Ciencia

Aquaculture 253 (2006) 322 – 333 www.elsevier.com/locate/aqua-online

Seasonal variation in metabolism of cultured Pacific oyster, Crassostrea gigas, in Sanggou Bay, China
Yuze Mao a,b, Yi Zhou b, Hongsheng Yang b,*, Rucai Wang a
b a Laboratory of Mariculture, Education Ministry of China, Ocean University of China, Qingdao, 266003, PR China Key Laboratory of Marine Ecology and EnvironmentalSciences, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, PR China

Received 10 January 2005; received in revised form 20 May 2005; accepted 24 May 2005

Abstract Rates of respiration and excretion of the Pacific oyster, Crassostrea gigas, were measured seasonally from June 2002 to July 2003 under ambient conditions of food, water temperature, pH, and salinity in SanggouBay, an important mariculture coast in north China. The aim of this study is to obtain fundamental data for further establishing an energy budget model and assessing the carrying capacity for cultivation of C. gigas in north China. Oysters were collected monthly or bimonthly from the integrated culture areas of bivalve and kelp in the bay. Oxygen consumption and ammonium and phosphorus excretionrates were measured, and ratios of O/N and N/P were calculated. One-way ANOVA was applied to determine differences among these parameters that act as a function of seasonal variation. All the physiological parameters yielded highly significant variations with season ( P b 0.01). The rate of respiration varied seasonally, with the highest oxygen consumption rate in July and the lowest rate inJanuary, ranging from 0.07 to 2.13 mg O2 hÀ 1 gÀ 1dry tissue weight (DW). Maximum and minimum ammonium excretion rates were recorded in August and January, respectively, ranging from 0.51 to 5.40 Amol NH4–N hÀ 1gÀ 1 DW. Rates of phosphorus excretion varied from 0.11 (in January) to 0.64 (in July) Amol PO4–P hÀ 1gÀ 1 DW. The O/N and N/P ratios changed from 9.2 (in January) to 59.8 (in July) and from 4.6(in January) to 10.9 (in August), respectively. For each season, the allometric relationship between the physiological response (e.g., rate of oxygen consumption, ammonium and phosphorus excretion) and DW of the animal was estimated using the formula: Y = a  DWb . D 2005 Elsevier B.V. All rights reserved.
Keywords: Seasonal variation; Metabolism; O/N; Pacific oyster; Crassostrea gigas;Aquaculture; Sanggou Bay

1. Introduction Aquaculture has grown rapidly over the last three decades (Wastson and Pauly, 2001; FAO, 2002) and has been largely responsible for the worldwide increase in global aquatic production. According to

* Corresponding author. Tel./fax: +86 532 2898582. E-mail addresses: hshyang@ms.qdio.ac.cn, maoyuze@263.net (H. Yang). 0044-8486/$ - see front matter D 2005 ElsevierB.V. All rights reserved. doi:10.1016/j.aquaculture.2005.05.033

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FAO (2002) statistics, aquaculture’s contribution to global supplies of fish, crustaceans and molluscs continues to grow, increasing from 3.9% of total production by weight in 1970 to 27.3% in 2000. Among them, the total production of molluscs was over 10 Â 106 tons in theworld in 2000 (FAO, 2002). Cultivation of filter-feeding bivalves is one of the potential and sustainable forms of mariculture which can be operated in large scale with no artificial food added, since the animals can get their nutrients from phytoplankton, microphytobenthos and other types of organic detritus (e.g., Cranford and Grant, 1990; Grant, 1999; Scholten and Smaal, 1999; Hawkins et al.,2001). Bivalves play a key role in many coastal ecosystems due to their high filtration capacity and culture density (Smaal et al., 2001; Zhou et al., 2002). Filter-feeding bivalves are the main cultured organisms in China, and their production has developed quickly since the 1980s. In 2000, production was close to 8.6 Â 106 tons, which is 81% of total mariculture production in China (Zhang,...