LONG-TERM CHANGES OF NUCULANA PERNULA COMMUNITY AS THE INDICATOR OF GLOBAL BENTHIC CHANGES IN SOUTH PART OF OKHOTSK SEA

V. S. Labay & Kochnev Yu. R. Research Institute of Fishery & Ocenography Localization Prologue

Standard opinion: "the Reason of decrease in a stock is an overfishing a flounder by fisherman" MATERIALS AND METHODS

Aniva bay The literary data: z 1949-1950 (The atlas of oceanographic bases…, 1955); z 1965 (Skalkin, 1970); z 1980 (Alekhnovich, 1980). 2005 (Own data) MATERIALS AND METHODS

49.4

49.2 Terpenia bay 49 The literary & archival data: 48.8 z 1949-1950 (The atlas of 48.6 oceanographic bases…, 48.4 1955); 48.2 z 1964 (Tabunkov, 1966); z 1970 (Skalkin, 1970); 48 z 1975 (Tabunkov, 1975). 47.8 2006 (Own data) 47.6

47.4

47.2 142.5 143 143.5 144 144.5 145 MATERIALS AND METHODS

Control area in z Benthos was sampled: August 2003; October and December 2004, May 2005; August 2005; August 2006; August 2007; September 2008. z Stations located at 300, 800 and 2000 m off the central point (coordinates 46°24.5,0' N and 142°55,0' E) to the north, east, south and west. MATERIALS AND METHODS

z Benthos was sampled from the R/V “Dmitry Peskov” using a Van- Veen grab (0,2 m2) – three samples from one station. z For construction of distributions the program “SURPHER 8.00” was used: Method of a linear triangulation; Filtration on average. Aniva bay: Change of a benthos biomass

For the period with 1949 on 2005 the average biomass has decreased almost 5 times! Aniva bay: Change of an area of community Nuculana pernula

Migration of community with 1949 on 2005 of the central southern deep- water part on periphery in more shallow areas was observed. Migration was accompanied by decrease Control in a biomass and change area of community structure: ƒ1949 – average 400 g/m2 (up to 900 g/m2); ƒ1965 – up to 64 g/m2; ƒ2005 – average 12 g/m2 (up to 15 g/m2) Aniva bay: Control area: Change of distribution Nuculana pernula

On a control area with 2003 to 2008 occurrence of a congestion of Nuculana pernula and its displacement on the north in the direction of coast was observed. Occurrence of a congestion was accompanied by growth of a biomass by 2006. After displacement of a congestion on the north the biomass has decreased almost up to initial. Aniva bay: Control area: Change of distribution Nuculana pernula

On a control area with 2003 Average biomass to 2008 occurrence of a congestion of Nuculana 12 pernula and its displacement on the north in 10 the direction of coast was 8 observed. 2 6 Occurrence of a congestion g/m B, was accompanied by growth 4 of a biomass by 2006. After 2 displacement of a 0 congestion on the north the 8–2003 1–2004 8–2005 8–2006 8–2007 9–2008 biomass has decreased Period almost up to initial. Aniva3.5 bay: Replacement of benthos communities

2.5 Nephthys ciliata+Onuphis iridescens

Golphingia margaritacea 1.5 Nuculana pernula Asychis disparidentata punctata 1-1-5 1-1-4 1-1-3 1-1-2 1-1-1 46.5 17 +Onuphis iridescens 27 0.5

Lumbriconereis heteropoda 1-2-6 1-2-7 1-2-8 1-2-91-2-10 1-2-11

15 16 26

Reorganization of bottom 1-3-17 1-3-16 1-3-15 1-3-14 1-3-131-3-12 biocenosis is observed: the 24 25 place of the community 1-4-18 1-4-19 1-4-20 1-4-21 1-4-22 1-4-23 1-4-24 Nuculana pernula displaced46 on the north is occupied communities with domination of Sipuncula and Polychaeta 142 142.5 143 143.5 Terpenia bay: Change of an area of community Nuculana pernula

49.5 - 1949 г.

Division uniform before an area - 1964 г. of community on parts and (> 500 г/м2 ) reduction of its area was - 1970 г. 49 observed with 1949 on 2006 (> 500 г/м2 ) division was accompanied by - 1975 г. decrease in a biomass : (> 500 г/м2 ) - 2006 г. ƒ1949 – average 1.5-2 kg/m2; 48.5 (> 400 г/м2 ) ƒ1964 – average 1.1 kg/m2 ; ƒ1970 - average 625 g/m2; 48 ƒ1975 – average 550 g/m2; ƒ2006 – average 94 g/m2

47.5 143 144 Terpenia bay: Change of an area of community Nuculana pernula

Division uniform before an area of community on parts and reduction of its area was Parameter 1964 1970 1975 2006 observed with 1949 on 2006 division was accompanied by Theareaofa decrease in a biomass : congestion, 5250 4550 4100 – 2 ƒ1949 – average 1.5-2 kg/m2; km ƒ1964 – average 1.1 kg/m2 ; Biomass more 2 > 500 > 500 > 500 – ƒ1970 - average 625 g/m2; than, g/m ƒ1975 – average 550 g/m2; Average 1108 625 552 94 ƒ2006 – average 94 g/m2 biomass, g/m2 The possible reasons of benthos changes

I-st hypothesis 2-nd hypothesis

Known fact: The total benthos biomass is defined by a level of a fodder Changes of a resource hydrological regime

Recession of bottom community is limited by lack of a fodder resource First hypothesis: Change of a hydrological regime z Conditions of dwelling: Cold spreading layer of water; negative temperature z The volatility of a cold down layer has no expressed law z On the average; area of down layer have not changed (1950-2006) z Hence, the hydrological regime of spreading layer does not determine change of bottom ecosystem Second hypothesis: Lack of a fodder resource

z Trophic characteristic of Dynamics of phytoplankton biomass Nuculana pernula: collecting detritophagous 5 z The basic supplier of 4 detrit: phytoplankton Spring Summer 2 z Decrease in productivity 3

of phytoplankton can be B, g/m the probable reason of 2 benthic changes 1

0 The literary data 1945 1955 1965 1975 1985 1995 2005 Years During the spring phytoplankton productivity is limited by temperature of water; summer – biogenes concentration (Tzhay, 2007)

Decrease in temperature of an upper layer during the warm period (1950-1999) (Schevchenko & other, 2003, 2004): z 1.4°C (HMSt ), z 2°C (HMSt Yuzhno-)

Thus, decrease in temperature of a superficial layer has probably led to reduction in productivity of phytoplankton and has caused benthic changes. The report puts more questions than gives answers z It is necessary to unit actions of scientist for detection of the similar phenomena in other parts of Pacific Ocean z Check of serviceability of the stated hypothesis is necessary z Long-term complex monitoring of a plankton, benthos and organic substance in a ground of a bottom is necessary

Thank for attention