Stage-V copepodites of Calanus sinicus and Calanus jashnovi (Copepoda: Calanoida) in mesopelagic zone of Sagami Bay as identified with genetic markers, with special reference to their vertical distribution

Nonomura, Takumi; Machida, Ryuji J.; Nishida, Shuhei

doi:10.1016/j.pocean.2008.02.001

Cited by 19 publications

(5 citation statements)

References 45 publications

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“…In addition to influences of particle flux from the epipelagic layer [20, 37], there are mesopelagic copepods with diel vertical migration to the epipelagic layer. Some copepods also migrate to the mesopelagic layer in order to avoid unfavorable environmental conditions in the epipelagic layer even in the warm waters, including those in the Kuroshio region [38]. A significant change of biomass and trophic efficiency is predicted to occur in mesopelagic nekton as well as in large zooplankton as a result of climate change [39]; thus, interactions between the epipelagic and mesopelagic layers are key regulators of local communities and diversity patterns in mesopelagic copepods.…”

Section: Discussionmentioning

confidence: 99%

Large-scale metabarcoding analysis of epipelagic and mesopelagic copepods in the Pacific

Hirai

Tachibana

Tsuda

2020

Preprint

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AbstractA clear insight into large-scale community structure of planktonic copepods is critical to understanding mechanisms controlling diversity and biogeography of marine taxa, owing to their high abundance, ubiquity, and sensitivity to environmental changes. Here, we applied a 28S metabarcoding approach to large-scale communities of epipelagic and mesopelagic copepods at 70 stations across the Pacific Ocean and three stations in the Arctic Ocean. Major patterns of community structure and diversity, influenced by water mass structures, agreed with results from previous morphology-based studies. However, large-scale metabarcoding approach could detected community changes even under stable environmental conditions, including changes in the north/south subtropical gyres and east/west areas within each subtropical gyre. There were strong effects of epipelagic environment on mesopelagic communities, and community subdivisions were observed in the environmentally-stable mesopelagic layer. In each sampling station, higher operational taxonomic unit (OTU) numbers and lower phylogenetic diversity were observed in the mesopelagic layer than in the epipelagic layer, indicating a recent rapid increase of species numbers in the mesopelagic layer. The phylogenetic analysis utilizing representative sequences of OTUs revealed trends of recent emergence of cold-water OTUs mainly distributed at high latitudes with low water temperatures. Conversely, high diversity of copepods at low latitudes was suggested to have been formed through long evolutionary history under high water temperature. The metabarcoding results suggest that evolutionary processes have strong impacts on current patterns of copepod diversity, and support the “out of the tropics” theory explaining latitudinal diversity gradients of copepods. Both diversity patterns in epipelagic and mesopelagic showed high correlations to sea surface temperature; thus, predicted global warming may have a significant impact on copepod diversity in both layers.Author SummaryMarine planktonic copepods are highly dominant and diverse, and revealing their community structure and diversity is important to understanding marine ecosystems. We used molecular-based metabarcoding to reveal a total of 205 copepod communities in the ‘sunlight’ or epipelagic layer (0– 200 m) and the ‘twilight’ or mesopelagic layer (200–500 m and 500–1,000 m), mainly in the Pacific Ocean (data for 70 stations), but also in the Arctic Ocean (data for three stations). Different copepod communities were found in each geographical region with different environmental conditions, including tropical, subtropical, transition, Kuroshio Current, California Current, subarctic and arctic areas. The metabarcoding method sensitively detected small changes of copepod community even in environmentally-stable subtropical ocean systems and the mesopelagic layer. A high diversity of copepods was detected at low latitudes, and copepod diversity was higher in the mesopelagic layer than in the epipelagic layer in each area. These diversity patterns were influenced by both evolutionary history and present environmental conditions. The copepod community in the mesopelagic layer was strongly influenced by environmental conditions in the epipelagic layer. Thus, predicted climate changes may affect marine ecosystems not only in the epipelagic layer but also in the mesopelagic layer.

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Section: Discussionmentioning

confidence: 99%

Large-scale metabarcoding analysis of epipelagic and mesopelagic copepods in the Pacific

Hirai

Tachibana

Tsuda

2020

Preprint

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“…In addition to the continuous flux of particles from the epipelagic layer, there are mesopelagic copepods with diel vertical migration to the epipelagic layer [36]. Some copepods also migrate to the mesopelagic layer to avoid adverse environmental conditions in the epipelagic layer even in warm waters [37]. A significant change in biomass and trophic efficiency is predicted to occur in mesopelagic nekton and large zooplankton as a result of climate change [38]; thus, interactions between the epipelagic and mesopelagic layers are key regulators of local communities and diversity patterns in mesopelagic copepods.…”

Section: Plos Onementioning

confidence: 99%

Large-scale metabarcoding analysis of epipelagic and mesopelagic copepods in the Pacific

2020

View full text Add to dashboard Cite

A clear insight into the large-scale community structure of planktonic copepods is critical to understanding the mechanisms controlling diversity and biogeography of marine taxa in terms of their high abundance, ubiquity, and sensitivity to environmental changes. Here, we applied a 28S metabarcoding approach to large-scale communities of epipelagic and mesopelagic copepods at 70 stations across the Pacific Ocean and three stations in the Arctic Ocean. Major patterns of community structure and diversity, influenced by water mass structures, agreed with results from previous morphology-based studies. However, a largescale metabarcoding approach could detect community changes even under stable environmental conditions, including changes in the north/south subtropical gyres and east/west areas within each subtropical gyre. There were strong effects of the epipelagic environment on mesopelagic communities, and community subdivisions were observed in the environmentally stable mesopelagic layer. In each sampling station, higher operational taxonomic unit (OTU) numbers and lower phylogenetic diversity were observed in the mesopelagic layer than in the epipelagic layer, indicating a recent rapid increase in species numbers in the mesopelagic layer. The phylogenetic analysis utilizing representative sequences of OTUs revealed trends of recent emergence of cold-water OTUs, which are mainly distributed at high latitudes with low water temperatures. Conversely, the high diversity of copepods at low latitudes was suggested to have been formed through long evolution under high water temperature conditions. The metabarcoding results suggest that evolutionary processes have strong impacts on current patterns of copepod diversity, and support the "out of the tropics" theory explaining latitudinal diversity gradients of copepods. Diversity patterns in both epipelagic and mesopelagic copepods was highly correlated to sea surface temperature; thus, predicted global warming may have a significant impact on copepod diversity in both layers.

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“…It is evident that more than 50% of C. sinicus CVs had granules throughout the water column. It should be noted that the CVs in the mesopelagic zone (>250 m), which are probably in diapause as suggested by Nonomura et al (2008), had granules as well as those in the epipelagic population. The day–night comparison in the upper 200 m (Table 2) shows that equally large proportions (>90%) of C. sinicus had granules both day and night, with the number of granules per individual ranging from 0 to 52.…”

Section: Resultsmentioning

confidence: 60%

Structure of novel exocrine glands in Calanus species with notes on their possible function

Nishida

Nonomura

2010

J. Mar. Biol. Ass.

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The structure of hitherto-unknown exocrine glands in the caudal rami of the pelagic copepods of the genus Calanus was investigated, together with the vertical, diel and seasonal variations in the occurrence of granules secreted from the glands. Zooplankton samples were collected in Sagami Bay by vertical tows of a net from 4 discrete layers at 250-m intervals in the upper 1000 m both day and night, with an additional seasonal sampling in the upper 200 m. The samples contained copepodids of Calanus sinicus (stages IV–VI), C. jashnovi (stages IV–V), and unidentified Calanus (stages I–III), which possessed the glands regardless of the developmental stage and sex. Each caudal ramus has an inner- and an outer gland each of which opens in a pore at the ventral base of a caudal seta. According to light microscopy the cavities of only the inner glands contained many transparent granules, some of which appeared to have been discharged to the environment. The granules were present regardless of day/night, depth, and season, with the maximum number of 52/copepod. The cells surrounding the inner cavity contained well-developed rough endoplasmic reticulum, mitochondria, Golgi-bodies, and secretory granules; the outer cavity contained granules of much lower density than those in the inner cavity. These observations rule out the possible functions of the glands for egg and sex pheromone production, and suggest most likely function is predator avoidance. However, neither has mechanical disturbance excited luminescence, nor has ultraviolet emission excited fluorescence, suggesting the secretion is non-luminescent. Alternative possible functions include secretion of defensive substances or substances that might enhance swarm formation. A survey of preserved copepod collections indicated presence of similar glands in Calanus helgolandicus, C. pacificus, Cosmocalanus darwinii, Mesocalanus tenuicornis, and Nannocalanus minor, suggesting evolution of the glands in the common ancestor of these species that comprise a monophyletic group within the Calanidae.

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Stage-V copepodites of Calanus sinicus and Calanus jashnovi (Copepoda: Calanoida) in mesopelagic zone of Sagami Bay as identified with genetic markers, with special reference to their vertical distribution

Cited by 19 publications

References 45 publications

Large-scale metabarcoding analysis of epipelagic and mesopelagic copepods in the Pacific

Large-scale metabarcoding analysis of epipelagic and mesopelagic copepods in the Pacific

Large-scale metabarcoding analysis of epipelagic and mesopelagic copepods in the Pacific

Structure of novel exocrine glands in Calanus species with notes on their possible function

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