Seasonality and diel variation in blue whale D calls recorded in the Southern California Bight
Passive acoustic data have been collected using HARPs (High-frequency Acoustic Recording Packages) and were used to assess (1) the seasonality of blue whale D calls in the Southern California Bight, (2) their interannual abundance during 2007-2012 and (3) their diel variation. This goal has been ach...
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Alma Mater Studiorum - Università di Bologna
2015
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ftunivbollaurea:oai:amslaurea.cib.unibo.it:8316 2023-05-15T15:45:08+02:00 Seasonality and diel variation in blue whale D calls recorded in the Southern California Bight Gambini, Chiara Fabbri, Elena Širović, Ana 2015-03-19 application/pdf http://amslaurea.unibo.it/8316/ http://amslaurea.unibo.it/8316/1/Gambini_Chiara_tesi.pdf en eng Alma Mater Studiorum - Università di Bologna http://amslaurea.unibo.it/8316/1/Gambini_Chiara_tesi.pdf Gambini, Chiara (2015) Seasonality and diel variation in blue whale D calls recorded in the Southern California Bight. [Laurea magistrale], Università di Bologna, Corso di Studio in Biologia marina [LM-DM270] - Ravenna <http://amslaurea.unibo.it/view/cds/CDS8024/> info:eu-repo/semantics/openAccess blue whales bioacoustics D calls HARPs detectors Biologia marina [LM-DM270] - Ravenna PeerReviewed info:eu-repo/semantics/masterThesis 2015 ftunivbollaurea 2022-05-01T15:16:03Z Passive acoustic data have been collected using HARPs (High-frequency Acoustic Recording Packages) and were used to assess (1) the seasonality of blue whale D calls in the Southern California Bight, (2) their interannual abundance during 2007-2012 and (3) their diel variation. This goal has been achieved running the GPL (Generalized Power-Law) automated detector. (1) Blue whale D calls were detected in the Southern California Bight from May through November with a peak in July, even though few detections were from December to April as well. A key predictor for blue whale distribution and movement in the California Current region has been identified with zooplankton aggregations, paying a particular attention to those euphausiid species, such as E. pacifica and T. spinifera, which are blue whale favorite krill. The Southern California Bight experiences seasonal upwelling, resulting in an increase of productivity and prey availability. The summer and early fall have been marked as the most favorable periods. This supports the presence of blue whales in the area at that time, supposing these marine mammals exploit the region as a feeding ground. (2) As to the interannual abundance during 2007-2012, I found a large variability. I observed a great increase of vocalizations in 2007 and 2010, whereas a decrease was shown in the other years, which is well marked in 2009. It is my belief that these fluctuations in abundance of D calls detections through the deployed period are due to the alternation of El Nino and La Nina events, which occurred in those years. (3) The assessment of the daily timing of D calls production shows that D calls are more abundant during the day than during the night with a peak at 12:00 and 13:00. Assuming that D calling is associated with feeding, the daily pattern of D calls may be linked to the prey availability. E. pacifica and T. spinifera are among those species of krill which undertake daily vertical migrations, remaining at depth during the day and slowly coming up towards the surface at night. Because of some anatomical arrangements, these euphausiids are very sensitive to the light. Given that we believe D calls have a social function, I hypothesize that blue whales may recognize the hours at the highest solar incidence as the best moment of the day in terms of prey availability, exploiting this time window to advert their conspecifics. Master Thesis Blue whale Università di Bologna: AMS Tesi di Laurea (Alm@DL) |
institution |
Open Polar |
collection |
Università di Bologna: AMS Tesi di Laurea (Alm@DL) |
op_collection_id |
ftunivbollaurea |
language |
English |
topic |
blue whales bioacoustics D calls HARPs detectors Biologia marina [LM-DM270] - Ravenna |
spellingShingle |
blue whales bioacoustics D calls HARPs detectors Biologia marina [LM-DM270] - Ravenna Gambini, Chiara Seasonality and diel variation in blue whale D calls recorded in the Southern California Bight |
topic_facet |
blue whales bioacoustics D calls HARPs detectors Biologia marina [LM-DM270] - Ravenna |
description |
Passive acoustic data have been collected using HARPs (High-frequency Acoustic Recording Packages) and were used to assess (1) the seasonality of blue whale D calls in the Southern California Bight, (2) their interannual abundance during 2007-2012 and (3) their diel variation. This goal has been achieved running the GPL (Generalized Power-Law) automated detector. (1) Blue whale D calls were detected in the Southern California Bight from May through November with a peak in July, even though few detections were from December to April as well. A key predictor for blue whale distribution and movement in the California Current region has been identified with zooplankton aggregations, paying a particular attention to those euphausiid species, such as E. pacifica and T. spinifera, which are blue whale favorite krill. The Southern California Bight experiences seasonal upwelling, resulting in an increase of productivity and prey availability. The summer and early fall have been marked as the most favorable periods. This supports the presence of blue whales in the area at that time, supposing these marine mammals exploit the region as a feeding ground. (2) As to the interannual abundance during 2007-2012, I found a large variability. I observed a great increase of vocalizations in 2007 and 2010, whereas a decrease was shown in the other years, which is well marked in 2009. It is my belief that these fluctuations in abundance of D calls detections through the deployed period are due to the alternation of El Nino and La Nina events, which occurred in those years. (3) The assessment of the daily timing of D calls production shows that D calls are more abundant during the day than during the night with a peak at 12:00 and 13:00. Assuming that D calling is associated with feeding, the daily pattern of D calls may be linked to the prey availability. E. pacifica and T. spinifera are among those species of krill which undertake daily vertical migrations, remaining at depth during the day and slowly coming up towards the surface at night. Because of some anatomical arrangements, these euphausiids are very sensitive to the light. Given that we believe D calls have a social function, I hypothesize that blue whales may recognize the hours at the highest solar incidence as the best moment of the day in terms of prey availability, exploiting this time window to advert their conspecifics. |
author2 |
Fabbri, Elena Širović, Ana |
format |
Master Thesis |
author |
Gambini, Chiara |
author_facet |
Gambini, Chiara |
author_sort |
Gambini, Chiara |
title |
Seasonality and diel variation in blue whale D calls recorded in the Southern California Bight |
title_short |
Seasonality and diel variation in blue whale D calls recorded in the Southern California Bight |
title_full |
Seasonality and diel variation in blue whale D calls recorded in the Southern California Bight |
title_fullStr |
Seasonality and diel variation in blue whale D calls recorded in the Southern California Bight |
title_full_unstemmed |
Seasonality and diel variation in blue whale D calls recorded in the Southern California Bight |
title_sort |
seasonality and diel variation in blue whale d calls recorded in the southern california bight |
publisher |
Alma Mater Studiorum - Università di Bologna |
publishDate |
2015 |
url |
http://amslaurea.unibo.it/8316/ http://amslaurea.unibo.it/8316/1/Gambini_Chiara_tesi.pdf |
genre |
Blue whale |
genre_facet |
Blue whale |
op_relation |
http://amslaurea.unibo.it/8316/1/Gambini_Chiara_tesi.pdf Gambini, Chiara (2015) Seasonality and diel variation in blue whale D calls recorded in the Southern California Bight. [Laurea magistrale], Università di Bologna, Corso di Studio in Biologia marina [LM-DM270] - Ravenna <http://amslaurea.unibo.it/view/cds/CDS8024/> |
op_rights |
info:eu-repo/semantics/openAccess |
_version_ |
1766379493719539712 |