

Kragh³

et al. 2011

Mar. Ecol. Prog. Ser.

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Elevated levels of biomass and productivity are often associated with ocean frontal systems. The Subtropical Convergence Zone (STCZ) in the southern Sargasso Sea shows pronounced and stable thermal fronts, but little is known about the ecological consequences of these hydrographic features. With the aim of improving the understanding of physical and lower trophic level processes in the area, we carried out field studies of physical, chemical and biological characteristics along 3 transects crossing thermal fronts associated with the STCZ in March to April 2007. Thermal and chemical stratification were evident at all stations within the STCZ, and a depletion of nitrate was measured in the upper ~150 m. The phytoplankton biomass was dominated by Prochlorococcus spp. with highest abundance, up to > 400 000 cells ml -1, at the chlorophyll a (chl a) maximum at 100 to 150 m depth. Synechococcus spp. were generally located higher in the water column. Picoalgae were less abundant, up to 8000 cells ml -1 , but explained most of the variation in chl a. Even though diatoms and dinoflagellates were few, the biomass of larger phytoplankton equalled or exceeded that of picoplankton at a few stations. Bacterial biomass was roughly equal to half of the phytoplankton biomass. We did not find elevated levels of primary production or biomass of specific phytoplankton groups associated with the STCZ, probably due to a pronounced variability between stations along transects. Nevertheless, distinct increases in chl a were associated with the zone and thermal fronts bordering the STCZ.

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“…1). Additional data on currents and the frontal hydrography of the sampled STCZ region have been presented elsewhere (Munk et al 2010).…”

Section: Methodsmentioning

confidence: 99%

Distribution and production of plankton communities in the subtropical convergence zone of the Sargasso Sea. I. Phytoplankton and bacterioplankton

Riemann¹,

Nielsen²,

Kragh³

et al. 2011

Mar. Ecol. Prog. Ser.

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“…This could be because of differences in temporal overlap of spawning time between the species across years, possibly mediated by a more southern or northern displacement of thermal fronts across years. Indeed, the thermal fronts where eels are assumed to spawn show considerable differences in intensity and geographical position between years (Munk et al, 2010).…”

Section: Has Hybridization In North Atlantic Eels Been Underestimated?mentioning

confidence: 99%

Assessing patterns of hybridization between North Atlantic eels using diagnostic single-nucleotide polymorphisms

et al. 2014

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The two North Atlantic eel species, the European eel (Anguilla anguilla) and the American eel (Anguilla rostrata), spawn in partial sympatry in the Sargasso Sea, providing ample opportunity to interbreed. In this study, we used a RAD (Restriction site Associated DNA) sequencing approach to identify species-specific diagnostic single-nucleotide polymorphisms (SNPs) and design a low-density array that combined with screening of a diagnostic mitochondrial DNA marker. Eels from Iceland (N ¼ 159) and from the neighboring Faroe Islands (N ¼ 29) were genotyped, along with 94 larvae (49 European and 45 American eel) collected in the Sargasso Sea. Our SNP survey showed that the majority of Icelandic eels are pure European eels but there is also an important contribution of individuals of admixed ancestry (10.7%). Although most of the hybrids were identified as F1 hybrids from European eel female Â American eel male crosses, backcrosses were also detected, including a first-generation backcross (F1 hybrid Â pure European eel) and three individuals identified as second-generation backcrosses originating from American eel Â F1 hybrid backcrosses interbreeding with pure European eels. In comparison, no hybrids were observed in the Faroe Islands, the closest bodies of land to Iceland. It is possible that hybrids show an intermediate migratory behaviour between the two parental species that ultimately brings hybrid larvae to the shores of Iceland, situated roughly halfway between the Sargasso Sea and Europe. Only two hybrids were observed among Sargasso Sea larvae, both backcrosses, but no F1 hybrids, that points to temporal variation in the occurrence of hybridization.

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“…For instance, many marine taxa have remarkable fidelity to specific reproductive areas, yet disperse widely over vast expanses of the ocean to forage [2]. Thus, processes that occur in one location may drive changes at distant sites or in other ecosystems through the ecological coupling of long-distance movement [3][4][5]. Gathering such information has proved difficult for species that spend much or all of their time in the open sea, where direct observation is hampered by logistical constraints [4][5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

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

Putman

Naro‐Maciel

2013

Proc. R. Soc. B.

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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.

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Oceanic fronts in the Sargasso Sea control the early life and drift of Atlantic eels

Cited by 90 publications

References 24 publications

Distribution and production of plankton communities in the subtropical convergence zone of the Sargasso Sea. I. Phytoplankton and bacterioplankton

Distribution and production of plankton communities in the subtropical convergence zone of the Sargasso Sea. I. Phytoplankton and bacterioplankton

Assessing patterns of hybridization between North Atlantic eels using diagnostic single-nucleotide polymorphisms

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

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