Species Card of Copepod
Calanoida ( Order )
    Diaptomoidea ( Superfamily )
        Acartiidae ( Family )
            Acartia ( Genus )
                Odontacartia ( Sub-Genus )
Acartia (Odontacartia) pacifica  Steuer, 1915   (F,M)
Syn.: Acartia spinicauda : Mori, 1937 (1964) (p.103, figs.F);
no Acartia pacifica : Brodsky, 1948 (p.73, figs.); 1950 (1967) (p.422, figs.F,M); Shen & Lee, 1963 (p.582); Chen & Zhang, 1965 (p.112, figs.F,M); Wellershaus, 1969 (p.275, figs.F);
Acartia pacifica forma typica : Steuer, 1923 (p.29, Rem.); Greenwood, 1978 (p.15, figs.F,M);
No Acartia pacifica: Al-Yamani & I. Prusova, 2003, (p.91, Figs.F,M).
Steuer, 1915 a (p.397, figs.F,M); 1923 (p.28, figs.F,M); Sewell, 1932 (p.397); ? Farran, 1936 a (p.120, figs.F,M); Tanaka, 1965 (p.391, figs.F,M); Greenwood, 1978 (p.15, figs.F,M, Rem.); Yoo & Hue, 1983? (p.11, figs.F,M); Chihara & Murano, 1997 (p.672, Pl.21, 22: F,M); Bradford-Grieve, 1999 b (p.226, figs.F,M, Rem., figs.187, 195); Al-Yamani & Prusova, 2003 (p.92, figs.F,M); Mulyadi, 2004 (p.146, figs.F,M, Rem.); Ueda & Bucklin, 2006 (p.84, figs.F,M, Rem.); Phukham, 2008 (p.58, figs.F,M).
Species Acartia (Odontacartia) pacifica - Plate 1 of morphological figuresissued from : Ueda H. & Bucklin A.C. in Hydrobiologia, 2006, 500. [Fig.5].
Female: a, b, fifth pediger and urosome (dorsal, lateral view); csecond to sixrth of right antennule (dorsal view); d, fifth legs (posterior view using a cover slip).

Male: e, f, fifth pediger and urosome (dorsal, lateral view); g, second and third urosomites (ventral view); h, fifth leg (posterior view using a cover slip).
Scales = 0.1 mm.

Species Acartia (Odontacartia) pacifica - Plate 2 of morphological figuresissued from : O. Tanaka in Publs Seto Mar. Biol. Lab., 1965, XII (5). [p.392, Fig.247].
Female: a, habitus (dorsal); b, last thoracic segment and urosome (left lateral side); c, proximal portion of A1; d, P5.
Nota: The urosome segments and furca are in proportional lengths as 43:21:15:21 = 100

Male: e, last thoracic segment and urosome (dorsal); f, P5.

Species Acartia (Odontacartia) pacifica - Plate 3 of morphological figuresissued from : J.G. Greenwood in Proc. R. Soc. Qd, 1978, 89. [p.16, Fig.7, a, b, d, f, i, j]. As Acartia pacifica forma typica.
Female (from Moreton Bay, E Australia): a, A1 (segments15-19); b, posterior metasome and urosome (dorso-lateral); i, j, P5.
Male: d, posterior metasome and urosome (dorso-lateral); f, P5.

Remarks: males A. pacifica and A. mertoni with ventrolateral setae on 2nd urosomal segment; 3rd urosomal segment ofmale mertoni with 2 larger spines dorsolaterally on posterior margin, row of 6-8 spinules between. Male P5 slightly different proportions in the two species: in A. pacifica inner projection of right exopodal segment 2 is larger (length from outer border similar to that of segment) with ridge on posterior surface giving slightly bifid appearance; length of left exopodal segment 1 similar to exopodal segment 2 and less than basal segment, inner spine on exopodal segment 2 less than twice length of segment, in A. mertoni length of inner projection on right exopodal segment 2 less than that of segment, inner end rounded, distal end flattened; left exopodal segment 1 longer than exopodal segment 2 or basal segment, inner spine on exopodal segment 2 more than twice length of segment. Females in both species with base of terminal spine gibbose and margins of spine finely denticulate, but seta and spine of similar length in A. mertoni, seta twice length of spine in A. pacifica.

Species Acartia (Odontacartia) pacifica - Plate 4 of morphological figuresissued from : G.P. Farran in Great Barrier Reef Expedition 1928-29. Scientific Reports, V, No.3. Copepoda. 1936 [p.120, Fig.22]. With doubt.
Female: a, last thoracic segment and urosome (dorsal); b, A1 (15th-18th segments).
Nota: Acute lateral prolongations of the 5th thoracic segment. Long furcal rami. A pair of large spines on the posterior margin of the genital segment. Slender spines of the 15th, 16th and 8th segments of A1. The terminal spine of P5 has a small lobe at its base.

Male: c, last thoracic segment and urosome (dorsal).

Species Acartia (Odontacartia) pacifica - Plate 5 of morphological figuresissued from : A. Steuer in Arb. zool. Inst. Innsbruck, 1923, 1 (5). [p.29, Figs.134-137].
Female (from 32°N, 157°W): 134, last thoracic segment and urosome (dorsal); 136a, P5 (ventral); 136b, distal segment of P5 (lateral).

Male: 135, last thoracic segment and urosome (dorsal); 137, P5.

Species Acartia (Odontacartia) pacifica - Plate 6 of morphological figuresissued from : A. Steuer in Arb. zool. Inst. Innsbruck, 1923, 1 (5). [Taf. III, Figs.20, 21].
Female: genital segment (lateral); 21, idem (ventral).

Species Acartia (Odontacartia) pacifica - Plate 7 of morphological figuresissued from : A. Steuer in Zool. Anz., 1915, 45 (9). [p.397, Figs.5, 6].
Female: 5, P5.

male: 6, P5.

Species Acartia (Odontacartia) pacifica - Plate 8 of morphological figuresissued from : N. Phukham in Species diversity of calanoid copepods in Thai waters, Andaman Sea (Master of Science, Univ. Bangkok). 2008. [p.142, Fig.16].
Female (from W Malay Peninsula): a, habitus (dorsal); b, A1; c, posterior part of thorax and urosome (left side); d, urosome (dorsal); e, P5.

Male: f, habitus (dorsal); g, last thoracic segment and urosome (dorsal); h, P5.

Body length after the drawings: F: = 1.159 mm; M = 1.10 mm.

Species Acartia (Odontacartia) pacifica - Plate 9 of morphological figuresissued from : Mulyadi in Published by Res. Center Biol., Indonesia Inst. Sci. Bogor, 2004. [p.146, Fig.83].
Female (from Indonesian Seas): a, habitus (dorsal); b, posterior part of last thoracic segment with P5 and genital segment (lateral); c, P1; d, P4; e, P5; f, A1.

Male: g, habitus (dorsal); h, P5.

Nota Female: Posterolateral ebds of last thoracic segment produced into strong and long spiniform processes, reaching to middle of urosomal segment 1, with a pair of small spines pn dorsal surface (Steuer’s specimen has a pair of single spine instead 2).
Dorsal surface of urosomal segments 1 and 2 each with 2 spinules on their dorsal margins distally ; spinules on urosomal segment 2 larger than those of urosomal segment 1. Urosomal segment 1 with a tuft of hairs on ventral surface near periphery of genital opening.
Caudal ramus long.
A1 reaches to distal end of urosomal segment, 1st and 2nd segments without spines.

Nota Male: Urosomal segment 1 with rows of short hairs on lateral and posterior margins ; urosomal segment 2 long and large with 2 ventral small spines ; urosomal segment 3 and 4 each with a pair of spines dorsolaterally ; urosomal 4 shortest.
Caudal rami shorter than that of female.
Right A1 with segments 13 and 14 finely serrated on anterior margin.
Distal segment of left P5 with a long and straight spine.

Species Acartia (Odontacartia) pacifica - Plate 10 of morphological figuresIssued from : M. Chihara & M. Murano in An Illustrated Guide to Marine Plankton in Japan, 1997. [p.679, Pl. 21, fig.15 a-c].
Female: 15 a, habitus (dorsal); b, last thoracic segment and urosome (dorsal); c, P5.

Nota: 1, proximal segment of A1 without spine; 2, P5 with swollen base of spine. Compare with A. japonica, A. bispinosa, A. erythraea.

Species Acartia (Odontacartia) pacifica - Plate 11 of morphological figuresIssued from : M. Chihara & M. Murano in An Illustrated Guide to Marine Plankton in Japan, 1997. [p.680, Pl. 22, fig.15 a-d].
Male: 15a, habitus (dorsal); 15b, last thoracic segment and urosome (dorsal); 15c, same (lateral); d, P5.

Nota: numbers show characteristics of this species to compare with A. erythrea, A. bispinosa, A. japonica.

Compl. Ref.:
Sewell, 1948 (p.322); Yamazi, 1958 (p.153, Rem.); Hanaoka, 1977 (p.267, 301, abundance); Chen Q-c, 1980 (p.794); Greenwood, 1981 (p.K591, fig.1: co-occurrence); Hirota 1981 (p.19, Table 1, length-weight-CHN); Uye & al., 1984 (p.390, resting eggs-survival); Madhupratap & Haridas, 1986 (p.105, tab.2); Othman & al., 1990 (p.561, 564, Table 1); Yoo, 1991 (tab.1); Dai & al., 1991 (tab.1); Hattori, 1991 (tab.1, Appendix); Yoo & al., 1991 (p.259); Myung & al., 1994 (tab.1); Shih & Young, 1995 (p.66); Ohno & al., 1996 (p.231, fig.1); Park & Choi, 1997 (Appendix); Ramaiah & Nair, 1997 (tab.1); McKinnon & Klumpp, 1998 (tab.1); Mauchline, 1998 (tab.40); Hsieh & Chiu, 1998 (tab.2); Noda & al., 1998 (p.55, Table 3, occurrence); Nair & Ramaiah, 1998 (p.274); Achuthankutty & al., 1998 (p.1, Table 2, fig.5, seasonal abundance vs monsoon); Dolganova & al., 1999 (p.13, tab.1); Hsiao & al., 2004 (p.325, tab.1); Rezai & al., 2004 (p.486, tab.2, 3, abundance); Chang & Fang, 2004 (p.456, tab.1); Wang & Zuo, 2004 (p.1, Table 2, dominance, origin); Lan & al., 2004 (p.332, tab.1); Lo & al., 2004 (p.89, tab.1); Jiang X. & al., 2004 (p.89, resting eggs vs sediment depth); Choi & al., 2005 (p.710: Tab.III); Rezai & al., 2005 (p.157, Table 2: spatial & temporal variations); Zuo & al., 2006 (p.163: tab.1); Hwang & al., 2006 (p.943, tab.I); Dur & al., 2007 (p.197, Table IV); Madhu & al., 2007 (p.54, Table 4, abundance vs monsoon); Jitlang & al., 2008 (p.65, Table 1); McKinnon & al., 2008 (p.843: Table. I, p.848: Tab. IV); Ohtsuka & al., 2008 (p.115, Table 5); Moon & al., 2008 (p.61); Lan Y.C. & al., 2008 (p.61, Table 1, % vs stations); Lan & al., 2009 (p.1, Table 2, % vs hydrographiv conditions); Jiang Z.-B. & al., 2009 (p.196, Table 1, 2); Zhang G.-T. & al., 2010 (p.492, Table 1, 2); Cornils & al., 2010 (p.2076, Table 3); Zengling & al., 2010 (p.233, UV-radiation response); Sun & al., 2010 (p.1006, Table 2); Fazeli & al., 2010 (p.153, Table 1); Hsiao S.H. & al., 2011 (p.475, Appendix I); Guo & al., 2011 (p.597, Table 2, fig.9, indicator, abundance); Maiphae & Sa-ardrit, 2011 (p.641, Table 2); Sun X.-H. & al., 2011 (p.741, figs. 5, 3, 4, tab.I, II, production); Zhang D. & al., 2011 (p.86, pH effects); Hsiao & al., 2011 (p.232, Table 1: abundance, %, Table 2: trace metal concentration); Beltrao & al., 2011 (p.47, Table 1, density vs time); Hsiao & al., 2011 (p.317, Table 2, indicator of seasonal change); Johan & al., 2012 (2013) (p.1, Table 1); Mulyadi & Rumengan, 2012 (p.202, Rem.: p.204); Yoshida & al., 2012 (p.644, fig.1, 3, Table 1, egg development time and hatching vs temperature); Lee D.B. & al., 2012 (p.88, co-occurrence, abundance, feeding); Huo & al., 2012 (p.1, Table 1: dominance); Yoshida & al., 2012 (p.251, feeding, egg production, Table 2: other data); Lee J. & al., 2012 (p.95, Table 2: abundance, annual & seasonal distribution); Zhang H. & al., 2013 (p.57, Rem. p.58); Suzuki, K.W. & al., 2013 (p.15, Table 2, 3, 4, estuaries, annual occurrence); Seo & al., 2013 (p.448, Table 1, occurrence); Oh H-J. & al., 2013 (p.192, Table 1, occurrence); Trottet & al., 2017 (p. 7, Table 3: resting stage)
NZ: 7

Distribution map of Acartia (Odontacartia) pacifica by geographical zones
Species Acartia (Odontacartia) pacifica - Distribution map 2
Chart of 1996
Species Acartia (Odontacartia) pacifica - Distribution map 3issued from : C.T. Achuthankutty, N. Ramaiah & G. Padmavati in Pelagic biogeography ICoPB II. Proc. 2nd Intern. Conf. Final report of SCOR/IOC working group 93, 9-14 July 1995. Workshop Report No. 142, Unesco, 1998. [p.8, Fig.6].
Salinity ranges for A. pacifica in coastal and estuarine waters of Goa (India).
Shaded area indicates the range of higher abundance.
Species Acartia (Odontacartia) pacifica - Distribution map 4Issued from : T. Yoshida, C.-F. Liong, A.M. Majid, T. Toda & B.H.R. Othman in Zoological Studies, 2012, 51 (5). [p.651, Fig.3].
Geographical records of A. pacifica, A. spinicauda, A. erythraea occurrences throughout the East Asian region.
Species Acartia (Odontacartia) pacifica - Distribution map 5Issued from : S.E. Moon, S. Ohtsuka, H. Ueda & H.Y. Soh in Zootaxa, 2008, 1841. [p.63, Fig.2].
Temperature-salinity-abundance diagram for A. ohtsukai and A. pacifica.
Aundance (ind./m3) of each species is estimated by multiplying numbers on scale by 100 for A. ohtsukai (black circle) and A. pacifica (white circle).
See nota in A. ohtsukai for explanation of the segregation of these two sibling species.
Species Acartia (Odontacartia) pacifica - Distribution map 6Issued from : D. Zhang, S. Li, G. Wang & D. Guo in Acta Oceanol. Sin., 2011, 30 (6). [p.89, Fig. 1 d].
Influence of seawater acidification on survival rate in Acartia pacifica.
Average pH of each pCO2 seawater culture. Control (380) 8.16-8.17; (800) : 7.84-7.85; (2000): 7.39-7.37; (5000): 7.19-7.24; (10 000): 6.92-6.94.
Species Acartia (Odontacartia) pacifica - Distribution map 7Issued from : D. Zhang, S. Li, G. Wang & D. Guo in Acta Oceanol. Sin., 2011, 30 (6). [p.90, Fig. 2 d].
Influence of seawater acidification on egg producton rate in Acartia pacifica.
Average pH of each pCO2 seawater culture. Control (380) 8.16-8.17; (800) : 7.84-7.85; (2000): 7.39-7.37; (5000): 7.19-7.24; (10 000): 6.92-6.94.
Species Acartia (Odontacartia) pacifica - Distribution map 8Issued from : J.G. Greenwood in Estuar. Coast. Shelf Sci., 1981, 13. [p.593, Fig. 1, a, b).
Salinity-temperature-dominance relationships in occurrences of two congeneric species pairs: Acartia tranteri (a) and Acartia pacifica (b).
DS scale refers to grades of dominance (see methods).
This diagram is used to demonstrate differences in ecological requirments of the congenors.
Samples taken by sampling monthly over three years at several stations within the Moreton Bay estuarine system.
The existence of such closely related sympatric species is of great interest concerning interspecific competition and the notion of 'niche theory'. The principles of these topics are summarized by Whittaker (1975), Odum (1971). Possible ways in which zooplanctonic populations may avoid or reduce direct competition have been summatrized by Pejler (1962) as 1- spatial (e.g. by differing horizontal/or vertical distributions; 2- functional differences, e.g. by selective feeding preferences; 3- temporal differences by species populations reaching maxima at different times of the year; and other factors as predators or toxicity.
The two sympatric species coexist within the total range of salinity and temperature conditions sampled in Moreton Bay, they have differing optimal ranges, with one species (A. tranteri) being more eurytopic and in this sense a 'generalist', the other (A. pacifica) finding optimal conditions toward one end of the range of conditions and being more 'specialist', at least in terms of these environmental features. The two species are apparently in close competition during spring and autumn when temperatures are suboptimal for both, the result of this competition depending on wether temperatures are rising or falling. Superimposed on this influence is a difference in salinity optima, with the less euryhaline and more warm thermophilie. A. pacifica competing successfully within its optimal temperature range in the absence of reduced salinities. Populations of A. pacifica may be more variable on a year-to-year basis than those of A. tranteri, depending on the degree of summer (wet season) dilution and that during rising temperatures, replacement of A. tranteri by A. pacifica may occur progressively from outer Bay areas toward inner and estuarine-influenced areas with a dominant status in the community being attained in estuary-mouth regions during periods of low flow.
SE Korea (Geumo Is.), Japan Sea, Japan, Ariake Bay, Fukuyama Harbor, Inland Sea, Tanabe Bay, south estuaries, off Sanriku, Kuchinoerabus Is., W, S & E Korea , Chunsu Bay, Asan Bay, Gwangyang Bay, S Kuril Is., China Seas (Bohai Sea, Yellow Sea, East China Sea, South China Sea, Pearl River, Changjian River estuary, Xiamen Harbour, Jiaozhou Bay), Taiwan Strait, Taiwan (N, E, SW, Tapong Bay, Kaohsiung Harbor, N: Mienhua Canyon, NW), Hong-Kong, off N Hawaii, Australia (Great Barrier, Moreton Bay, Haughton Riv., North West Cape, G. of Carpentaria), India (Gulf of Oman, Bombay, Goa, Penang Is., Cochin, Kerala, Porto Novo), Bay of Bengal, W Malay Peninsula (Andaman Sea), Straits of Malacca, E Thailand, Singapore, Indonesia-Malaysia, Cilacap Bay (S Java), off Labuan, Jakarta Bay-Seribu Is., off Tegal, off Surabaya, Lombok Sea, Manado Bay (S Celebes Sea), Bintulu coast (Sarawak, NW Borneo), Viet-Nam (Cauda Bay).
N: 93
?(34) F: 1,34-1,32; M: 1,3-1,26; (119) F: 1,23; M: 1,23; (164) F: 1,196-1,15; M: 1,124; (290) F: 1,2-1,35; M: 1-1,2; (866) F: 1-1,3; M: 1-1,2; (1122) F: 1,06; M: 1,0; {F: 1,00-1,35; M: 1,00-1,30}
Rem.: Littoral, ± brackish. Epipelagic.
Existence of resting eggs in sediments (Jiang & al., 2004, p.89).
Acartia pacifica mertoni Steuer,1923 (F,M)
: Cf. Acartia mertoni.
Confounded before 2006 with Acartia othsukai. Some complementary references are uncertain, lacking figures and precise description.
Last update : 12/12/2017
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