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1.
《African Journal of Marine Science》2013,35(3):323-330
Heavy nutrient loads in coastal waters often lead to excessive growth of microalgal and macroalgal epiphytes on seagrass leaves, with varying effects on the underlying seagrasses. This study evaluates the photosynthetic performance, epiphytic biomass and tissue nutrient content of two tropical seagrasses, Cymodocea serrulata and Thalassia hemprichii, in two intertidal areas along the Dar es Salaam coast in the Indian Ocean, a nutrient-rich region at Ocean Road (near the city centre), and a nutrient-poor region at Mjimwema (south of the city centre). Epiphyte biomass was significantly higher at the nutrient-rich site, and epiphytes were associated with reduced photosynthetic performance in both seagrass species at both sites. Likewise, nitrogen and phosphorus tissue content was higher in both species at the nutrient-rich site than at the nutrient-poor site. Epiphytic species composition on the seagrass leaves varied between seagrass species and between sites. Cymodocea serrulata had a higher number of epiphytic species at Mjimwema than at Ocean Road, whereas Thalassia hemprichii had more epiphytic species at Ocean Road than at Mjimwema. Seagrass photosynthetic performance, epiphytic biomass and nutrient content of the seagrasses were shown to be affected by nutrient concentration in the water column. Thus, for the future monitoring of the seagrass meadow, we recommend the use of combined measures such as seagrass performance, epiphytic biomass, nutrient contents and nutrient concentration levels in the water column. 相似文献
2.
海草床是滨海三大典型生态系统之一,具有极其重要的环境改善、资源养护和减灾防灾等生态功能,亦是全球重要的碳库。2016年8月,通过对荣成马山里海域的现场调查,发现了面积为58.26 hm2的海草床,其海草的种类为红纤维虾形草（Phyllospadix iwatensis）和丛生鳗草（Zostera caespitosa）。红纤维虾形草分布面积为54.50 hm2,占该海域海草床总面积的93.5%,分为北部和南部2个带状区域,平均茎枝密度为（368.0±18.2）shoots/m2,平均生物量（干重,下同）为（297.0±41.5）g/m2。丛生鳗草分布面积为3.76 hm2,占海草床总面积的6.5%,呈现斑块状分布,与红纤维虾形草交错而生,平均茎枝密度为（691.2±17.1）shoots/m2,平均生物量为（534.0±70.7）g/m2。马山里海域海草床主要分布在平均水深为（2.8±0.3） m的以岩礁为主的底质上。海草的生长状况存在显著的空间差异,与水温呈现显著的正相关,与水深和陆源污染物存在显著的负相关。结合历史资料,发现该海域海草床退化现象较严重,其主要威胁因素是人为干扰,主要包括渔业生产、养殖活动和陆源污染输入。建议合理规划周边海域的养殖规模和密度、加强陆源污染物管控和开展海草床生态修复工程,以期为温带海草床的有效保护和科学管理提供参考。 相似文献
3.
Temporal and spatial changes of macroalgae and phytoplankton in a Mediterranean coastal area: the Venice lagoon as a case study 总被引：5，自引：0，他引：5
Since the late 1980s the lagoon of Venice, a shallow Mediterranean coastal area, has experienced strong environmental changes. Macroalgae, which were the predominant primary producers of the lagoon, reduced markedly, but neither phytoplankton nor seagrasses replaced them. Temporal and spatial changes in macroalgal standing crop (SC) and phytoplankton concentration were investigated between 1987 and 1998. Maps of macroalgal SC show a marked declining trend. Biomass in fresh weight decreased from: 558 ktonnes in 1987, to 85 ktonnes in 1993 and to 8.7 ktonnes in 1998. As a whole, the biomass in 1998 was only 1.6% of the biomass recorded in 1987. Similarly the macroalgal net (NPP) and gross (GPP) primary production decreased from ca. 1502 and 9721 ktonnes year(-1) to ca. 44 and 229 ktonnes year(-1), respectively. In the early 1990s the clam Tapes philippinarum Adams & Reeve and seagrasses, especially Zostera marina Linnaeus, colonised the bottoms free of macroalgae, but the development of intense clam-fishing activities prevented both phytoplankton blooms and seagrass spreading. Maps of chlorophyll a drawn according to data collected in parallel to macroalgal standing crop show unchanged concentrations. Macroalgae changes are enhanced by comparing annual trends in four areas of the central lagoon during 1989-1992 and 1998-1999. In those areas phytoplankton also decreased significantly. Marked changes of some environmental variables strongly associated with the primary production were recorded both during the lagoon mapping and in the areas studied on a yearly basis. 相似文献
4.
Understanding the temporal dynamics of seagrasses and the major influences on seagrass growth is critical for seagrass habitat conservation and administration. However, little work has been done regarding these issues in southern China. To examine inter-annual and seasonal variations of the intertidal Halophila ovalis community in southern China, we conducted quarterly sampling using the SeagrassNet methodology and assessed environmental conditions as well as direct anthropogenic impacts on the seagrass meadow from July 2008 to October 2014. Our study demonstrated strong inter-annual and seasonal dynamics of the intertidal seagrass meadow in the study area. Generally, the community performed best (highest seagrass cover, leaf area, shoot density, total biomass) in summer and worst in spring among the 4 seasons. The temporal variations in the seagrass community attributes (e.g. above-ground biomass) were significantly affected by precipitation, atmospheric visibility, and salinity, while leaf width was significantly negatively correlated with temperature, atmospheric visibility and salinity. Temperature was a major factor influencing the seagrass community (both macroalgae and seagrass), with temperature data showing an inverse relationship between seagrass and macroalgae. The above-ground: below-ground biomass ratio and leaf width of H. ovalis were the most sensitive plant parameters monitored when assessing environmental interactions. Human physical disturbances did not have a significant effect on seagrass dynamics in the study area. We concluded that long-term monitoring (like SeagrassNet) is valuable in understanding the relationship between environmental variables and seagrasses. 相似文献
5.
Sea urchin overgrazing of seagrasses: A review of current knowledge on causes, consequences, and management 总被引：1，自引：0，他引：1
J.S. Eklf M. de la Torre-Castro M. Gullstrm J. Uku N. Muthiga T. Lyimo S.O. Bandeira 《Estuarine, Coastal and Shelf Science》2008,79(4):569-580
Sea urchins are one of the most common seagrass macro-grazers in contemporary seagrass systems. Occasionally their grazing rates exceed seagrass growth rates, a phenomenon sometimes referred to as overgrazing. Because of a reported increasing frequency of overgrazing events, concomitant with loss of seagrass-associated ecosystem services, it has been suggested that overgrazing is one of the key threats to tropical and subtropical seagrasses. In light of this, we review the current knowledge on causes, consequences, and management of sea urchin overgrazing of seagrasses. Initially we argue that the definition of overgrazing must include scale and impairment of ecosystem services, since this is the de facto definition used in the literature, and will highlight the potential societal costs of seagrass overgrazing. A review of 16 identified cases suggests that urchin overgrazing is a global phenomenon, ranging from temperate to tropical coastal waters and involving at least 11 seagrass and 7 urchin species. Even though most overgrazing events seem to affect areas of <0.5 km2, and recovery often occurs within a few years, overgrazing can have a range of large, long-term indirect effects such as loss of associated fauna and decreased sediment stabilization. A range of drivers behind overgrazing have been suggested, including bottom-up (nutrient enrichment), top-down (reduced predation control due to e.g. overfishing), “side-in” mechanisms (e.g. changes in water temperature) and natural population fluctuations. Based on recent studies, there seems to be fairly strong support for the top-down and bottom-up hypotheses. However, many potential drivers often co-occur and interact, especially in areas with high anthropogenic pressure, suggesting that multiple disturbances—by simultaneously reducing predation control, increasing urchin recruitment and reducing the resistance of seagrasses—could pave the way for overgrazing. In management, the most common response to overgrazing has been to remove urchins, but limited knowledge of direct and indirect effects makes it difficult to assess the applicability and sustainability of this method. Based on the wide knowledge gaps, which severely limits management, we suggest that future research should focus on (1) identification and quantification of ecosystem and societal scale effects of overgrazing; (2) assessment of the relative importance and interactions of different drivers; and (3) development of a holistic proactive and reactive long-term management agenda. 相似文献
6.
海草是一类生长于海洋环境中的单子叶植物。细菌、真菌、微藻、古生菌和病毒等微生物栖息在海草器官及其周围环境中,对海草生长、营养和健康以及海草床物质循环起着重要作用。本文通过分析与总结国内外参考文献,简要介绍了海草床微生物的一些新的研究进展,并讨论了将来可能进行的研究方向。海草微生物组与沉积物和海水中的微生物群落存在较大差异,其分布在离散且高度异质性的生态位,且该模式在广泛的地理尺度上保持不变,不是受海草种类和沉积物类型控制,而是主要取决于环境驱动与海草代谢。大部分海草核心微生物群落都参与硫循环。今后可采用模拟实验、生态模型、基因组、宏基因组、转录组与代谢组等技术方法研究海草床微生物的多样性、组成、功能、定植与病害等。此外,揭示海草床中微生物、海草和环境之间的相互关系,对保护受威胁的海草床具有重要意义。 相似文献
7.
8.
中国海草的“藻”名更改 总被引：2，自引：0，他引：2
黄小平 江志坚 范航清 陈小勇 周毅 张景平 李文涛 张沛东 郑凤英 韩秋影 邱广龙 方静威 林幸助 孙涛 于硕 刘松林 吴云超 张晓梅 赵鹏 林海英 《海洋与湖沼》2016,47(1):290-294
海草(Seagrasses)是地球上可完全生活在海水中的被子植物,是由陆地植物演化到适应海洋环境的高等植物。然而,高等植物海草在中国经常被冠以低等植物"藻"的名称。中国海草现有22种,隶属于4科10属,其中科名、属名和种名分别有3科、7属和16种是以"藻"命名的,易让人们把海草误以为是海藻(Seaweed),造成混乱,同时给中国海草的研究、保护和利用带来不利影响。值此"第十一次国际海草生物学研讨会"(The 11th International Seagrass Biology Workshop)首次在中国举行之际,国内众多的海草研究专家得以共聚,有机会共同探讨中国海草的"藻"名更改。经过研讨,专家们形成一致意见,建议将这些被命名为"藻"的海草统一命名为"草",以期促进我国海草研究与保护的全面推进。随着未来中国海草种类与分布的深入调查,以后新发现的海草种类名称建议也统一命名为"草"名。 相似文献
9.
鳗草(ZosteramarinaL.)广布于北半球温带浅海海域,其形成的鳗草床具有重要的生态价值。近些年来,我国黄渤海海域鳗草退化严重,较大面积、连续分布的海草床已经非常少见。在渤海兴城-觉华岛海域发现较大面积的海草床,可以作为渤海沿海海草床的典型代表。基于此,2018年5月、9月、11月和2019年3月对该海草床进行了初步调查,探究了渤海兴城-觉华岛海草床鳗草种群补充等生态特征,分析了海草床生境的主要威胁,并提出了对海草床进行有效保护和科学管理的相关建议。结果表明:渤海兴城-觉华岛海草床总面积为791.61ha,海草种类为鳗草和日本鳗草(Z.japonica),以鳗草为优势种,日本鳗草极少且呈斑块状分布;鳗草生物量在2018年5月达到最大值(1241.22—1632.64g/m2);鳗草叶片碳、氮、磷元素含量分别为35.35%—36.57%、1.89%—3.35%、0.14%—0.48%;鳗草海草床以无性繁殖为主要补充方式,有性繁殖补充比例平均仅为1.92%,明显低于国内其他鳗草草床,具有鲜明的独特性;该海草床主要受围填海、捕蛤、围网捕鱼等人类活动的严重影响,并致使海草床边缘区域呈现斑块化趋势。建议对这片珍贵的海草床加以保护和修复。 相似文献
10.
硫化物胁迫对海草影响的研究进展 总被引：1，自引：1，他引：0
硫酸盐的还原作用是沿海海洋沉积物中有机质厌氧矿化的主要终点过程，该过程会生产有毒的硫化物。迄今为止，在所研究的大多数海草中都发现了硫化物侵入植株组织内部的现象，而且在温带和热带区域已经发生过多起因为草床沉积物中硫化物浓度过高而导致海草大面积死亡的事件。本文综述了近三十年来硫化物胁迫对海草影响的相关研究工作，主要内容包括以下四方面：（1）硫化物对海草产生胁迫的环境条件主要有缺氧、缺铁、有机质富集以及高盐；（2）硫化物侵入海草组织的途径是由根部吸收进而转移到地下茎和叶片中，而随着时间的推移，硫化物在海草组织中最终主要以单质硫、硫酸盐以及有机硫的形式存在；（3）硫化物对海草的危害主要是通过直接破坏海草的分生组织并进一步抑制海草的光合作用发生的，对海草的生长带来严重的负面影响；（4）不同海草物种受硫化物的侵入情况不同，主要与海草物种的形态学和内部结构差异有关。最后提出三方面的展望，包括硫化物胁迫下海草组织、细胞层面的深入研究，分子应答机制的研究以及有效的海草床修复手段的探索。本文有助于全面了解海草与硫化物胁迫之间的关系，并为将来开展更深入的研究提供参考。 相似文献
11.
文章以海南岛新村湾、黎安港和潭门港海草床为研究区域, 选取褐篮子鱼(Siganus fuscessens)、点斑篮子鱼(Siganus guttatus)、四带牙鯻(Pelates quadrilineatus)和细鳞鯻(Terapon jarbua) 4种代表性鱼类为研究对象, 分析其体长与体质量的关系, 并探讨4种鱼类对海草资源量变化的响应。结果表明, 除栖息于潭门港海草床的4种鱼为负异速生长, 其他区域海草床的鱼类均为正异速或等速生长; 4种鱼的体质量生长速率(即异速生长因子b)和肥满度呈现黎安港>新村湾>潭门港的趋势, 并与3个海草床的海草覆盖率、密度和生物量的变化趋势一致; 推测海草资源量下降可能增加鱼类的被捕食压力和减少食物来源, 从而导致生活于海草床的代表性鱼类生长速率下降。 相似文献
12.
海草床是海岸带最富生产力的生态系统之一，支撑着各种各样的伴生生物。热带的印度和太平洋地区被认为拥有海草植物种类多样性最高，且分布面积最广，然而，这个区域的海草床大型底栖生物我们知之甚少。为了填补认知的空白，我们在该区域开展了一项生态调查，旨在描述该区热带海草床大型底栖生物的丰度和多样性，以及确定大型底栖生物丰度、物种丰富度和群落结构是否明显存在断面内的站间变化和样地间变化。2014年5月和2015年10月我们分别在北苏拉威西省东海岸和西海岸开展野外工作，使用柱状取样器采集海草床大型底栖生物样品。所得样品共计鉴定14大类149种底栖生物，种类最为丰富的类别为多毛类（56种，占26%的总个体数），十足类（20种，占9%的总个体数）和端足类（18种，占35%的总个体数）。东、西海岸海草床大型底栖生物表现出不同的空间分布模式。在东海岸，同一断面的大型底栖生物和端足类的丰度存在显著的站间差异；而在西海岸，大型底栖生物和多毛类的种类丰富度和丰度都表现出明显的站间变化，这可能归结于同一断面底质不均所造成。单因素ANOSIM以及MDS排序表明了北苏拉威西省东海岸和西海岸海草床大型底栖生物群落结构存在显著不同，正好对应于将海草床分成两大类型的栖息地，即西海岸的红树林-海草床-珊瑚连续体和东海岸的海草床-珊瑚连续体。与在热带海区开展的其他研究相比，本研究的大型底栖生物丰度和多样性处于中等水平。东、西海岸海草床大型底栖生物群落存在显著区别，其原因可能源于多方面，包括了沉积物模式，海草床结构和时间变化。 相似文献
13.
海草床可以为海洋动物提供产卵、索饵、繁育等场所。目前, 海草床面积急剧下降, 其中我国关于虾形草属(Phyllospadix)海草的研究相对较少, 对于虾形草主要繁育载体种子的描述、显微观察和萌发过程方面存在较多空白。本研究以红纤维虾形草(Phyllospadix iwatensis)为研究对象, 对其生长环境、种子外部特征、内部结构、萌发过程等进行了定性定量描述。结果表明, 虾形草果实种子对于海洋环境有着外部形态与内部结构的适应性, 外部形态特点包括独特的果序和果实形状, 以及翅状结构和内侧鬃毛, 其中果序呈弯虾形, 平均长度3.4cm, 果实呈马掌形, 直径3~4mm, 内部结构特征包括胚乳占比大、果皮种皮解剖结构复杂等, 具有作为海岸带植被修复工具种的优势。本研究补充了目前对虾形草等海洋沉水植物种子的研究资料, 为虾形草海草种质库保护与海草床修复提供了建议和参考。 相似文献
14.
Impacts of Typhoons Tianying and Dawei on seagrass distribution in Xincun Bay, Hainan Province, China 总被引：1，自引：0，他引：1
More than 50% of the typhoons landing in China have landed on the southeast coast, where they have caused great pressure on the coastal environment. Seagrass, one of the most important constituents of coastal ecosystems, is also greatly affected by typhoons. In order to clarify how seagrass distribution variation is affected by typhoons in coastal areas in southeast China, data of Typhoons Dawei and Tianying (category 4 and category 2 respectively, which just ran through the southern part of Hainan province) have been studied. In situ observation and satellite remote sensing data (CBERS-China Brazil Earth Resources Satellite) in 2004 and 2006 were used to retrieve seagrass distribution in Xincun Bay, Hainan province. In situ observations showed that leaf length, stem biomass and above ground biomass on average showed evidence of reduction after Typhoons Tianying and Dawei. However, seagrass density showed no evidence of reduction after typhoon Tianying and Dawei passed by and increased rapidly in January 2006. From results of satellite remote sensing data, seagrass distribution can be detected with high accuracy, and the area of seagrass distribution on the south coast of Xincun Bay in 2006 after the typhoon passed by was smaller than that in 2004 in region A and B. However, in region C, area of seagrass coverage under 20% increased. These results demonstrated that typhoons Tianying and Dawei damaged seagrass bed and helped seagrass to get rid of aged and dead leaves, and this correspondingly facilitated seagrass growth. 相似文献
15.
Benthic macrofauna changes in areas of Venice lagoon populated by seagrasses or seaweeds. 总被引：12，自引：0，他引：12
Two areas of the Venice lagoon populated by seagrasses (three stations covered by Cymodocea nodosa (Ucria) Asherson, Zostera marina Linnaeus, Zostera noltii Hornemann) or seaweeds (two stations: one covered by Ulva rigida C. Agardh and another at present without seaweed biomass) were monitored by means of six surveys over a year in order to study macrofaunal composition and seasonal changes. The seagrass stations showed a mean species richness (28-30 S m(-2)), individual abundance (1854-4018 N m(-2)) and biomass (22.3-37.7 g m(-2) ash-free-dry-weight, AFDW) ca. 3-8 times higher than those populated by seaweeds (10-15 S m(-2), 494-1395 N m(-2) and 5.6-13.7 g m(-2) AFDW). Differences among seagrass or seaweed stations were much lower. The Ulva-dominated station showed a macrofauna completely different both from the other stations and the communities recorded ca. 30 years ago, before the prolific growth of Ulva. In this station, frequent biomass decompositions and anoxic crises created critical conditions for life favouring organisms with reduced life cycles, younger individuals and the epifaunal species instead of the infaunal ones. In particular, Ulva grazers and scrapers such as Gammarus aequicauda Stock and Gibbula adriatica Philippi were found to be by far the most abundant species, whereas the taxa characteristic of the associations found in the past, in the presence of seagrasses or seaweeds and typical of low eutrophicated environments, appear strongly reduced. Marked differences in the macrophyte dominance and in the bio-physico-chemical variables which characterise the main environmental conditions of the Venice lagoon support the different distribution and composition of macrofaunal communities. Seaweed stations appear mainly governed by the seasonal cycles of these un-rooted macrophytes which, by alternating periods of production and decomposition, are responsible for the drastic reduction of macrofauna biodiversity and biomass. Conversely, seagrass stations exhibit a better oxidisation of the environment and show conditions more favourable for macrofauna colonisation, especially in the presence of macrophytes which are characterised by very well developed below-ground systems such as Cymodocea nodosa. 相似文献
16.
Sediment deposition and production in SE-Asia seagrass meadows 总被引：1，自引：0，他引：1
E. Gacia C. M. Duarte N. Marb J. Terrados H. Kennedy M. D. Fortes N. H. Tri 《Estuarine, Coastal and Shelf Science》2003,56(5-6):909-919
Seagrass meadows play an important role in the trapping and binding of particles in coastal sediments. Yet seagrass may also contribute to sediment production directly, through the deposition of detritus and also the deposition of the associated mineral particles. This study aims at estimating the contribution of different seagrass species growing across an extensive range of deposition to inorganic (carbonate and non-carbonate) and organic sediment production. Total daily deposition measured with sediment traps varied from 18.8 (±2.0) g DW m−2 d−1 in Silaqui (Philippines) to 681.1 (±102) g DW m−2 d−1 in Bay Tien (Vietnam). These measurements correspond to a single sampling event and represent sedimentation conditions during the dry season in SE-Asia coastal areas. Enhalus acoroides was the most common species in the seagrass meadows visited and, together with Thalassia hemprichii, was present at sites from low to very high deposition. Halodule uninervis and Cymodocea species were present in sites from low to medium deposition. The mineral load in seagrass leaves increased with age, and was high in E. acoroides because it had the largest and long-lived leaves (up to 417 mg calcium carbonate per leaf and 507 mg non-carbonate minerals per leaf) and low in H. uninervis with short-lived leaves (4 mg calcium carbonate per leaf and 2 mg non-carbonate minerals per leaf). In SE-Asia seagrass meadows non-carbonate minerals accumulate at slower rates than the production of calcium carbonate by the epiphytic community, consequently the final loads supported by fully grown leaves were, as average, lower than calcium carbonate loads. Our results show that organic and inorganic production of the seagrasses in SE-Asia represents a small contribution (maximum of 15%) of the materials sedimented on a daily base by the water column during the sampling period. The contribution of the carbonate fraction can be locally significant (i.e. 34% in Silaqui) in areas where the depositional flux is low, but is minor (<1%) in sites were siltation is significant (i.e. Umalagan and all the visited sites in Vietnam). 相似文献
17.
The diet of different macrozoobenthic trophic groups was investigated in the Arcachon Bay—a semi-enclosed macrotidal ecosystem that shelters the largest Zostera noltei seagrass meadow in Europe—in early spring and late summer 2009, using stable isotopes and fatty acids. Fatty acid profiles and literature information about the biology and physiology of benthic consumers were combined to identify the main organic matter sources for the benthic primary consumers. An isotope mixing model was then run to evaluate the contribution of each organic matter source to each identified trophic group (suspension feeders, sub-surface deposit feeders, micro-and macrograzers, suspension-oriented interface feeders and deposit-oriented interface feeders). Variations in organism' diets with respect to both habitats (intertidal seagrass meadows, intertidal bare sediments and subtidal bare sediments) and study periods were also investigated. At the scale of this study, it appeared that the diet of macrozoobenthos primary consumers was based exclusively on autochthonous material (no use of terrestrial organic matter): mainly microphytobenthos, seagrasses and their epiphytes, and phytoplankton. In addition, the different trophic groups relied on different organic matter pools: for instance, suspension feeders mainly fed on microphytobenthos and phytoplankton, whereas subsurface deposit feeders fed on microphytobenthos, decayed seagrasses and bacteria, and grazers mainly fed on microphytobenthos, and seagrasses and their epiphytes. The same pattern was observed in both early spring and late summer, indicating a stability of the benthic system at a six-month time scale. Finally our results showed that, in Arcachon Bay, the seagrass meadow directly or indirectly (through detritus) plays a significant role in the diet of most benthic consumers. 相似文献
18.
Simone Libralato Roberto Pastres Fabio Pranovi Sa&#;a Raicevich Angela Granzotto Otello Giovanardi Patrizia Torricelli 《Marine Ecology》2002,23(S1):228-236
Abstract. The energy flows of two habitats are quantified and compared by using a trophic network model. The habitats are representative of two typical subsystems of the Venice Lagoon: the seagrass meadows, which represent a mature stage in the ecological succession of lagoon environments, and the Tapes philippinarum fishing grounds, which are subjected to mechanical clam harvesting.
The results obtained for the 'seagrass habitat'are consistent with other field studies, confirming the'key-stone'role played by phanerogams in a lagoon environment. The results for the 'Tapes habitat'show that the energy flow from the sediment to the water column is extremely important. Indeed, the high T. philippinarum biomass cannot be supported solely by the primary production of the local phytoplankton. Instead, this biomass could be supported by a supply provided by the sediment resuspension caused by intensive clam fishing. These findings suggest the presence of a positive feedback between fishing effort and T. philippinarum standing crop. 相似文献
The results obtained for the 'seagrass habitat'are consistent with other field studies, confirming the'key-stone'role played by phanerogams in a lagoon environment. The results for the 'Tapes habitat'show that the energy flow from the sediment to the water column is extremely important. Indeed, the high T. philippinarum biomass cannot be supported solely by the primary production of the local phytoplankton. Instead, this biomass could be supported by a supply provided by the sediment resuspension caused by intensive clam fishing. These findings suggest the presence of a positive feedback between fishing effort and T. philippinarum standing crop. 相似文献
19.
《African Journal of Marine Science》2013,35(4):523-531
Seagrasses support a great diversity of epiphytic organisms. There are no detailed published accounts of algae and animals growing on seagrasses in South Africa. The seagrass Thalassodendron leptocaule (previously known as Thalassodendron ciliatum) is unique among southern African seagrasses in that it occurs on exposed rocky outcrops along the Mozambican and north-eastern South African coasts; most other seagrasses are restricted to sheltered bays and estuaries. Here we present accounts of species of flora and fauna identified growing epiphytically on this seagrass in northern KwaZulu-Natal. A total of 52 taxa of macroalgae and 204 species of macroinvertebrates were identified as epiphytic on South African T. leptocaule. The most frequently observed macroalgal epiphytes were predominantly Rhodophyta and were common among periodically exposed, intertidal and subtidal habitats. The crustose red coralline algae Pneophyllum amplexifrons and Hydrolithon farinosum were frequently observed, primarily on stems and leaves of the seagrass respectively. The most diverse groups of epiphytic invertebrates were Arthropoda, Annelida and Mollusca, which together comprised 76% of the macroinvertebrate species recorded. This seagrass species is evidently an important substratum and ecosystem that supports a hidden wealth of biodiversity. 相似文献
20.
Frederick T. Short Evamaria W. Koch Joel C. Creed Karine M. Magalhães Eric Fernandez & Jeffrey L. Gaeckle 《Marine Ecology》2006,27(4):277-289
Seagrasses are an important coastal habitat worldwide and are indicative of environmental health at the critical land–sea interface. In many parts of the world, seagrasses are not well known, although they provide crucial functions and values to the world's oceans and to human populations dwelling along the coast. Established in 2001, SeagrassNet, a monitoring program for seagrasses worldwide, uses a standardized protocol for detecting change in seagrass habitat to capture both seagrass parameters and environmental variables. SeagrassNet is designed to statistically detect change over a relatively short time frame (1–2 years) through quarterly monitoring of permanent plots. Currently, SeagrassNet operates in 18 countries at 48 sites; at each site, a permanent transect is established and a team of people from the area collects data which is sent to the SeagrassNet database for analysis. We present five case studies based on SeagrassNet data from across the Americas (two sites in the USA, one in Belize, and two in Brazil) which have a common theme of seagrass decline; the study represents a first latitudinal comparison across a hemisphere using a common methodology. In two cases, rapid loss of seagrass was related to eutrophication, in two cases losses related to climate change, and in one case, the loss is attributed to a complex trophic interaction resulting from the presence of a marine protected area. SeagrassNet results provide documentation of seagrass change over time and allow us to make scientifically supported statements about the status of seagrass habitat and the extent of need for management action. 相似文献