Investigation of the 2006 Alexandrium fundyense bloom in the Gulf of Maine: In-situ observations and numerical modeling

In-situ observations and a coupled bio-physical model were used to study the germination, initiation, and development of the Gulf of Maine (GOM) Alexandrium fundyense bloom in 2006. Hydrographic measurements and comparisons with GOM climatology indicate that 2006 was a year with normal coastal water temperature, salinity, current and river runoff conditions. A. fundyense cyst abundance in bottom sediments preceding the 2006 bloom was at a moderate level compared to other recent annual cyst survey data. We used the coupled bio-physical model to hindcast coastal circulation and A. fundyense cell concentrations. Field data including water temperature, salinity, velocity time series and surface A. fundyense cell concentration maps were applied to gauge the model's fidelity. The coupled model is capable of reproducing the hydrodynamics and the temporal and spatial distributions of A. fundyense cell concentration reasonably well. Model hindcast solutions were further used to diagnose physical and biological factors controlling the bloom dynamics. Surface wind fields modulated the bloom's horizontal and vertical distribution. The initial cyst distribution was found to be the dominant factor affecting the severity and the interannual variability of the A. fundyense bloom. Initial cyst abundance for the 2006 bloom was about 50% of that prior to the 2005 bloom. As the result, the time-averaged gulf-wide cell concentration in 2006 was also only about 60% of that in 2005. In addition, weaker alongshore currents and episodic upwelling-favorable winds in 2006 reduced the spatial extent of the bloom as compared with 2005.     

Effects of crab burrows on pore water flows in salt marshes

Macro-pores such as crab burrows are found commonly distributed in salt marsh sediments. Their disturbance on the soil structure is likely to influence both pore water flows and solute transport in salt marshes; however, the effects of crab burrows are not well understood. Here, a three-dimensional model simulated tidally driven pore water flows subject to the influence of crab burrows in a marsh system. The model, based on Richards’ equation, considered variably saturated flow in the marsh with a two-layer soil configuration, as observed at the Chongming Dongtan wetland (Shanghai, China). The simulation results showed that crab burrows distributed in the upper low-permeability soil layer, acting as preferential flow paths, affected pore water flows in the marsh particularly when the contrast of hydraulic conductivity between the lower high-permeability soil layer and the overlying low-permeability soils was high. The burrows were found to increase the volume of tidally driven water exchange between the marsh soil and the tidal creek. The simulations also showed improvement of soil aeration conditions in the presence of crab burrows. These effects may lead to increased productivity of the marsh ecosystem and enhancement of its material exchange with coastal waters.     

Internal structure of the aeolian sand dunes of El Fangar spit, Ebro Delta (Tarragona, Spain)

This paper presents an analysis of the dune field dynamics of El Fangar Spit in the Ebro Delta (Spain), associating it with the internal structure of dunes carried out with ground-penetrating radar and supported by data from topographic DGPS. These analyses are of great importance to ascertain the state of the internal structure of dunes as an important element in their stability and, therefore in their evolution. The internal structure shows accretion and progradation sequences of dunes over beach deposits, which depend on dune morphology (height, crest orientation) and location, as well as the processes acting on them.     

闽江河口湿地芦苇和互花米草氮、磷养分季节动态

于2007年对闽江河口湿地优势本地种芦苇(Phragmites australis)和外来入侵种互花米草(Spartina alterniflora)N、P养分含量与生物量进行1 a的观测.结果表明,两种植物地上部分N、P含量的器官分配模式为叶最高,花次之,茎最低,其中芦苇叶N含量显著高于互花米草(n=3,p<0.05);两种植物绿色部分N、P含量高于立枯部分;季节动态为冬、春季节高于夏、秋季节;N、P积累在不同器官的分布大致趋势为叶最高,茎次之,花最低,其中互花米草绿色茎和绿色叶N、P积累量显著高于芦苇(n=3,p<0.05);芦苇地下部分N、P含量变化趋势为0～15 cm最高,15～30 cm次之,30～60 cm最低,而互花米草与之相反;两种植物地下N、P积累量变化都为0～15 cm最高,15～30 cm次之,30～60 cm最低;芦苇地下部分N、P积累量在各个季节始终高于地上部分,但互花米草与之相反.从N/P看,N素为两种植物生产力的重要限制营养因子.     

Legal protection is not enough: Posidoniaoceanica meadows in marine protected areas are not healthier than those in unprotected areas of the northwest Mediterranean Sea

Using the Conservation Index, which measures the proportional amount of dead matte relative to live Posidonia oceanica, we assessed the health of 15 P. oceanica meadows at a regional scale along the coast of Liguria (NW Mediterranean). These areas were characterized by different degrees of anthropization, from highly urbanized sites to marine protected areas. Two different scenarios were identified according to depth: in shallow zones, the health of P. oceanica meadows was related to the degree of anthropization along the coastline. In contrast, in deep zones, most meadows exhibited poor health, independent of both the degree of disturbance and the legal measures protecting the area. Working synergistically with the regional impact of increased water turbidity, local impacts from the coast were recognized as the main causes of the severe regression of most Ligurian P. oceanica meadows. We conclude that marine protected areas alone are not sufficient to guarantee the protection of P. oceanica meadows. We emphasize the need for a management network involving the Sites of Community Interest (SCIs) containing P. oceanica meadows.     

Quantification of submarine groundwater discharge(SGD) using radon,radium tracers and nutrient inputs in Punnakayal,south coast of India

The present study focused on the estimation of submarine groundwater discharge(SGD)and the effects of nutrient fluxes due to the SGD process.The parameters of SGD such as magnitude,character,and nutrient flux in Punnakayal region of South East coast of India were evaluated using multiple tracers of groundwater inputs in 2019.It was found that the elevated values for the tracers in the study area,displayed a gradational change in the values as move from estuarine part to the offshore.Simultaneous occurrence of fresh and saline SGD is observed on the study sites.Also,indicated that the SGD fluxes ranged from 0.04 to 0.12 m^3 m^-2d^-1 at the estuary and0.03-0.15 m^3 m^-2d^-1at the groundwater site.A substantially increased value for 222 Rn activities is distinguished in the estuary to values over 312 dpm L^-1.Nutrient embellishments were generally greatest at locations with substantial meteoric elements in groundwater;however,the recirculation of saltwater through the geological formation could provide a way of transferring terrestrially-derived nutrients to the coastal zone at many places.     

海岸湿地退化对胶州湾渔业和生物多样性保护的影响

文章简要分析了胶州湾海岸湿地退化过程以及海岸湿地退化对渔业生产和生物多样性保护的影响。近40～50a来由于围垦、滩涂养殖、污染、城市化、填海造陆、河流断流、海面上升等原因,胶州湾海岸湿地呈现严重的退化趋势,表现为各类湿地面积不断萎缩,潮上带湿地植被退化和景观分维数下降,潮间带湿地底质和潮下带湿地水质不断恶化等。认为海岸湿地退化导致胶州湾海洋渔业资源严重衰退和生物多样性受损,并且对珍稀鸟类保护有不利影响。     

太湖湖滨带的生态建设

太湖湖滨带是太湖流域重点污染控制区之一。本文根据流域生态学与流域管理学的原理,提出了太湖湖滨带生态建设的途径。（1）发展生态农业,减少农田污染。（2）入湖河道沿岸两侧建设河岸林带,成为农田与河流间的缓冲带。（3）加强沿岸丘陵的水土保持。（4）充分利用湖泊湿地的净化功能,作为治理太湖富营养化的有效措施。（5）选择入湖河道河口,在试验基础上建立人工湿地。推动太湖湖滨带生态建设工程顺利开展的措施：（1）提高全社会的环境保护意识。（2）从组织和制度上加强湖滨带污染控制管理。（3）建立环境监测和信息管理系统。（4）开展湖滨带污染控制工程的试验研究。     

辽宁沿海湿地生物多样性评价研究

辽宁沿海湿地资源对辽宁沿海经济带生物多样性保护具有重要意义。在辽宁沿海经济带战略环评中,根据科学性、代表性和实用性的原则,提出了生物多样性评价的4个指标,即物种丰富度、生态系统类型多样性、物种特有性和外来物种入侵度。建立了沿海湿地生物多样性评价指标体系,并对沿海湿地生物多样性进行了评价。评价结果表明:辽宁沿海6地市及其4个国家级自然保护区的生物多样性丰富。该项研究为辽宁沿海经济带的战略开发决策提供了科学的生物多样性保护措施和建议。