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Bloom fitoplanctonici e presenza stagionale di squalo balena (rhincodon typus) lungo la costa di gibuti – golfo di aden

Authors:
  • Centro Studi Squali - Sharks Studies Centre - Scientific Institute
  • Centro Studi Squali-Sharks Studies Center
  • AGC98 S.r.l.
Article

Bloom fitoplanctonici e presenza stagionale di squalo balena (rhincodon typus) lungo la costa di gibuti – golfo di aden

Abstract

During a 5 days research expedition performed in January, some observations on a whale shark population were performed. Just 7 specimens have been observed and identified. This number of sharks is lower than that observed in previous report and similar research efforts. Recent remote sensing studies showed summer phytoplanktonic bloom higher than in autumn, but no sharks have been recorded suggesting that the quantity of phytoplankton could be not linked with the presence of the whale sharks.
PHYTOPLANKTONBLOOM AND SEASONAL PRESENCE OF WHALE SHARK (RHINCODON TYPUS)
ALONG THE COAST OF DJIBOUTI
Micarelli P1., Romano
C
1Centro Studi Squali-
Aquarium Mondo Marino
3
Dipartimento di Biologia, Ecologia e Scienze
A R T I C L E I N F O
INTRODUCTION
Whale sharks (Rhincodon typus
) are panoceanic planktivores
that were first described from a specimen captured in the
Western Indian Ocean in 1828 (Smith, 1828)
filtering apparatus of the R. typus
is unlike that of the other
filter feeding sharks. Rhincodon typus
are able to feed by
suction, which may allow them to target more mobile prey
and so they are better suited to dense prey aggregations, while
C. maximus and M. pelagios
are apparently better
feeding on lower densities of prey organisms, filtering large
volumes of water (Taylor et al
., 1983). Whale sharks can be
uniquely identified by spot patterns on their skin, the area
posterior to the fifth gill slit being particularly suited to this
purpose (Arzoumanian et al., 2005).
Anecdotal reports
suggested that whale sharks occur during th
October to February in the Arta Bay area, (11° 35’N, 42°
49’E) on the southern coast of the western end of the Gulf of
Tadjoura some 33 km from Djibouti city (Rowat
Waters in the lower central gulf and southern coastal region
demonstrated maximum Chl-
a concentrations during autumn
(late November), indicating that the major phytoplankton
growth period in these regions occurs during the northeast
monsoon when the northeasterlies prevail (
2017). The improved spatial coverage of OC
-
International Journal of Current Advanced Research
ISSN: O: 2319-6475, ISSN: P: 2319
Available Online at
www.journalijcar.org
Volume 6; Issue 5; May
2017; Page No.
DOI:
http://dx.doi.org/10.24327/ijcar.2017.
Article History:
Received 20th February, 2017
Received in revised form 10th March, 2017
Accepted 8th April, 2017
Published online 28th May, 2017
Key words:
Whale shark, planctonic blooms,
Djibuti
Copyright©2017 Micarelli P et al.
This is an open access article distributed under the Creative Commons Attribution License, which permits
unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
*Corresponding author: Micarelli P
Centro Studi Squali-
Aquarium Mondo Marino Loc.Valpiana
Via della Cava, Massa Marittima GR, Italia
PHYTOPLANKTONBLOOM AND SEASONAL PRESENCE OF WHALE SHARK (RHINCODON TYPUS)
ALONG THE COAST OF DJIBOUTI
-
GULF OF ADEN
C
1., Buttino I2., Reinero F1,3., Serangeli C4
and
Aquarium Mondo Marino
Loc.Valpiana Via della Cava, Massa Marittima GR, Italia
2ISPRA piazzale dei marmi 12, Livorno
Dipartimento di Biologia, Ecologia e Scienze Della Terra, Università della Calabria, Rende (CS)
4AGC98 – Roma
A B S T R A C T
During a 5 days research expedition performed in January, some observations on a whale
shark population were performed. Just 7 specimens have been observed and identified. This
number of sharks is lower than that observed in previous repo
similar research efforts. Recent remote sensing studies showed summer phytoplanktonic
bloom higher than in autumn, but no sharks have been recorded suggesting that the quantity
of phytoplankton could be not linked with the presen
ce of the whale sharks.
) are panoceanic planktivores
that were first described from a specimen captured in the
Western Indian Ocean in 1828 (Smith, 1828)
. The pad-like
is unlike that of the other
are able to feed by
suction, which may allow them to target more mobile prey
and so they are better suited to dense prey aggregations, while
are apparently better
adapted to
feeding on lower densities of prey organisms, filtering large
., 1983). Whale sharks can be
uniquely identified by spot patterns on their skin, the area
posterior to the fifth gill slit being particularly suited to this
Anecdotal reports
suggested that whale sharks occur during th
e months of
October to February in the Arta Bay area, (11° 35’N, 42°
49’E) on the southern coast of the western end of the Gulf of
Tadjoura some 33 km from Djibouti city (Rowat
et al., 2007).
Waters in the lower central gulf and southern coastal region
a concentrations during autumn
(late November), indicating that the major phytoplankton
growth period in these regions occurs during the northeast
monsoon when the northeasterlies prevail (
Gittings et al.,
-
CCI data in the
Gulf of Aden allowed, for the
the full seasonal succ
ession of phytoplankton biomass and
analysis of indices of phytoplankton phenology (bloom
timing). This revealed distinct phytoplankton growth periods
in different parts of the gulf: a large peak during August (mid
summer) in the western part of the gulf,
during November (mid-
autumn) in the lower central gulf and
along the southern coastline. The summer bloom developed
rapidly at the beginning of July, and its peak appeared
approximately three times higher than that of the autumnal
bloom (Gittings et al., 2017)
. Despite the presence of large
planctonic blooms, during summer whale shark presence was
not observed.
MATERIAL AND METHODS
The Gulf of Tadjoura, (11° 40’N, 43° 00’E) at the southern
entrance to the Red Sea, is an inlet of the Indian Ocean caused
by the fault line of the northerly end of the East African Rift
Valley that transects Djibouti, Ethiopia and Kenya (Rowat
al., 200
7). Data were collected from 16th to 20th January
2017 between
Arta Beach (11°34’N, 42°49’E), Ras Korali
(11°34’N, 42°47’E) and Escape Bay (11°34’N, 42°49’E)
Daily, 3 whale sharks monitoring activities were performed
from two tenders at the following day
15-
17. Observations were randomly performed 50m far the
coast, covering an area of about 20 km of diameter from Ras
Korali. The recognition of individuals was made by
underwater cameras; time of observation and location were
International Journal of Current Advanced Research
6505, Impact Factor: SJIF: 5.995
www.journalijcar.org
2017; Page No.
3948-3949
http://dx.doi.org/10.24327/ijcar.2017.
3949.0403
This is an open access article distributed under the Creative Commons Attribution License, which permits
unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Aquarium Mondo Marino Loc.Valpiana
PHYTOPLANKTONBLOOM AND SEASONAL PRESENCE OF WHALE SHARK (RHINCODON TYPUS)
GULF OF ADEN
and
Sperone E1,3
Loc.Valpiana Via della Cava, Massa Marittima GR, Italia
Della Terra, Università della Calabria, Rende (CS)
During a 5 days research expedition performed in January, some observations on a whale
shark population were performed. Just 7 specimens have been observed and identified. This
number of sharks is lower than that observed in previous repo
rts in the same period for
similar research efforts. Recent remote sensing studies showed summer phytoplanktonic
bloom higher than in autumn, but no sharks have been recorded suggesting that the quantity
ce of the whale sharks.
Gulf of Aden allowed, for the
first time, an investigation into
ession of phytoplankton biomass and
analysis of indices of phytoplankton phenology (bloom
timing). This revealed distinct phytoplankton growth periods
in different parts of the gulf: a large peak during August (mid
-
summer) in the western part of the gulf,
and a smaller peak
autumn) in the lower central gulf and
along the southern coastline. The summer bloom developed
rapidly at the beginning of July, and its peak appeared
approximately three times higher than that of the autumnal
. Despite the presence of large
planctonic blooms, during summer whale shark presence was
MATERIAL AND METHODS
The Gulf of Tadjoura, (11° 40’N, 43° 00’E) at the southern
entrance to the Red Sea, is an inlet of the Indian Ocean caused
by the fault line of the northerly end of the East African Rift
Valley that transects Djibouti, Ethiopia and Kenya (Rowat
et
7). Data were collected from 16th to 20th January
Arta Beach (11°34’N, 42°49’E), Ras Korali
(11°34’N, 42°47’E) and Escape Bay (11°34’N, 42°49’E)
.
Daily, 3 whale sharks monitoring activities were performed
from two tenders at the following day
time: 07-09, 11-13 and
17. Observations were randomly performed 50m far the
coast, covering an area of about 20 km of diameter from Ras
Korali. The recognition of individuals was made by
underwater cameras; time of observation and location were
Research Article
International Journal of Current Advanced Research Vol 6, Issue 05, pp 3948-3949, May 2017
3949
recorded. Chemical and physical analysis of water were daily
monitored, plankton samples were collected with a WP2
plankton net (200 µm mesh net) at the passage of the whale
sharks.
RESULTS
About 60 hours have been dedicated to the monitoring of
animals. During this time, 7 specimens of whale shark were
photographed and identified. Their sizes ranged between <2
m and <4.5 m. Among these animals, 4 were males, 1 was
female, and for 2 the sex determination was not possible.
CONCLUSIONS
Whale shark monitoring showed that sharks are still present in
January but fewer than in previous reports in the same period,
23 specimens have been observed in 2006 by Rowat et al.
(2006), 20 and 16 in 2007 and 2009 by Rezzolla et al. (2010).
No information are available if sharks are present also in
summer. Monitoring will be continued in summer (August)
when important phytoplankton blooms occur. More detailed
information must be collected in order to check if differencies
existed between summer and autumn planktonic biodiversity.
Acknowledgments
Special thanks to Expedition Staff;. Marsella A, Ciaramella
M,.Ragosta S, Robutti S, Cresti I, Anello V,Tempesti J,
Madonia N, Ph.D. Student Boldrocchi G, Elegante boat team
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How to cite this article:
Micarelli P et al (2017) 'Phytoplanktonbloom and seasonal presence of Whale shark (Rhincodon typus) along the coast of
Djibouti - Gulf of Aden ', International Journal of Current Advanced Research, 06(05), pp. 3948-3949.
DOI: http://dx.doi.org/10.24327/ijcar.2017.3949.0403
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Megamouth–a new species, genus and family of laminoid shark (Megachasma pelagios, Family Megachasmidae) from the Hawaiian Islands
  • L R Taylor
  • L J V Compagno
  • P J Struhasaker
Taylor L. R., Compagno L. J. V. & Struhasaker P. J. (1983). Megamouth–a new species, genus and family of laminoid shark (Megachasma pelagios, Family Megachasmidae) from the Hawaiian Islands. Proceedings of the California Academy of Science 43, 87–110.
Phytoplanktonbloom and seasonal presence of Whale shark (Rhincodon typus) along the coast of Djibouti-Gulf of Aden
  • P Micarelli
Micarelli P et al (2017) 'Phytoplanktonbloom and seasonal presence of Whale shark (Rhincodon typus) along the coast of Djibouti-Gulf of Aden ', International Journal of Current Advanced Research, 06(05), pp. 3948-3949.