scholarly journals Feeding habits of juvenile surface migratory myctophid fishes (family Myctophidae) in the Kuroshio region of the western North Pacific

2002 ◽  
Vol 236 ◽  
pp. 263-272 ◽  
Author(s):  
H Watanabe ◽  
K Kawaguchi ◽  
A Hayashi
Keyword(s):  
North Pacific ◽  
Western North Pacific ◽  
Feeding Habits ◽  
The Kuroshio ◽  
Kuroshio Region

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.

scholarly journals Distribution of ultraphytoplankton in the western part of the North Pacific subtropical gyre during a strong La Niña condition: relationship with the hydrological conditions

2013 ◽  
Vol 10 (9) ◽  
pp. 5947-5965 ◽  
Author(s):  
M. Girault ◽  
H. Arakawa ◽  
A. Barani ◽  
H. J. Ceccaldi ◽  
F. Hashihama ◽  
...  
Keyword(s):  
El Niño ◽  
North Pacific ◽  
El Nino ◽  
Subtropical Gyre ◽  
La Niña ◽  
North Pacific Subtropical Gyre ◽  
Heterogeneous Distribution ◽  
La Nina ◽  
The Kuroshio ◽  
Kuroshio Region

Abstract. The distribution of ultraphytoplankton was investigated in the western North Pacific Subtropical Gyre (NPSG) during La Niña, a cold phase of El Niño Southern Oscillation (ENSO). Observations were conducted in a north-south transect (33.6–13.25° N) along the 141.5° E meridian in order to study the ultraplankton assemblages in various oligotrophic conditions. Analyses were performed at the single cell level by analytical flow cytometry. Five ultraphytoplankton groups (Prochlorococcus, Synechococcus, picoeukaryotes, nanoeukaryotes and nanocyanobacteria-like) defined by their optical properties were enumerated in three different areas visited during the cruise: the Kuroshio region, the subtropical Pacific gyre and a transition zone between the subtropical Pacific gyre and the Warm pool. Prochlorococcus outnumbered the other photoautotrophs in all the investigated areas. However, in terms of carbon biomass, an increase in the relative contribution of Synechococcus, picoeukaryotes and nanoeukaryotes was observed from the centre of the subtropical gyre to the Kuroshio area. In the Kuroshio region, a peak of abundance of nanoeukaryotes observed at the surface suggested an increase in nutrients likely due to the vicinity of a cold cyclonic eddy. In contrast, in the salinity front along the isohaline 35 and anticyclonic eddy located around 22.83° N, the mainly constant distribution of Prochlorococcus from the surface down to 150 m characterised the dominance by these microorganisms in high salinity and temperature zone. Results suggested that the distribution of nanocyanobacteria-like is also closely linked to the salinity front rather than low phosphate concentration. The maximum abundance of ultraphytoplankton was located above the SubTropical Counter Current (STCC) at depths > 100 m where higher nutrient concentrations were measured. Finally, comparison of the ultraphytoplankton concentrations during El Niño (from the literature) and La Niña (this study) conditions seems to demonstrate that La Niña conditions lead to higher concentrations of Synechococcus in the Subtropical gyre and a lower abundance of Synechococcus in the Kuroshio region. Our results suggest that the west part of NPSG is a complex area, where different water masses, salinity fronts and eddies lead to a heterogeneous distribution of ultraphytoplankton assemblages in the upper layer of the water column.

scholarly journals Recent Warming in the Western North Pacific in Relation to Rapid Changes in the Atmospheric Circulation of the Siberian High and Aleutian Low Systems*

2012 ◽  
Vol 25 (10) ◽  
pp. 3476-3493 ◽  
Author(s):  
Young-Hyang Park ◽  
Jong-Hwan Yoon ◽  
Yong-Hoon Youn ◽  
Frédéric Vivier
Keyword(s):  
Wind Stress ◽  
North Pacific ◽  
Western North Pacific ◽  
Rossby Waves ◽  
Delayed Response ◽  
Aleutian Low ◽  
Wind Stress Curl ◽  
Siberian High ◽  
Sst Variability ◽  
The Kuroshio

Abstract On the basis of a new East Asian winter monsoon (EAWM) index and by analyzing the relationship between sea surface temperature (SST) anomalies and different atmospheric and oceanic factors in winter, this study investigates the causes of the recent unusual warming in the western North Pacific Ocean. Analyses presented here emphasize the dual contribution from the atmosphere and ocean to the local SST variability, with the relative importance of each contributor varying with the period and place. During the period 1970–89, the EAWM, controlled mostly by the Siberian high, is predominantly responsible for the SST variability in most of the western North Pacific, whereas in the period 1990–2005 ocean dynamics become increasingly important in most places or even dominant in the Kuroshio–Oyasio Extension (KOE) region. The delayed response of the KOE SST to basinwide wind stress curl forcing via Rossby waves is epoch dependent and is significant at lags of 1, 3, and 4 yr before 1990 but only at 1 yr afterward. This epoch dependency of the impact of Rossby waves is related to the different locations of the centers of action of wind stress curl in the midlatitude North Pacific between the two epochs. In addition, mean advection of the EAWM-driven anomalous SST from the southern East China Sea, which can be transported into the KOE region in about a year by the Kuroshio, likely affects the KOE SST lagged by 1 yr. The strongest positive SST trend observed in the western North Pacific results from the combined effects of the abrupt weakening of the EAWM due to the unprecedented decline of the Siberian high and the increasing role of the ocean. The latter is best evidenced by the 1-yr delayed response of the western North Pacific via the gyre circulation adjustment to the basinwide decadal-scale wind stress curl change associated with the northward shift of the strengthened Aleutian low.

Comparison of feeding habits of myctophid fishes and juvenile small epipelagic fishes in the western North Pacific

2009 ◽  
Vol 156 (4) ◽  
pp. 641-659 ◽  
Author(s):  
Kaori Takagi ◽  
Akihiko Yatsu ◽  
Hiroshi Itoh ◽  
Masatoshi Moku ◽  
Hiroshi Nishida
Keyword(s):  
North Pacific ◽  
Western North Pacific ◽  
Feeding Habits
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