Distribution patterns of larval myctophid fishes in the transition region of the western North Pacific

2004 ◽  
Vol 144 (3) ◽  
pp. 417-428 ◽  
Author(s):  
C. Sassa ◽  
K. Kawaguchi ◽  
Y. Oozeki ◽  
H. Kubota ◽  
H. Sugisaki
Keyword(s):  
Transition Region ◽  
North Pacific ◽  
Western North Pacific ◽  
Distribution Patterns

Feeding ecology of Symbolophorus californiensis larvae (Teleostei: Myctophidae) in the southern transition region of the western North Pacific

2009 ◽  
Vol 90 (6) ◽  
pp. 1249-1256 ◽  
Author(s):  
Chiyuki Sassa
Keyword(s):  
Transition Region ◽  
North Pacific ◽  
Western North Pacific ◽  
Developmental Stages ◽  
Feeding Habits ◽  
Larval Growth ◽  
Trophic Niche ◽  
Size Class ◽  
Gut Contents ◽  
Wide Range

The feeding habits of myctophid larvae of Symbolophorus californiensis were examined in the southern transition region of the western North Pacific where the main spawning and nursery grounds of S. californiensis are formed. This species is a key component of the pelagic ecosystems of this region, and their larvae attain one of the largest sizes among myctophids. To analyse gut contents larvae, including most life history stages after yolk-sac absorption (3.7 to 22.2 mm body length (BL)), were collected in the upper 100 m layer in 1997 and 1998. Feeding incidence was higher during the day than at night (53.1–92.3% versus 0–5.6%), and daytime feeding incidence increased gradually with larval growth. Larvae fed mainly on copepods of various developmental stages. Larvae of S. californiensis showed an ontogenetic change in their diet: larvae ≤7.9 mm BL (i.e. preflexion stage) fed mainly on copepod eggs and nauplii, while the larvae ≥8 mm BL consumed mainly calanoid copepodites such as Pseudocalanus and Paracalanus spp. In the largest size-class (16–22.2 mm BL), the furcilia stage of euphausiids was also an important prey item. There was an increase in the average prey size with growth in larvae ≤11.9 mm BL, while the number of prey eaten positively correlated with growth in larvae ≥12 mm BL. The trophic niche breadth also increased with larval growth, which would ensure a wide range of available food resources for the larger size-class larvae.

Early development of Diaphus garmani (Myctophidae) in the transition region of the western North Pacific

2003 ◽  
Vol 50 (1) ◽  
pp. 94-97 ◽  
Author(s):  
Chiyuki Sassa ◽  
Kouichi Kawaguchi ◽  
Valerie J. Loeb
Keyword(s):  
Transition Region ◽  
Early Development ◽  
North Pacific ◽  
Western North Pacific

Patterns in Rhizosolenia- and Guinardia-associated Richelia abundances in the tropical marginal seas of the western North Pacific

2021 ◽  
Author(s):  
Sing-How Tuo ◽  
Margaret R Mulholland ◽  
Yuh-Ling Lee Chen ◽  
P Dreux Chappell ◽  
Houng-Yung Chen
Keyword(s):  
North Pacific ◽  
Statistical Models ◽  
Western North Pacific ◽  
Distribution Patterns ◽  
Southwest Monsoon ◽  
Free Living ◽  
Multivariate Statistical ◽  
Marginal Seas ◽  
Key Factor ◽  
Time Periods

Abstract Richelia is a widespread, heterocystous, N2-fixing cyanobacterium that occurs in oligotrophic seas. It can be symbiotic within rhizosolenoid hosts, including Rhizosolenia (R-R) and Guinardia (G-R), and occasionally occurs as free-living (FL-R) filaments. We investigated the Richelia abundances in the South China (SCS) and Philippine Seas (PS) during the northeast (NEM) and southwest monsoon (SWM) seasons between 2001 and 2016. Field results showed that G-R was most abundant in the SCS during the SWM. Both R-R and FL-R were more abundant in the PS than the SCS and during the SWM versus the NEM. In general, R-R were more abundant than G-R, except at the SCS-SWM stations where abundances were comparable. Multivariate statistical models indicate that as R-R and G-R were abundant in warmer seawaters, nitrate plus nitrite was a key factor negatively controlling R-R abundance while silicate was more positively related to G-R. Positive correlation between G-R and FL-R abundances and microscopic observations imply that like Rhizosolenia-associated Richelia, filaments released from Guinardia hosts can remain viable outside their diatom hosts for time periods on the order of days. Overall, results reveal different distribution patterns between the two rhizosolenoid-Richelia symbioses and both G-R and R-R likely contribute to FL-R in the field.

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