山东荣成海带病害原因的初步调查及分析

Investigation and Analysis of Reason of Diseased Kelp(Saccharina japonica)in Rongcheng,Shandong Province

为了解2021年底荣成沿岸养殖海带(Saccharina japonica)突发大面积病害对海带产生的影响,采用方差分析及判别分析比较研究荣成沿岸4个海区(122°32'~122°40'E,37°08'~37°22'N)海带的形态特征和组织成分含量,并结合海区营养盐浓度分析了可能的致病原因。结果显示,此次海带病害以点状白烂病和绿烂病为主,由荣成湾逐渐向南蔓延,海带平均体长、体宽和鲜重分别为(617.1±310.5)mm、(124.6±70.5)mm和(46.5±44.5)g。成山和俚岛海带主要为点状白烂,叶片颜色较浅,其中受影响较早的成山海带溃烂脱落严重,平均体长、体宽和鲜重分别为(270.3±110.0)mm、(69.3±31.8)mm和(10.8±8.7)g,瓦屋石和寻山海带主要为绿烂,病情较轻。4个海带群体的形态差异显著,综合判别率为94.6%。病害造成了海带色素及可溶性蛋白等组织成分含量的下降,严重发病的成山和俚岛海带与病症最轻的寻山海带相比,叶绿素a含量降低41.3%~54.3%,可溶性蛋白含量降低26.4%~56.0%。调查海区无机氮和活性磷酸盐的浓度较低,分别为(0.045±0.028)mg·L-1和(0.003±0.002)mg·L-1。初步推测,养殖海区贫瘠的营养条件和光照强度的变化,可能是此次病害发生的主要诱因。

Kelp(Saccharina japonica)cultured in the coastal waters of Rongcheng,Shandong Province suffered from a severe disease in a large sea area unexpectedly at the end of 2021,causing very serious losses in the kelp cultivation.In order to investigate the impact of this kelp disease,4 populations of kelp cultured were sampled in the coastal waters of Rongcheng including Chenshan,Lidao,Wawushi and Xunshan(122°32'~122°40'E,37°08'~37°22'N)to compare the differences in morphology and biochemical component content by variance analysis and discriminant analysis.Possible reasons for this kelp disease were discussed with the statistical measurements of the kelp biochemical component content and the seawater nutrients.Observation showed that spot white rot and green rot were the main symptom and the disease spreaded from Rongcheng Bay to southward gradually.The diseased kelp sporophytes in Rongcheng Bay had average body length of(617.1±310.5)mm,body width of(124.6±70.5)mm and fresh body weight of(46.5±44.5)g.The kelp disease in Chengshan and Lidao was mainly spot white rot,with lighter color sporophyte.The kelp in Chengshan affected first and broke off severely with average body length of(270.3±110.0)mm,body width of(69.3±31.8)mm,and fresh body weight of(10.8±8.7)g.The main mild symptom was found to be green rot in Wawushi and Xunshan kelp,with significant difference in morphology in the 4 populations,with the total discrimination accuracy of 94.6%.The disease caused decline in pigment and soluble protein contents in the kelp.Compared with the kelp in Xunshan mild symptom,Chengshan and Lidao kelp decreased by 41.3%~54.3%in chlorophyll a content and 26.4%~56.0%in soluble protein content.The water quality analysis showed that the average concentrations of inorganic nitrogen(0.045±0.028)mg·L-1 and active phosphorus(0.003±0.002)mg·L-1 nutrients in the sea water were low.It is speculated that the poor nutrient environment and the varying illumination intensity caused by the changes in sea transparency maybe the main reason of this kelp disease.