海洋外来物种入侵对南海生态系统的影响及防控对策

外来海洋物种入侵已成为继海洋栖息地破坏之后世界海洋生态环境面临的第二个重大威胁。为了全面了解我国南海外来物种的状况,本文阐述了南海主要外来物种的生物学和生态学特征及其对生态系统的影响,并提出相应的防控对策。结果表明:(1)在我国南海最主要分布和已经报道的外来物种共有35种,多为无意引进。其中,海洋外来藻类最多,为16种,占总种类数的45.7%;其次是海洋污损动物,为11种,占31.4%;外来微生物,为5种,占14.3%;潮间带滩涂植物主要有3种,占8.6%。(2)外来入侵物种主要通过4个方面危害海洋生态系统:弱化海洋生态系统群落结构,降低其物种多样性;改变海洋生态系统遗传多样性,降低其遗传变异性;影响海洋生态系统稳定性,造成外源病害肆虐;加剧海洋生态灾害。本文对南海不同种类外来物种生物学特征分析可为南海外来物种入侵的进一步研究提供基础资料,防控对策的提出可为管理部门制定海洋外来物种入侵管理策略提供参考,以期更好地保护南海海洋生态系统。

Composition and Distribution of Planktonic Ciliates in the Southern South China Sea During Late Summer： Comparison Between Surface and 75 m Deep Layer

Ciliates are very important components in most marine ecosystem. They are trophic link between the microbial food web and grazing food chain. In this study, ciliates were collected from 11 sites in the southern South China Sea （SCS） during August 25 to September 28, 2011. Their composition and distribution at the surface and 75m deep depth of the ocean were studied. A total of 30 species belonging to 22 genera were identified, and 22 species of 15 genera were Tintinnids. Eutintinnusfraknoii and E. stramentus were the most common species. The other dominants were strombidiids ciliates including Strombidium conicum and S. globosaneum, which were followed by the tide form, Mesodinium pulex. Ciliates abundance ranged from 46 indL-1 to 368 indL-1 in the open sites, 46-368indL-1 at surface and 73-198indL-1 at 75m deep layer. In the Yongshu reef, ciliates abundance ranged from 167indL-1 to 365 ind L-1 in the water colunm, similar to that in Sanya coral reef waters. Ciliates composition showed obvious difference between surface and 75m deep layer at station S2 （P〈0.05）, while no similar result was observed at other sites. At 75m deep layer, salinity was negatively related to mixed layer depth （P〈 0.05）, but positively to chlorophyll a concentration （P〈 0.05）, indicating that the change of vertical mixing in water column influenced vertical distribution of ciliates in the southern SCS.

Quantitative Appraisement on Ecological Carrying Capacity in Coastal Rapid Developing Region of Hainan Province

The ecological carrying capacity,an important indica- tor to evaluate the sustainable development of the ecosystem, means the potential ability of the natural ecosystem to carry so- cioeconomic development while the ecosystem is healthy.It is limited by the carrying capacity of natural resources and environ- ment and the elasticity of the ecosystem.It will be greatly signifi- cant to study the ecological carrying capacity of Hainan Province, the first ecological province admitted by the State Environmental Protection Administration in China.Not only is the natural eco- system reflected,but also the effects of human activities are em- phasized by integrating the ecosystem health analysis into the ecological carrying capacity research.The research results,using the Factor Analysis tools of software SPSS,indicate that the eco- logical carrying capacity of Hainan Province fluctuated obviously from 1996 to 2005.The level of the ecological carrying capacity of Hainan Province was relatively high in 1996,and reached into trough from 1997 to 1999.It has steadily ascended to be above the middle level since the 21st century.The results also show that policy factors,especially the implementation of the 'Ecological Province' strategy,were important driving forces to influence the ecological carrying capacity.With the population rapidly increas- ing,the land and water resources per capita have decreased quickly.The amount of the ecological carrying capacity was pro- moted remarkably by socioeconomic development especially economic growth and technology applications.All of these will provide useful suggestions to establish and enact regional devel- opment policies,especially for protecting and reconstructing the ecology and environment of Hainan Province.

Regional hard coral distribution within geomorphic and reef flat ecological zones determined by satellite imagery of the Xisha Islands,South China Sea

Coral reefs in the Xisha Islands （also known as the Paracel Islands in English）, South China Sea, have experienced dramatic declines in coral cover. However, the current regional scale hard coral distribution of geomorphic and ecological zones, essential for reefs management in the context of global warming and ocean acidification, is not well documented. We analyzed data from field surveys, Landsat-8 and GF-1 images to map the distribution of hard coral within geomorphic zones and reef fiat ecological zones. In situ surveys conducted in June 2014 on nine reefs provided a complete picture of reef status with regard to live coral diversity, evenness of coral cover and reef health （live versus dead cover） for the Xisha Islands. Mean coral cover was 12.5% in 2014 and damaged reefs seemed to show signs of recovery. Coral cover in sheltered habitats such as lagoon patch reefs and biotic dense zones of reef flats was higher, but there were large regional differences and low diversity. In contrast, the more exposed reef slopes had high coral diversity, along with high and more equal distributions of coral cover. Mean hard coral cover of other zones was 〈10%. The total Xisha reef system was estimated to cover 1 060 km2, and the emergent reefs covered -787 km2. Hard corals of emergent reefs were considered to cover 97 km2. The biotic dense zone of the reef flat was a very common zone on all simple atolls, especially the broader northern reef flats. The total cover of live and dead coral can reach above 70% in this zone, showing an equilibrium between live and dead coral as opposed to coral and algae. This information regarding the spatial distribution of hard coral can support and inform the management of Xisha reef ecosystems.

Could Acid Sulfate Soils Be a Potential Environmental Threat to Estuarine Ecosystems on the South China Coast?

Acid sulfate soils (ASS) contain considerable amounts of reduced sulfur compounds (mainly pyrite) which produce sulfuric acid upon their oxidation. ASS-derived environmental degradation widely occurs in the coastal lowlands around the world, especially in the tropical and subtropical areas. The presence of ASS in the South China has been recognized but their distribution may be largely underestimated because the soil survey data concerning ASS are based on unreliable methods and techniques. ASS in the South China have been traditionally used for rice cultivation and this practice has been proved sustainable if appropriate improvement measures are adopted. Recently, the rapid economic growth in the region has resulted in intensified coastal development which frequently involves activities that may disturb ASS. Construction of roads, foundations and aquaculture ponds may cause the exposure of ASS to air and bring about severe environmental acidification. There is currently insufficient awareness of the problems among the researchers, policy-makers and land managers in the South China. More atteation must be paid to the possible ASSderived environmental degradation in order to ensure a sustainable development of the coastal lowlands in the South China region.

Seasonal Community Structure of Mesozooplankton in the Daya Bay,South China Sea

Mesozooplankton are key components of coastal ecosystems,linking the microbial food web to the classic food chain.In this study,species composition and abundance of mesozooplankton is studied for the Daya Bay in April(spring) and October(fall),2006.A total of 27 species of mesozooplankton were identified in spring and 58 species in fall.Dominant species were Oithona tenuis,Flaccisagitta enflata,Penilia avirostris and Centropages tenuiremis in spring,shifting to Microsetella norvegica,Oithona tenuis and Parvocalanus crassirostris in fall.Higher mesozooplankton abundance was found at Aotou Cove and Dapeng'ao Cove compared to other stations,indicating the influence of eutrophication on mesozooplankton community in the Daya Bay.The outbreak of Noctiluca scintillans bloom in spring reduced the species diversity and abundance of mesozooplankton.

A study of response of thermocline in the South China Sea to ENSO events

This paper investigates the response of the thermocline depth(TD) in the South China Sea(SCS) to the El Ni?o-Southern Oscillation(ENSO) events using 51-year(from 1960 to 2010) monthly seawater temperature and surface wind stress data acquired from the Simple Ocean Data Assimilation(SODA), together with heat flux data from the National Centers for Environmental Prediction(NCEP), precipitation data from the National Oceanic and Atmospheric Administration(NOAA) and evaporation data from the Woods Hole Oceanographic Institution(WHOI). It is indicated that the response of the SCS TD to the El Ni?o or La Ni?a events is in opposite phase. On one hand, the spatial-averaged TDs in the SCS(deeper than 200 m) appear as negative and positive anomalies during the mature phase of the El Ni?o and La Ni?a events, respectively. On the other hand, from June of the El Ni?o year to the subsequent April, the spatial patterns of TD in the north and south of 12°N appear as negative and positive anomalies, respectively, but present positive and negative anomalies for the La Ni?a case. However, positive and negative TD anomalies occur almost in the entire SCS in May of the subsequent year of the El Ni?o and La Ni?a events, respectively. It is suggested that the response of the TD in the SCS to the ENSO events is mainly caused by the sea surface buoyancy flux and the wind stress curl.

Counteracting the Effects of Sea Level Rise in Southeast Florida

Over the past 100 years, worldwide surface temperatures have increased at an unprecedented rate, contributing to warming of the oceans, melting ice fields and glaciers, and other adverse climatic effects. Southeast Florida＇s vulnerability derives from its geographic location, low elevation, porous geology, unusual ground and surface water hydrology, subtropical weather patterns, and proximity to the Atlantic Ocean. The region is especially susceptible to sea level rise. After several millennia of stable sea levels prior to the 20th century, sea levels have been rising at accelerating rates due to thermal expansion of the oceans and from land-based ice melt The Everglades ecosystem and the water supplies for southeast Florida are particularly vulnerable as neither can be protected without significant expenditures of public dollars, and even these efforts may not prove to be successful. New approaches may be required to improve the resilience and prolong the sustainability of the region＇s water resources and ecosystem. The efforts to adapt to sea level changes in both the urban area and ecosystem as outlined herein are date and incident based-climate changes may occur earlier or later so instead of spending limited public dollars early, expenditures can be adjusted given future information.

From sea to land: assessment of the bio-transport of phosphorus by penguins in Antarctica

In Antarctica, the marine ecosystem is dynamically interrelated with the terrestrial ecosystem. An example of the link between these two ecosystems is the biogeochemical cycle of phosphorus. Bio- vectors, such as penguins, transport phosphorus from sea to land, play a key role in this cycle. In this paper, we selected three colonies of penguins, the most important seabirds in Antarctica, and computed the annual quantity of phosphorus transferred from sea to land by these birds. Our results show that adult penguins from colonies at Ardley Island, the Vestfold Hills, and Ross Island could transfer phosphorus in the form of guano at up to 12 349, 167 036, and 97 841 kg/a, respectively, over their breeding period. These quantities are equivalent to an annual input of 3.96× 10^9-1.63 × 10^10 kg of seawater to the land of Antarctica. Finally, we discuss the impact of phosphorus on the ice-flee areas of the Antarctica.

Ecosystem assessment and protection effectiveness of a tropical rainforest region in Hainan Island, China

Ecosystem services have become one of the core elements of ecosystem management and evaluation. As a key area of ecosystem services and for maintaining national ecological security, ecosystem changes and implementation effect evaluation are important in national key ecological function zones, for promoting the main function zone strategy and for improving the construction of an ecological civilization. This article studies the ecological zone of a tropical rainforest region in the central mountain area of Hainan Island, China. Multi-source satellite data and ground observation statistics are analyzed with geo-statistics method and ecological assessment model. The core analysis of this paper includes ecosystem patterns, quality and services. By means of spatial and temporal scale expansion and multidimensional space-time correlation analysis, the trends and stability characteristics of ecosystem changes are analyzed, and implementation effect evaluation is discussed. The analysis shows a variety of results. The proportion of forest area inside the ecological zone was significantly higher than the average level in Hainan Island. During 1990–2013, settlement gradually increased inside the ecological zone. After implementation of the zone in 2010, human activity intensity increased, with the main land use being urban construction and land reclamation. Water conservation in the ecological function zone was higher than that outside the zone. In general, it increased slightly, but had obvious fluctuations. Soil conservation inside the zone was also better than that outside. However, it demonstrated dramatic fluctuations and relatively poor stability during 1990–2013. The human disturbance index inside the zone was significantly lower than that outside, and had a lower biodiversity threat level. Especially in 2010–2013, the increased range of the human disturbance index inside the zone was significantly less than that outside.

Modeling the contribution of the microbial carbon pump to carbon sequestration in the South China Sea

The two key mechanisms for biologically driven carbon sequestration in oceans are the biological pump(BP) and the microbial carbon pump(MCP); the latter is scarcely simulated and quantified in the China seas. In this study, we developed a coupled physical-ecosystem model with major MCP processes in the South China Sea(SCS). The model estimated a SCSaveraged MCP rate of 1.55 mg C m^(-2) d^(-1), with an MCP-to-BP ratio of 1:6.08 when considering the BP at a depth of 1000 m.Moreover, the ecosystem responses were projected in two representative global warming scenarios where the sea surface temperature increased by 2 and 4°C. The projection suggested a declined productivity associated with the increased near-surface stratification and decreased nutrient supply, which leads to a reduction in diatom biomass and consequently the suppression of the BP. However, the relative ratio of picophytoplankton increased, inducing a higher microbial activity and a nonlinear response of MCP to the increase in temperature. On average, the ratio of MCP-to-BP at a 1000-m depth increased to 1:5.95 with surface warming of 4°C, indicating the higher impact of MCP in future ocean carbon sequestration.

Black band disease as a possible factor of the coral decline at the northern reef-flat of Yongxing Island,South China Sea

Black band disease （BBD）, characterized by the Cyanobacterial dominated pathogenic consortium, is thought to play a key role in the global decline of the coral reef ecosystems. The present paper originally documents a case of BBD from Yongxing Island （Xisha Islands, South China Sea）, and further probes the reasons of this abnormal phenomenon. Prior to 2007, corals at northern reef-flat of Yongxing Isand were in healthy growth. Catastrophic coral mortality occurred between 2007 and 2008. The 16S rRNA gene sequencing and PCR amplification, with universally conserved primers, were applied to detect the conta- gious bacterial community of the microbial mat. The results demonstrated that six bacterial divisions constituted the clone libraries derived from the BBD mat, and that Cyanobacteria are the most diversely represented group that inhabit BBD bacteri- al mats, despite the fact that species in five others divisions （a-Proteobacteria, y-Proteobacteria, Bacteroidetes, Verrucomi- crobia and Actinobacteria） are also consistently diverse within the BBD mats of diseased coral. Other factors such as coral bleaching, typhoons, ocean acidification and crown-of-thorns starfish outbreaks, are not primarily responsible for the coral mortality within such a short time interval. The disaster expansion of BBD associated with Cyanobacterial blooms is a more likely mechanism impacting these coral reefs. Excessive human activity enhances the eutrophication of the marine water of the reefal region and may result in occurrence of the BBD.