River-Sea change of zooplankton species composition: a case of the Bay (Japan/East Sea) by Victoria V. Nadtochy, Yury I. Zuenko, & Eugene I. Barabanshchikov Pacific Fisheries Research Center (TINRO), , ; [email protected]

Ussuriysk

Artyom a n i h Vladivostok C ay B Big Stone r u Texas m A

Zarubino Peter the Great Bay The Goal of my study – is to describe quantitatively changes of zooplankton composition from river to sea; and to reveal and describe the zooplankton communities formed by river-sea interaction. Scheme of the stations in the Amur Bay in May- June of 2000 and 2003 Scheme of water structure in the estuary of Suyfun River; temperature and salinity at sea-river section, June 2000

Pre-Estuarine Outer Estuary Inner Estuary станции, дистанция 1 миля станции, дистанция 1 миля 0 zone

-1 River Plume of brackish water water -2 -3

-4 Cline of Pre-Estuarine water brackish

м -5

, water -6

глубина -7

-8 depth, meters -9 -10

-11

-12 o Temperature, C Salinity, psu

In the estuary of Suyfun River, two transition estuarian zones are formed with brackish water (S = 10…30 psu) that spreads as near-bottom cline in the inner estuary and as superficial plume in the outer estuary. Salinity at sea surface and at sea bottom in the Amur Bay in early June, 2003

Surface Bottom Surface<31 psu Bottom 31 32.5 33.5

32

33.0 Vladivostok

Surface City

33 20

>33.5 psu 50 Profiles of temperature and salinity averaged within zones of certain types of vertical water structure in the Amur Bay, May 27 – June 10, 2003

Temperature, deg. C Salinity, psu 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 30 31 32 33 34 0 0

5 5

10 10

15 15

20 20 depth, m 25 depth, m 25

30 30

35 35

40 40

plume pre-estuarine zone frontal zone coastal zone plume pre-estuarine zone frontal zone coastal zone

Within the Amur Bay, there is no significant difference of thermal conditions between the zones, but 3 zones are distinguished by salinity in surface layer: plume of brackish water; pre-estuarine zone; and coastal zone. Scattering diagrams of averaged temperature and salinity of water layers at the stations in the Suyfun River estuary and in the Amur Bay

34 Suyfun River estuary, June 20-22, 2000 nothern Amur Bay, May 27-30, 2003 34 33 32 31 30 29 28 33 27 26 25 24 23 22 21 20 32 19 18 17 16

15 s a linity, ps u

s a linity, ps14 u 13 12 31 11 10 9 8 7 6 5 4 3 30 2 0 2 4 6 8 10 12 14 16 18 20 22 24 1 0 temperature, deg. C 0 2 4 6 8 10 12 14 16 18 20 22 24 34 temperature, deg. C southern Amur Bay, June 7-10, 2003

Subarctic Subsurface Water 33

Coastal Surface Water 32 salinity, psu salinity,

Pre-Estuarine Water 31

Estuarine Water (plume & cline) 30 0 2 4 6 8 10 12 14 16 18 20 22 24 River Water temperature, deg. C Scheme of summer water structure in the area of river-sea interaction

Coastal Pre-Estuarine Outer Inner River zone front zone Estuary Estuary

Plume River water

P r e – E s t u a r i n e Coastal Surface w a t e r Cline Water seasonal pycnocline

The interaction occurs in surface layer only with thickness 5-20 m; Subarctic Subsurface Water Two specific water modifications are formed between proper river water (fresh) and proper marine water of coastal zone (salt): i) brackish water of near-bottom cline in inner estuary and superficial plume in outer estuary, ii) pre-estuarine water with relatively low salinity; By differentiation of surface water masses, the area of river-sea interaction could be divided onto 5 zones Zones with different types of vertical water structure in June, 2000, 2003. Stations of the survey in late May – early June, 2003 are shown.

Zones: river

inner estuary

outer estuary

pre-estuarine II

frontal

coastal Mass species of zooplankton in the Amur Bay in early summer

Acartia Pseudocalanus Oithona Schmackeria Sinocalanus hudsonica newmani similis inopina tenellus Total zooplankton abundance

1000 to 10000 Numbers, specimens / m3 Biomass, mg / m3 10 to 100

10001 to 20000 101 to 250

20001 to 30000 251 to 500

30001 to 35000 501 to 1000

35001 to 70000 1001 to 3000 Distribution of Pseudocalanus newmani and Oithona similis, specimens / m3

0 to 1500

1501 to 3000

3001 to 10000

10001 to 20000

20001 to 35000 Distribution of Acartia hudsonica, specimens / m3

0 to 90

91 to 1000

1001 to 2500

2501 to 7500

7501 to 37000 Relative abundance of mass species of zooplankton

• La rva biva lvia S. inopina S. tenellus A.hudsonica P.newmani O.similis Bray-Curtis coefficient of similarity

P Σi =1 2min (yij,yik) Sjk = 100 % , P Σi =1 (yij+yik) where Sjk – Bray-Curtis coefficient of similarity between samples j and k; P – number of common species in samples j and k; yij, yik – share of the species i in samples j and k; min(yij,yik) – minimum from the pare yij and yik.

Clarke K.R., Warwick R.M. Statistical analysis and interpretation of marinе community data // IOC Training Course Report.- Oslo, 1986.- N.19.- Annex.3.- 116 p. Dendrogram of zooplankton composition similarity between station located in the certain hydrological zones

% 100 90 80 70 60 50 40 30 20 10 0

River 58 57 56 Inner estuary 55 54 53 Pre-estuarine 5 1 19 9 11 Outer estuary 12 7 6 4 3 2 52 Pre-estuarine 14 34 20 16 17 10 8 51 46 33 23 21 Coastal 30 18 25 27 50 30 41 43 31 40 44 45 42 32 38 37 35 39 28 29 22 15 Arrangement of zooplankton clusters, a according to Bray-Curtis similarity

Zones: river

inner estuary

outer estuary

pre-estuarine

pre-estuarine

coastal Percent ratio of mass species of zooplankton in the clusters corresponded to the zones with different salinity

N.cirripe dia 100% Larva polychaeta 90% Larva gastropoda 80% La rva biva lvia

70% Fritilla ria s p. S a gitta s p. 60% O.similis 50% P.newmani 40% A.hudsonica

30% Conochiloides sp. As pla nchna s p. 20% Cyclops sp. 10% S. tenellus 0% S. inopina RiverРека ВнутреннийInner OuterВнешний ПриэстуарнаяPre-estuarine зона zone ПрибреCoastal жны е Estuaryэстуарий Estuaryэстуарий zoneводы Change of the dominant zooplankton species at a river-sea section Change of salinity in the surface layer is shown by thick green curve

100 S < 3 psu 10-30 25-31 31-33 psu 32-34 psu 35 90 30 80 70 25 salinity, psu 60 20 50 15 40 30 %total of numbers 10 P.newmani 20 O.similis 5 10 A.hudsonica 0 0 S.inopina -6 -5 -3 0 1 4 7 9 12 14 16 20 23 27 S.tenellus distance from river mouth, n.miles

River Inner Outer Pre-Estuarine Coastal Estuary Estuary zone zone River-Sea change of zooplankton species composition: a case of the Amur Bay (Japan/East Sea)

P.newmani A.hudsonica S.inopina O.similis S.tenellus

Coastal Pre-Estuarine Outer Inner River zone zone Estuary Estuary

CONCLUSION By the way from river to sea, species composition of zooplankon

change completely in the succession: RIVER-ESTUARINE- COASTAL that corresponds to water regime change from the proper river zone to the zone with permanent or episodic events of brackish water and farther to the zone never influenced by brackish water. In

early summer, one or two dominant species are typical for each type

of regime (Schmackeria inopina and Sinocalanus tenellus – for river community, Acartia hudsonica – for estuarine community, Pseudocalanus newmani and Oithona similis – for coastal community), but within the communities the species ratio changed according to real-time water properties.