Influence of monsoon-driven hydrographic features on thaliacean distribution in waters around Taiwan, western North Pacific Ocean

Abstract

Background: The mesoscale distribution of thaliaceans associated with hydrographic conditions in the waters around Taiwan was investigated during two different monsoon seasons in 2004 in order to elucidate possible influences of hydrological conditions driven by seasonal monsoons on distributional patterns of thaliaceans. Results: In total, 18 thaliacean species, belonging to 12 genera and 3 families, were identified in our samples. Thalia rhomboides, Doliolum denticulatum, Doliolum nationalis, Thalia orientalis, Pyrosoma verticillatum, and Thalia democratica were the six predominant species and contributed 93% to the total thaliacean collection by number. Thaliacean assemblages were similar in composition between seasons, but abundances and species numbers were higher in summer than in winter. Spatial distribution patterns of doliolids and salps clearly differed and were closely associated with hydrographic characteristics. Doliolids were mainly found in lower-salinity and nutrient-rich shelf and neritic waters; among them, D. denticulatum could be used as an indicator species of the China Coastal Current. Most salp species showed higher abundances in warm oceanic waters, such as the Kuroshio Current, Kuroshio Branch Current, and South China Sea Surface Current.Conclusions: This study showed that the succession of water masses driven by monsoons affects seasonal and particularly spatial distributions of abundances of the thaliacean assemblage in the area studied.

Variation in the Occurrence of Salp and Doliolid Assemblages in the Northeastern East China Sea from 2019 to 2023

“…During the survey period, the species identified in the northeastern East China Sea were similar to those found in the neighboring waters of Northeast Asia (Table 5). The list of salps and doliolids from countries neighboring South Korea includes a total of 30 species across 13 genera, including 13 species identified in our study [3,15,16,[43][44][45][46]. Particularly, we confirmed that doliolid species such as Dolioletta gegenbauri, Doliolum denticulatum, and Doliolum nationalis and salp species such as Cyclosalpa affinis, Salpa fusiformis, Thalia cicar, T. orientalis, and T. sibogae are commonly distributed around South Korea, China, Japan, and Taiwan (Table 5).…”

“…Pelagic thaliaceans (salps, doliolids, and pyrosomes) are planktonic, gelatinous zooplankton belonging to the phylum Chordata. These organisms are filter feeders that consume phytoplankton of various sizes in marine ecosystems [1][2][3]. Salps and doliolids exhibit a unique life cycle that alternates between asexual and sexual reproduction to maintain their population [4].…”

“…The distribution of thaliaceans is known to be influenced by hydrodynamic conditions such as the sea temperature and salinity [3,8], the influx intensity of water masses within the study region [3,9], the availability of food [10], and various biological factors, including prey competition and predator-prey relationships [11][12][13]. Salpa fusiformis is the widest-ranging and most abundant thaliacean species worldwide, occurring in Pacific waters [12][13][14][15][16].…”

The unique ecological role of pyrosomes in the Eastern Tropical Pacific

“…Perissinotto et al (2007) found higher retention efficiencies for cells greater than 10 μm in P. atlanticum, and fatty acids indicated a mixed phytoplankton diet of diatoms, dinoflagellates, and prymnesiophytes. P. atlanticum carcasses also contribute to carbon export, which can be substantial following blooms (Lebrato and Jones 2009;Liao et al 2013).…”

Unveiling the diversity of thaliaceans (Chordata, Thaliacea) from the the South Brazilian Bight and Southern Subtropical Shelf (22° - 33° S)

“…3D). Hereu et al 2006;Liao et al 2013). Indian Ocean (Godeaux 1980;Godeaux 1974;1997;Weikert & Godeaux 2008;Batistić et al 2014).…”