底物颜色和附着物对牡蛎和藤壶自然补充量影响

Effects of substrate colour and fouling organisms on the recruitment of oysters and barnacles:results from field experiment

为检验底物物理特性对牡蛎幼体附着的影响,通过野外实验分别检验了底物颜色(实验I:黑板和白板)、附着物(实验II:近江牡蛎Crassostrea ariakensis、熊本牡蛎C.sikamea、牡蛎壳、藤壶Balanus albicostatus)对熊本牡蛎和藤壶自然补充量的影响。实验I结果显示,底物颜色显著影响牡蛎自然补充量,在实验开始后15 d和30 d时,白板上牡蛎自然补充量显著高于黑板(P<0.05),45 d时白板和黑板间牡蛎自然补充量没有显著差异(P>0.05);底物颜色没有显著影响藤壶自然补充量(P>0.05)。实验II结果显示,活牡蛎(熊本牡蛎或近江牡蛎)或牡蛎壳的存在在第1次实验时(8月15日)显著降低了牡蛎自然补充量(P<0.05),而在第2次实验时(8月22日)没有显著影响牡蛎自然补充量(P>0.05);藤壶的存在显著降低了牡蛎自然补充量(P<0.05)。活体牡蛎、牡蛎壳和藤壶的存在均未显著影响藤壶自然补充量(P>0.05)。研究结果表明,在潮间带牡蛎礁生态修复时,应选择颜色浅且表面干净(没有污损)的底物,且礁体建造须避开高藤壶附着量的地点和时段。

Adequate larvae supply and substrates suitable for larvae settlement are two key factors for successful oyster reef restoration.Oyster settlement and recruitment are influenced by a variety of physiological and external environmental factors,including larval physiological status,temperature,pH,light,hydrology,substrate texture,direction,angle,shape,color and transparency,biofilm,fouling organisms,and the presence of conspecifics.It is highly important to understand the settlement and recruitment of oysters and barnacles for oyster reef restoration.Previous studies have examined the effects of substrate types,new and old shells and substrate size on settlement and recruitment of Crassostrea sikamen.This study examined the effects of substrate color(experimentⅠ:white and black tiles)and fouling organisms(experimentⅡ:Crassostrea ariakensis,C.sikamea,oyster shell and barnacle)on natural recruits of Crassostrea sikamen and barnacle through field experiments at a natural oyster reef of Jiantiao Bay,Zhejiang Province.The experiment I compared the surface temperature and oyster recruits between the black tiles and white tiles with five replicates through field observations.The results of oneway ANOVA showed that the surface temperature on the black tiles was significantly higher than that on the white tiles(q=20.104,P<0.05);the maximum temperature difference between these two tiles reached 4.0℃,with an average difference of(2.5±0.1)℃.Substrate color significantly influenced natural oyster recruits.The white tiles had significantly greater oyster recruits than the black tiles at 15 and 30 d after the initiation of the experiment(P<0.05),but the difference in recruits disappeared at 45 d(P>0.05).The color of substrate did not affect natural recruits of barnacle(P>0.05).The experimentⅡexamined the differences on the natural recruitment of oysters and barnacles among experimental tiles settled by living Crassostrea ariakensis,C.sikamea,oyster shell,living barnacle alone.The results indicated that the presence of live oysters(C.ariakensis or C.sikamea)or oyster shells sometimes did not affect or significantly decreased natural oyster recruits.It was consistent with that the presence of barnacles significantly reduced natural oyster recruits.In contrast,the presence of live oysters,oyster shells and barnacles did not affect natural barnacle recruits on the experimental substrates(P>0.05).The experimental studies found that oyster recruits on the white tiles was significantly higher than those on the black tiles,while barnacle recruits had no difference between these two colored substrates.The presence of live Crassostrea sikamea,live C.ariakensis,and oyster shells did not facilitate the natural recruits of oysters,while barnacles actually inhibited oyster settlement and recruitment.It was found that the fouling organisms had no effect on settlement and recruitment of barnacles.The study concludes that substrates with light color and clean surface without fouling organisms is recommended for oyster reef restoration projects,and the reef should be constructed away from places and times with high barnacle recruitment.