A. PRUSHKOVSKAYA

Il’ichev Pacific Oceanological Institute, FEB RAS, Vladivostok, RUSSIA E-mail: prushkovskaya@poi.dvo.ru

The Amurskiy Bay is an interior bay of the large Peter the Great Bay. Numerous streams and rivers enter to the Amurskiy Bay. The Primorye’s largest river Razdolnaya rather greatly freshens (to 22–27 ‰) sea water in the innermost part of the bay (Rostov et al., 2007). The total annual river runoff is up to 2.5 km³ (Podorvanova et al., 1989). The salinity in the bay, in general, not exceeding 32.5 ‰.

Samples of surface sediments (0–1 cm) were collected in Amurskiy Bay in 2010 during a cruise of the small ship Impulse. Bottom-sediment samples were taken with an Okean grader- type bottom grab. The thirteen samples collected along a north-south transect from depths of 7.8 to 23.7 m were examined. Diatoms from bottom sediments were isolated using a heavy potassium-cadmium liquid (Zhuze, 1962). The studied diatom flora is represented by 221 species and intraspecific taxa belonging to 83 genera. The bulk of the diatom flora was constituted by marine (72.4 %) and brackish (14.5 %) species, which also dominated in abundance. Freshwater diatoms, which were usually encountered in single numbers, contributed a noticeable proportion (11.3 %). A minor part of the flora (1.8 %) consisted of freshwater species that became extinct in the Neogene: Aulacoseira praegranulata var.

praeislandica and A. praegranulata var. praeislandica f. curvata. In terms of the number of species, benthic species (121 species or 63 %) predominated among marine and brackish- water diatoms; among planktonic species, there were 55 neritic (28.6 %) and 16 oceanic species (8.3 %). Neritic species (66.4 %) dominated in abundance, benthic species (31.2 %) were subdominant, oceanic species were found in low numbers (2.4 %). The number of species and intraspecific taxa in the studied samples varied from 60 (stn. 39) to 116 (stn. 12).

Most stations were characterized by a high abundance of the benthic estuarine species Diploneis smithii (7–21 %). Among benthic species, the following were found consistently but in single numbers: Amphora proteus, Arachnoidiscus ehrenbergii, Auliscus sculptus, Campylodiscus angularis, Cocconeis scutellum, Diploneis subcincta, Grammatophora oceanica, Hyalodiscus scoticus, Lyrella lyra, Navicula directa, Pinnularia quadratarea, Surirella fastuosa, Trachyneis aspera. The ecological structure of diatom assemblages from surface sediments in the Amurskiy Bay on the north-south transect was fairly uniform: neritic species were dominant (50.5–75.9 %), benthic species were subdominant (20–37.5 %). The share of oceanic species was 0–5.7 %. Freshwater species were recorded in single numbers (0.9–2.8 %) at almost all stations, except station 39, where they represented up to 7.5 %. This station was located at about 7 km away from the mouth of the Razdolnaya River, thus accounting for the increased content of freshwater diatoms in the sediments. Here, we found a noticeable quantity of extinct species of freshwater diatoms (5 %), which could apparently be introduced via river runoff from an adjacent land. Thus, this ecological structure of diatom assemblages is characteristic of a narrow shallow marine bay with a river mouth zone.

This study was partially supported by RFBR (project № 15-05-06845) and the program "Far East" (project

№ 15-I-1-005o).

Key words: ecological structure, diatoms, surface sediments, Amurskiy Bay, Sea of Japan

(O41) THE URBAN STREAM RESTORATION: HOW THE MACROPHYTE COULD PROMOTE THE RECOVERY OF BIODIVERSITY

OF AQUATIC ORGANISMS

X. QU^{1, 2}*, Ya. YU², M. ZHANG², W. PENG^{1, 2}

1State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin, China Institute of Water Resources and Hydropower Research, Beijing, People’s Republic of CHINA

2Department of Water Environment, China Institute of Water Resources and Hydropower Research, Beijing, People’s Republic of CHINA

*E-mail: quxiaodong@iwhr.com

The reclaimed water provided important water resources for the urban streams. The water quality severely degraded in the urban ditches because of the multiple high level nutrients and toxic pollutants. It is important to recover the water quality and re-built the healthy aquatic ecosystems based on the stream ecological theories. By field monitoring and controlled re-plantation in the urban streams, the succession of constructed aquatic community of macroinvertebrates was continually monitored. The efficiency and mechanisms of water quality recovery would be compared under different substrate composition, different contamination condition and type of macrophytes in the urban channelized streams. The main results showed that high levels of nutrient enrichment existed in the reclaimed water. Under this condition, the recovery of macroinvertebrate restoration was limited in comparing with natural streams. The communities of macroinvertebrates characterized with loss of sensitive taxa, limited abundance of moderate tolerant taxa, high relative abundance of gather-collectors and burrowers, and the low level of biodiversity. The positive correlation between the taxa richness of macrophytes and macroinvertebrates, and macrophyte cover and taxa richness of macroinvertebrates was confirmed by using linear regression analysis. Even though the nutrient enrichment dominated the community biodiversity of macroinvertebrate, however, the existence of macrophyte significantly increased the types of functional feeding groups and live types. Conductivity, ammonia nitrogen, chemical oxygen demands and dissolved oxygen were the dominant chemical parameters affected the biodiversity of macroinvertebrates. The working schemes of water quality recovery and healthy aquatic ecosystem construction would be provided for the urban ditches. The corresponding adjustment rules of systematic process for sustaining the healthy waterway would be submitted.

Key words: river health, urban streams, macroinvertebrates, macrophytes, nutrient enrichment

(O42) PRODUCTIVITY OF THE PACIFIC OYSTER CRASSOSTREA GIGAS THUNBERG FROM OYSTER CULTURE

IN POSSJET BAY (SEA OF JAPAN) V.A. RAKOV

V.I.Il’ichev Pacific Oceanological Institute, FEB RAS,Vladivostok, RUSSIA E-mail: vladimir.rakov@mail.ru

Data collected over 20 years from Possjet Bay of the Sea of Japan is the major oyster culture in Far East Russia. The cultivation of the Pacific oyster Crassostrea gigas involves collection of oyster larvae, spat rearing in collectors in summer of first years and growth for 1.5–2 years until they are an acceptable size (80–100 mm). The oyster shell height was from 80 to 180 mm. The highest growth rates were in Novgorodskaya Bay and Expedition Bay, where they reaches of commercial size at 1–1.5 year old. The total number and weight of oysters was about 0.5 million individuals weighing 100 tons.

The intensive development of oyster farming in the South Primorye in recent years has created conditions where it is becoming very important to determine the productivity of the farms. The development of Pacific oyster gonads, larvae, spat settling, feeding, growth depends on the water temperature and, particular, the variation of the temperature during years. The water temperature over 10 ^oC in spring and summer over the active period of gonads development and growth oyster. The critical temperature for spawning of Pacific oyster in Possjet Bay is 18 ^oC. Growth of larvae and spat settling generally occurs at temperature of over 15–18 ^oC. In the future these parameters will be used to project spat density and productivity of Pacific oyster.

Key world: Pacific oyster, oyster culture, South Primorye

(P31) PALLIAL GONOGUCT HISTOLOGY OF SEMISULCOSPIRA SPECIES (GASTROPODA: SEMISULCOSPIRIDAE) FROM KUSHU ISLAND (JAPAN)