Geology topics

Research about North Atlantic Ocean

Source-linked reports with geographic coverage including North Atlantic Ocean.

4 recordsLinked to original sources

USGS2020

Spatial ecology of closely-related taxa: The case of the little shearwater complex in the North Atlantic Ocean

Seabirds inhabiting vast water masses provide numerous examples where opposing phenomena, such as natal and breeding philopatry vs. vagility have dug cryptic taxonomic boundaries among closely related taxa. The taxonomy of little shearwaters of the North Atlantic Ocean (Little–Audubon’s shearwater complex, Puffinus assimilis – lherminieri ) still remains unclear, and complementary information on non-breeding distributions and at-sea behaviour becomes essential to unravel divergent local adaptations to specific habitats. Using miniaturized light-level geolocators from seven study areas in the North Atlantic, we evaluate the spatial and habitat segregation, estimate the timing of their key life-cycle events and describe the at-sea behaviour of three taxa of these little shearwaters year-round to distinguish ecological patterns and specializations that could ultimately unravel potential lineage divergences. We also assess morphometric data from birds that were breeding at each study area to further discuss potential adaptations to specific habitats. Our results show that, while birds from different taxa segregated in space and habitats, they share ecological plasticity, similar annual phenology and diel foraging behaviour. These ecological inconsistencies, while defining the evolutionary stressors faced by these taxa, do not suggest the existence of three Evolutionary Significant Units. However, they confirm the recent evolutionary divergence among the three little shearwaters of the North Atlantic.

Zoological Journal of the Linnean Society↗

USGS2012

Latitudinal species diversity gradient of marine zooplankton for the last three million years

High tropical and low polar biodiversity is one of the most fundamental patterns characterising marine ecosystems, and the influence of temperature on such marine latitudinal diversity gradients is increasingly well documented. However, the temporal stability of quantitative relationships among diversity, latitude and temperature is largely unknown. Herein we document marine zooplankton species diversity patterns at four time slices [modern, Last Glacial Maximum (18 000 years ago), last interglacial (120 000 years ago), and Pliocene (~3.3–3.0 million years ago)] and show that, although the diversity-latitude relationship has been dynamic, diversity-temperature relationships are remarkably constant over the past three million years. These results suggest that species diversity is rapidly reorganised as species' ranges respond to temperature change on ecological time scales, and that the ecological impact of future human-induced temperature change may be partly predictable from fossil and paleoclimatological records.

Ecology Letters↗

USGS2011

Bathymetric controls on Pliocene North Atlantic and Arctic sea surface temperature and deepwater production

The mid-Pliocene warm period (MPWP; ~ 3.3 to 3.0 Ma) is the most recent interval in Earth's history in which global temperatures reached and remained at levels similar to those projected for the near future. The distribution of global warmth, however, was different than today in that the high latitudes warmed more than the tropics. Multiple temperature proxies indicate significant sea surface warming in the North Atlantic and Arctic Oceans during the MPWP, but predictions from a fully coupled ocean–atmosphere model (HadCM3) have so far been unable to fully predict the large scale of sea surface warming in the high latitudes. If climate proxies accurately represent Pliocene conditions, and if no weakness exists in the physics of the model, then model boundary conditions may be in error. Here we alter a single boundary condition (bathymetry) to examine if Pliocene high latitude warming was aided by an increase in poleward heat transport due to changes in the subsidence of North Atlantic Ocean ridges. We find an increase in both Arctic sea surface temperature and deepwater production in model experiments that incorporate a deepened Greenland–Scotland Ridge. These results offer both a mechanism for the warming in the North Atlantic and Arctic Oceans indicated by numerous proxies and an explanation for the apparent disparity between proxy data and model simulations of Pliocene northern North Atlantic and Arctic Ocean conditions. Determining the causes of Pliocene warmth remains critical to fully understanding comparisons of the Pliocene warm period to possible future climate change scenarios.

Palaeogeography, Palaeoclimatology, Palaeoecology↗

USGS1987

North Atlantic Quaternary silicoflagellates, Deep Sea Drilling Project Leg 94

Quaternary silicoflagellates from Deep Sea Drilling Project (DSDP) Mid-Atlantic Leg 94 are generally sparse and dissolution-thinned. Mesocena quadrangula, a low-latitude biostratigraphic guide species, occurs at all four sites studied (606, 607, 609, and 611), allowing identification of low-latitude zones—Dictyocha aculeata Zone, Mesocena quadrangula Zone, and Dictyocha stapedia stapedia Zone. A lack of cool-water Distephanus speculum speculum reflects warm relative paleotemperature values (Ts 74 to 98) for Leg 94. Comparison with assemblages at coastal DSDP Hole 397, off Africa, shows that Hole 397 has more abundant D. speculum speculum, suggesting that upwelling nutrient supply may significantly affect the total numbers of this species. The siliceous record of Leg 94 is sporadic, with several levels of nonpreservation that make paleotemperature trends difficult to establish by silicoflagellates. The northern range of M. quadrangula is extended to 52°50'N at Hole 611C. Opal phytoliths occur at southern Holes 606 and 607. These grasslands-produced nannofossils, representing eolian sedimentation from northwestern Africa, were likely distributed most widely during arid glacial intervals.

Initial Reports of the D.S.D.P.↗