scholarly journals Multi-year presence of humpback whales in the Atlantic sector of the Southern Ocean but not during El Niño

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Elena Schall ◽  
Karolin Thomisch ◽  
Olaf Boebel ◽  
Gabriele Gerlach ◽  
Sari Mangia Woods ◽  
...  
Keyword(s):  
Southern Ocean ◽  
El Niño ◽  
El Nino ◽  
Humpback Whales ◽  
Low Latitude ◽  
Sea Ice Extent ◽  
Atlantic Sector ◽  
Acoustic Data ◽  
Breeding Grounds ◽  
Passive Acoustic

AbstractHumpback whales are thought to undertake annual migrations between their low latitude breeding grounds and high latitude feeding grounds. However, under specific conditions, humpback whales sometimes change their migratory destination or skip migration overall. Here we document the surprising persistent presence of humpback whales in the Atlantic sector of the Southern Ocean during five years (2011, 2012, 2013, 2017, and 2018) using passive acoustic data. However, in the El Niño years 2015 and 2016, humpback whales were virtually absent. Our data show that humpback whales are systematically present in the Atlantic sector of the Southern Ocean and suggest that these whales are particularly sensitive to climate oscillations which have profound effects on winds, sea ice extent, primary production, and especially krill productivity.

scholarly journals Large-scale spatial variabilities in the humpback whale acoustic presence in the Atlantic sector of the Southern Ocean

2020 ◽  
Vol 7 (12) ◽  
pp. 201347
Author(s):  
Elena Schall ◽  
Karolin Thomisch ◽  
Olaf Boebel ◽  
Gabriele Gerlach ◽  
Stefanie Spiesecke ◽  
...  
Keyword(s):  
Southern Ocean ◽  
High Latitude ◽  
Large Scale ◽  
Austral Summer ◽  
Humpback Whale ◽  
Humpback Whales ◽  
Stock Management ◽  
Atlantic Sector ◽  
Acoustic Activity ◽  
Passive Acoustic

Southern Hemisphere humpback whales ( Megaptera novaeangliae ) inhabit a wide variety of ecosystems including both low- and high-latitude areas. Understanding the habitat selection of humpback whale populations is key for humpback whale stock management and general ecosystem management. In the Atlantic sector of the Southern Ocean ( ASSO ), the investigation of baleen whale distribution by sighting surveys is temporally restricted to the austral summer. The implementation of autonomous passive acoustic monitoring, in turn, allows the study of vocal baleen whales year-round. This study describes the results of analysing passive acoustic data spanning 12 recording positions throughout the ASSO applying a combination of automatic and manual analysis methods to register humpback whale acoustic activity. Humpback whales were present at nine recording positions with higher acoustic activities towards lower latitudes and the eastern and western edges of the ASSO . During all months, except December (the month with the fewest recordings), humpback whale acoustic activity was registered in the ASSO . The acoustic presence of humpback whales at various locations in the ASSO confirms previous observations that part of the population remains in high-latitude waters beyond austral summer, presumably to feed. The spatial and temporal extent of humpback whale presence in the ASSO suggests that this area may be used by multiple humpback whale breeding populations as a feeding ground.

Seasonal climate summary for the southern hemisphere (autumn 2017): the Great Barrier Reef experiences coral bleaching during El Niño–Southern Oscillation neutral conditions

2019 ◽  
Vol 69 (1) ◽  
pp. 310
Author(s):  
Grant A. Smith
Keyword(s):  
Western Australia ◽  
Coral Bleaching ◽  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Maximum Temperature ◽  
Sea Ice Extent ◽  
Antarctic Sea Ice ◽  
Dry Conditions ◽  
The Mean

Austral autumn 2017 was classified as neutral in terms of the El Niño–Southern Oscillation (ENSO), although tropical rainfall and sub-surface Pacific Ocean temperature anomalies were indicative of a weak La Niña. Despite this, autumn 2017 was anomalously warm formost of Australia, consistent with the warming trend that has been observed for the last several decades due to global warming. The mean temperatures for Queensland, New South Wales, Victoria, Tasmania and South Australiawere all amongst the top 10. The mean maximum temperature for all of Australia was seventh warmest on record, and amongst the top 10 for all states but Western Australia, with a region of warmest maximum temperature on record in western Queensland. The mean minimum temperature was also above average nationally, and amongst top 10 for Queensland, Victoria and Tasmania. In terms of rainfall, there were very mixed results, with wetter than average for the east coast, western Victoria and parts of Western Australia, and drier than average for western Tasmania, western Queensland, the southeastern portion of the Northern Territory and the far western portion of Western Australia. Dry conditions in Tasmania and southwest Western Australia were likely due to a positive Southern Annular Mode, and the broader west coast and central dry conditions were likely due to cooler eastern Indian Ocean sea-surface temperatures (SSTs) that limited the supply of moisture available to the atmosphere across the country. Other significant events during autumn 2017 were the coral bleaching in the Great Barrier Reef (GBR), cyclone Debbie andmuch lower than average Antarctic sea-ice extent. Coral bleaching in the GBR is usually associated on broad scales with strong El Niño events but is becoming more common in ENSO neutral years due to global warming. The southern GBR was saved from warm SST anomalies by severe tropical cyclone Debbie which caused ocean cooling in late March and flooding in Queensland and New SouthWales. The Antarctic sea-ice extent was second lowest on record for autumn, with the March extent being lowest on record.

scholarly journals Humpback whale song recordings suggest common feeding ground occupation by multiple populations

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Elena Schall ◽  
Karolin Thomisch ◽  
Olaf Boebel ◽  
Gabriele Gerlach ◽  
Sari Mangia Woods ◽  
...  
Keyword(s):  
Southern Ocean ◽  
Behavioral Plasticity ◽  
Prey Availability ◽  
Humpback Whale ◽  
Sea Ice Concentration ◽  
Atlantic Sector ◽  
Feeding Ground ◽  
Breeding Grounds ◽  
Spatio Temporal ◽  
Feeding Grounds

AbstractHumpback whale males are known to sing on their low-latitude breeding grounds, but it is well established that songs are also commonly produced ‘off-season’ on the feeding grounds or during migration. This opens exciting opportunities to investigate migratory aggregations, study humpback whale behavioral plasticity and potentially even assign individual singers to specific breeding grounds. In this study, we analyzed passive acoustic data from 13 recording positions and multiple years (2011–2018) within the Atlantic sector of the Southern Ocean (ASSO). Humpback whale song was detected at nine recording positions in five years. Most songs were recorded in May, austral fall, coinciding with the rapid increase in sea ice concentration at most recording positions. The spatio-temporal pattern in humpback whale singing activity on Southern Ocean feeding grounds is most likely shaped by local prey availability and humpback whale migratory strategies. Furthermore, the comparative analyses of song structures clearly show a differentiation of two song groups, of which one was solely recorded at the western edge of the ASSO and the other song group was recorded throughout the ASSO. This new finding suggests a common feeding ground occupation by multiple humpback whale populations in the ASSO, allowing for cultural and potentially even genetic exchange among populations.

scholarly journals The polar expression of ENSO and sea-ice variability as recorded in a South Pole ice core

2002 ◽  
Vol 35 ◽  
pp. 430-436 ◽  
Author(s):  
Eric A. Meyerson ◽  
Paul A. Mayewski ◽  
Karl J. Kreutz ◽  
L. David Meeker ◽  
Sallie I. Whitlow ◽  
...  
Keyword(s):  
Sea Ice ◽  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Function Analysis ◽  
Ice Core ◽  
South Pole ◽  
Proxy Record ◽  
Sea Ice Extent ◽  
Southeastern Pacific

AbstractAn annually dated ice core recovered from South Pole (2850 m a.s.l.) in 1995, that covers the period 1487–1992, was analyzed for the marine biogenic sulfur species methanesulfonate (MS). Empirical orthogonal function analysis is used to calibrate the high-resolution MS series with associated environmental series for the period of overlap (1973–92). Utilizing this calibration we present a ~500 year long proxy record of the polar expression of the El Niño–Southern Oscillation (ENSO) and southeastern Pacific sea-ice extent variations. These records reveal short-term periods of increased (1800–50, 1900–40) and decreased sea-ice extent (1550–1610, 1660–1710, 1760–1800). In general, increased (decreased) sea-ice extent is associated with a higher (lower) frequency of El Niño events.

scholarly journals An Investigation of the Southern Ocean Surface Temperature Variability Using Long-Term Optimum Interpolation SST Data

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Megha Maheshwari ◽  
Rajkumar Kamaljit Singh ◽  
Sandip Rashmikant Oza ◽  
Raj Kumar
Keyword(s):  
Southern Ocean ◽  
El Niño ◽  
El Nino ◽  
Linear Trend ◽  
Critical Role ◽  
La Niña ◽  
Optimum Interpolation ◽  
La Nina ◽  
Sst Anomaly

An attempt is made to understand the long-term variability of SST using NOAA optimum interpolation SST data for the period (1982–2011) in the Southern Ocean. This dataset has been used (i) to study the interannual variability in SST anomaly and (ii) to carry out regression analysis to compute linear trend in the annual averaged Southern Ocean SST. It is observed that summer season exhibits more variability than winter. Moreover, El Nino/La Nina events apparently play a critical role in the variability of Southern Ocean SST. Thus, higher SST anomalies were observed in El Nino years (e.g., 1983), while cooler anomalies were seen during La Nina years (e.g., 1985). In addition, the eastern and western sides of Antarctica experience episodes of warm and cold SST. Western parts of the Southern Ocean experienced higher anomalies during 1992, 1993, and 1994, while the eastern part experienced positive anomalies in 1997, 1998, 2002, and 2003. The paper also highlights the different regions of the Southern Ocean showing statistically significant positive/negative trends in the variability of interannual average SST. However, in general, the Southern Ocean as a whole is showing a weak interannual cooling trend in SST.

scholarly journals Application of sediment core modelling to interpreting the glacial-interglacial record of Southern Ocean silica cycling

2007 ◽  
Vol 3 (3) ◽  
pp. 387-396 ◽  
Author(s):  
A. Ridgwell
Keyword(s):  
Southern Ocean ◽  
Sediment Core ◽  
Polar Front ◽  
Antarctic Polar Front ◽  
Sea Ice Extent ◽  
Atlantic Sector ◽  
Silica Cycling ◽  
The North ◽  
Late Neogene ◽  
Primary Driver

Abstract. Sediments from the Southern Ocean reveal a meridional divide in biogeochemical cycling response to the glacial-interglacial cycles of the late Neogene. South of the present-day position of the Antarctic Polar Front in the Atlantic sector of the Southern Ocean, biogenic opal is generally much more abundant in sediments during interglacials compared to glacials. To the north, an anti-phased relationship is observed, with maximum opal abundance instead occurring during glacials. This antagonistic response of sedimentary properties provides an important model validation target for testing hypotheses of glacial-interglacial change against, particularly for understanding the causes of the concurrent variability in atmospheric CO2. Here, I illustrate a time-dependent modelling approach to helping understand climates of the past by means of the mechanistic simulation of marine sediment core records. I find that a close match between model-predicted and observed down-core changes in sedimentary opal content can be achieved when changes in seasonal sea-ice extent are imposed, whereas the predicted sedimentary response to iron fertilization on its own is not consistent with sedimentary observations. The results of this sediment record model-data comparison supports previous inferences that the changing cryosphere is the primary driver of the striking features exhibited by the paleoceanographic record of this region.

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