Integrated assessment of a coastal lagoon ecological status based on benthic macroinvertebrates
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Abstract Coastal lagoons are considered as one of the most productive ecosystems worldwide but are also vulnerable to the growing human-made stressors. This study aimed at assessing, for the first time, the ecological status of the Oualidia lagoon (Atlantic coast of Morocco) using benthic macroinvertebrates as bioindicators. An integrative ecological monitoring approach based on spatial diversity patterns of species assemblages (examined using taxonomic indices, structural trophic guilds as indicators of the functional biodiversity, and marine biotic indices) in relation to sedimentary and hydrological descriptors was performed. Results showed that hydrodynamic conditions, represented by intra-lagoon currents and the watershed, govern the entire sediment distribution within the lagoon and establish a longitudinal downstream-upstream gradient and transverse right-left banks, which explained 66% of the total variation observed in benthic assemblage composition. Seagrass meadows affect positively the abundance of dominant species but do not support high diversity. Overall, macrozoobenthos spatial pattern consists in modification of the relative abundance of species, independently of species composition. The average score of the ecological classes obtained from five biotic indices (AMBI, BENTIX, H’, MAMBI and ITI) showed an acceptable status of the benthic assemblages. This integrated analysis resulted in a holistic view of the benthic-ecosystem that will serve in implementing an ecosystem-based approach to the management of the Oualidia lagoon.Keywords:
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Marine ecosystem
Abstract Marine mammals are an important part of ecosystems, and their trophic role and potential impact have been increasingly studied. One key question is how these large animals interact with fisheries or compete for similar resources. Consequently, some models once used only for fisheries management are now including pinnipeds and cetaceans. However, fish and marine mammals do not share the same ecology and bioenergetics, and complex ecosystem models may not be the best way to assess the impact of pinnipeds or cetaceans in food webs. Indeed, simpler methods based on thermodynamics might give us reasonable answers with limited amounts of data. Here, we present an assessment of two different approaches to assess the trophic role of marine mammals in the northern Gulf of St. Lawrence (Canada): mixed trophic impacts ( MTI ) based on ecosystem modeling and surface index ( SI ) impact based on bioenergetics. Our results show that while modeling represents a good way of getting a holistic view of the role of marine mammals in ecosystems, trophic impact estimates based on fundamental thermodynamics principles can also give us answers requiring less data. The body surface area approach presented here might provide a practical tool for ecologists, who are not necessarily ecosystem modelers, to study this issue.
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Atmospheric methane (CH4) is the second strongest greenhouse gas and it is emitted to the atmosphere naturally by different sources. It is crucial to define the dimension of these natural emissions in order to forecast changes in atmospheric CH4 mixing ratio in future scenarios. However, CH4 emissions by seagrass ecosystems in shallow marine coastal systems have been neglected although their global extension. Here we quantify the CH4 production rates of seagrass ecosystems in the Red Sea. We measured changes in CH4 concentration and its isotopic signature by cavity ring-down spectroscopy on chambers containing sediment and plants. We detected CH4 production in all the seagrass stations with an average rate of 85.09 ± 27.80 µmol CH4 m-2 d-1. Our results show that there is no seasonal or daily pattern in the CH4 production rates by seagrass ecosystems in the Red Sea. Taking in account the range of global estimates for seagrass coverage and the average seagrass CH4 production, the global CH4 production and emission by seagrass ecosystems could range from 0.09 to 2.7 Tg yr-1. Because CH4 emission by seagrass ecosystems had not been included in previous global CH4 budgets, our estimate would increase the contribution of marine global emissions, hitherto estimated at 9.1 Tg yr-1, by about 30%. Thus, the potential contribution of seagrass ecosystems to marine CH4 emissions provides sufficient evidence of the relevance of these fluxes as to include seagrass ecosystems in future assessments of the global CH4 budgets.
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Blue carbon
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The importance of seagrass meadows as a habitat for fishes, including several of economic importance, is widely acknowledged. The complexity of seagrass beds might offer a different condition of habitat for fishes. The physical nature of the seagrass canopy is thought to play a major role, potentially influencing available shelter, food, and protection from predators. Structural complexity of seagrass such as shoot and leaf density is also an important factor in determining ecological function of seagrass in the marine environment. The objective of the research is to assess the ecological function of different seagrass beds (in terms of spesies and density) in supporting fish community. The study found 28 species of fish originating from 14 families and Pomacentridae were dominantly found. Abundance of fish found to be higher in seagrass beds with high densities both composed by one species of seagrass (monospesific) or by more than one species of seagrass (multispesific), compared to the seagrass beds with low density and bare areas. Fish community diversity index was found higher in dense seagrass beds composed of many species of seagrass compared to the rare and consists of only one species of seagrass. The presence of epiphytes as nutrients for the fish that live in seagrass beds may contribute to the finding.Keywords: Seagrass, fish, Barrang Lompo Island
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在中国的 Seagrass 研究仍然在它的幼年期。尽管最近有进步，仍然有很多研究，需要获得 seagrass 的更好的理解。在这篇文章，我们从二个方面在中国在 seagrass 研究考察并且讨论进展：(1 ) seagrass 种类和他们的分发；(2 ) 在中国的 seagrass 研究包括他们的分类上的研究，生态学，光合作用，在水产业的应用，咸忍耐的机制和其它研究话题。属于 8 个类的 18 seagrass 种类的一个总数在中国(包括的香港和台湾) 在九个省和区域被散布，以及 Xisha 和 Nansha 群岛。他们能被划分成二个组：一个诺思中国组和一个华南组。基于 seagrass 分发，中国大陆海岸能被划分成三节：诺思中国 Seagrass 海岸，中间的中国 Seagrass 海岸，和华南 Seagrass 海岸。生态的研究在山东，广东， Guangxi，和海南的关键区域在 seagrass 社区，在 seagrass 生态系统骑车的营养素，基因差异，污染生态学和研究上包括研究。在关键区域的 Seagrass 种类和他们的地点，社区结构，生态的评估，附生植物，生态的功能和威胁也被总结。另外的研究集中了于 seagrass，中国的威胁的 seagrass 种类，和 Halophila ovalis 的花粉形态学的遥感。关键词 seagrass - seagrass 草地 - 海洋的生态系统 n ] Guangxi 科学基础(号码 0832030 ) 支持的中国， Guangxi 大学(2008 ) 的科学研究资金， UNDP/GEF/SCCBD 工程(SCCBD/CPR/02/31 ) 和 Guangxi 给实验室资金(号码 07109007 ) 调音
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A recurring pattern of declining mean trophic level of fisheries landings, termed "fishing down the food web," is thought to be indicative of the serial replacement of high-trophic-level fisheries with less valuable, low-trophic-level fisheries as the former become depleted to economic extinction. An alternative to this view, that declining mean trophic levels indicate the serial addition of low-trophic-level fisheries ("fishing through the food web"), may be equally severe because it ultimately leads to conflicting demands for ecosystem services. By analyzing trends in fishery landings in 48 large marine ecosystems worldwide, we find that fishing down the food web was pervasive (present in 30 ecosystems) but that the sequential addition mechanism was by far the most common one underlying declines in the mean trophic level of landings. Specifically, only 9 ecosystems showed declining catches of upper-trophic-level species, compared with 21 ecosystems that exhibited either no significant change (n = 6) or significant increases (n = 15) in upper-trophic-level catches when fishing down the food web was occurring. Only in the North Atlantic were ecosystems regularly subjected to sequential collapse and replacement of fisheries. We suggest that efforts to promote sustainable use of marine resources will benefit from a fuller consideration of all processes giving rise to fishing down the food web.
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Trophic cascade
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Ascidians belonging to the ‘Phylum Chordata’ are effectively used as bio-indicators of anthropogenic disturbance in marine ecosystems. Each and every day marine coastal communities are exposed to several chemical compounds which are commonly used in agriculture and industrial activities. Among the various criteria, functional qualities may represent useful tools for monitoring environmental impact in coastal areas, in order to consider the impact of anthropogenic activities on the aquatic ecosystem and to insure fulfillment with regulation. Biomonitoring involves the use of indicator species such as filter feeding organisms like ascidians and they represent a reliable bioindicator; and so represent a valuable tool for the rapid and simple monitoring of impact on marine ecosystem. In this paper, the role of tunicates is reviewed as model organism for testing coastal pollution. Keywords: Marine, ascidians, bio indicators, pollution Cite this Article Rajaram Murugan, Ganakkan Ananthan, Chinnathambi Stalin. Ascidians as the potential bioindicators of marine ecosystem: A review. Research & Reviews: A Journal of Life Sciences. 2016; 6(1): 1–5p.
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Seagrass have an important role in coastal habitats. However, its existence is now under threat. Can the production of artificial seagrass mimic the function of natural seagrass? This paper discusses the potential of artificial seagrass to mimic natural seagrass.
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Five seagrass species have been identified in Guangxi shoal water,Beibu Gulf.They are.Zostera japonica,Syringodium isoetifolium,Halodule uninervis,Halophila ovalis and Halophila beccarii.As a total,there are about 640hm2 seagrass beds in Guangxi coastal areas,of which 540hm2 distributes in Hepu,about 100hm2 in Pearl Bay of Fangchenggang and a few in Beihai.The areas of seagrass beds obviously changed in season and annual,and degraded in general.The seagrass bed in Hepu is one of the most important habitats to China seagrass conservation.The collected data and papers showed that only a few scientific studies had been conducted on Guangxi seagrass.All seagrass habitats except Hepu were only reported in the past six years.The ecological services of seagrass,human and natural threats to Guangxi seagrass and a brief review on China and Guangxi seagrass researches are released.More studies and monitoring are required to the Guangxi seagrass for the special role of seagrass in maintaining offshore environment and marine biodiversity during the bloom of Guangxi coastal economy.
Thalassia testudinum
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