Potential importance of volcanic emissions on marine biogeochemical cycles and clouds over the North Pacific

Mitsuo Uematsu¹, Shigenobu Takeda², Hiroshi Furutani¹ and Itsushi Uno³

Large volcanic eruptions have been observed and their impacts have been reported on land and they have affected peoples’ lives during the past several decades. Included are such eruptions as Mt. St. Helens (USA) in 1980, Pinatubo (The Philippines) in 1991, and Mt. Eyjafjallajökull (Iceland) in 2010. Volcanoes emit a number gases (H₂O, CO₂, H₂S, SO₂, HCl, HF, H₂, N₂, Ar, CH₄, CO, NH₃) and ash particles that contain Si, Al, Fe Ca, and P, both through sporadic explosions and continuous eruptions. It is well known that those gases and particles affect the composition of the atmosphere and, through this global climate. However, there is very little knowledge of their impact on the marine environment, although many volcanic activities have been reported in oceanic regions. In this talk three case studies addressing different marine-related processes are introduced, and the importance of sporadic volcanic emission on biogeochemical cycles and climate, especially over the North Pacific, are discussed: (Case 1) Supply of nitrogen compounds emitted from the Miyake-jima Volcano, Tokyo, Japan; (Case 2) Supply of Iron from volcanic ash of Mt. Okmok, Aleutian Islands, USA; and (Case 3) Effect on marine clouds caused by Kilauea Volcano on Hawaii Island, USA.

Projected changes in the North Pacific Ocean mixed layer depth and their impacts on primary production

Chan Joo Jang, Jisoo Park, Taewook Park and Sinjae Yoo

This study investigates changes in the mixed layer depth (MLD) in the North Pacific Ocean in response to global warming and their impacts on primary production by comparing outputs from 11 models of the coupled model intercomparison projects phase 3. The MLD in the 21st century decreases in most regions of the North Pacific, whereas the spatial pattern of the MLD is nearly unchanged. The overall shoaling results in part from intensified upper-ocean stratification caused by both surface warming and freshening. A significant MLD decrease (> 30 m) is found in the Kuroshio Extension (KE), which is predominantly driven by reduced surface cooling, caused by weakening of wind. Associated with the mixed layer shoaling in the KE, the primary production component resulting from seasonal vertical mixing will be reduced by 10.7-40.3% (ranges of medians from 11 models) via decreased nitrate fluxes from below. Spring blooms in most models are projected to initiate earlier in the KE by 0-13 days (ranges of medians from 11 models). Despite the overall trends, the magnitude of changes in primary production and timing of spring blooms are quite different depending on models and latitudes.

When, where and why skipjack tuna, red flying squid and pacific saury potential fishing zones are likely to overlap in the western North Pacific: A proof of concept

Robinson M. Mugo^1,2, Sei-Ichi Saitoh^1,3, Fumihiro Takahashi^1,3, Akira Nihira⁴ and Tadaaki Kuroyama⁵

Skipjack tuna, the neon flying squid (warm water species) and pacific saury (cold water species) fishing grounds show some spatial synchrony in autumn in the western North Pacific (WNP). To assess possible spatial habitat overlaps between skipjack tuna, pacific saury and/or neon flying squid along the Oyashio and/or sub-arctic front in the WNP, skipjack tuna fishery presence-only data and monthly (August-November) satellite remotely sensed SST, chlorophyll a and sea surface height anomaly images were used to calculate habitat suitability indices (HSIs) using maximum entropy models (MaxEnt) between 30-50°N and 140-160°E. A second set of HSIs for the same area was calculated using presence-only data derived from DMSP/OLS nightlight images, (which indicate fishing areas for neon flying squid and pacific saury) and the same set of environmental parameters. Model performances were evaluated using the area under the curve (AUC) statistic and jack-knife tests. Maps of both sets of HSIs were compared and areas of overlap identified using a joint probability and longitudinal transects. Results indicate that an area of spatial overlap exists among the species habitats, gradually increasing from August to November. The causes of these overlaps include the presence of strong thermal gradients between cold Oyashio waters and warm Kuroshio waters, and also the presence of the sub-arctic front. We conclude that a spatial overlap of habitats observed could be as a result of skipjack tuna and neon flying squid foraging on nekton on the warmer edges of thermal gradients while pacific saury aggregate on cold edges of such gradients.

Jellyfish blooms in the Far Eastern Seas of Russia: Significance for ecosystems and socialeconomic consequences

Alexander V. Zavolokin

Recently, jellyfish blooms have occurred in many regions of the world. Increasing jellyfish abundance can have significant consequences for marine ecosystems, fisheries, industries and tourism. Jellyfish blooms in the Far- Eastern Seas and Northwest Pacific in comparison with other regions of the World Ocean were studied. Potential impacts of jellyfish on marine communities and human societies were examined. It is shown that jellyfish biomass and abundance in the Far-Eastern Seas and adjacent waters are relatively low and their blooms don’t have largescale negative ecological and social-economic consequences.

Population ecological parameters of elkhorn sculpin (Alcichthys alcicornis) along the Uljin area of Korea

Soojeong Lee¹, Jaebong Lee², Hyeokchan Kwon¹ and Changik Zhang¹

Population ecological parameters of elkhorn sculpin were estimated along the Uljin area of Korea. Age and growth of elkhorn sculpin were examined. Ages were estimated from otolith assuming that annuli are formed once per year in January. A generalized von Bertalanffy growth function provided the best fit based on AIC and BIC statistics among four alternative functions. Estimated growth parameters for this species were = 29.41cm, K= 0.247/year and t₀= -0.609 year. The GSI for both sexes was the highest in February, indicating February as the main spawning month. Based on bootstrapped data, lengths at which 50% of the female and male fish had attained maturity were 14.30 cm and 17.42 cm, respectively. Survival rate and total mortality was estimated to be 0.334 and 1.096/year, respectively. Natural mortality (M) estimates for the elkhorn sculpin were derived from a meta-analysis of seven different M estimators. The overall M estimate was based on a random effects inverse variance weighting of each method. M was estimated to be 0.467/year for the elkhorn sculpin along the Uljin area of Korea. The age at first capture of this species was estimated to be 2.41 years.

Fishery Income fluctuation by selecting fishing ground in the Japanese coastal squid jigging fishery

Osamu Tamaru¹, Kazushi Miyashita², Yasuzumi Fujimori³, Toshihiro Watanabe¹ and Teisuke Miura⁴

In recent years in Japan, falling fish prices and rising fuel costs have worsened conditions for many fisheriesdependent
households. Typically, fishermen have operated their fisheries with their own knowledge and / or intuition, without a scientific basis. In general, many fishermen select the fishing ground in which they can maximize their total catch, even when such grounds are very far from their home harbor. As a result, fishermen have the potential to select the fishing ground in which they do not maximize their income. Especially the Japanese coastal squid jigging fishermen need development of the energy-saving squid jigging fishery, because it uses a lot of fuel in comparison with other kind of fishery. This study shows that income fluctuations are caused by many factors, by using the Management Simulation Method. We used the social factors (such as fuel price and squid price) and the fishing ground factors (such as distance from harbor to fishing ground, and squid catches) in this simulation. According to the simulation results, small changes in social and fishing ground situations can result in changes to the optimal fishing grounds. We concluded that fishermen's selection of fishing grounds based only with their own knowledge and / or intuition might not result in choices that maximize their income, and it is necessary to develop the scientific methods to choose fishing ground in which can maximize their income.

Oral (FIS-P-7628), FIS Paper Session

Reproductive biology of Benthosema pterotum (Pisces: Myctophidae) in the shelf region of the East China Sea

Chiyuki Sassa, Seiji Ohshimo, Hiroshige Tanaka and Youichi Tsukamoto

Benthosema pterotum is a dominant myctophid in the shelf region of the East China Sea (ECS). They are a key species linking secondary producers and upper trophic levels, but information on their reproduction is limited. We examined the sex ratio, sexual maturity, spawning period, oocyte development, and batch fecundity of B. pterotum in the ECS, based on 3,065 specimens [10.7-54.8 mm standard length (SL)] sampled in 1999 and 2004-2009. Between 15 and 30 mm SL, the ratio of females to males was ca. 40%; it increased with SL and all individuals ≥45 mm SL were females. The gonadosomatic index (GSI) at 50% sexual maturity of females and males was 3.91 and 0.24, respectively. Based on this criterion for GSI, females and males can mature larger than 28 mm and 24 mm SL, respectively. Although mature females having GSI ≥3.91 occurred during May-January, mean GSI of females peaked sharply during August-September, i.e., the primary spawning period. The hepatosomatic index peaked during April-July, and declined during August-September, indicating storage of materials and energy for reproduction. Based on data from seasonal bottom trawl surveys, small individuals of B. pterotum began to occur abundantly in autumn, and modal body lengths increased progressively during spring-summer, corresponding with the above reproductive seasonality. Oocytes at various sizes were found in mature ovaries, indicating that they are multiple spawners. Egg size at hydration ranged from 0.57-0.91 mm. Batch fecundity was positively correlated with SL, and ranged from 253-1,942 eggs in fish from 30.1-54.8 mm SL.

Oral (S7-7561), MEQ Topic Session

Effect of salmon-derived nutrients and organic matter on riparian ecosystems in the Shiretoko World Natural Heritage area

Yousuke Koshino¹, Masao Minagawa², Hideaki Kudou³, Yuxue Qin¹ and Masahide Kaeriyama³

Pacific salmon (Oncorhynchus spp.) transport marine-derived nutrients (MDN) and organic matter to inland ecosystems, and play a significant role in delivery of ecosystem services such as biodiversity and productivity in sea-land cosystems of the North Pacific rim. Shiretoko Peninsula is one of the few regions where wild chum (O. keta) and pink (O. gorbuscha) salmon reproduce in Japan. Despite designation as a World Natural Heritage area, the Shiretoko Peninsula has many dams that interrupt salmon escapement. We evaluated the salmon MDN contributions for freshwater and riparian ecosystems in this area using carbon and nitrogen stable isotope analysis. At the spawning site, carbon and nitrogen stable isotopes of biofilm, aquatic invertebrates and fishes increased 1-6‰ and 1-8‰ respectively. Thus, their MDN enrichment was 21-30% in the river. Brown bears (Ursus arctos) exhibit four life-history patterns based on analysis of growth sections in the hair. Most bears fed on pink salmon as a source of overwintering energy. In terrestrial ecosystems, the riparian vegetation was enriched 24% MDN by the vector (e.g., brown bear) and by flooding. However, MDN enrichment in the Shiretoko Peninsula was equal or lower than the riparian ecosystems in North America. Pacific salmon function as a keystone species in sealand interactions and during transport of ecosystem-transboundary materials (ETM) in the Shiretoko Peninsula. However, the anthropogenic impact of construction has harmed and disturbed the ETM system. Potential adaptive management strategies that are based on the ecosystem approach should be explored immediately to protect the ETM system in this area.

Poster (S7-7608), MEQ Topic Session

Levels of 4-NP in coastal waters in the Russian zone of Japan/East and Bering Seas

Aleksandra S. Kondakova¹ and Andrey P. Chernyaev²

The organic compound 4-nonylphenol (4-NP) is a breakdown product of nonylphenol ethoxylates (NPEs). NPEs have many uses including emulsifiers, wetting agents, in pesticide production, and as surfactants in detergent formulations for both industrial and domestic uses. The major part of the NPEs used as surfactants appear as pollutants in coastal water. NPEs are toxic and have an effect upon aquatic organisms including bioaccumulation in the tissues of fish. In anoxic conditions NPEs decompose to short-chain and degrade into NP. 4-NP has an estrogenic effect, which can cause the feminization of marine organisms. Therefore, determination of the levels of 4-NP in natural waters is very important. Levels of 4-NP were determined in seawater of the Bering and Japan/East Seas. Analysis has been developed using liquid-liquid extraction with methylene chloride, after concentration samples are analyzed by HPLC with fluorescence detection. Water samples were collected in summer and autumn of 2010. Concentrations of 4-NP in seawater ranged from levels below the detection limits up to 8.26 μg/L. According to the Baronti Classification, waters of the Japan/East Sea are classified as slightly contaminated and waters of the Bering Sea are classified as contaminated.

Hanna Na and Kwang-Yul Kim

Upper-ocean (0–400 m) heat content variability in the Northwestern Pacific is investigated using a 40-year reanalysis dataset from 1967 to 2006. The first and second modes of the upper-ocean heat content variability represent the seasonal cycle and a cooling signal, respectively. The cooling signal during the 40 years is large along the latitude band between 30°N and 45°N. The third mode shows decadal variability with positive and negative anomalies in different regions of the Northwestern Pacific. Southern regions to the south of about 35°N, including the East/Japan Sea, exhibit significant warming related to this decadal variability during the 40 years, while northern regions show cooling during the same period. Physical aspects of the decadal variability are examined by regression analysis using sea surface height, sea surface temperature and subsurface temperature in the Northwestern Pacific.

Poster (POC-P-7596), POC Paper Session

Possible impact of tropical El Niño Modoki on SST of China’s offshore and its adjacent waters

Hong-jian Tan and Rong-shuo Cai

Key Laboratory of Global Change and Marine-Atmospheric Chemistry, Third Institute of Oceanography, SOA, 178 Daxue Rd., Xiamen, Fujian, 361005, PR China. E-mail: rscai@163.com

El Niño Modoki, a new type of tropical Pacific phenomenon, which is similar but different from the canonical El Niño, has been observed since the late 1970s, followed by its unique influence on global climate. In this paper, relationships between SST during the four seasons in the offshore area of China and its adjacent waters and El Niño Modoki have been comparatively analyzed based on the HadISST dataset and NCEP\NCAR wind data, respectively. The results indicate that (1) a significant negative correlation is found between El Niño Modoki in summer and SST in the offshore area of China and its adjacent waters in autumn, with the significant regions located east of the Kuroshio and (2) during the El Niño Modoki period, anomalous northerlies prevail over the northern part of the Philippines to the offshore area of China. It is therefore suggested that the northerlies are unfavorable for the transport of warm water from the western tropical Pacific to the mid-latitude area. Consequently, El Niño Modoki in summer may contribute to cold SSTs in the offshore area of China and its adjacent waters in autumn by the Kuroshio, with a lag response of the ocean to the atmospheric wind field.

Oral (S9-7681), MONITOR Topic Session

Phytoplankton and nutrient dynamics in the western Seto Inland Sea, Japan based on observation and a modified NEMURO model

Naoki Yoshie¹, Xinyu Guo¹, Naoki Fujii² and Tomohiro Komorita³

We studied the ecosystem and nutrient dynamics in the Seto Inland Sea using both field observations and numerical modeling. We investigated spatiotemporal variations in the group composition of phytoplankton and nutrient concentrations in the Iyo-Nada, Hoyo strait and Bungo Channel (parts of the Seto Inland Sea) with monthly field observations in 2009. From spring to early summer, nano- and pico-phytoplankton dominated in all three regions. From late summer to autumn, micro-phytoplankton (diatom) bloomed in the Iyo-Nada and Hoyo strait, while no pronounced bloom was observed in the Bungo Channel. This autumn diatom bloom was probably caused by nutrient supply associated with breakdown of the bottom cold water dome. For understanding the mechanisms of the nutrient cycle and plankton dynamics, we developed a plankton functional types model eNEMURO (4 Nutrient, 4 Phytoplankton, 4 Zooplankton, 3 Detritous), building on PICES’ original lower-trophic-level marine ecosystem model, NEMURO. Model eNEMURO introduces the microbial food web, phosphorous cycles and dividing diatoms into two compartments according to temperature dependency. The nutrients and phytoplankton dynamics observed in both the Iyo-Nada and Bungo channel were successfully reproduced by eNEMURO.

Oral (S9-7651), MONITOR Topic Session

North Pacific database of pelagic and bottom trawl surveys from Russian EEZ applicable to Ecosystem Based Management

Vladimir V. Kulik and Igor V. Volvenko

Laboratory of Applied Biocenology, Pacific Research Institute of Fisheries and Oceanography (TINRO-Center), 4 Shevchenko Alley, Vladivostok, Primorsky Kray, 690091, Russia. E-mail: vladicon82@gmail.com

The review covered published estimates of abundance of about 1037 species and higher taxons of fish, squids, jellyfish and other large zooplankton species. Published results of fishery-independent pelagic trawl surveys carried out by specialists from TINRO-Center 1977-2010 were averaged by 4 to 11 year periods and biostatistical regions or one degree trapeziums. The level of abstraction used for publication is not suitable for precise validating, or for initial conditions of mathematical dynamic ecosystem models. The database compiled at the Laboratory of Applied Biocenology of TINRO-Center, which is not directly accessible by the public, includes verified data collected from 62926 stations for the same period of time during pelagic and bottom trawl surveys. Our current work adds data sets about zooplankton abundance estimates and stomach contents of animals obtained from the same expeditions. The problem of connecting discrete biological data with continuous fields of environmental parameters at different spatial and temporal scales is discussed. More robust ecosystem models adapted for Ecosystem Based Management (EBM) are needed to fill the big gap between remote sensing data and information products for commercial fisheries management interests. Because of this gap our fishery managers are forced to estimate the amounts of allowable catches primarily by using single-species cohort models without environmental parameters. We outline our reliable biological spatiotemporal sets which can be used for EBM model development and validation.

Poster (W4-7786), TCODE Topic Session

Characteristics of anomalous summertime coastal upwelling events off the east coast of Korea during 2003-2009

Jaehyung Park and Kyung-Il Chang

School of Earth and Environmental Sciences, Seoul National University, 599 Gwanak-ro, Gwanak-gu, Seoul, 425-600, R Korea. E-mail: kichang@snu.ac.kr

East coast of Korea is characterized by seasonally changing monsoon winds, the East Korean Warm Current at the sea surface flowing northward, and the subsurface North Korean Cold Current flowing southward. High productivity in the southwestern East Sea has often been attributed to wind-induced coastal upwelling and offshore movement of the upwelled cold and nutrient-rich water in the flow of the East Korean Warm Current. Ocean buoy observations in 2003-2009 identified 19 events of the sea surface temperature drops greater than 5°C: 5 events in 2003, 6 events in 2004, no data for 2005, no events in 2006, 3 events in 2007, 2 events in 2008, and 3 events in 2009. Among these 19 events, the temperature drops exceeded 10°C for three times: in 2003 (12°C drop), 2004 (11°C drop), and 2007 (17°C drop). These 3 anomalous events are considered in detail focusing on understanding the affecting factors, i.e., winds, background currents, and stratification. The temperature drops are thought as concerned to coastal upwelling driven by southerly winds. However, observed wind-stress impulses were lower than required values for most of the 19 events including 3 anomalous ones. Besides, a thick layer of cold water carried by the North Korean Cold Current was found prior to 2 upwelling events (in 2003 and 2004). The strongest upwelling in summer 2007 was caused by thermocline inclination at the coast on periphery of the East Korean Warm Current combined with persistent action of southerly winds.