Oceanographic Factors Influencing Squid Larval Distribution in the Southwest Atlantic

Home , Abralia redfieldi, Brachioteuthidae, Brachioteuthis riisei

Not to be cited without prior reference to the author

ICES CM 2001/K:12 The Response of Cephalopod Populations and Fisheries to Changing Environment and Ecosystems

OCEANOGRAPHIC FACTORS INFLUENCING SQUID LARVAL DISTRIBUTION IN THE SOUTHWEST ATLANTIC

Golub A.N.

Atlantic Research Institute of Fisheries and Oceanography (AtlantNIRO), 5 Dm.Donskoy st., Kaliningrad, 236000, Russia [Tel.: (0112)225885; Fax: (0112)219997); E-mail: [email protected]]

ABSTRACT

Data of the six research cruises in the Southwest Atlantic (35°-54°S, from exclusive economic zones to 35°W) have been used to describe squid larval distribution in respect to major oceanographic factors. A total of 427 hauls of the different plankton samplers, mostly by paired Big Bongo nets, were carried out in the upper 100-m layer. A total of 222 squid larvae belonging to 16 species were found in 611 samples studied. Meso-and bathypelagic squids (12 species) represented 91% of the sampled larvae, eurybathic squids (3 species, 7% of larvae), and deep water Batyteuthis scolops (2% of larvae) were of a minor importance. Three oceanographic regions with different larval complexes were revealed: 1. North of the Southern Subtropical Convergence (SSC), in the Brazil Current waters the squid larval population was represented by tropical and subtropical species: Ommastrephes bartrami, Lycoteuthis diadema, Abralia redfieldi, Onychoteuthis banksi, Onykia carribboea, Ancystroteuthis lichtenshteini, Liocranchia reinchardti, Teuthowenia richardsoni. 2. In the SSC zone (generally between 41° and 45°) the bulk of larvae was represented by the south-subtropical, notal, and eurythermic wide-tropical species. 3. South of the SSC some notal- and subantarctic species occurred, though both south- subtropical and notal Gonatus antarcticus and Brachioteuthis riisei were still dominating (more than 60% of the larvae sampled in the open waters of the Argentina Basin).

INTRODUCTION

Data on early stages’ ecology are the key factor to understand functional structure of the species ranges, distribution and fluctuations of abundance in cephalopod molluscs with pelagic larval stage (Okutani, Watanabe1983). A presence of this pelagic stage and respective interaction with oceanographic situation variability assume a dependence of onthogenesis patterns as well as stock size on water mass structure and distribution. There are very few data on cephalopod larvae distribution in the Southwest Atlantic high seas (Argentina Basin) (Nesis, 1974; Rodhouse, et.al.,1992; Nesis, 1999).

This paper is aimed to summarise results of the Soviet investigations in 1974-1990 carried out onboard of the different research vessels.

MATERIAL AND METHODS

Data of six expeditions in the Southwest Atlantic (35-54ûS, from the Argentina EEZ border to 35ûW) have been used to describe cephalopod early stages’ distribution over the Argentine Basin and in adjacent regions (Fig.1).

1. RV Foton, October-December 1974 ( F-74), horizontal hauls ( HL) with IKS-80 net used, 13 stations (S) , 35 samples ( SS) , 1 cephalopod paralarvae (CL).

2. RV Stvor, November 1975-April 1976 (S-75), HL by IKS-80, 34 S , 35 SS , 17 CL.

3. RV Kvant, January - April 1977 (K-77), HL by Bogorov net , 38 S, 97 SS, 11 CL.

4. RV 1500 let Kievu, March-April 1985, (K-85), oblique hauls (OH) by Bongo-61 net (B61), 88 S , 88 SS, 12 CL.

5. RV Evrika, August-October 1988 (E-88), stepped hauls (SH) B61,117 S , 164 SS , 36 CL.

6. RV Evrika, November 1989- February 1990, (E-89), SH B61, 137 S, 172 S, 145 CL.

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Argentina

-39.00

-44.00

South Atlantic Ocean

-49.00

-54.00

-65.00 -60.00 -55.00 -50.00 -45.00 -40.00 -35.00

Fig.1 Occurrence of larvae of the different squid

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Lycoteuthis diadema Illex argentinus

Abralia redfildti Ommastrephes bartrami

Abraliopsis sp. Batoteuthis scolops

Onichoteuthis banksi Chiroteuthis sp.

Onykia carriboae Liocranchia richardsoni

Gonatus antarcticus Teuthowenia reihardti

Histioteuthis sp. Cranchidae sp.

Brachioteuthis riisei

Generally hauls were carried out in the upper 100-m layer (mostly between 0 and 50 m). Investigations took place almost round the year, excluding the stormy very winter (June-July). A total of 427 stations were done, 611 samples collected, and 222 cephalopod paralarvae and early juveniles were found at sample processing. All the paralarvae were identified to the lowest possible taxonomic level, mostly to the species, their dorsal mantle length (ML) being measured within 0.1 mm. For each haul the water mass and its parameters (temperature, salinity) are given when possible. The following abbreviations were assigned: SSW – Subtropical Surface Water, SASW – Subantarctic Surface Water,

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ASW – Antarctic Surface Water, TSSW – transformed SSW, TSASW – transformed SASW, TASW – transformed ASW, SW – shelf waters, ST/SA – transformed waters appeared as a mixture of SSW and SASW.

RESULTS

Lycoteuthidae

Lycoteuthis diadema ( Chun,1900)

E-89,13.11.89, 42° 02' S 52° 57' W, N=7, ML= 3.2, 3.5, 5.5, 6.1, 6.1, 6.2, 6.5 mm; 2 nd sample N= 4, ML= 2.2, 4.0, 4.2, 4.2 mm.

Enoploteuthidae . Abralia redfieldi Voss , 1955 S-75, 23.12.75, 40°00' S 44°50'W, N=1, ML=3.6 mm; 25.12.75 г., 37°50'S 45°45' W, N=1, ML=4.0 mm; 29.12.75, 40°00' S 53° 20' W, N=1, ML=2.5mm; 2.01.76, 44°00' S 49°00'W, N=1, ML= 4.6 mm; 2.02.76 г., 44° 00'S, 54°00'W, N=5, ML= 3.2, 3.6, 3.6, 3.7,4.0 mm K-77,11.03.77г., 42°00' S 50°43' W, N=1, ML=3.6 mm.

Abraliopsis sp.

E-88, 4.08.89, 37°30' S 49°44' W, N=1, ML= 2.4 mm, SSW, Т=15.9°, S= 35,63‰.

Onychoteuthidae.

Onychoteuthis banksi (Leach,1817)

S-75, 31.12.75, 42°00' S 53°20'W, N= 1, ML= 6.5 mm;16.01.76, 44°20' S 58°00'W, N=1, ML=4.2 mm; 26.01.76, 40°00'S 39°00'W, N=1, ML=3.6 mm;2 8.01.76, 43°00'S 53°00'W, N=2, ML=2.6,3.2 mm. K-77, 7.03.77, 36°51'S 49°04'W, N=2, ML=2.0,2.4 mm. K-85, 6.04.85, 46°59' S 58°28'W, N=1, ML= 12 mm. E-88, 2.08.88, 36°30' S 49°10'W, N=1, ML= 2.6 мм., SSW, T=17.3°, S=35.96‰.

Onykia carriboea Le Sueur, 1821

E-89, 19.01.90, 47°30' S, 59°35' W; N=1, ML= 6,7 mm, SSW; 27.01.90 г., 46°22' S 51°03'W; N=1, ML= 7.8 mm, SSW; 4.02.90, 41°58' S,54°00' W; N=2 ML=6.7, 6.7 mm, TSSW.

Ancistroteuthis lichtensteini ( Ferussas et d’Orbigny,1839)

E-88, 4.08.88, 37°30' S 49°44W, N=1, ML=4.3mm, SSW, Т=14.7-15.6°, S=35.52‰.

Сем. Gonatidae. Gonatus antarcticus Lonnberg, 1898

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S-75, 2.01.76, 44°00'S 49°00'W, N=1, ML=4,7 mm. K-85, 2.04.85, 44°57'S 58°58'W, N=1, ML=3,2 mm. E-88, 3.09.88, 47°30'S 58°04'W, N=2, ML=5.3,6.7 mm, TASW, Т=4.2-4.3°, S=34.07‰; 4.09.88, 47°30'S 54°33'W, N=1, ML=8.3 mm, SASW, Т=5.8-5.9°, S=34.24‰; 8.09.88, 45°00'S 57°39'W, N=4, ML= 4.1, 5.0, 5.1, 7,6 mm, TASW, Т=4.8°; 9.09.88г., 45°00'S 56°38'W, N=1 ML=5.5 mm, ST/SA, Т=9.0°, S=34.58 - 34.60‰; 10.09.88, 45°03'S 54°37'W, N=1, ML=5.0 mm, ST/SA, Т=11.6-11.7°, S= 34.95-35.02‰; 6.10.88, 42°52'S 53°03'W, N=3, ML=5.2, 9,6, 11,2 mm, ST/SA, Т=10,0-10.1°, S= 34.81-34.82‰; 8.10.88, 46°09'S 50°01'W, 1 экз. ML=8.2 mm, ST/SA, Т=11.0°, S=35,00‰; 11.10.88, 46°09'S 45°00'W, N=1, ML=6.0 mm, SASW, Т=7.6-7.7°, S= 34.45- 34.40‰; 12.10.88, 45°01'S 44°39'W, N=1, ML=5.4мм, SASW, Т=7.8 - 7. 9°, S= 34.41‰; 12.10.88, 43°13'S 45°02'W, N=3, ML=7.0, 9.2, 15.2 mm, SASW, Т=7.9 – 8.0°, S= 34.43‰; E-89, 8.11.89, 41°11' S 53°56' W; N=2, ML=6.8, 11.5 mm, SASW; 8.11.89, 40°59' S 54°58' W; N=1, ML=5.6 mm, SASW; 9.11.89, 42°03' S 55°23' W; N=1, ML= 11.6 mm, SASW; 9.11.89, 41°59' S 57°19' W; N=11, ML=8.9, 9.3, 9.4, 9.5, 10 2, 11.1, 12.0, 12.0, 13.0, 13.1, 13,3 mm, SASW; 10.11.89, 41°55' S 56°31' W; N=1, ML=12.8мм, SASW; 14.11.89, 43°30' S 54°04' W; N=3, ML=1.3, 1.4, 1.6 mm, SASW; 15.11.89, 43°32' S 54°44' W; N=3, ML=11.1,11.2, 13.,1 mm, SASW; 17.11.89, 43°33' S 58°50' W; N=3, ML=14.8, 15.7,16.2 mm; 2nd haul N=6, ML=10.1, 12.7,12.7, 13.1, 14.5, 16.2 mm, SASW; 18.11.89, 44°59' S 59°18' W; N=1, ML=14.5 mm, SASW; 20.11.89, 46°00' S 53°47' W; N=1, ML= 8.5 mm, SASW; 21.11.89, 46°00' S 53°19' W; N=1, ML=10.5 mm, SASW; 21.11.89, 46°01' S 54°02' W; N=2, ML=9.0, 10.2 mm, SASW; 23.11.89, 46°00' S 57°27' W; N=1, ML=13.4 mm, SASW; 24.11.89, 47°29' S 59°37' W; N=1, ML=16.2 mm, SASW; 26.11.89, 47°25' S 58°14' W; N=1, ML=14.2 mm, SASW; 28.11.89, 41°57' S 57°29' W; N=1, ML=15.6 mm, SASW; 9.12.89, 41°59' S 52°00' W; N=1, ML=15.6 mm, SASW; 15.12.89, 47°26' S 48°04' W; N=14, ML=4.2, 4.2, 4.8, 5.0,5.0, 5.2, 5.8, 6.0, 6.0, 6.3, 6.5, 6.7, 7.0, 7.1 mm, SASW; 3.10.90, 46°19' S 35°59' W; N=1, ML=6.5 mm; N=2, ML=5.6, 7.0 mm, SASW; 8.01.90, 48°19' S 55°15' W; N=1, ML=8.1mm, SW; 26.01.90, 46°57' S 51°01' W; N=1, ML=16,2 mm, SASW; 31.01.90, 43°27' S 58°59' W; N=1, ML=7,8 mm, SASW;

Histioteuthidae. Histioteuthis sp.

K-85, 15.03.85, 46°29' S 59°30'W, N=1, ML=19.5 mm; 16.03.85, 47°59' S 60°01'W, N=1, ML=5.1 mm; E-88, 14.10.88, 41°35'S 43°20'W, N=1, ML=2.3 mm, SASW, Т=8.2-8.9°, S=34.45 - 34.51‰; E-89, 7.11.89, 40°59' S 53°00' W; N=1, ML=3.2 mm, TSSW; 10.11.89г., 41°59' S 56°31' W; N=1, ML=8.8 mm, SASW;N=1, ML=5.5 mm, SASW; 12.11.89, 42°00' S 55°58' W; N=1, ML=3.2 mm, SASW; 15.11.89, 43°32' S 54°44' W; N=2, ML=10.4, 8.8 mm, SASW; 17.11.89, 43°33' S 58°50' W; N=1, ML=5.0 mm, SASW; 27.12.89, 43°42' S 44°00' W; N=2, ML=5.0, 6.5 mm, SASW; 28.12.89 , 48°25' S 39°57' W; N=1, ML=9.5 mm, SASW; 8.12.90, 48°19' S 55°15' W; N=1, ML=4.8 mm, SASW.

Сем. Brachioteuthidae. Brachioteuthis “riisei”

F-74, 9.11.74, 40°00'S 51°10'W, Т=13.2°, N=3,5 mm. S-75, 25.12.75, 37°50'S 45°45'W, N=1, ML=9.0 mm.

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K-77, 17.02.77, 43°30' S 59°00' W, N=1, ML=5.6 mm; 2.03.77, 38°09' S 50°37' W, N=1, ML=3.2 mm; K-85, 21.03.85, 46°01' S 57°56'W, N=1, ML=15.1 mm; 2.04.85, 44°59' S 58°01'W, N=1, ML=9.0; 6.04.85 г., 46°30' S 59°30'W, N=2, ML=11.0, 15.0 mm; 8.04.85, 46°59' S 59°59'W, N=1, ML=12.2 mm; 23.04.85, 45°57' S 60°07'W, N=1, ML=28.0 mm; E-88, 3.09.88, 47°30'S 56°00'W, N=1, ML=24.0 mm, SASW, Т= 5.3°, S=34.12 ‰; E-89, 12.11.89, 41°59' S, 53°37' W; 1 экз. - 27.0 mm, SASW; 13.11.89, 42°02' S 52°57' W; N=1, ML= 8.5 mm, SASW; 8.01.90, 48°19' S 55°15' W; N=4, ML=10.1, 12.0, 16.6, 20.5 mm, SASW; 20.01.90, 47°30' S 58°59' W; N=1, ML=18.3 mm, SASW; 20.01.90, 47°52' S 56°27' W; N=15, ML=11.0, 11.0,13.5, 14.5, 15.0, 16.0, 16.2, 16.4, 16.9, 17.4, 18.0, 18.1, 18.8, 19.0, 19.0 mm, SASW; 21.01.90, 48°09' S 56°13' W; N=3, ML=5.8, 12.9, 17.0 mm, SASW; 22.01.90, 49°03' S 53°56' W; N=1, ML=14.6 mm, SASW; 23.01.90, 53°06' S 52°56' W; N=4, ML=8.0, 11.0, 12.9, 19.6 mm, SASW; 24.01.90, 53°11' S 52°30' W; N=9, ML=6.0, 6.2, 7.8, 8.3, 13.7, 14.0, 14.2, 16.7 mm, SASW; 24.01.90, 52°04' S 51°03' W; N=4, ML=7.2, 8.7, 12.6, 14.5 mm, SASW; 2nd haul N=1, ML=9.8 мм, SASW; 25.01.90, 51°30' S 51°30' W; N=2, ML=7.2, 9.1 mm, SASW; 26.01.90, 49°04' S 50°51' W; N=5, ML=8.2, 9.6, 12.5, 14.5, 21.2 mm, SASW; 28.01.90, 46°00' S 54°15' W; N=1, ML=14.0 mm, SASW; 31.01.90, 44°58' S 59°04' W; N=1, ML=19.2 mm, SASW; 2nd haul, N=1, ML=19.7 mm, SASW; 31.01.90, 43°28' S 58°59' W; N=1, ML=7.5 mm, SASW; 2.02.90, 42°00' S 57°01' W; N=1, ML=9.3 mm, SASW; 4.02.90, 44°02' S 53°51' W; N=1, ML=7.5 mm, SASW; 7.02.90, 43°59' S 58°24' W; N=1, ML=9.4 mm, SASW;

Ommastrephidae.

Illex argentinus (Castellanus, 1960)

E-88, 2.08.88, 36°30'S 49°00'W, N=1, ML=4.4 mm, SSW, Т=17.3 - 17.4°, S=35.96 - 35.98 ‰; 4.08.88, 37°30'S 47°44' W, N=4, ML=4.0, 4.0, 4.2, 4.7 mm, SSW, Т= 15.9°, S=35.63 - 35.68‰;

Ommastrephеs bartrami ( LeSueur,1821)

K-77 , 10.02.77, 38°10'S - 39°08'W, N=1, ML= 4 mm. E-88, 2.08.88, 36°30'S 49°00'W, N=1, ML=2.5 mm, SSW, Т=17.3 - 17.4°, S=35.96 - 35.98 ‰; 30.08.88, 41°11'S - 52°58' W, N=1, ML=19.6 mm, SSW, Т= 15.3 - 15.5°, S=34.42 - 35.51‰;

Batoteuthidae.

Batoteuthidae skolops Yung et Roper, 1968

E-88, 23.08.88, 42°02'S - 49°36'W, N=1, ML=20 mm, ST/SA, Т=9.6-9.8°, S=34.57-34.60‰; 5.09.88, 45°59'S 57°02'W, N=1, ML=12 mm, SASW, Т=6.4-6.5°, S=34.14‰; E-89, 17.11.89, 43°34' S, 58°50' W; N=34 mm, SASW; 25.12.89, 49°43'S - 44°02'W, N=1, ML=48 mm, TASW.

Сем. Chiroteuthidae.

Chiroteuthis sp.

K-77, 21.03.77, 39°40'S 53°20'W, N=4, ML=2.6, 2.4, 2.3, 2.3 mm.

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Сем. Cranchiidae .

Liocranchia reihardti ( Steenstrup, 1856)

K-77, 23.03.77, 40°30'S 50°00'W, N=1, ML=11.5 мм.

Teuthowenia richardsoni (Dell,1955)

E-88, 17.08.88, 40°29'S 51°43'W, N=2, ML= 5.9, 9.7 mm, SSW, Т= 14.3-14.4°, S=35.49‰; 40°32'S 52°39'W, N=1, ML=4.5 mm, SSW, Т= 14.6°, S=35.58‰; 15.10.88, 42°11'S 42°43'W, N=1, ML=8.0 mm, SSW, Т= 11.5-11.6°, S=35.02 - 35.03‰;

Cranchiidae gen. sp.

S-75, 29.12.76 , 40°00'S - 53°00'W, N=1, ML=2.5 mm. K-85, 24.04.85, 46°30' S 60°10'W, N=1, 8.9 mm;

DISCUSSION

Most of the squid early stages belonged to deep-sea meso- and batypelagic species that represented 92% of the sampled animals and predominated by species number: A. redfeldti, Abraliopsis sp., A. lichtensteini, G. antarcticus, B. “riisei”, Histioteuthis sp., Chiroteuthis sp., L. reihardti, T. richardsoni, Cranchiidae sp. Paralarvae of the shelf-slope squid Illex argentinus represent the mid-water spawning complex. Surface squid species larvae were rare (6%), and were represented by eurybathic O. bartrami, O.banksi, and epipelagic O. carriboa. Deep-sea squids were represented by B.scolops (2%). Early stages of tropical and subtropical squids inhabiting the Brazil Current waters predominated in the north of the Argentina Basin (O.bartrami, L.diadema, A.redfeldti, O.banksi, O.carriboea, A.lichtensteini, L.reichardti, T. Richardsoni). Generally, the southern limit of their distribution coincides with the Subtropical Convergence, though some of them could be transported by TSSW southward as far as to 47ûS. Among notal (south temperate) species, the B.”riisei” paralarvae only penetrate beyond the Subtropical Convergence in TASW. The Subtropical Convergence was very well expressed because of diverse tropical, south subtropical and notal squid species inhabiting its complicate oceanographic structures. The most abundant squid fauna was found whereabouts of a cyclonic gyre produced by an interaction of the quasi-stationary meander of the Brazil Current. Subtropical species predominated in its northern part, whereas notal species were more abundant in the south and southwest part.

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South of the Subtropical Convergence the squid fauna was represented mostly by notal B.scolops, G.antarcticus, and B.”riisei”. Paralarvae of the latter two species predominated in both SASW and TASW (more than 65% of sampled paralarvae). These species probably spawn in the central, deep-sea part of the basin that is testified of the maximum larvae abundance in the zone of divergence, where paralarvae were carried by an upwelling up to the surface transformed productive waters. The Falkland Current waters carry early stages of meso-, and bathypelagic squids into productive waters of oceanic fronts. The maximum number of notal species paralarvae were found in the frontal zone between the Falkland Current on one hand, and shelf and slope waters in west and SSW in the north on the other hand. Juveniles at growth went down in the sinking regions of zones of convergences to the lower epipelagial and mesopelagial. Hatching of B.scolops and G.antarcticus is seasonal with a summer peak of paralarvae abundance.

CONCLUSION

The three zones of cephalopod early stages occurrence were revealed in the Argentina Basin. 1. South subtropical zone. It is inhabited by early stages of the tropical and subtropical squids. Its southern border is situated at about 41ûS. 2. Transient zone or zone of the Subtropical Convergence. South subtropical - notal, and most eurytherm both south-subtropical and notal species reproduce there. 3. Notal zone is populated by notal and subantarctic species. In its northern part a few numbers of south subtropical-notal species paralarvae occur, and occasionally tropical species could be found. Paralarvae and early juveniles of the Subtropical Species, such as O.banksi were found east of the Argentina EEZ down to 47ûS. No shelf and slope cephalopod paralarvae were found in pelagic hauls, but a few I.argentinus in the northern outskirts of the Basin. It means that the Falkland Current is a insurmountable barrier for Argentinean shelf- and slope cephalopods to cross. Only in the northern part of the region such kind of early stages could be carried offshore into high seas.

Acknowledgements

The author sincerely thanks Ch.M. Nigmatullin for organization of sampling, formulation of the objective of this paper and discussion of results; A.V.Parfenyuk for consultations on water mass properties at the stations of RV Evrica’s cruises; T.S.Dubinina for processing of early samples collected in 1970-ies, and V.V.Laptikhovsky for a comprehensive help of the paper preparation.

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REFERENCES

Nesis K.N. 1974. Oceanic cephalopod molluscs of the Southwest Atlantic. Trydy IOAN AN SSSR, 98: 51-75 (In Russian).

Nesis K.N. 1999. Cephalopods. In: South Atlantic zooplankton, vol. 2. (Ed: Boltovskoy, D) Leiden, Netherlands: Backhuys Publishers

Okutani T., Watanabe T. 1983. A preliminary approach to stock assessment of the winter population of Todarodes pacificus Steenstrup (Cephalopoda: Ommastrephidae) by larval surveys with a review of early works. Biol. Oceanography, 2 (2-4): 401-431.

Rodhouse P.G., Symon C., Hatfield E.M.C. 1992. Early life cycle of cephalopods in relation to the major oceanographic features of the southwest Atlantic Ocean. Mar.Ecol.Prog.Ser., 89: 183-195.