海南西岛珊瑚群落变化及其影响因素 *

在2018年的海南三亚西岛珊瑚群落分布和水质环境因子调查中, 共记录到造礁石珊瑚68种, 多孔螅2种。基于珊瑚礁底质类型的非度量多维标度分析, 可将西岛站位划分为区域1(东-南侧)和区域2(西侧)。全岛活珊瑚覆盖率为13.6%, 区域1和区域2分别为4.2%和27.7%, 区域2珊瑚多样性高于区域1。区域1珊瑚礁处在显著退化状态, 而区域2相对健康, 但是优势种类单一。与历史资料对比分析, 东侧站位造礁石珊瑚覆盖率从2011年的近40%降至2018年不足4%, 退化显著, 而西侧站位珊瑚礁无明显退化; 丛生盔形珊瑚(Galaxea fascicularis)逐渐取代分枝状的鹿角珊瑚成为绝对优势种类; 珊瑚礁区浊度、溶解无机氮(dissolved inorganic nitrogen, DIN)和喇叭藻的δ¹⁵N均值分别为2.54NTU、9.63μmol·L^-1和5.09‰, 均处在较高水平。相关性分析表明, 环境因子的空间变化并不能解释珊瑚群落的空间分布。因此, 推测人类活动引起的极端扰动事件可能是导致西岛珊瑚群落空间分布和东侧站位珊瑚近几年显著退化的主要原因, 如三亚河清淤在三亚湾随意倾倒引起的浑浊事件。应加强对三亚湾清淤和西岛人类活动的管控, 减轻颗粒物沉积和营养盐富集的影响, 促进西岛珊瑚礁逐渐恢复。     

环境DNA分析大亚湾夜光藻藻华对真核浮游生物群落的影响*

夜光藻是全球广泛分布的藻华种之一, 其摄食作用对浮游生物的群落结构有着重要影响。利用环境DNA技术和Spearman相关性分析, 文章研究了2021年1月中旬大亚湾夜光藻高丰度站位浮游生物的群落结构与生物相关性。结果显示, 夜光藻高丰度站位的海水温盐条件为温度 14.4~18.3℃、盐度 32.52‰~33.14‰。夜光藻丰度较高的站位中, 卡顿藻科、海链藻科等浮游植物类群的相对丰度均值为2.41%和2.23%, 明显高于其他站位的0.75%和0.62%; 同时拟哲水蚤科与长腹剑水蚤科等类群的相对丰度均值为8.22%和4.46%, 明显低于其他站位的64.13%和11.12%。结合Spearman相关性分析表明, 夜光藻丰度增加可能导致其对拟哲水蚤科等类群摄食压力增加, 拟哲水蚤科类群丰度减少降低了卡顿藻科、海链藻科、原甲藻科、隐芽藻科等浮游植物类群的摄食压力, 使其生物丰度增加; 同时夜光藻摄食压力增加使得裸甲藻科、圆筛藻科等浮游植物丰度下降。因此, 夜光藻丰度增加影响了水域中真核浮游生物群落结构。综上结果表明, 环境DNA技术有助于认识夜光藻在浮游生物群落中的生态地位, 可用于浮游生物各类群之间的关系分析。     

三亚红塘湾珊瑚礁生态状况研究

为研究三亚红塘湾珊瑚礁生态系统现状,采用人工潜水调查方法开展三亚红塘湾造礁石珊瑚分布及生态状况调查。本次调查共发现三亚红塘湾造礁石珊瑚分布总面积为149.25 hm~2;种类包括8科17属28种,主要优势种为二异角孔珊瑚(Goniopora duofasciata),珊瑚覆盖率14.3%,硬珊瑚补充量为1.34 ind·m~(-2);水质总体良好,但有50%站位溶解氧含量超一类海水水质标准,且部分站位悬浮物含量较高;珊瑚礁区底质以礁石为主,但泥沙沉降物覆盖严重,覆盖率高达60.8%。调查结果表明,红塘湾珊瑚礁生态系统出现严重退化,悬浮物含量较高和沉降物覆盖严重是制约红塘湾造礁石珊瑚正常生长发育的主要因素。     

2012年春季渤海湾天津近岸海域网采浮游植物群落结构初探

于2012年春季(5月)调查了渤海湾天津近岸海域的网采浮游植物群落,经初步分析发现网采浮游植物共2门17属28种,其中硅藻26种,占种类组成的92.9%;甲藻2种,占种类组成的7.1%。调查海域浮游植物以广温型近岸种为主,主要优势种为柔弱几内亚藻Guinardia delicatula、中华齿状藻Odontella sinensis、布氏双尾藻Ditylum brightwellii和格氏圆筛藻Coscinodiscus granii;调查海域网采浮游植物细胞丰度的分布主要由浮游硅藻的分布所决定,高值区主要分布在塘沽、大港和歧口周围海域;20个站位根据浮游植物的物种及丰度相似性可以划分为5组;浮游植物物种多样性指数在0.43～3.59之间,平均为2.15,多样性指数出现由南、北向中央逐渐缩小的趋势;水温、DO、pH值和无机氮与浮游植物种类组成和细胞丰度分布呈最大等级相关,这4个环境因子是对观察到的群落结构的最好解释。     

海南岛三亚珊瑚礁区大型底栖动物群落特征

为了解海南省三亚市3个典型珊瑚礁区的底栖生物群落现状,并依此反映该区域珊瑚礁生态系统的健康现状和受扰动程度,作者于2011年11月22日~23日在海南岛三亚西岛、鹿回头和亚龙湾3个珊瑚礁自然保护区内采用潜水方法采集底栖动物,并对分析群落的物种组成、优势类群、丰度、生物量、Shannon-Wiener指数、物种丰富度指数和物种均匀度指数以及生物量/丰度比较曲线特征等进行研究。结果共获得三亚珊瑚礁大型底栖动物166种,优势类群为甲壳动物,优势种为珊瑚铠甲虾(Galathea coralliophilus)。调查区底栖动物平均栖息丰度为566.29个/m2,平均生物量为82.146 g/m2;Shannon-Wiener指数、物种丰富度指数和均匀度指数的平均值分别为3.0581、7.9116和0.8494。其中亚龙湾的上述3项指数均高于其他两个采样地点。生物量/丰度比较曲线表明亚龙湾的底栖群落最稳定,受扰动程度最小。     

2013年夏季北黄海浮游植物群集

利用Utermöhl方法,对2013年夏季取得的北黄海浮游植物样品进行鉴定分析,共鉴定出浮游植物3门60属114种(不包括未定名种),其中,硅藻42属75种,甲藻16属37种,金藻2属2种。群落组成以硅藻为主,其次是甲藻,然后是金藻。调查海区浮游植物的生态类型以温带近岸性为主,主要优势种为:小等刺硅鞭藻 Dictyocha fibula、裸甲藻 Gymnodinium sp.、螺旋环沟藻 Gyrodinium spirale、蜂腰双壁藻 Diploneis bombus 和具槽帕拉藻 Paralia sulcata。浮游植物细胞丰度介于0.037 0 × 10³ ～ 32.3 × 10³ cells·L^-1,平均值为2.04 × 10³ cells·L^-1;浮游植物细胞丰度大致从近岸到外海呈逐步降低趋势,在北黄海西部近岸的表层水体达到最高值32.3 × 10³ cells·L^-1,调查区东南部靠近外海区域也出现了丰度高值区;浮游植物垂直分布总体特征是随水深的增加而减少,由近岸向外海逐步降低。香农-威纳多样性指数在调查区西南部较高,而Pielou均匀度指数则在东部呈现高值区域。典范对应分析(CCA)显示,影响浮游植物优势种丰度分布的主要因素是营养盐,而跟盐度和温度的相关性不明显。     

北部湾涠洲岛珊瑚礁底栖贝类的群落特征

珊瑚礁是全球生物多样性最高的海洋生态系统之一,底栖贝类是该生态系统的重要组成类群。为了解北部湾涠洲岛珊瑚礁底栖贝类的群落现状及特征,于2015年秋季(10月)与2018年春季(5月)采用水肺潜水截线样条定量调查法对涠洲岛珊瑚礁区6个断面的底栖贝类进行了调查,并分析了物种组成、丰度、生物多样性指数等群落特征。综合两次调查结果显示涠洲岛珊瑚礁区共有底栖贝类128种,分别属于多板纲1科1属3种,腹足纲25科46属68种,双壳纲22科31属57种。优势种为斑顶拟舌骨牡蛎、粗衣蛤、刺荔枝螺、马蹄螺、杂色牙螺、青蚶、旗江珧、甲虫螺、蕾丝蟹守螺、珠母爱尔螺。2018年春季定量断面采集到的样品为2纲14科43种,各断面的丰度、生物量、多样性指数、物种丰度指数和均匀度指数均值分别为3.39个/m2、86.94 g/m2、3.31、3.50、0.37。通过对两年的调查数据比较,发现2015?2018年涠洲岛珊瑚礁区的贝类生物群落呈现良好演替发育趋势。南海珊瑚礁区贝类群落结构可能受到了人为干扰强度和纬度的双重影响。本研究全面掌握了涠洲岛珊瑚礁底栖贝类的种类、分布区及群落的结构与变化,可为该地区海洋生物资源开发利用、珊瑚礁保护和生态修复等工作提供数据支持。     

2009 年春季辽东湾网采浮游植物群落结构

分析了2009 年春季(5 月)渤海辽东湾网采浮游植物物种组成, 丰度分布, 生物多样性指数及群落相似性。春季共鉴定出浮游植物3 门23 属32 种, 主要隶属硅藻门和甲藻门, 生态类型多为温带近岸型和广布型种类, 少部分为暖海性物种或大洋性物种。优势种有夜光藻(Noctiluca scientillans)、翼鼻状藻(Proboscia alata)、旋链角毛藻(Chaetoceros curvisetus)、巨圆筛藻(Coscinodiscus gigas)和尖刺伪菱形藻(Pseudo-nitzschia pungens)等。浮游植物在各站位的细胞丰度分布不均匀, 其平面分布呈现由沿岸海域向海湾中部海域递减的趋势。Shannon-Wiener 指数、Pielou 指数较低, 群落结构简单, 稳定性较差。聚类分析结果表明群落之间的相似性较高。     

海水酸化和升温对孔石藻（Porolithon onkodes）共附生细菌及其诱导珊瑚幼虫附着的影响

珊瑚藻是珊瑚礁生态系统中一类主要的钙化生物,不仅能够构建、稳固礁体,而且与造礁石珊瑚关系密切,其对造礁石珊瑚幼虫附着的促进作用是退化石珊瑚群落恢复的关键。但是,面对未来气候变化,珊瑚藻对珊瑚幼虫的诱导作用会如何响应,以及该过程是否与藻体共附生细菌群落有关,目前尚不清楚。本文选取了广泛分布于我国南海珊瑚礁生态系统中的孔石藻（Porolithon onkodes）为研究对象,分别采用不同pCO2和温度培养孔石藻31 d,研究不同处理后孔石藻对鹿角杯形珊瑚幼虫附着的影响,并通过分析藻体共附生细菌群落的变化情况,探究细菌多样性与孔石藻对珊瑚幼虫诱导功能的关系。结果表明,与对照组相比,酸化（1200 ppm/1800 ppm pCO2）和升温（30 ℃/32 ℃）均没有显著影响孔石藻诱导鹿角杯形珊瑚（Pocillopora damicornis）幼虫附着,其中温度30 ℃,pCO2 1200 ppm时,珊瑚幼虫附着率最高100.00%。采用16s rRNA高通量测序技术分析了不同处理组孔石藻共附生细菌群落结构及多样性。结果表明,孔石藻共附生细菌主要由变形菌门、拟杆菌门和绿弯菌门等菌群构成,其中变形菌门含量达到40.34%~73.45%;与酸化相比,孔石藻共附生细菌群落对温度变化更敏感,其中32 ℃处理组具有更高的细菌多样性,但经Kruskal-wallis秩和检验显示不同温度和CO2浓度处理组,在门、纲、属水平上细菌多样性、丰度及组成均无显著性差异,说明孔石藻共附生细菌群落结构相对稳定,推测这可能与孔石藻诱导珊瑚幼虫附着不受温度和酸化影响密切相关。研究结果对预测未来气候变化对珊瑚礁生态系统的影响、制定珊瑚礁生态系统保护与修复策略具有重要的理论价值和生态意义。     

长江口邻近海域夏季底栖纤毛虫的多样性与群落结构特点

采用Ludox-QPS方法,研究了2011年8月采自长江口邻近海域9个站位沉积物中纤毛虫的群落结构及分布特点,并结合沉积环境进行综合分析。结果表明,表层8cm沉积物中底栖纤毛虫的平均丰度为(2782±1493)cells/10cm2,生物量为(10.06±6.41)μgC/10cm2。长江口海域北部站位的丰度和生物量呈从近岸向外海增加,南部的站位呈现相反的分布趋势。在垂直分布上, 62%的底栖纤毛虫分布在表层2cm, 12%分布在5—8 cm。本研究共检获纤毛虫106种,隶属于15纲/亚纲, 24目, 69属,前口纲在丰度及生物量上均为最优势类群(丰度占45.5%,生物量占56.4%),核残迹纲在生物量上居第二位。就食性来看,肉食性纤毛虫物种数最多(44种),其丰度和生物量所占比例也最高(40.3%,66.8%),但在长江口外站位(M1站),菌食性纤毛虫为最优势摄食类群。分析表明,研究海域底栖纤毛虫群落结构与底层水盐度最相关。聚类分析结果显示,由于较多量的伪钟虫属(Pseudovorticella)和原领毛虫属(Prototrachelocerca)种类出现导致长江口北部L1站的纤毛虫群落结构不同于其他站位。本研究所获底栖纤毛虫的丰度和生物量较东海离岸海域已有研究结果均高,表层8cm沉积物中纤毛虫的丰度约是上层30m水柱中浮游纤毛虫的116倍,生物量约是后者的150倍。基于目前黄东海有关底栖纤毛虫物种多样性的已有报道,其多样性在长江口离岸海域高于近岸潮间带,且在离岸海域东海低于黄海。     

The effects of trophic interactions and spatial competition on algal community composition on Hawaiian coral reefs

Much of coral reef ecology has focused on how human impacts change coral reefs to macroalgal reefs. However, macroalgae may not always be a good indicator of reef decline, especially on reefs with significant sea urchin populations, as found in Kenya and Hawaii. This study tests the effects of trophic interactions (i.e. herbivory by fishes and sea urchins) and spatial competition (between algae and coral) on algal community structure of reefs surrounding two Hawaiian Islands that vary in their level of human impacts. Reef‐building organisms (corals and crustose coralline algae) were less abundant and turf algae were more abundant on Maui as compared to Lanai, where human impacts are lower. In contrast to previous studies, we found no evidence that macroalgae increased with human impacts. Instead, low turf and macroalgal abundance were best explained by the interactive effects of coral cover and sea urchin abundance. Fishing sea urchin predators appeared to have cascading effects on the benthic community. The absence of sea urchin predators and high sea urchin densities correspond to a disproportionately high abundance of turf and crustose coralline algae. We propose that high turf algal abundance is a better indicator of reef decline in Hawaii than high macroalgal abundance because turf abundance was highest on reefs with low coral cover and few fish. The results of this study emphasize that understanding changes in community composition are context‐dependent and that not all degraded reefs look the same.     

An analysis of sponge diversity and distribution at three taxonomic levels in the Thousand Islands/Jakarta Bay reef complex, West-Java, Indonesia

Very few coral reefs are located close enough to large cities to study the influence of large urban populations on reef assemblages. An exception is the Thousand Islands reef complex to the north of Jakarta, the capital city of Indonesia, and one of the largest conurbations in the world. Here we present data from a detailed survey where sponge assemblages were assessed at 30 patch reefs associated with islands in three coastal zones along an in-to-offshore gradient. Sponge assemblages are described at three taxonomic levels of detail (species, genus and family level). We recorded a total of 118 sponge species, 64 genera and 36 families, Aaptos suberitoides (Brønsted, 1934), Clathria (Thalysias) reinwardti (Vosmaer, 1880), Petrosia (Petrosia) nigricans (Lindgren, 1897) and Xestospongia testudinaria (Lamarck, 1813) were the most common species overall. There was a pronounced difference in composition among zones with the most distinct difference between the inshore zone and the other two zones. The inshore environment was characterised by very high turbidity and low live coral cover; the dominant substrate consisted of algal turf and sand. Environmental conditions improved and sponge diversity increased further offshore, although most areas appeared to have been affected by some form of disturbance. Ordinations were also largely congruent, at species, generic and family levels of taxonomic resolution. This indicates that variation in composition at higher taxonomic levels is a good indicator of variation at lower taxonomic levels, at least when there is a pronounced environmental gradient.     

Nature and biological composition of the New Caledonian outer barrier reef slopes

The Grande Terre of New Caledonia is enclosed by one of the longest barrier reefs in the world. For the first time, the fore-reef slopes of this barrier reef have been sampled by dredging, from 40 to 320 m deep, in order to analyze their sedimentological and biological characteristics. The rocks and sediments can be divided into seven sedimentary facies: bindstones dominated by coralline algal crusts, bindstones dominated by foraminiferal crusts, bindstones dominated by bryozoan crusts, coral framestones, bindstones and interstratified packstones rich in skeletal debris, packstones/wackestones and grainstones rich in rock gravels. Radiocarbon dating performed on encrusting organisms (coralline algae and acervulinids) and corals provide ages relatively young. These ages confirm that the encrusting organisms are modern and the corals mainly dated of Holocene are reworked due to the instability of the fore-reef slopes, especially during storms. Because the biological assemblages are distributed according to a bathymetric range depending on light intensity, a model of distribution of modern encrusting calcareous organisms can be proposed from our observations and analyses. From the upper reef slopes to approximately 90 m, thick coralline algal crusts are dominant and distributed in three groups. Group C, the shallowest parts of the fore slopes, is mainly characterized by mastophorids (Hydrolithon reinboldii, H. cf. munitum, Lithoporella melobesoides, Aethesolithon cf. problematicum, Neogoniolithon sp. and undetermined species) and lithophylloids (Lithophyllum sp., L. pustulatum). Group B, composed of lithophylloids (Lithophyllum sp., L. cf. kotschyanum, L. cf. moluccence, L. pustulatum), Mesophyllum sp. and Peyssonnelia sp. occurs from 15 to 40 m. Group A, rich in Mesophyllum sp., M. cf. mesomorphum, Peyssonnelia sp. and Sporolithon sp. is characteristic of deep reef slopes up to 90 m. Below approximately 90 m, when the light intensity decreases, the encrusting foraminifera acervulinids progressively replace the coralline algal crusts. Such a model is particularly useful to interpret and reconstruct the past Quaternary reef environments rich in crusts of coralline algae and/or foraminifera.     

Differences in physiological response to increased seawater temperature in nearshore and offshore corals in northern Vietnam

Effects of elevated seawater temperature show high spatial heterogeneity and variation within and among coral species. The objective of this study was to investigate how two coral species, Porites lutea and Galaxea fascicularis, from two high latitude reefs differently exposed to chronic disturbance, respond to elevated seawater temperatures. Corals were collected from reefs nearshore (i.e. subjected to high sediment load, higher chlorophyll α concentrations, turbidity etc.) and offshore (i.e. less exposed). The corals were exposed in the lab to gradually increasing temperatures (25.5-33.5?°C) for 72?h after which they were allowed to recover to ambient temperature (25.5?°C) for 24?h. Production and respiration were measured after 24, 48, 72 and 96?h. The results show that P. lutea from nearshore reefs suffered an initial decrease in gross primary production/respiration (GP/R) ratio after 24?h, after only a moderate temperature increase (+2?°C, from 25.5 to 27.5?°C), while there was no difference in GP/R ratio between heat-exposed and controls the other days, indicating that the chronic disturbance in the nearshore reef had no effect on their thermotolerance. Furthermore, P. lutea from the offshore reef showed a decrease in GP/R ratio both after 24?h and 72?h (33.5?°C) of exposure. In comparison, G. fascicularis showed a decrease in GP/R ratio after 48?h, 72?h and 96?h of exposure for the nearshore corals. Also, after 72?h these corals had withdrawn their polyps. There were no differences between heat-treated and controls for the offshore G. fascicularis. This implies that the chronically disturbed G. fascicularis had lower thermotolerance when exposed to a temperature increase. This study, hence, shows that the response of corals to elevated seawater temperature varies with species and environmental background history.     

Coral Reef Community Structure at Caño Island, Pacific Costa Rica

Abstract. Around the Biological Reserve of Caño Island, Pacific Costa Rica, there are five large coral reef flats (with size ranges of 0.8–4.2 ha) built mainly of dead Pocillopora spp. At present, they are covered mainly by crustose coralline algae and microatolls of Porites lobata . From the upper reef slope to the reef base several corals grow in small patches (e. g., Pavona clavus, Pavona varians, Pavona gigantea, Gardineroseris planulata, Psammocora superficialis, Pocillopora elegans, Pocillopora damicornis); the massive coral Porites Iobata is predominant. Pocilloporid species are predominant on most other eastern Pacific reefs.
The Caño Island reef is typical of a community whose structure has been controlled by both physical (in shallow water) and biological (in deeper water) factors. Shallow reef areas are influenced by strong wave action and extreme low tides. The distribution, abundance, and feeding preferences of corallivorous organisms (e. g., Acanthaster planci, Arothron meleagris, Pseudobalistes naufragium, Quoyula monodonta) on the deeper reef suggest that most pocilloporids are affected and limited by them. Although there is no evidence of any predator on Porites lobata at Caño Island, the triggerfish Pseudobalistes naufragium breaks off fragments of the coral while searching for food. These fragments often survive to form new colonies. Together, this dispersal mechanism, rapid injury recovery, and high resistance to environmental stress seem to enhance the distribution and dominance of the massive coral Porites lobata at Caño Island.     

Dynamic simulation of tropical coral reef ecosystem being disturbed by multiple situations

In consideration of the rapid degradation of coral reef ecosystems, the establishment of models is helpful to comprehend the degradation mechanism of coral reef ecosystems and predict the development process of coral reef communities. According to the characteristics of complex ecosystem of tropical coral reefs in China, the coral reef functional group is the core level variable; combined with the multiple feedback effects of coral reef functional groups and environmental changes, the study presents a coral reef ecosystem dynamics model with hermatypic corals as the core. Based on the simulation of the assumed initial value and the internal feedback of the system, the results show that in the basic simulation(relative health conditions), the coverage area of live corals and coral reefs generally decreased first and then increased, and increased by 4.67% and 6.38% between2010 and 2050, respectively. Based on the calibration model and the current situation of the studied area, the multi-factor disturbance effects of coral reef communities were simulated and explored by setting up three scenarios involving fishing policy, terrestrial deposition, and inorganic nitrogen emissions. Among them, in the single factor disturbance, the fishing policy exerts the most direct impact on the community decline; and the succession phenomenon is obvious; the terrestrial sedimentation has a faster and more integrated effect on the community decline; the effect of inorganic nitrogen emission on the community decline is relatively slow. In the double/multi-factor disturbance, the superimposed disturbance will aggravate the multi-source feedback effect of the coral reef communities development, accelerate the community decay rate, and make its development trajectory more complicated and diverse. This method provides a scientific and feasible method for simulating the damage of long-term coral reef community and exploring the development law and adaptive management of coral reef ecosystems. In the future, it can be further studied in the ecological restoration process and decisionmaking direction of coral reefs.     

Long‐term temporal and spatial patterns in bioeroding sponge distribution at the Abrolhos Bank,Brazil, Southwestern Atlantic

Bioeroding sponges belong to the most dominant bioeroders, significantly contributing to the erosion of coral reefs. Some species are tolerant or even benefit from environmental conditions such as ocean warming, acidification, and eutrophication. In consequence, increases in sponge bioerosion have been observed on some coral reefs over the last decades. The Abrolhos Bank is the largest coral reef system in the South Atlantic. It has been affected by sedimentation, eutrophication, overfishing, and climate change, mainly affecting coastal reefs, and at lesser intensity outer ones as well. This study aimed to describe spatial and temporal patterns in bioeroding sponge distribution in carbonate substrates in the Abrolhos Bank. Photo‐quadrats were used to compare bioeroding sponge abundance between two shallow reefs: a coastal, Pedra de Leste (PL), and an outer reef, Parcel dos Abrolhos (PAB). Each individual was delimitated over the substrate by determining the sponge surface through a line connecting the outermost papillae. The study was conducted over 6 years in 2008–2009 and 2013–2016. Four species of bioeroding sponges were identified: Cliona carteri Ridley, 1881, C. delitrix Pang, 1973, C. cf. schmidtii Ridley, 1881, and Siphonodictyon coralliphagum Rützler, 1971. The distribution and abundance of species varied between the inner and outer reefs and across the years, and displayed certain selectivity for the calcareous substrates recorded. Crustose coralline algae (CCA) were the main substrate excavated by the most abundant bioeroding species, C. carteri, and represented 70% of the substrate types occupied by this sponge (CCA, coral overgrown by CCA and plain coral). The highest abundance of bioeroding sponges observed in photo‐quadrats was 21.3 individuals/m² at the outer reefs (PAB) in 2014. The abundances or areal extents of bioeroding sponges were up to 10 times greater on the outer reefs than on the coastal ones, where sedimentation is higher and more strongly influenced by siliciclastic material. Moreover, a higher herbivorous fish biomass has been reported on outer reefs which could also influence the higher abundance of bioeroding sponges in outer reefs. During the study period of 6 years, an increase in bioeroding sponge abundance was observed at the outer reefs (PAB), with the sea surface temperature increase. As CCA have an important role in reefal cementation and carbonate production in the Abrolhos reefs, a bioerosion impact might be expected, in particular, on the outer reefs.     

A potential new threat on the coral reefs of Puerto Rico: The recent emergence of Ramicrusta spp.

The rapid appearance of Ramicrusta spp. is described and analyzed from 40 permanent monitoring coral reef stations in Puerto Rico. Before 2016, Ramicrusta had not been observed from any of the reef monitoring stations. By 2018, it was present at 76% of all the monitoring stations. Ramicrusta was the dominant substrata type at all of the shallow reef sites sampled on the east coast (e.g., Fajardo, Culebra, and Vieques), reaching a cover (±SE) as high as 63.0 ± 5.8%. The spread of Ramicrusta occurred at the expense of historically resilient living benthic elements, such as turf algae. Since its detection in 2016, colonization of hard substrata by Ramicrusta remained constant, with the exception of two shallow reefs in Fajardo and Culebra, where the cover was significantly reduced by the scouring and or abrasive effects of two major hurricanes. The ecological implications of Ramicrusta prevalence on Puerto Rican reefs remain unclear; however, increasing herbivory might be a useful mitigation tool in the reduction of Ramicrusta abundance on coral reefs.     

Horizontal spatial and temporal distribution patterns of nearshore larval fish assemblages at a temperate rocky shore

There have been no previous studies of the composition of nearshore larval fish assemblages along the coast of Portugal. We aimed to describe the composition and horizontal distribution patterns of larval fish assemblages and their temporal dynamics near a rocky reef at depths shallower than 13 m (inshore) and at two miles (3.70 km) from shore (offshore), as well as along transects perpendicular to the shoreline, from the reef to 10 miles offshore (18.52 km). Samples were taken using 5 min sub-surface trawls at the rocky shore of the Arrábida Marine Park (W Portugal). A total of 1021 larvae were collected, belonging to 61 taxa inshore and to 29 taxa offshore. Along transects, 626 larvae of 52 taxa were collected. Most larvae belonged to coastal species associated with rocky reefs. Total larval abundance and diversity were higher from May to July, which is consistent with the spawning activity of adults. Diversity and total larval abundance decreased significantly with increasing distance from shore, both in the inshore/offshore comparison and in the transects, where this decrease was evident at a very small spatial scale (within the first mile from the reef). Species assemblages differed in the pattern of distribution, with most species clearly associated to the extreme nearshore. The distribution patterns obtained were independent of the spawning mode of species. Results are discussed in the light of the possible physical mechanisms that can potentially act at the Arrábida Marine Park to facilitate larvae retention and the role of larval behaviour.