Seasonal variations in the trophic relationship between the scyphomedusa Aurelia aurita s.l. and mesozooplankton in a eutrophic brackish-water lake, Japan

The seasonal variations in trophic relationship between the moon jelly Aurelia aurita s.l. and mesozoo- plankton were investigated in a brackish-water lake, Honjo District, Japan from June 2005 to August 2006. The medusae occurred abundantly (average abundance and biomass: 0.55 medusae m � 3 and 58.8 mg C m � 3 , respectively) during warm seasons (i.e. June-November, 2005), but were very scarce or absent during the remaining seasons. The mesozooplankton biomass fluctuated from 1.3 to 150 mg C m � 3 (overall average: 60.5 mg C m � 3 ) irrespective of the medusa biomass variation. Mesozooplankton were preyed upon by medusae almost non-selectively; the small copepod Oithona davisae and bivalve larvae were the predominant prey, comprising 52-99% (average: 85%) of the gastric pouch contents. The medusa population ingestion rate on mesozooplankton varied from 0.11 to 12.8 mg C m � 3 d � 1 , which corresponded to 0.6 to 29% of the mesozooplankton biomass per day and to 1.6 to 47% of mesozooplankton daily production rate. A. aurita medusae were certainly a key component of the zooplankton community, but they did not exert any significant top-down control as to suppress mesozooplankton biomass in this eutrophic lake.

[1]  J. Purcell,et al.  Anthropogenic causes of jellyfish blooms and their direct consequences for humans: a review , 2007 .

[2]  J. Hiromi,et al.  Abundance and biomass of scyphomedusae, Aurelia aurita and Chrysaora melanaster, and Ctenophora, Bolinopsis mikado, with estimates of their feeding impact on zooplankton in Tokyo Bay, Japan , 2006 .

[3]  S. Uye,et al.  Unusual population explosion of the giant jellyfish Nemopilema nomurai (Scyphozoa: Rhizostomeae) in East Asian waters , 2006 .

[4]  H. U. Riisgård,et al.  Clearance rates of jellyfish and their potential predation impact on zooplankton and fish larvae in a neritic ecosystem (Limfjorden, Denmark) , 2005 .

[5]  J. Purcell.  Climate effects on formation of jellyfish and ctenophore blooms: a review , 2005, Journal of the Marine Biological Association of the United Kingdom.

[6]  S. Uye,et al.  Population biomass, feeding, respiration and growth rates, and carbon budget of the scyphomedusa Aurelia aurita in the Inland Sea of Japan , 2005 .

[7]  H. Hirche,et al.  Seasonal development of scyphozoan medusae and the predatory impact of Aurelia aurita on the zooplankton community in the Bornholm Basin (central Baltic Sea) , 2005 .

[8]  S. Uye,et al.  Potential Use of Extremely High Biomass and Production of Copepods in an Enclosed Brackish Water Body in Lake Nakaumi, Japan, for the Mass Seed Production of Fishes , 2004 .

[9]  S. Uye,et al.  Recent increase of jellyfish populations and their nuisance to fisheries in the Inland Sea of Japan , 2004 .

[10]  H. Ishii,et al.  Food and feeding of Aurelia aurita in Tokyo Bay with an analysis of stomach contents and a measurement of digestion times , 2001, Hydrobiologia.

[11]  Tomoko Watanabe,et al.  In situ estimation of ephyrae liberated from polyps of Aurelia aurita using settling plates in Tokyo Bay, Japan , 2001, Hydrobiologia.

[12]  M. Arai.  Pelagic coelenterates and eutrophication: a review , 2001, Hydrobiologia.

[13]  J. Purcell,et al.  Interactions of pelagic cnidarians and ctenophores with fish: a review , 2001, Hydrobiologia.

[14]  Claudia E. Mills,et al.  Jellyfish blooms: are populations increasing globally in response to changing ocean conditions? , 2001, Hydrobiologia.

[15]  M. Dawson,et al.  Geographic variation and ecological adaptation in Aurelia (Scyphozoa, Semaeostomeae): some implications from molecular phylogenetics , 2001, Hydrobiologia.

[16]  M. Dawson,et al.  Macro-morphological variation among cryptic species of the moon jellyfish, Aurelia (Cnidaria: Scyphozoa) , 2003 .

[17]  N. Godhantaraman,et al.  Geographical and seasonal variations in taxonomic composition, abundance and biomass of microzooplankton across a brackish-water lagoonal system of Japan , 2003 .

[18]  H. Takeoka,et al.  Unusual aggregations of the scyphomedusa Aurelia aurita in coastal waters along western Shikoku, Japan , 2003 .

[19]  J. Purcell.  Predation on zooplankton by large jellyfish, Aurelia labiata, Cyanea capillata and Aequorea aequorea, in Prince William Sound, Alaska , 2003 .

[20]  G. Hunt,et al.  Increases in jellyfish biomass in the Bering Sea: implications for the ecosystem , 2002 .

[21]  S. Uye,et al.  Geographical and Seasonal Variations in Abundance , Biomass and Estimated Production Rates of Meso-and Macrozooplankton in the Inland Sea of Japan , 2002 .

[22]  J. Purcell,et al.  Prey selection and dietary overlap among zooplanktivorous jellyfish and juvenile fishes in Prince William Sound, Alaska , 2001 .

[23]  H. González,et al.  Gelatinous zooplankton assemblages associated with water masses in the Humboldt Current System, and potential predatory impact by Bassia bassensis (Siphonophora: Calycophorae) , 2001 .

[24]  Ryan M. Kroutil,et al.  Size-based Prey Selectivity and Dietary Shifts in the Jellyfish, Aurelia aurita , 2001 .

[25]  F. Koike,et al.  Surface water exchange rate of the Honjo area in Lake Nakaumi estimated from salinity change , 1999 .

[26]  G. Schneider,et al.  TOP : DOWN CONTROL IN A NERITIC PLANKTON SYSTEM BY AURELIA AURITA MEDUSAE : A SUMMARY , 1998 .

[27]  H. Miyake,et al.  Life History and Environment of Aurelia aurita , 1997 .

[28]  S. Uye,et al.  Geographical and seasonal variations in abundance, biomass and estimated production rates of microzooplankton in the Inland Sea of Japan , 1996 .

[29]  Olesen Nj.  Clearance potential of jellyfish Aurelia aurita, and predation impact on zooplankton in a shallow cove , 1995 .

[30]  M. Omori,et al.  Life history strategy of Aurelia aurita (Cnidaria, Scyphomedusae) and its impact on the zooplankton community of Tokyo Bay , 1995 .

[31]  B. K. Sullivan,et al.  Prey selection by the scyphomedusan predator Aurelia aurita , 1994 .

[32]  G. Schneider,et al.  Population dynamics and the trophic role of Aurelia aurita medusae in the Kiel Bight and western Baltic , 1994 .

[33]  S. Rajagopal,et al.  Some observations on the problem of jelly fish ingress in a power station cooling system at Kalpakkam, east coast of India , 1989 .

[34]  L. Hernroth,et al.  Phyto-Zooplankton Community in Coastal Waters of Western Sweden -An Ecosystem Off Balance? , 1983 .

[35]  S. Uye.  Length-weight relationships of important zooplankton from the Inland Sea of Japan , 1982 .

[36]  S. Pearre.  Estimating Prey Preference by Predators: Uses of Various Indices, and a Proposal of Another Based on χ2 , 1982 .

[37]  H. Moller.  Scyphomedusae as predators and food competitors of larval fish , 1980 .

[38]  Shuichi Sato,et al.  Ecological Studies on the Medusa, Aurelia aurita LAMARCK-I , 1969 .