Improvement in recruitment of Japanese sardine with delays of the spring phytoplankton bloom in the Sea of Japan

Abstract

To evaluate the impact of temporal variation of primary productivity on the recruitment of Japanese sardine (Sardinops melanostictus) in the Sea of Japan, the phenology of sea surface phytoplankton abundance was estimated from 8 day multiple satellite (SeaWiFS, MODIS‐Aqua, MERIS, and VIIRS) derived sea surface chlorophyll (SSChl) a concentrations from January 1998 to December 2015. Because relationships between SSChl a and in situ chlorophyll a concentrations were significantly different among periods based on the satellite combinations used, maximum and minimum SSChl a concentrations of 1 year were relativized as 1 and 0, respectively. Spatio‐temporal variation of relativized SSChl a concentrations was determined by using empirical orthogonal function (EOF) analysis. Scores in the first EOF mode denoted the basin‐scale variations of SSChl a concentrations in the Sea of Japan, and the major peak from the end of February to the end of May displayed the spring bloom. The logarithm of recruitment per spawner (LNRPS) for sardine was positively affected by delays in the start and end dates of the spring phytoplankton bloom. The delay of the date of the lowest sea surface temperature contributed to the delay of the end of the spring bloom during the period 1998–2015 and elevated the LNRPS during the period 1982–2015. Sardine spawns in the southern Sea of Japan from April to May, hence, delays of the spring bloom prolonged its overlap with sardine larval periods, and thus improved the recruitment of Japanese sardine in the Sea of Japan.

Sensitivity of Shelf Sea Marine Ecosystems to Temporal Resolution of Meteorological Forcing

“…Phytoplankton phenology is known to be strongly impacted by meteorological variables, particularly wind and solar irradiance. The timing of spring and autumn phytoplankton blooms have consequences that cascade through the food web (Edwards & Richardson, 2004) and have been shown to affect fish stocks and spawning, copepod reproduction and shrimp survival (Kodama et al, 2018;Leaf & Friedland, 2014;Marrari et al, 2019;Platt et al, 2003;Richards et al, 2016). If high-resolution meteorological data is not available, the ability of hydrodynamic-ecosystem models to capture the impact of short-term fluctuations in wind stress, light availability and other key meteorological variables on bloom phenology and carbon cycling is limited.…”

Phytoplankton temporal dynamics in the coastal waters of the north-eastern Adriatic Sea (Mediterranean Sea) from 2010 to 2017

“…The diversity and dynamics of phytoplankton assemblages are complex processes driven by several interacting abiotic and biotic factors and, in addition to other physical-chemical drivers, biological interactions, such as grazing pressure and/or viral infections can have a role in shaping phytoplankton assemblages. The implications of a decreased bloom can be significant if one considers the importance of the synchronisation of the phenological cycles of primary producers and their consumers for matter and energy transfer through the food web (e.g., Edwards and Richardson 2004;Thackeray et al 2016;Kodama et al 2018). In the same way, changes in the composition of these blooms can also affect consumers because the food quality of various species can differ both in terms of stoichiometric composition and morphological characteristics, such as the presence of setae or cell projections (e.g., Finkel et al 2010).…”

One‐Dimensional Turbulence‐Ecosystem Model Reveals the Triggers of the Spring Bloom in Mesoscale Eddies

“…In the Japan Sea, the timing of spring blooms has been linked to the Japanese sardine recruitment. Later blooms are suggested to enhance the success of recruitment because of increased overlap between PHY blooming and the spawning period of Japanese sardine (Kodama et al, ). The early blooms observed in CEs possibly benefit other species with early spawning period as observed in other regions (e.g., Platt et al, ).…”

“…The spring bloom, a recurring phenomenon in the temperate regions, is an important event for higher trophic levels and carbon export (e.g., Kodama et al, ; Koeller et al, ; Omand et al, ; Platt et al, ). The role of physical drivers in controlling the spring bloom has been central to the discussion of the mechanisms initiating a bloom since the early works of Riley (), Sverdrup (), and others.…”