Feeding of a pelagic chaetognath,Sagitta nagae Alvariño in Suruga Bay, Central Japan

Nagasawa, Sachiko; Marumo, Ryuzo

doi:10.1007/bf02108551

Cited by 40 publications

(20 citation statements)

References 11 publications

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“…• Although several authors have found no relationship between feeding rates of chaetognaths and prey abundance (Pearre, 1973;Nagasawa and Marumo, 1972;Kuhlmann, 1977), as in the present study, this only appears to hold true at low prey densities. At very high prey densities, high NPC's are frequently recorded: e.g.…”

Section: Methodscontrasting

confidence: 61%

Diel migration and feeding patterns of the chaetognath, Sagitta friderici, off the west coast of South Africa

Stuart¹,

Verheye²

1991

J Mar Res

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The vertical distribution patterns of adult and juvenile Sagitta friderici were investigated over a 48 h period, using samples collected at different depth strata with an RMT 1 x 6 net.Juvenile chaetognaths were generally found at depths of less than 50 m throughout the day and night, and exhibited limited diel migration patterns. Adults, on the other hand, migrated more extensively and were generally found below 50 m during the day and scattered throughout the water column or near the surface at night. Using the mean depths at each sampling time, the migration patterns of adult chaetognaths closely followed that of the large calanoid copepods. Juvenile chaetognaths, on the other hand, showed no significant correlation with any group of copepods. The greatest proportion of chaetognaths with food in their guts were not found at the depths of maximum cope pod abundance, suggesting that the chaetognaths had not been feeding at the depths where they were caught. There was little evidence of a diel feeding rhythm, with no significant difference between the number of prey per chaetognath during the day or night. The majority of food items ingested were cope pods (85.7%), while cannibalism on smaller chaetognaths occurred in 2.4% of the samples. The size of copepods consumed by adult chaetognaths was estimated from the width of the copepod mandibular blade, and was found to range from 0.16-1.96 mm prosome length. Although there was a large range of prey sizes which any given predator could consume, there was a clear trend of increasing prey size with increasing predator size. The energetic equivalent of ingesting a single cope pod represented 47.4% of the body carbon of the juveniles, but only 16.7% for the adults. Consumption of two or more copepods increased this to 30.3% body carbon of the adults, but cannibalism on smaller chaetognaths represented an average of 46.8% of adult body carbon. Assuming equal handling costs, this implies that cannibalism is energetically much more advantageous for the adults than consuming copepods. Digestion times of cope pod prey items were estimated from an exponential equation relating digestion time to temperature using values from the literature for six different chaetognath species. This yielded an ingestion rate of 0.5 copepods chaetognath-I d-', which resulted in 1.0-5.3% ofthe cope pod standing stocks or 2.4-14.0% of the copepod production being consumed per day by the Sagitta friderici population.

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Section: Methodscontrasting

confidence: 61%

Diel migration and feeding patterns of the chaetognath, Sagitta friderici, off the west coast of South Africa

Stuart¹,

Verheye²

1991

J Mar Res

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“…When mass occurrences of N. nomurai occurred, the biomass of N. nomurai was substantial and equivalent to that of the common squid in the Japan Sea. The amount of zooplankton consumed as prey by N. nomurai was not great enough to influence zooplankton biomass in the Japan Sea as a whole; however, dense aggregations of N. nomurai in small areas would lead to some competition for food resources with planktivorous pelagic fish and carnivorous zooplankton that ingest copepods, such as the Japanese anchovy Engraulis japonicus Temminck & Schlegel, 1846, Japanese jack mackerel Trachurus japonicus (Temminck & Schlegel, 1844) (Tanaka et al 2006), and the pelagic chaetognath Zonosagitta nagae (Alvariño, 1967) (Nagasawa and Marumo 1972). Kawahara et al (2006) showed that the growth exponents of N. nomurai were 0.11 for 20-48 day old jellyfish in the laboratory and 0.02 based on field observations from August to December in the southwestern Japan Sea.…”

Section: Copepod Biomass and Productionmentioning

confidence: 99%

Biomass, body elemental composition, and carbon requirement of Nemopilema nomurai (Scyphozoa: Rhizostomeae) in the southwestern Japan Sea

Iguchi

Iwatani

Sugimoto

et al. 2017

Plankton Benthos Res

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Biomass and body elemental composition of the giant jellyfish Nemopilema nomurai in the southwestern Japan Sea were studied using specimens collected with mid-water trawl nets during September and October 2006, 2007. The average biomass of N. nomurai was calculated as 0.26-0.93 g wet weight (WW) m . Body elemental composition of N. nomurai was water=95.8% of WW, carbon=6.6% of dry weight (DW), nitrogen=1.7% of DW, and phosphorus=0.14% of DW. Carbon requirements for growth and respiration were estimated in per unit area using biomass data. For growth analysis, size-frequency distributions of bell diameter (BD) were examined from specimens collected using set-nets in Wakasa Bay during August-January in 2005-2007 and the growth rate was calculated as 1.5 cm d . Biomass and carbon requirement data of N. nomurai were compared to the biomass of the common squid Todarodes pacificus and copepod production, respectively, in the Japan Sea. In the present study, it was demonstrated that when mass incidences of N. nomurai occurred in the Japan Sea, the biomass of N. nomurai was substantial and equivalent to that of the common squid. The amount of zooplankton consumed as prey by N. nomurai was not large enough to influence the biomass of zooplankton as a whole; however, it was critical for dense aggregations in a small area.

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“…Predation is related to the abundance, size, form, swimming behaviour and migration pattern of preys (Nagasawa & Marumo, 1972;Gibbons, 1992) as well as the age and size of predators (Reeve & Walter, 1972;Pearre, 1976). In this study, the dominance of the cladoceran P. avirostris and salps in the plankton at certain stations did not correspond to a higher percentage of these preys in chaetognath guts.…”

Section: Feeding Habitsmentioning

confidence: 99%

“…In this study, in average, less than 10% was found with food in their gut. Some factors that affect the frequency of individuals containing preys are the capture of chaetognaths at depths and times where feeding does not occur (Nagasawa & Marumo, 1972;Oresland, 1987), evacuation of gut content due to stress provoked by sampling (Baier & Purcell, 1997) and inhibition of ingestion due to high concentration of preys (Sullivan, 1980;Reeve, 1980).…”

Section: Feeding Habitsmentioning

confidence: 99%

Distribution, abundance and biomass of Chaetognaths off São Sebastião region, Brazil in February 1994

Liang

Vega-Pérez

2002

Rev. Bras. Oceanogr.

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(Praça do Oceanográfico, SP, Brasil) lavega@usp.br• Abstract: The distribution, abundance, biomass, population structure and feeding habits of chaetognaths collected off São Sebastião region, Brazil, in February 1994 are described. Bongo nets were hauled obliquely to collect zooplankton samples. Forty-three samples obtained with the 333 urn mesh were analysed. In this study, 7 chaetognath species belonging to two genera were identified. Sagitta friderici, S. tenuis and S. bipunctata were grouped into the neritic category, and Sagitta enflata, S. hispida, S. minima and Krohnita pacifica into the semi-neritic group. The analysis of the community structure distinguished 3 zones: 1) a nearshore zone evidenced by low richness; 2) an offshore zone evidenced by higher number of species and 3) another offshore zone, located south and south-westward of São Sebastião Island, characterised by higher richness but with dominance of one species. The nearshore zone was dominated by the neritic species S. friderici and S. tenuis, whereas the offshore zone was dominated by S. enflata. Abundance and biomass increase from nearshore toward offshore zones by about two orders of magnitude. Gut content analysis revealed over 90% of empty guts. The chaetognath population was composed mainly of juveniles. The diets among the different chaetognath species was very similar, composed mostly of small copepods and appendicularians.• Resumo: No presente trabalho foram estudados a distribuição, abundância, biomassa, estrutura da população e hábito alimentar dos quetógnatos coletados na região de São Sebastião, Brasil, em fevereiro de 1994. As 43 amostras de zooplâncton utilizadas na elaboração deste trabalho foram obtidas através de arrastos oblíquos usando uma rede Bongô (333 um), providas de fluxômetro. Foram identificadas sete espécies de Chaetognatha pertencentes a dois gêneros. Sagitta friderici, S. tenuis e S. bipunctata foram agrupadas como espécies neríticas, enquanto que Sagitta enflata, S. hispida, S. minima e Krohnita pacifica semi-neriticas. A análise da estrutura da comunidade, mostrou a existência de 3 zonas: 1) zona costeira caracterizada por poucas espécies; 2) zona oceânica com muitas espécies e 3) zona oceânica, ao sul e sudoeste da Ilha de São Sebastião, com muitas espécies, mas predominância de uma espécie. A zona nerítica foi dominada pelas espécies S. friderici e S. tenuis, e a zona oceânica por S.enflata. Abundância e biomassa do grupo aumentou da região costeira para a oceânica. A população foi composta principalmente de jovens. A análise do conteúdo intestinal revelou mais de 90% de indivíduos com o trato digestivo vazio. A dieta das diferentes espécies foi bastante similar, sendo composta principalmente de pequenos copépodos e apendiculários.

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Feeding of a pelagic chaetognath,Sagitta nagae Alvariño in Suruga Bay, Central Japan

Cited by 40 publications

References 11 publications

Diel migration and feeding patterns of the chaetognath, <I>Sagitta friderici,</I> off the west coast of South Africa

Diel migration and feeding patterns of the chaetognath, <I>Sagitta friderici,</I> off the west coast of South Africa

Biomass, body elemental composition, and carbon requirement of <i>Nemopilema nomurai</i> (Scyphozoa: Rhizostomeae) in the southwestern Japan Sea

Distribution, abundance and biomass of Chaetognaths off São Sebastião region, Brazil in February 1994

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