scholarly journals Habitat Preference Modeling of Prehistoric Giant Shark Megalodon During Miocene in Bentang Formation of West Java Coast

2021 ◽  
Vol 6 (2) ◽  
pp. 264-272
Author(s):  
Andriwibowo Andriwibowo ◽  
Adi Basukriadi ◽  
Erwin Nurdin ◽  
Muh Aydava Mubarok

In the Miocene era about 20 million years ago, the South Coast of West Java was a sea and habitat for marine organisms including giant sharks Megalodon measuring about 18 meters long. This study aimed to model the habitat preference of the prehistoric gigantic shark Otodus megalodon population based on the fossil record. From fossil teeth, it revealed that the rock layer where the teeth found was Bentang formation from Miocene era. Many fossils of Megalodon had been unearthed from Bentang formation which is part of the South Coast of West Java. The habitat model was developed using the Sea Level Rise Inundation Tool of ArcGIS to estimate the sea depth and Megalodon’s habitat during the Miocene. The length of the teeth of O. megalodon found was ranged from 13 to 19 cm, indicating the presence of juvenile and adult O. megalodon. Based on the model, in the Miocene era, half of West Java was a sea with a depth ranging from 0 to 200 meters. At that time, it was estimated that juvenile O. megalodon occupied waters with a depth of 0-40 meters with an area of 1365 km2. Meanwhile, adult O. megalodon prefers a depth of 80-160 m and the frequency of habitat use increases at a depth of 200 m. The declining population of O. megalodon is associated with climate change and declining prey populations.

2021 ◽  
Vol 33 (5) ◽  
pp. 187-194
Author(s):  
Young Hyun Park ◽  
Woo-Sun Park

The damage caused by typhoons is gradually increasing due to the climate change recently. Hence, many studies have been conducted over a long period of time on various factors that determine the characteristics of storm surge, and most of relationships have been discovered. Because storm surge is complexly determined by various factors, it often show different results and draw different conclusions. For this reason, this study was conducted to understand the various characteristics of storm surge caused by changes in the forward speed of typhoons. This study was carried out with a numerical model, and the effect of forward speed could be analyzed by simplifying other factors as much as possible. When forward speed is increased, storm surges caused by typhoons tended to increase gradually. The storm surge showed a wide and gentle increase at a slow speed, but a narrow and steep one at a fast speed. In the case of the same forward speed, it was found that the storm surge was significantly influenced by the water depth of actual sea area. It was confirmed that the change in forward speed after passing Jeju Island did not significant affect on the storm surge in the south coast of Korea.


1978 ◽  
Vol 1 (16) ◽  
pp. 53
Author(s):  
J. Graff ◽  
D.L. Blackman

Along the south coast of England, series of observed annual maximum sea levels, ranging from 16 years to 125 years have been analysed for each of 10 ports. The Jenkinson method of analysis was used to compute the frequency of recurrence of extreme levels. For a number of these ports the series of annual maxima are shown to have significant trends of the same order as those for mean sea level. The Jenkinson method can be simply adjusted to cope with maxima having a component linear trend, making it possible to allow for such trends in computing the frequency of recurrence of extreme levels. If a trend in the annual maxima varies throughout the sample of observations it is shown that difficulties arise in using the Jenkinson method to compute acceptable statistics. It is also shown that for certain ports having long series of observed annual maxima it may be necessary to restrict the sample size of observations in order to compute estimates of the recurrence of extreme levels within reasonable return periods.


Author(s):  
Norihisa Usui ◽  
Koji Ogawa ◽  
Kei Sakamoto ◽  
Hiroyuki Tsujino ◽  
Goro Yamanaka ◽  
...  

Abstract Using a coastal assimilation model, generation mechanism of unusually high sea level (UHSL) at the south coast of Japan in September 2011 is investigated. Both model results and tide gauge observations indicate that sea level rise associated with the UHSL event occurred twice in the middle and end of September. The first one, which is localized around the eastern part of the Seto Inland Sea, is caused by a cyclonic circulation in the Kii Channel formed as a result of northward migration of the Kuroshio axis toward Cape Shionomisaki. The second sea level rise, which is the main contributor to this UHSL event, is observed in wide areas not only at the south coast of Japan, but also at the coast of the Japan Sea. It is brought about by a coastal trapped wave (CTW) induced as a result of a fluctuation of the Kuroshio path to the south of the Boso Peninsula. The CTW with positive SSH anomalies propagates westward along the south coast of Japan, and then goes into the coast of the Japan Sea. Sensitivity experiments and a modal characteristic analysis indicate that the CTW is mainly characterized by the first mode baroclinic Kelvin wave. The phase speed for the first mode is calculated at 2.96 m s$$^{-1}$$ - 1 , which compares well with that estimated by tide gauge observations.


1889 ◽  
Vol 5 (12) ◽  
pp. 625-637 ◽  
Author(s):  
H. B. Guppy
Keyword(s):  

2015 ◽  
Vol 72 (8) ◽  
pp. 2341-2349 ◽  
Author(s):  
Corey B. Wakefield ◽  
Ian C. Potter ◽  
Norman G. Hall ◽  
Rodney C. J. Lenanton ◽  
Sybrand A. Hesp

Abstract The timing and duration of spawning and maturation schedules of Chrysophrys auratus were determined for populations in one subtropical (∼25°S on the upper west coast) and two temperate regions (∼32°S on the lower west and ∼35°S on the south coasts) over >2000 km of coastline along the west coast of Australia. This study thus encompassed the wide latitudinal range of this recreationally and commercially important sparid in this region. The results were used, in conjunction with previously published data, to explore traditional paradigms regarding the relationships between the reproductive characteristics and variations in water temperature. Spawning at each latitude occurred mainly at 19–21°C, but following a decline in temperature in the subtropical region and after a rise in temperature in the two temperate regions. Spawning on the upper west coast thus occurred between mid-autumn and early spring (∼7 months) as opposed to late winter to early summer on the lower west coast (∼6 months). Spawning on the south coast was mainly restricted to mid-spring to early summer (∼2–3 months) in 2003 and 2004 and did not occur in 2005 when temperatures in this period were the coldest on record. Thus, marked interannual differences in the prevalence of mature fish on the south coast probably reflect the “marginality” of the population. The length (L50) and age (A50) at which C. auratus matured increased markedly from 25 to 32°S. Studies such as this allow for latitudinal variations in reproductive characteristics to be incorporated into population models to optimize fisheries sustainable yield, and contribute towards appropriate spatial scales for sustainable management strategies (e.g. minimum legal lengths consistent with latitudinal variation in length-based maturity schedules). The narrow temperature range over which this species spawns accounts for its current latitudinal distribution and enables predictions of how this distribution might alter with climate change. This study provides relevant information for management and climate change implications for similar subtropical and temperate marine teleosts.


2003 ◽  
Vol 199 (1-2) ◽  
pp. 45-63 ◽  
Author(s):  
David Mallinson ◽  
Albert Hine ◽  
Pamela Hallock ◽  
Stanley Locker ◽  
Eugene Shinn ◽  
...  

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