scholarly journals Estimation of mean movement rates for blue sharks in the northwestern Pacific Ocean

2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Mikihiko Kai ◽  
Yuki Fujinami

Abstract Background The blue shark Prionace glauca is a highly migratory species with a circumglobal distribution. Mean movement rate, defined by the horizontal tracking distance between two data points over the duration of time, is commonly used to understand the horizontal displacement of highly migratory species across a wide range. However, the estimation of mean movement rates for blue sharks has never been conducted using a statistical model. We therefore investigated the mean movement rates using a generalized linear mixed model with data from satellite tags to estimate the range of mean movement rates for 10 blue sharks in the northwestern Pacific Ocean and to reveal the interaction of mean movement rate with several factors. Results (1) Estimations of mean movement rates for the 10 blue sharks were significantly influenced by behavioral differences among individuals; (2) uncertainty in the estimation (i.e., predictive and confidence intervals) of mean movement rates for these blue sharks was larger over shorter time periods, and (3) the predictive intervals of mean movement rates for the sharks ranged widely from 0.33 to 5.02 km/h. Conclusion Blue sharks are considered to opportunistically change their mean movement rates regardless of differences in sex, movement direction, or season.

2016 ◽  
Vol 50 (6) ◽  
pp. 527-537 ◽  
Author(s):  
Tatsuo Nozaki ◽  
Ayaka Tokumaru ◽  
Yutaro Takaya ◽  
Yasuhiro Kato ◽  
Katsuhiko Suzuki ◽  
...  

2019 ◽  
Vol 58 (4) ◽  
pp. 903-917 ◽  
Author(s):  
Manman Ma ◽  
Yu Zhen ◽  
Tiezhu Mi

AbstractStudies of the community structures of bacteria in marine aerosols of different particle sizes have not been reported. Aerosol samples were collected using a six-stage bioaerosol sampler over the Bohai Sea, the Yellow Sea, and northwestern Pacific Ocean in the spring of 2014. The diversity and composition of these samples were investigated by Illumina high-throughput sequencing, and 130 genera were detected in all of the samples; the most abundant bacterial genus was Bacteroides, followed by Prevotella and Megamonas. The Chao1 and Shannon diversity indices ranged from 193 to 1044 and from 5.44 to 8.33, respectively. The bacterial community structure in coarse particles (diameter larger than 2.1 μm) was more complex and diverse than that in fine particles (diameter less than 2.1 μm) in marine bioaerosols from over the Yellow Sea and northwestern Pacific Ocean, while the opposite trend was observed for samples collected over the Bohai Sea. Although we were sampling over marine regions, the sources of the bioaerosols were mostly continental. Temperature and wind speed significantly influenced the bacterial communities in marine aerosols of different particle sizes. There may be a bacterial background in the atmosphere in the form of several dominant taxa, and the bacterial communities are likely mixed constantly during transmission.


Zootaxa ◽  
2018 ◽  
Vol 4418 (3) ◽  
pp. 287 ◽  
Author(s):  
KEITA KOEDA ◽  
TAKUMA FUJII ◽  
HIROYUKI MOTOMURA

Heteroconger fugax sp. nov. (Congridae: Heterocongrinae) is described from a single specimen collected from Amami-oshima island, Japan. The new species is most similar to Heteroconger tomberua Castle & Randall 1999, known from Fiji and New Caledonia, in having a remarkably slender body with numerous small spots and a vertebral count close to 200. However, it can be distinguished from H. tomberua by the presence of a large distinct white blotch on the opercle; more numerous, dense spots over the entire head, including lips; ground color of body uniformly cream, without microscopic melanophores; numerous small conical cirri on the chin; and dorsal-fin origin located more posteriorly to appressed pectoral-fin tip. A survey of underwater photographs of Heteroconger on photographic database revealed H. fugax to be widely distributed in the northwestern Pacific Ocean, from the Ryukyu Archipelago to Borneo.


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