May 31, 9:05 (S5-3609)Invited

An aspect of functional groups of zooplankton in oceanic ecosystems

Akira Taniguchi

TokyoUniversity of Agriculture Okhotsk, Abashiri, Hokkaido 099-2493, Japan. E-mail:

Identification of function of zooplankton in oceanic ecosystems is difficult and classification of functional groups is not simple, even if this aspect is limited to their feeding habitat. Zooplankton usually complete their whole life history in the same water body, during which their body size changes from small to adult size. They always coexist with phytoplankton of similar size and nutritional composition to themselves. Therefore, most zooplankton feed on a mixture of phyto- and zooplankton and so called ‘ecological cannibalism’ easily occurs among them. To predict structural change of the ecosystems or species alternation under changing environment, knowledge about the length and mode of the life history is essential. When we predict a change at the level of fish populations, we must take possible change in structure ofwhole food webs into account. These all make identification and classification of zooplankton functional groups extremely complex. Since the current Census of Marine Life Program indicates that there may be millions of unknown species in the ocean, to construct an ecosystem model involving every existing species is almost impossible. To involve as many as functional groups into the model is right but not always practical nor better. The controversy about ‘right’ or ‘better’ will arise among people with different philosophies. Since one can easily fall into self-conceit under such situation, continuous discussion among the people is important.

May 31, 9:35 (S5-3569)

Classification of Zooplankton Life History Strategies

David Mackas1 and Jackie King2

1Fisheries and Oceans Canada, Institute of Ocean Sciences, PO Box 6000, Sidney, BC, CanadaV8L 4B2

E-mail:

2Fisheries and Oceans Canada., Pacific Biological Station, 3190 Hammond Bay Road, Nanaimo, BC, CanadaV9T 6N7

Life history and reproductive strategies, morphology, and feeding niche are all likely to affect how well individual zooplankton species can exploit and persist in changing ocean environments. Examples ofpotentially important factors include: presence/absence of seasonal dormancy, generation length, trophic level (herbivory vs. omnivory vs. carnivory), fecundity vs body size, broadcast vs brooding of eggs, depth distribution, and the degree to which morphology and trophic niche are stage/age dependent. We use multivariate ordination and clustering of these traits to group taxa into strategist guilds (as done by King and McFarlane 2003 for marine fishes), and then examine the extent to which seasonal and interannual changes in abundance map onto guild-membership.

May 31, 9:55 (S5-3740)

Climate and gelatinous carnivores in semi-closed, small-oceans: The NW Mediterranean case study

Juan-Carlos Molinero1, Michele Casini2 and Emmanuelle Buecher3

1Institut National de la Recherche Agronomique, Station d’Hydrobiologie Lacustre, BP 511 – av. de Corzent 74203 Thonon CedexFrance.E-mail:

2Swedish Board of Fisheries, Institute of Marine Research, Box 4, 45321 Lysekil, Sweden.

3Zoology Department, University of the Western Cape, Private Bag X17, Bellville 7535, South Africa

Pelagic gelatinous carnivores are of particular interest because of their potential effect on the population size of mesozooplankton, fish eggs and larvae. High abundances of gelatinous carnivores may channel the flow of energy away from fish and therefore drastically affect the ratio fish:primary production. Here we investigate potential connections between the population size of gelatinous carnivores and climate variability in the Northwestern Mediterranean. The species investigated belong to three main groups: Hydromedusae, Siphonophores and Ctenophores. The approach used is based on a downscaling model through which the interannual variability of large- and meso-scale climate variables in the Northwestern Mediterranean region was related to the abundance of gelatinous carnivores. The results show that modifications in the hydrological regime, i.e. water temperature and low water column mixing, that are ultimately mediated by climate variability may shift abundances of these populations but also affect their seasonal peak. It is then suggested that gelatinous carnivores integrate the climate related changes in the Northwestern Mediterranean, and therefore a substantial part of their variance may be forecast according to climate variability. Overall, our study contributes towards forecasting the abundance changes in gelatinous carnivores in the Mediterranean Sea since it reveals patterns that have been elusive so far, and suggests underlying mechanisms linking climate and the population size of these organisms.

May 31, 10:15 (S5-3282)

Community structure and trace elements in zooplankton in Sunderban mangrove wetland, Northeast part of Bay of Bengal, India

Santosh Kumar Sarkar and Bhskar Dev Bhattacharya

Department of Marine Science, University of Calcutta, 35 Ballygunge Circular Road, Calcutta 700019, India.E-mail :

Copepods, by their sheer abundance and diversity, formed thedominant group of the zooplankton communityconstituting73.0 - 96.4% of the totalbiomass. Copepods showed a bimodal type of distribution with maximum abundance during the high saline premonsoon period. Out of 32 genera and 54 copepod species, calanoidswere represented by 17 genera and 37 species, cyclopoids by 7 genera and 9 species,and harpacticoidsby 8 genera each having a single species. During the monsoon months, a good assemblage of oligohaIine species e.g., Acartiella keralensis, Neodiaptomus strigilipes, Pseudodiaptomus binghami, Halicyclops tenuispina,Mesocyclops sp., and Cyclops sp., was observed.The positive correlation between any two pairs among the families Paracalanidae, Pontellidae, Eucalanidae, Oithonidae and Laophontidae provides evidence that these families combine to form a group by themselves while the families Acartiidae and Pseudodiaptomidae showed negative correlations with other families. Significant correlation coefficient (r) values have been obtained among some zooplankters, salinity and pH. A positive and highly significant partial correlation between the perennial chaetognath Sagitta bedoti and salinity, eliminating the effect of water temperature, suggests that this species is greatly influenced by the salinity gradient. The frequency of mature chaetognaths (stage III) was noticeably smaller in comparison to the juveniles (stage I), which might be due to their presence in the deeper layers. Wide variations of trace elements (Fe, Mn, Zn, Cu, Co, Ni, Se) in diverse group of zooplankters were recorded which may be due to the combination of factors affecting the uptake rate of these metals. An in-depth biomonitoring is recommended to establish the studied biota as bioindicator species.

May 31, 11:00 (S5-3418)

Biological responses to oceanic climate variability off Oregon and WashingtonUSA in three calanoid copepods: Acartia tonsa, Calanus pacificus andParacalanus parvus

Jesse F. Lamb1, William T. Peterson2, Cheryl A. Morgan1 and Julie E. Keister3
1Cooperative Institute for Marine Resources Studies, Oregon State University, Hatfield Marine Science Center, 2030 S. Marine Science Dr., Newport, OR97365, USA. Email:

2NOAA Fisheries, NorthwestFisheriesScienceCenter, HatfieldMarineScienceCenter, 2030 S. Marine Science Dr., Newport, OR97365, USA

3College of Oceanic and Atmospheric Sciences, OregonStateUniversity, 104 COAS Admin. Bldg., Corvallis, OR97331, USA

Recent studies have demonstrated the feasibility of using zooplankton taxa as an early indicator of ecosystem response to seasonal and large scale environmental changes in the Northeast Pacific.Copepod biodiversity and community structure can be useful indicators of climate variability, but also lower trophic level indicators of the relative health of an ecosystem.Using data from a ten year time series, we will examine three “warm water” species that have inhabited the Oregon continental shelf ecosystem: Acartia tonsa, Calanus pacificus,and Paracalanus parvus.We will take into account the specific parameters of these individual species (ontogeny, egg production, temperature/salinity tolerance, etc.) in order to explore which species are the most sensitive indicators of specific environmental conditions.We will also explore the opposite: whether any of these species have the potential to be more opportunistic in a wider range of environmental variability are therefore more spatially and temporally broad.Such fine-scale information is essential for biological modeling with precise forecasting of both local and event-scale climate forced ecological events as the goal.We will compare plankton net data collected from multiple surveys off of the Oregon and Washington continental margins, from 42o to 48o N latitude.Data on individual copepod species will be compared with large-scale climate data (PDO and upwelling data) and the matching physical data from the corresponding cruises.

May 31, 11:20 (S5-3388)

Dominant zooplankton shift in the Strait of Georgia: An educated guess on the trophic implications and the probable biophysical context

Martha J. Haro-Garay 1and Leonardo Huato-Soberanis

CIBNOR, S.C. Mar Bermejo #195. Col, Palo Playa de Sta Rita. La Paz, B.C.S. 23090 México. E-mail:

Temperate pelagic environments have a high biological production that is also localized in time. Such biological production is often dependent on a few key species that control biomass flow.Their trophic pathways are linked to zooplankton species, clupeoid species and major pelagic fish. In the North Pacific key organisms are the copepod Neocalanus plumchrus, the herring and the salmon. Within this geographic region the Strait of Georgia (SG) shares this trophic pathway.Typically in the SG this path develops during the spring phytoplankton bloom, followed by a massive population growth of N. plumchrus that dominates zooplankton biomass, on which salmon and other fish species feed.A second production peak occurs during the summer, other copepod species and the euphausiid Euphausia pacifica account for the bulk of zooplankton biomass during this season.Nevertheless, in 1997 the dominance in community structure shifted from the key species N. plumchrus and E. pacifica to theamphipods Parathemisto pacifica and Cyphocaris challengeri. Analyses of this information, along with results on feeding habits of substitute species, indicates the need to reassess the ecological role of small copepod species such as Pseudocalanus minutus, Oithona similis and Oncaea borealis, in the biological production of the Strait of Georgia.

May 31, 11:40 (S5-3398)

Spatial and seasonal variations in distribution and abundance of net zooplankton functional groups on the continental shelf of the Yellow Sea

Song Sun1and Yuanzi Huo1, 2

1Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology,ChineseAcademy of sciences, 7 Nanhai Road,Qingdao, 266071, China. E-mail:

2GraduateSchool of the ChineseAcademy of Sciences, 100039, Beijing,China

Spatial and seasonal changes in distribution and abundance of net zooplankton functional groups (ZFGs) were studied in the south of Yellow Sea (SYS) during 2000-2005.Five key ZFGs were defined: (a) Medusae, (b) Chaetognaths, (c) macrozooplankton, (d) mesozooplankton, (e) microzooplankton.The most important ZFGs in the Yellow Sea were macrozooplankton and mesozooplankton, and the Yellow Sea Cold Water Mass playsa vital role in the distribution and abundance of the main ZFGs.In SYS, Chaetognaths were more abundant predators than Medusae because of their high abundance, especially in the center and northern part of SYS in autumn/winter.In March, microzooplankton was the important functional group because of high biomass and occurrence of abundant fish larvae, and that the replacement of function could not occur between macrozooplankton and mesozooplankton, mesozooplankton and microzooplankton.While in May, macrozooplankton, mesozooplankton and microzooplankton were all important functional groups, and the replacement could be processed between mesozooplankton and microzooplankton.In summer (June, July and August), microzooplankton was the primary functional group, and could displace mesozooplankton absolutely, in addition, macrozooplankton was also the important functional group.In autumn (October, November), macrozooplankton was the main functional group, microzooplankton taking the second place, and macrozooplankton and microzooplankton could replace the function of mesozooplankton.In winter (January), the biomass of every functional group was very low, but results indicated that macrozooplankton could replace mesozooplankton, and mesozooplankton could displace microzooplankton partially.

May 31, 12:00 (S5-3335)

Modern status of zooplankton in the northwest part of Japan Sea

Natalia T. Dolganova

Pacific Fisheries Research Centre (TINRO-centre), 4 Shevchenko Alley, Vladivostok, Russia, 690950. E-mail:

The total biomass ofzooplankton in the shelf zone and in the deep-water area in the northwest part ofJapanSea in the spring-summer period 2002-2006 has decreased on average by a factor of1.5 in comparison with 1990s. It is shown that spring processes in planktonic community began to be observed later than in the 1990s.A high concentration of net phytoplankton was observed in April - May,2-3 times higher that the previous decade and the peak didnot coincide with the spring peak of zooplankton. In this connection dominant species of copepods, amphipods, euphausiids and chaetognaths were also observed 1-1.5 months later. Therefore the dimensional structure of the plankton in the spring 2002-2006 was characterized by an extraordinariyy low share of the small-size fraction (animals with body size less then 2 mm) - from 7 up to 33 % of the total biomass. The high share of large-size(more than 3.5 mm) fraction is abnormal,from 50 up to 86 % usually dominating over late summer till late autumn. The specific structure of the planktonic community, in general, has not undergone significant interannual changes, but the share of the seven dominant species, usually exceeding 65 %, both in the spring and in the summer 2002-2006 has increased by 10-12 %. Thus the total biomass of minor species of zooplankton during last ten years has not changed. Thus, reduction of total biomass of zooplankton has taken place just due to reduction of number of dominant species, (Neocalanus plumchrus, Neocalanus cristatus, Metridia pacifica, Oithona similis and Themisto japonica), but also Chaetognaths, whose share has gone down 1.5 times, and is proportional to the downturn of the total zooplankton biomass.

May 31, 12:20 (S5-3332)

North-south comparisons of plankton communities in the OkhotskSea

Elena Dulepova,

Pacific Scientific Research Fisheries Centre (TINRO-Center), 4, Shevchenko Alley, Vladivostok, 690950, Russia.

E-mail:

Interannual comparisonsof zooplankton communities were carried out in the northern and southern parts of OkhotskSea based upon hydrographic and biological data for the period 1997-2005. The results show that in the northern part of the OkhotskSea zooplankton productivity is higher compared to southern part. This is due to the regional differences in composition and P/B-efficiency of the zooplankton communities, as well as to the influence of hydrological conditions. For example zooplankton abundance and productivity in the northeastern and northwestern OkhotskSea is influenced by interannual hydrological differences, resulting in either decreased or increased extent of sea ice cover as well as thesynoptic situation. The years 2000 and 2001 may be referred to as years of “cold” type, due to the significant extent of ice cover. Based on ice cover extent, the years of 2004 and 2005 can be referred to as “warm” years due to the decreased extent of ice cover. “Cold” and “warm” years did not differ significantly in terms of scale zooplankton biomass. However, in the northeast OkhotskSea zooplankton abundance increased during the“cold” years. The different years differed significantly in thetaxonomicstructure of macroplankton community.The biomass of copepods increased in the warm years but biomass of Sagittaincreased in cold years in the northern OkhotskSea. Allthese parameters have an influence on the production of zooplankton community. The total zooplankton community production in the northeastern and northwestern OkhotskSea is approximately the same in cold years.Production of the zooplankton community was much higherin the northwestern OkhotskSea in warm years.

Poster S5-2767

Bioecological observations of epipelagic zooplankton in Sharm El-Sheikh, Red Sea

M.M. Dorgham, El-Sherbini, M. and M.Hanafi

1Oceanography Department, Faculty of Science, AlexandriaUniversity, Moharrem Bey, Alexandria21511, EGYPT.

E-mail:

2Department of Marine Sciences, Faculty of Science, Suez CanalUniversity.

The dynamics of the zooplankton community and associated ecological conditions were studied seasonally in the epipelagic zone of the Sharm EL-Sheikh region in the Red Sea. The physico-chemical characteristics of the water column demonstrated pronounced seasonal variations. Water temperature decreased within the upper 100m by 2.1oC in most seasons and by 7.7 oC in summer. The water column appeared to be well aerated with more or less homogeneous vertical distribution of dissolved oxygen, except for relatively low values in the deep layer in spring. The nutritional conditions classified the study area as oligotrophic, whereas the reactive phosphate and dissolved inorganic nitrogen fluctuated between undetectable levels to a maximum of 0.7 M for both nutrients. In contrast, concentrations of silicate were on some occasions comparatively high in the deep layer (6.5 M). Relative to these conditions phytoplankton production was generally low. The zooplankton community was represented by 69 species only, mainly copepods, with generally low standing crop (annual average of. 4250 individuals m-3). The maximum zooplankton abundance was often found in the uppermost layer (0-25m) in most seasons, but in spring abundance was greatest in the deeper layer (25-50m). There were different seasonal patterns of vertical distribution of the dominant species. Sixteen bathypelagic species were reported in the epipelagic plankton of the Red Sea, three species as new records, and twenty nine species as newly transferred from the southern part to the northern part of the Red Sea and to the Gulf of Aqaba. Other species were considered to be immigrants from the Mediterranean Sea southward to the Red Sea.

Poster S5-3277

Zooplankton biomass along the Jordanian and Israeli sections of the Gulf of Aqaba, Red Sea

Tariq Al-Najjar1, Bracha-Viviana Farste2and Amatzia Genin2

1Marine Science Station, POB 195, Aqaba, Jordan. E-mail:

2The Interuniversity Institute for Marine Sciences, H. Steinitz Marine Biology, Laboratory, POB 469, Eilat88103, Israel.

E-mail: ,

The objective of work is to examine the variations in the surface zooplankton biomass on a temporal scale of 2 months to 1 year and on a spatial scale of 1 to 10 km\'s, In addition, zooplankton biomass was examined in term of time and space, vertical cross shore- offshore profile, using existing approaches in a new way.The results indicate significant variations in zooplankton biomass between months, but no major variation between stations. The most important size fractions, contributing to the total biomass in the Gulf of Aqaba, are those of 200-500µm and >1000µm. No spatial relationship between zooplankton biomass and eithertemperature, chl-a concentration or nutrients was apparent. Meanwhile, changes in zooplankton biomass co-varied with changes in surface chl a concentration measured from the pier of the Underwater Observatory. The biomass obtained from the three different stations shows that biomass tends to increase at the upper water interval compared to the lower one. However, the monthly average of zooplankton biomass at each sampling station shows that the biomass decreased towards the offshore water.