温度对海带幼孢子体生长和光合作用的影响

The impacts of temperature on growth and photosynthesis of Laminaria japonica juvenile sporophytes

根据欧盟项目的总体研究计划 ,在室内和围隔实验中研究了海带幼孢子体在不同温度条件下的生长情况和光合作用曲线 ,得出幼孢子体在 15°C下生长情况最好 ,而且其长度和重量的日增加量均和温度有线性相关关系。 Pm 值在 15℃时为 5 79mol O2 / (g DW· h) ,围隔实验中为 6 4 2 (mol O2 / (g DW· h)。由于围隔实验海区的光照强于室内 ,使得围隔中海带的光合作用曲线其光饱和点高于室内实验海带的光饱和点。海带光饱和参数 (Ik)与温度有线性相关关系 (R2 =0 .736 7,p<0 .0 5 )。5℃时 ,Ik 值平均为 96μE/ (m2 · s) ,10℃时为 71μE/ (m2 · s) ,15℃时为 31μE/ (m2 · s)。呼吸速率 R值在 5℃时最低 ,为 5 4μmol O2 / (g DW·h) ,10℃、15℃和围隔中均高于 5℃时的呼吸速率 ,并且在 10℃达到最高。本次实验研究得出的生长和光合作用参数将有助于合理确定桑沟湾中海带的养殖容量。

This work is based on an EU project which intends to conduct research work on the carrying capacity for aquaculture and environmental in two semi-enclosed and shallow bays in North China, Jiaozhou Bay and Sanggou Bay. Sanggou Bay is located at 37°01′~37°09′N, 122°2′~122°35′E with an area of about 133km^2, which is fully exploited by aquaculture activities, and 1/3 of the total surface is dedicated to the culture of kelp and shellfish. Kelp grows on ropes in the field from October to April-May. Kelp yield reaches 81000 metric tons in Sanggou Bay in 1994. This species is considered as winter plants, with growth of sporophytes occurring at low temperature during winter and early spring.Accompanying the fast development of aquaculture, some problems have been brought out, such as serious mortality of scallops and perishment of kelps without disease. Therefore, an integrated programme that establishes the limits of carrying capacity and the impacts in terms of temperature conditions, nutrient uptake, biodeposition and food consumption is urgently required for the sustainable development of aquaculture in these alongshore environments. In this paper researches on growth and P/I curves of Laminaria japonica juvenile sporophytes, sampled from Sanggou Bay, were studied by indoor and mesocosm experiments under different temperatures.The equipment for measuring P/I curves was integrated with oxygen monitoring box, oxygen electrode unit DW3, red light source control box LC1, red light source 660 nm, experimental chamber, stirrer, light meter, computer and temperature regulator et al.. After being measured all the parameters were calculated by software, including photosynthesis rate (P_m), light saturated parameter (I_k) and respiration rate (R). The results showed that the growth of juvenile sporophytes was good in 15℃, and the development percent day of length and wet weight were linear with temperature. The P_m value was 579μmol O_2/(g DW·h) at 15℃, and it was 642μmol O_2/((gDW·h)) in mesocosm (14.4℃). The light saturated point of P/I curves in mesocosm experiement was higher than indoor experiment due to the higher outdoor light intensity. There was significant correlation between light satureated parameter (I_k) and temperature. The average I_k was 96, 71, 31μE/(m^2·s) at 5℃, 10℃ and 15℃ respectively. The respiration rate value was 54μmol O_2/(gDW·h) at 5℃, which was lower than that at 10℃ and 15℃. All the parameters of growth and photosynthesis from these experiments, will help to make simulation of the impact of Laminaria japonica culture, and to evaluate the carring capability of Laminaria japonica in Sanggou Bay.