Stability analysis of reef fish communities based on symbiotic graph model

The community stability of coral reefs and fish is the focus of ecological monitoring of coral reefs.Among them,the realization of effective metrics of variations in reef fish communities(i.e.,the combined communities of coral reefs and fish)is important for analyzing the stability of communities as well as maintaining the ecological balance of coral reefs.Based on coral reef and fish data collected at St.John’s Island from 2004 to 2010,this study proposes a symbiotic graph modeling method to express the biological relationships of reef fish communities,and a Pyramid Match graph kernel method for fusing Attributes(PMA)to quantify community fluctuations to measure interannual variability of communities.The results showed that the community similarity was low in 2006,2007,and 2008.The total coral cover rate in the study area decreased by 32.04% from 2006 to 2007 and increased by 24% in 2008.The total number of fish fell from 3780 in 2006 to 2596 in 2007 and rose to 6249 in 2008.Among them,the proportion of herbivorous fish decreased to 30.84% in 2007.Furthermore,we have combined the Louvain algorithm with the proposed PMA method to effectively identify the regions that should be prioritized for protection.Experiments were conducted on real datasets with good results,demonstrating the potential of the proposed method to assist in the analysis of community stability and identification of priority conservation areas.

Species composition and succession of coral reef fishes in Huaguang Reef,Xisha Islands

A list of coral reef fish species of Huaguang Reef was compiled in 2023 using hand fishing,diving fishing,underwater video,and eDNA detection,combined with historical data from 1979 and archival records from the South China Sea Fisheries Research Institute of the Chinese Academy of Fisheries Sciences for the years of 1998,1999,2003,and 2005.Successional characteristics of coral reef fishes through time were also explored.The findings revealed:(1)A total of 299 coral reef fish species were identified in Huaguang Reef,categorized into 2 classes,16 orders,and 56 families,with Perciformes exhibiting the highest species count(234),constituting 78.26%of all species.(2)In comparison to the period of 1979–2005,there was a reduction in the number of species at the order and family levels in 2023 at Huaguang Reef.Both the average taxonomic distinctness(Δt)and the variation in taxonomic distinctness(Λt)exhibited a declining trend,indicating disturbances in the fish ecosystem.(3)The proportion of herbivorous fish at Huaguang Reef remained relatively stable in 2023 compared to the 1979–2005 period.Notably,the similarity coefficient of herbivorous fish was the highest among different feeding types,signifying a degraded state of the Huaguang Reef habitat.(4)In contrast to the 1979–2005 period,a significant decline was observed in large-sized and carnivorous fish species at Huaguang Reef in 2023.The low similarity coefficients for both categories,with undiscovered fish species accounting for 58.49%and 45.76%of their respective taxa in the total list,respectively,suggested a notable impact of overfishing on coral reef fishes.The succession patterns revealed in this study provide a theoretical foundation for advancing the sustainable development of coral reef fish resources in the Xisha Islands and offer valuable insights for the protection and management of coral reef fishes.

Spawning ascent durations of pelagic spawning reef fishes

Predation risks have been hypothesized to influence spawning behaviors of coral reef fishes that broadcast gametes pelagically. The duration of spawning ascents of 13 species were measured from video footage at a single spawning site for mul- tiple coral reef fishes to investigate ff this behavior was influenced by varying risks of predation. Fishes that spawned in pairs had as- cents of longer duration than group-spawning species. Duration of spawning ascents did not vary between fishes spawning at daytime and dusk, nor between group-spawning species with specific anti-predatory morphological adaptations. These results indicate that risk of predation may not significantly influence the duration of spawning ascents of pair spawning reef fishes at our study site, while group-spawning behaviors are influenced by predation. Avoidance of egg predation by benthic organisms and female mate choice are more likely to influence the pelagic spawning behaviors of all fishes observed [Current Zoology 58 （1）： 95-102, 2012].

Application of hydroacoustics to investigate the distribution,diel movement,and abundance of fish on Zhubi Reef,Nansha Islands,South China Sea

A combination of traditional fish sampling methods(hand-line and gill net) and modern hydroacoustic techniques were used to study fish community structure,distribution,and diel movements of fish on Zhubi Reef to enhance understanding of the ecosystem.We collected 126 individuals from 29 species,20 genera,17 families,three orders,and two classes using traditional gear.Perciforms were the dominant group in terms of species richness and biomass.The acoustic data indicated that very small(target strength[TS],dB) <-60 dB) and small(-60 dB≤TS<-45 dB) fish contributed the most to abundance and species richness on the coral reef,and that the proportion of medium-sized(-45 dB≤TS<-35 dB) and largesized(-35 dB≤TS) fish increased gradually as depth increased.The single-target detection method revealed two distinct size classes during the day in the 12-16 and 16-20-m layers.One group consisted of very smallsized fish(TS<-60 dB) and the other consisted of medium and large-sized fish(TS>-55 dB).The number of single-target detections was significantly higher during the night than during the day(P<0.05).The singletarget TS frequency distribution during the day was significantly different than during the night at depths of4-8,8-12,12-16,and 16-20 m.Significant differences were observed among the 4-8,8-12,12-16,and16-20-m-depth layers during day and night.Diel vertical movement was evidenced as fish began to spread and move upward just before sunset and began to assemble and descend shortly(15 min) after sunrise.

Mooring Tension and Motion Characteristics of A Submerged Fish Reef with Net in Waves and Currents Using Numerical Analysis

A numerical model was used to analyze the motion response and mooring tension of a submerged fish reef system. The system included a net attached to a rigid structure suspended up from the bottom with a single, high tension mooring by fixed flotation. The analysis was performed by using a Morison equation type finite element model configured with truss elements. Input forcing parameters into the model consisted of both regular and irregular waves, with and without a steady current. Heave, surge and pitch dynamic calculations of the reef structure were made. Tension response results of the attached mooring line were also computed. Results were analyzed in both the time and frequency domain in which appropriate, linear transfer functions were calculated. The influence of the current was more evident in the tension and heave motion response data. This is most likely the result of the large buoyancy characteristics of the reef structure and the length of the mooting cable. Maximum mooting component tension was found to be 13.9 kN and occurred when the reef was subjected to irregular waves with a co-linear current of 1.0 m/s velocity. The results also showed that the system had little damping （in heave） with damped natural periods of 2.8 s. This combination of system characteristics promotes a possible resonating situation in typical open sea conditions with similar wave periods.

Evaluation on Fishery Resources in Daxingshan Artificial Reef Area of Huidong County

In order to evaluate placement of artificial reefs in Huidong County and observe biological aggregating effect of fishery resources,background investigation and follow-up investigation were carried out for trawl fishing and gill-net fishing in Daxingshan artificial reef area.The biological resource density index(D),Margalef species richness index(R),Shannon-Winener diversity index(H'),and Pileou evenness index(J')were used to study diversity of water biological population and resource density.Trawl fishing investigation indicated that after placement of reefs,there was significant increase in quantity of species of nekton,total resource density,species richness index,and diversity index in reef area,which were 1.321,2.07,1.012 and 1.084 times the value before placement of reefs respectively.Gill-net fishing investigation indicated that after placement of reefs,the quantity of species of nekton,total resource density,species richness index,and diversity index in reef area were 2.571,7.976,2.399 and 2.667 times the value before placement of reefs respectively.After reef placement,fishes and crabs become dominant population.It showed that after reef placement,attraction effect of fishes is significant,community structure is obviously optimized,and water environment in reef area is significantly improved.Thus,it proved that the multiplication system through artificial reefs has been basically established in Daxingshan reef area of Huidong County.

西沙群岛玉琢礁珊瑚礁鱼类种类组成及演变

玉琢礁是西沙群岛中的重要环礁,拥有多样化的珊瑚礁生态系统和丰富的鱼类资源。为掌握玉琢礁珊瑚礁鱼类的资源状况及其演变特征,于2023年采用手钓、水下潜捕、水下视频和eDNA等方法,对其珊瑚礁鱼类资源进行调查。共发现鱼类220种,其中eDNA方法共发现鱼类111种,结合2003年中国水产科学研究院南海水产研究所的历史档案数据,截至目前在玉琢礁共发现鱼类265种,隶属于12目50科128属,其中鲈形目占绝对优势。鱼类群落组成以小型鱼类为主,平均分类差异指数(Δ^(+))和变异分类差异指数(Λ^(+))分别为56.08和122.4;相似性分析表明,2003与2023年之间,鱼类在种类组成、食性组成和不同体型层面的相似性均表现为不相似或极不相似。与历史调查数据进行比较,共有45种鱼类未被监测到,其中大型肉食性鱼类受到自然与人类扰动的影响最为显著,植食性鱼类所受到的影响相对较小,分类多样性指数(Δ^(+)、Λ^(+))显著下降。初步推断不可持续的捕捞、生境衰退和温度上升等因素导致了玉琢礁珊瑚礁鱼类的更替。研究结果可为玉琢礁的珊瑚礁鱼类资源保护与管理、珊瑚礁生态系统的恢复提供参考。

基于灰色-马尔科夫模型评估石雀滩海洋牧场岩礁鱼类碳储量

本研究以石雀滩海洋牧场许氏平鲉(Sebastes schlegelii)、大泷六线鱼(Hexagrammos otakii)、褐菖鲉(Sebasticus marmoratus)、铠平鲉(Sebastes hubbsi)、厚头平鲉(Sebastes pachycephalus)等岩礁鱼类为研究对象,基于2017—2020年地笼网采捕的渔获量数据,采用元素分析法和灰色-马尔科夫模型,统计并预测了岩礁鱼类现存生物量的碳储量(以下简称岩礁鱼类碳储量)。结果显示,岩礁鱼类干样碳含量分布范围为42.95%~50.19%,平均值为(46.11±2.34)%;鲜样碳含量分布范围为11.05%~13.25%,平均值为12.30%。2017年春季、2018年冬季、2019年春季和2020年冬季鱼礁区岩礁鱼类碳储量分别为293.46、104.49、119.40和48.48 t,呈波动式下降趋势;对照区分别为21.64、59.07、6.73和0 t,呈先上升后下降的趋势。灰色-马尔科夫模型验证数据平均相对误差为8%,较GM(1,1)模型预测精度提升了12%。经预测,鱼礁区岩礁鱼类碳储量呈下降趋势,2021年春季、2022年冬季、2023年春季和2024年冬季分别为64.84、49.84、25.28和19.43t。研究结果可为评估岩礁鱼类碳汇潜力提供依据,为建立渔业碳汇基础上的海洋牧场岩礁鱼类资源开发策略提供科学参考。

西沙群岛北礁珊瑚礁鱼类种类组成及变化特征

西沙群岛北礁的珊瑚礁鱼类由于受到人类扰动和气候变化等影响,其渔业资源发生了明显变化。在西沙群岛北礁开展鱼类资源调查,综合历史数据,分析北礁鱼类物种组成及其变化特征。截止2023年4月在北礁共发现鱼类270种,隶属于12目49科121属,其中鲈形目(Perciformes)种类最多,为212种,占总物种数的78.52%。北礁珊瑚礁鱼类群落结构较历史发生明显改变。大型鱼和肉食性鱼类的物种数量明显减少,未采集到比例分别为43%和27%,属于不同体型和食性分组中的最高值。并且与历史相比相似度均小于0.25,为极不相似。鱼类组成平均分类差异指数(Delta+)和变异分类差异指数(Lambda+)均明显下降,由1998—2003年的56.72和163.8降为2023年的54.57和107.6。同时,鱼类目、科和属与种类数的比例明显下降,分别减少了48.21%、34.67%和15.45%。另外,不同时期鱼类物种组成目、科、属、种的相似性分别是0.50、0.37、0.23和0.10,为不相似和极不相似。研究结果显示,北礁珊瑚礁鱼类已经发生了由肉食性向植食性、大型鱼向小型鱼和复杂性向简单性的演变趋势。该研究有助于更好地掌握和预测北礁珊瑚礁鱼类的物种组成和演变趋势,对于确保珊瑚礁生态系统的健康和恢复具有重要意义。

西沙群岛10种鹦嘴鱼鱼体形态学研究

为探究鹦嘴鱼鱼体形态的主要种间差异及其在物种鉴别中的重要作用,于2019—2022年在西沙群岛海域采集到10种鹦嘴鱼,选取24个形态学性状对其进行测量,采用多元分析方法对鹦嘴鱼物种进行形态差异判别分析。单因素方差分析结果表明,鹦嘴鱼种间所有形态学指标均存在显著性差异(P<0.05);主成分分析提取了7个特征值大于1的形态学指标,累积方差贡献率为66.86%,各物种间的形态差异主要表现在反映食性和游泳能力的特征上;采用判别分析方法对所有鹦嘴鱼样本进行判别,综合判别率为81.1%;10种鹦嘴鱼的形态学聚类结果与鱼类分类结果一致,与已有研究的进化树结果差异显著,说明鹦嘴鱼的表型特征除了受遗传因素控制外,也会受环境因素影响。

西沙海域长棘海星潜在鱼类捕食者鉴定

长棘海星的暴发对我国乃至印度−太平洋海域的珊瑚礁造成了严重的破坏。鱼类捕食者被认为是控制长棘海星种群暴发的重要因素,但我国对于可捕食长棘海星的鱼类的研究尚属空白。通过采集西沙5个长棘海星暴发礁区的珊瑚礁鱼类,利用PCR技术检测了鱼肠道内容物中的长棘海星DNA,并与已报道的长棘海星鱼类捕食者进行了比较分析。结果显示,本次调查共捕获了62尾鱼,共23科36属50种。在4种鱼的肠道内容物中检测到长棘海星DNA,分别是颊吻鼻鱼(Naso lituratus)、网纹宅泥鱼(Dascyllus reticulatus)、三叶唇鱼(Cheilinus trilobatus)和赤鳍裸颊鲷(Lethrinus erythropterus)。其中颊吻鼻鱼、三叶唇鱼和赤鳍裸颊鲷为首次报道的长棘海星潜在捕食者。本研究首次鉴定了我国长棘海星潜在鱼类捕食者种类,为开发长棘海星早期防控技术提供了重要参考。

西沙群岛银屿珊瑚礁的生态快速退化及其对鱼类的影响

珊瑚礁生态系统退化能够改变珊瑚礁三维结构的复杂性及底栖生物组成,从而对珊瑚礁鱼类群落产生重要影响。南海珊瑚礁在近几十年来处于快速退化之中,但其退化对珊瑚礁鱼类群落造成的生态影响仍不清楚。西沙群岛珊瑚礁近年受高温和长棘海星暴发等的影响而出现生态退化,因此,本文以西沙群岛银屿珊瑚礁为研究对象,通过水下录像样带调查和差异性检验、线性回归评估其珊瑚礁生态退化状况及其对珊瑚礁鱼类群落的影响。结果表明:2020至2021年,银屿活珊瑚覆盖率从33.27%下降到9.07%,草皮海藻覆盖率从8.38%上升到36.50%,珊瑚补充量从21.42ind.·m^(−2)下降到3.64ind.·m^(−2),珊瑚物种丰富度从40.00下降到16.83,珊瑚Shannon-Weaner指数从3.26下降到2.14。鱼类密度从177.16ind·100m−2下降到105.07ind.·100m^(−2),鱼类物种丰富度从30.56下降到17.17,鱼类Shannon-Weaner指数从2.24下降到1.63,珊瑚食性鱼类生物量从2.45g·m^(−2)减少到0.43g·m^(−2),肉食性鱼类生物量从7.35g·m^(−2)减少到1.70g·m^(−2),杂食性鱼类生物量从7.04g·m^(−2)减少到0.95g·m^(−2),鱼类总生物量从32.99g·m^(−2)减少到11.66g·m^(−2)。短短2年内,银屿珊瑚礁已经被草皮海藻和大型海藻占据优势,但是鱼类群落对珊瑚礁区的藻类并没有表现出自上而下的控制效应。在4种类群的鱼类中,植食性鱼类受到生态退化的影响最小。珊瑚礁鱼类的物种丰富度和多样性均受限于珊瑚物种丰富度。基于以上结果,推测银屿珊瑚礁的快速退化是导致珊瑚礁区鱼类群落物种多样性和密度下降,改变珊瑚礁鱼类群落的结构的主要原因。希望未来进一步增加调查的频率和范围,以便更深入地揭示鱼类群落与珊瑚礁生态变化的动态关系。

一种刺参增殖礁结构设计及流场效应研究

人工鱼礁是一种设置在水中的人工构筑物,通过人工鱼礁的建设,能够为鱼类等水生生物营造良好的生态环境,从而达到保护和增殖渔业资源的目的。根据刺参自身特点和生长习性,设计一种刺参增殖礁作为人工附着基,通过对刺参增殖礁的水动力学试验,分析刺参增殖礁单体结构对礁体周围流场效应的影响,得出在相同入流速度的情况下刺参增殖礁的受力情况;根据模拟结果,计算出刺参增殖礁上升流体积和背涡流体积,同时对刺参增殖鱼礁单体稳定性进行探讨。结果表明:刺参增殖鱼礁,由于孔径小、间隙密,上升流区和背涡流区的体积均较大。当入流流速为0.5 m/s时,刺参增殖鱼礁抗滑移系数和抗倾覆系数均大于1,表明其具有良好的安全性能。运用水动力模型模拟鱼礁区的流场效应,优化鱼礁结构设计,促进鱼礁的生物诱集和增殖效应最大化,可以为鱼礁区的建设提供理论指导和技术支持。

枸杞岛筏式贻贝养殖海域鱼类群聚特征

为探究筏式贻贝养殖生境鱼类资源养护功能,于2020年9-12月对枸杞岛筏式贻贝养殖生境(分表层区和底层区)及周边岩礁生境的鱼类进行了多网目组合刺网采样。应用相对重要性指数IRI、多样性指数并结合等级聚类、非度量多维标度排序(nMDS)分析鱼类组成和群落结构。结果显示,在2种生境中共采集鱼类55种,隶属于10目34科47属,其中贻贝养殖生境采集到37种(底层和表层分别为29和20种);岩礁生境共采集到40种。在鱼类组成上,中国花鲈和鲻是贻贝养殖生境表层区的典型优势种,而黄姑鱼和褐菖鲉是贻贝养殖生境底层区的典型优势种;褐菖鲉同时也是岩礁生境的典型优势种。多样性分析表明,贻贝养殖生境的总体鱼类多样性要高于岩礁生境,但尚不显著。多元分析显示,各月份2种生境中的鱼类群落格局均可分为3种类型,虽与养殖表层区、养殖底层区和岩礁区并非严格一致,但各群落间差异依然显著。研究表明,大规模筏式养殖设施的存在吸引了众多中上层鱼类及底层鱼类,也为岩礁生境优势鱼类提供了额外的栖息环境,发挥了近似于浮鱼礁系统的资源养护作用。研究结果可为岛礁海域海洋牧场目标种的选择和人工生境构建模式的应用提供重要参考。

钢渣在生态型人工渔礁中的应用技术

本项目利用建筑垃圾、钢渣等固废材料,不仅可以大力改善人工鱼礁的性能,还可以突破固废材料利用率低的技术瓶颈,实现大宗固废材料的高效资源化利用。利用建筑垃圾、钢渣等固废材料协同制备生态混凝土人工鱼礁,是一个全新的研究方向。本项目的研究方向和研究方法在本行业具有一定的创新性和前瞻性。

基于DNA条形码技术的徐闻角尾海域夏、秋季仔稚鱼鉴定研究

采用DNA条形码技术的标准COⅠ基因片段作为DNA条形码,对徐闻角尾珊瑚礁海域夏、秋季仔稚鱼进行分子鉴定,并探讨其在鱼类早期阶段物种鉴定的适用性。本研究共获得199条仔稚鱼样品COⅠ序列,其中有69个序列鉴定到种水平、110个序列鉴定到目、科、属水平。本研究共成功鉴定了32个类群,隶属6目19科20属,其中17个类群鉴定到种的水平,5个类群鉴定到属的水平,9个类群鉴定到科的水平,1个类群鉴定到目的水平,另有9个类群未能鉴定。在科级水平上,虾虎鱼科种类和数量最多,种类数占比为17.07%,数量占比为31.16%;其次为鲾科,种类数占比为7.31%,数量占比为8.04%。以上研究结果表明,依据DNA条形码技术鉴定徐闻珊瑚礁海域的仔稚鱼,鉴定到种的水平比例偏低,成鱼DNA条形码序列的缺乏是一个重要因素。因此,亟需构建本海域分布的鱼类DNA条形码数据库,并结合传统形态学方法,以便更加准确地鉴定仔稚鱼物种。

天津市大神堂海洋牧场海域人工鱼礁区声学初步调查

人工鱼礁是一种设置在水中的人工构筑物,能够为鱼类等水生生物的栖息、生长和繁殖提供必要和安全的场所,达到保护增殖生物资源和修复栖息地的目的。在鱼礁建设阶段和完成的评估工作中,传统方法难以对大规模的人工鱼礁形成宏观监测。本研究利用侧扫声呐、多波束测深、差分GPS信标机空间定位和GIS软件数字化相结合的声学方法,开展了天津大神堂海洋牧场人工鱼礁区声学调查,解决了常规方法无法在水下对人工鱼礁进行监测的难题,首次在天津大神堂海洋牧场海域获得了人工鱼礁的空间分布细节信息。结果表明:人工鱼礁的分布比较密集,保存现状较好,大多数礁体呈现竖置状态,位于海床表面以上;全部位于海洋牧场既定范围之内,未发生迁移;人工鱼礁对牡蛎的增殖效果非常明显,验证了人工鱼礁建设对牡蛎礁的修复作用。侧扫声呐和多波束测深等综合声学技术解决了在浅滩淤泥质海域水体能见度低难以开展大规模的人工鱼礁精准监测等难题,是海洋牧场建设效果评估方法的补充与完善。研究成果可有效应用于渤海湾海洋牧场建设效果评估。

永兴岛附近海域珊瑚礁鱼类群落结构特征

为更好地保护和管理西沙永兴岛附近海域珊瑚礁鱼类,于2020—2021年对永兴岛上岸渔获物进行了调查研究,分析了鱼类群落结构组成及其变化和演替特征。结果表明:调查共发现永兴岛附近海域珊瑚礁鱼类101种,隶属于5目21科,以鲈形目鱼类最多,占总种类的84.16%,生物量超总渔获物的90%;科级水平鹦嘴鱼科鱼类最多,达21种,生物量超总渔获物的45%。28种珊瑚礁鱼类是永兴岛附近海域主要捕捞对象,占总渔获物的80%以上。永兴岛附近海域珊瑚礁鱼类呈现过度捕捞,一是主要渔获物中的中大型鱼类均重偏小;二是本海域个体体型最大的鱼类出现较多消亡;三是肉食性鱼类大量消亡;四是植食性鱼类生物量占比超过了肉食性鱼类。永兴岛附近海域珊瑚礁鱼类已经演替到以植食性鱼类为主导的生态系统;大量海胆的出现,表明了这一珊瑚礁生态系统在进一步衰退,向以海胆为主导的生态系统演变。保护西沙永兴岛附近海域珊瑚礁鱼类已经刻不容缓,需要严格地控制本海域的捕捞强度。

秋季涠洲岛珊瑚礁主要鱼类营养关系的初步研究

本研究利用碳、氮稳定同位素(δ^(13)C、δ^(15)N)技术,估算了秋季涠洲岛珊瑚礁主要鱼类的营养级(TL)和主要碳源,结合6个群落营养结构量化指标,初步分析秋季涠洲岛珊瑚礁主要鱼类的营养关系。结果表明,不同鱼类之间的δ^(13)C和δ^(15)N值差异显著(p<0.01),其中,δ^(13)C值介于-18.3‰~-15.4‰,δ^(15)N值介于12.9‰~16.3‰。鱼类TL介于2.5~3.4,平均TL为3.0±0.8,显示涠洲岛的鱼类以肉食性为主。涠洲岛鱼类的有机碳源比较复杂,但大型海藻和底栖微藻是驱动鱼类食物网的关键碳源。鱼类群落的食源多样性水平和营养级长度(CR和NR)分别为2.35和3.09。凸多边形总面积(TA)、平均离心距离(CD)、平均最近相邻距离(MNND)和最近相邻距离的标准差(SDNND)分别为4.48、0.89、0.40和0.29,表明涠洲岛珊瑚礁鱼类群落的营养结构具有营养冗余程度较高,但食物链较短和营养多样性低等特征。以上结果表明,涠洲岛珊瑚礁生态系统食物网结构不完整,未来有必要开展适当的管控和修复措施恢复涠洲岛珊瑚礁生态系统的结构和功能。