Comparison of intestinal microbiota and activities of digestive and immune-related enzymes of sea cucumber A postichopus japonicus in two habitats

Sea cucumber A postichopus japonicus stock enhancement by releasing hatchery-produced seeds is a management tool used to recover its population under natural environmental conditions. To assess the suitability of releasing sites, we examined the microbiota of the gut contents of A. japonicus from two populations(one in sandy-muddy seagrass beds and one in rocky intertidal reefs) and the microbiota in their surrounding sediments. The activities of digestive and immune-related enzymes in the A. japonicus were also examined. The results indicated that higher bacterial richness and Shannon diversity index were observed in all the seagrass-bed samples. There were significant differences in intestinal and sediment microorganisms between the two habitats, with a 2.87 times higher abundance of Firmicutes in the seagrass bed sediments than that in the reefs. Meanwhile, Bacteroidetes and Actinobacteria were significantly higher abundant in the gut content of A. japonicus from seagrass bed than those from the reefs. In addition, the seagrass-bed samples exhibited a relatively higher abundance of potential probiotics. Principal coordinates analysis and heatmap showed the bacterial communities were classifi ed into two groups corresponding to the two habitat types. Moreover, compared to A. japonicus obtained from rocky intertidal habitat, those obtained from the seagrass bed showed higher lysozyme, superoxide dismutase and protease activities. Our results suggest that bacterial communities present in seagrass beds might enhance the digestive function and immunity of A. japonicus. Therefore, compared with the rocky intertidal reef, seagrass bed seems to be more beneficial for the survival of A. japonicus.     

大气CO2浓度升高对鳗草植株生长的影响

在人工模拟大气CO_2浓度升高的调节系统条件下,研究了4个不同大气CO_2浓度(380×10~(-6)(对照组,当前大气CO_2浓度)、750×10~(-6)(对应21世纪末大气CO_2浓度)、1 900×10~(-6)(对应23世纪末大气CO_2浓度)、变化组(CO_2浓度由380×10~(-6)逐步升高至1 900×10~(-6)))对鳗草(Zostera marina)存活、生长、光合色素含量、过氧化物酶(POD)活力、可溶性糖含量及叶片和茎节气道面积的影响,分析了鳗草植株应对大气CO_2浓度升高的生长响应和生理适应过程。研究显示,经过30 d培育实验,大气CO_2浓度升高对鳗草植株的存活率( 98%)、生产力和叶片光合色素含量等指标无明显影响;大气CO_2浓度升高显著提高了植株叶片延伸率和茎节直径,均在1 900×10~(-6)时达到最大值,分别是对照组的1.4和1.1倍;随大气CO_2浓度升高,鳗草植株的叶绿素a/叶绿素b、可溶性糖含量和气道面积等指标均呈现逐渐升高的趋势,在1 900×10~(-6)时达到最大值,显著高于对照组(P0.05)。研究结果表明,大气CO_2浓度升高对鳗草植株的生长、光合作用、物质代谢和气体交换等生理过程具有促进作用,且CO_2浓度越高促进作用越显著。     

山东荣成马山里海域大型藻类群落结构时空变化研究

山东半岛东端以岩基海岸为主,而浅海多为岩礁底质,适宜大型藻类生长。为探究该海域的大型藻类群落结构特征,于2018年11月(秋)、2019年2月(冬)、5月(春)和8月(夏)对山东荣成马山里海域的3个典型生境(草床区、天然礁区和泥沙区)中的大型藻类进行了调查。结果显示:3种生境共鉴定出大型藻类23种,其中红藻门15属15种,褐藻门3属4种,绿藻门3属4种。物种数最高值出现在天然礁区(22种),最低值出现在泥沙区(12种)。生物量最高值为春季草床区(1 567.44±21.29) g·m^-2、最低值为秋季的泥沙区(594.45±107.06) g·m^-2。大型藻类优势种在不同生境、不同季节不同:草床生境为小珊瑚藻(Corallina pilulifera),在4个季节中均占绝对优势;礁区为绿藻向红藻、褐藻变化;泥沙区为从红藻到褐藻变化。Pielow均匀度指数的最高值在3个生境中相近且均出现在冬季;多样性指数最高值、最低值分别出现在礁区与泥沙区; Margalef丰富度指数的最高值出现在秋季的礁区,而最低值出现在夏季的泥沙区;聚类与排序结果表明,大...     

大叶藻移植方法的研究

为探索适宜的大叶藻(Zostera marina)移植修复方法,2008年10～11月,利用沉子法、枚钉法、直插法、夹苗法和整理箱法,在山东荣成俚岛近岸海域进行了大叶藻移植试验,监测了移植后1个月内大叶藻的生长、存活与渗透压的变化,比较了天然大叶藻和移植大叶藻之间的差异,并分析了移植海区主要环境因子与大叶藻生长与存活之间的关系。结果显示,5种移植方法大叶藻的平均存活率为沉子法(100%)>枚钉法(86.7%)>直插法(66.7%)>夹苗法(20%)>整理箱法(0%);移植大叶藻的平均绝对生长率为沉子法(0.358 cm/d)>直插法(0.242 cm/d)>对照组(0.211 cm/d)>枚钉法(0.083 cm/d)>夹苗法(0.067 cm/d);与天然大叶藻相比,移植后大叶藻根的渗透压显著升高,而茎和叶的渗透压则显著降低(P<0.01);移植后大叶藻的生长与存活和移植海区水流、光照、底质等主要环境因子显著相关。研究结果为研发适宜的低成本大叶藻受损生物群落生态修复技术提供了参考。     

Seasonal variation in species composition and abundance of demersal fish and invertebrates in a Seagrass Natural Reserve on the eastern coast of the Shandong Peninsula,China

Seagrass habitats are structurally complex ecosystems, which support high productivity and biodiversity. In temperate systems the density of seagrass may change seasonally, and this may influence the associated fish and invertebrate community. Little is known about the role of seagrass beds as possible nursery areas for fish and invertebrates in China. To study the functioning of a seagrass habitat in northern China, demersal fish and invertebrates were collected monthly using traps, from February 2009 to January 2010. The density, leaf length and biomass of the dominant seagrass Zostera marina and water temperature were also measured. The study was conducted in a Seagrass Natural Reserve(SNR) on the eastern coast of the Shandong Peninsula, China. A total of 22 fish species and five invertebrate species were recorded over the year. The dominant fish species were Synechogobius ommaturus, Sebastes schlegelii, Pholis fangi, Pagrus major and Hexagrammos otakii and these species accounted for 87% of the total number of fish. The dominant invertebrate species were Charybdis japonica and Octopus variabilis and these accounted for 98% of the total abundance of invertebrates. There was high temporal variation in species composition and abundance. The peak number of fish species occurred in August–October 2009, while the number of individual fish and biomass was highest during November 2009. Invertebrate numbers and biomass was highest in March, April, July and September 2009. Temporal changes in species abundance of fishes and invertebrates corresponded with changes in the shoot density and leaf length of the seagrass, Zostera marina.     

海草植株移植方法的研究进展

海草是世界上最重要的初级生产者之一[1],也是海洋生态系统食物链中的重要一环[2],海草床具有非常复杂的群落结构,它为一些幼鱼和贝类提供重要栖息地及隐蔽保护场所[3],也为一些植食性鱼类、某些水鸟和一些大型动物如海龟(Chelonia my-das)、儒艮(Dugong dugon)等提供觅食场所[4-5]。同时,海草床还可以调节水体中的悬浮物、溶解氧、叶绿素、重金属和营养盐[6],减缓水流速度[7],对浅水水质的净化与底质的巩固发挥着关键作用。此外,海草通过叶片及地下茎将吸收的氮、磷及可溶性有机物等释放到周围环境及水体中,供附生生物及其他生物利用[8]。并有研究表明,海草床在维持全球碳平衡和氮平衡中也起到重要作用[9],碳的固定率几乎可以和热带雨林相比[10]。然而,自20世纪以来,受人类活动频繁加剧的影响,海草床在世界范围内呈现严重衰退趋势,有些地区的海草床甚至已完全消失[8]。据统计,全世界海草的分布面积大约有17.7×104 km2,约相当于海洋面积的0.15%[11]。然而仅1993年至2003年就有大约2.6×104 km2的海草床消失,大约减少了15%[12]。     

Ca2+突变对褐牙鲆幼鱼血清渗透压和组织离子转运酶活力的影响

研究了Ca2+由自然海水浓度突变到低浓度和高浓度时,褐牙鲆(Paralichthys olivaceus)幼鱼渗透调节能力的变化。通过测定实验鱼的血清渗透压、鳃、肠、肾Na+-K+-ATPase和Ca2+-ATPase活力及血清离子含量的变化,探讨了褐牙鲆幼鱼应对水体Ca2+突变时的渗透调节机制。结果表明,海水盐度不变,Ca2+浓度在1.25～100mmol.L-1之间发生突变时,褐牙鲆幼鱼血清渗透压无显著变化,其主要通过调节鳃、肠、肾Na+-K+-ATPase和Ca2+-ATPase活力及改变血清Ca2+和Mg2+含量来维持体液离子的动态平衡。