Littoral vegetation of Lake Tohopekaliga: community descriptions prior to a large-scale fisheries habitat-enhancement project

An extreme dry-down and muck-removal project was conducted at Lake Tohopekaliga, Florida, in 2003-2004, to remove dense vegetation from inshore areas and improve habitat degraded by stabilized water levels. Vegetation was monitored from June 2002 to December 2003, to describe the pre-existing communities in terms of composition and distribution along the environmental gradients. Three study areas (Treatment-Selection Sites) were designed to test the efficacy of different treatments in enhancing inshore habitat, and five other study areas (Whole-Lake Monitoring Sites) were designed to monitor the responses of the emergent littoral vegetation as a whole. Five general community types were identified within the study areas by recording aboveground biomasses and stem densities of each species. These communities were distributed along water and soils gradients, with water depth and bulk density explaining most of the variation. The shallowest depths were dominated by a combination of Eleocharis spp., Luziola fluitans, and Panicum repens; while the deeper areas had communities of Nymphaea odorata and Nuphar luteum; Typha spp.; or Paspalidium geminatum and Hydrilla verticillata. Mineralized soils were common in both the shallow and deep-water communities, while the intermediate depths had high percentages of organic material in the soil. These intermediate depths (occurring just above and just below low pool stage) were dominated by Pontederia cordata, the main species targeted by the habitat enhancement project. This emergent community occurred in nearly monocultural bands around the lake (from roughly 60–120 cm in depth at high pool stage) often having more diverse floating mats along the deep-water edge. The organic barrier these mats create is believed to impede access of sport fish to shallow-water spawning areas, while the overall low diversity of the community is evidence of its competitive nature in stabilized waters. With continued monitoring of these study areas long-term effects of the restoration project can be assessed and predictive models may be created to determine the efficacy and legitimacy of such projects in the future.

Characterization of a dissolved oxygen sensor made of plastic optical fiber coated with ruthenium-incorporated solgel

A dissolved oxygen sensor made of plastic optical fiber as the substrate and dichlorotris (1, 10-phenanthroline) ruthenium as a fluorescence indicator is studied. Oxygen quenching characteristics of both intensity and phase were measured; the obtained characteristics showed deviation from the linear relation described by the Stern-Volmer equation. A two-layer model is proposed to explain the deviation, and main parameters can be deduced with the model. (C) 2009 Optical Society of America

Final Evaluation Memorandum: Strategies for Resolving Low Dissolved Oxygen and Methylmercury Events in Northern Suisun Marsh

The purpose of the project is to improve our understanding about best management practices that can be utilized on diked managed wetlands in Suisun Marsh for reducing the occurrence of low dissolved oxygen (DO) and high methylmercury (MeHg) events associated primarily with fall flood-up practices. Low DO events are of concern because they can lead to undue stress and even mortality of sensitive aquatic organisms. Elevated MeHg levels are of concern because MeHg is a neurotoxin that bio-magnifies up the food chain and can cause deleterious effects to higher trophic level consumers such as piscivorous fish, birds, and mammals (including humans). This study involved two years (2007-2008) of intensive field data collection at two managed wetland sites in northwest Suisun Marsh and their surrounding tidal sloughs, an area with prior documented low DO events. In addition, the study collected limited soils and water quality field data and mapped vegetation for three managed wetland sites in the central interior of Suisun Marsh, for the purpose of examining whether wetlands at other locations exhibit characteristics that could indicate potential for similar concerns. In Year 1 of the study, the objective was to identify the baseline conditions in the managed wetlands and determine which physical management conditions could be modified for Year 2 to reduce low DO and MeHg production issues most effectively. The objective of Year 2 was to evaluate the effectiveness of these modified management actions at reducing production of low DO and elevated MeHg conditions within the managed wetlands and to continue improving understanding of the underlying biogeochemical processes at play. This Final Evaluation Memorandum examined a total of 19 BMPs, 14 involving modified water management operations and the remaining five involving modified soil and vegetation management practices. Some of these BMPs were previously employed and others have not yet been tested. For each BMP this report assesses its efficacy in improving water quality conditions and potential conflicts with wetland management. It makes recommendations for further study (either feasibility assessments or field testing) and whether to consider for future use. Certain previously used BMPs were found to be important contributors to poor water quality conditions and their continued use is not recommended. Some BMPs that could improve water quality conditions appear difficult to implement in regards to compatibility with wetland management; these BMPs require further elaboration and feasibility assessment to determine whether they should be field tested. In practice for any given wetland, there is likely a combination of BMPs that would together have the greatest potential to address the low DO and high MeHg water quality concerns. Consequently, this report makes no sweeping recommendations applicable to large groups of wetlands but instead promotes a careful consideration of factors at each wetland or small groups of wetlands and from that assessment to apply the most effective suite of BMPs. This report also identifies a number of recommended future actions and studies. These recommendations are geared toward improving the process understanding of factors that promote low DO and high MeHg conditions, the extent of these problems in Suisun Marsh, the regulatory basis for the DO standards for a large estuarine marsh, the economics of BMPs, and alternative approaches to BMPs on diked managed wetlands that may address the water quality issues. The most important of these recommendations is that future BMP implementation should be carried out within the context of rigorous scientific evaluation so as to gain the maximum improvement in how to manage these water quality issues in the diked managed wetlands of Suisun Marsh.

A riqueza e diversidade de anfíbios anuros da Serra do Mendanha, Estado do Rio de Janeiro, RJ: grau de conservação da floresta, variação altitudinal e uso de recursos hídricos

Os anfíbios anuros que habitam o bioma Mata Atlântica, especialmente em sua floresta ombrófila densa, são pouco conhecidos sob diversos aspectos de sua ecologia, existindo poucas informações disponíveis na literatura científica. Estes dados estão limitados a poucas localidades, geralmente estudos realizados em fragmentos remanescentes do sudeste brasileiro. A mata bem conservada que recobre os 3300 ha da Serra do Mendanha, apesar de localizada na região metropolitana do Estado do Rio de Janeiro, ainda não tinha sua anurofauna conhecida. No presente estudo, recolhemos informações ecológicas sobre as espécies que habitam a região, especialmente da assembléia encontrada no folhiço que recobre o solo, com o uso de diferentes metodologias: armadilhas de queda; parcelas cercadas; procura visual e auditiva em transecções e encontros ocasionais; assim como dados abióticos do ambiente regional (profundidade do folhiço; níveis de pH; taxa de oxigênio dissolvido; temperaturas do ar e da água; umidade do ar). Exemplares-testemunho foram fixados e depositados na coleção de anfíbios do Museu Nacional, Rio de Janeiro. A anurofauna da Serra do Mendanha é composta por pelo menos 44 espécies que estão distribuídas em 12 famílias, sendo a família Hylidae com o maior número de espécies (50%, n = 22), enquanto que Physalaemus signifer foi a espécie mais abundante (18%, n = 272), sendo habitante do folhiço. A espécie Rhinella ornata contribuiu com a maior biomassa (m = 548 g). Identificamos uma nova espécie de anuro (Brachycephalidae), que também habita o folhiço das cotas altimétricas acima de 700 m. Biogeograficamente a comunidade de anuros da área estudada indicou ser mais similar (68%) com a comunidade da região da Serra da Tiririca e arredores. Comparando-se os três tipo de fisionomias, ou mesohábitats, existentes na Serra do Mendanha, em termos de riqueza e diversidade, a floresta secundária indicou ter os mais elevados índices, seguido pela floresta pouco perturbada e pela monocultura de bananeiras. A assembléia de anuros que habita o folhiço da Serra do Mendanha é composta por nove espécies, que pouco diferiu ao longo de um gradiente altitudinal (0 a 900 m), com o registro das espécies Euparkerella brasiliensis, H. binotatus, Leptodactylus marmoratus e Zachaenus parvulus na maioria das cotas altimétricas. A altitude, a declividade e profundidade do folhiço foram as variáveis abióticas que mais influenciaram na distribuição de abundância e de riqueza de espécies do folhiço. Na estação úmida (setembro a março) a densidade de anuros no folhiço foi de 10,4 ind./100m2, enquanto que na estação seca (abril a agosto) houve uma redução de 34,6% (6,8 ind./100m2). As assembléias de anuros utilizam os recursos hídricos disponíveis na Serra do Mendanha (água da chuva, córregos, fitotelmas, rios e umidade do ar), de diferentes formas, associadas diretamente ao modo reprodutivo de cada espécie. A altitude, a temperatura da água e o pH afetaram a distribuição de espécies de girinos nos diferentes sítios reprodutivos. O modo reprodutivo 1 foi o mais freqüente (n = 18) entre os 14 modos identificados. O estudo de 12 poças (lênticas e lóticas) indicou que estas diferiram consistentemente entre si, seja nas suas dimensões, na composição de suas assembléias de girinos e nos seus componentes abióticos. Diversos predadores de girinos foram encontrados em algumas poças. A assembléia de girinos de cada poça indicou ser moldada pela interação de diferentes fatores ambientais, ecológicos e filogenéticos de cada espécie

Habitat availability and heterogeneity and the Indo-Pacific warm pool as predictors of marine species richness in the tropical Indo-Pacific

Range overlap patterns were observed in a dataset of 10,446 expert-derived marine species distribution maps, including 8,295 coastal fishes, 1,212 invertebrates (crustaceans and molluscs), 820 reef-building corals, 50 seagrasses and 69 mangroves. Distributions of tropical Indo-Pacific shore fishes revealed a concentration of species richness in the northern apex and central region of the Coral Triangle epicenter of marine biodiversity. This pattern was supported by distributions of invertebrates and habitat-forming primary producers. Habitat availability, heterogeneity and sea surface temperatures were highly correlated with species richness across spatial grains ranging from 23,000 to 5,100,000 km2 with and without correction for autocorrelation. The consistent retention of habitat variables in our predictive models supports the area of refuge hypothesis which posits reduced extinction rates in the Coral Triangle. This does not preclude support for a center of origin hypothesis that suggests increased speciation in the region may contribute to species richness. In addition, consistent retention of sea surface temperatures in models suggests that available kinetic energy may also be an important factor in shaping patterns of marine species richness. Kinetic energy may hasten rates of both extinction and speciation. The position of the Indo-Pacific Warm Pool to the east of the Coral Triangle in central Oceania and a pattern of increasing species richness from this region into the central and northern parts of the Coral Triangle suggests peripheral speciation with enhanced survival in the cooler parts of the Coral Triangle that also have highly concentrated available habitat. These results indicate that conservation of habitat availability and heterogeneity is important to reduce extinction and that changes in sea surface temperatures may influence the evolutionary potential of the region.

内蒙古高原成熟和退化羊草草原群落物种功能特性与土壤微生物量C、N、P对氮素添加响应

氮素是大多数陆地生态系统初级生产力的主要限制因子。由于人类的工业和农业生产活动不断加剧，导致全球性氮沉降增加，使大多数生态系统氮素的可获得性增强。从而降低或消除了氮素对生态系统的限制作用，加速了生态系统生物地球化学过程，对物种多样性和生态系统结构与功能产生了显著的影响。但由于成土母质、气候条件、地形地貌、植被组成等的差异，不同生态系统类型对氮素增加的响应也不尽相同。欧洲和北美一些发达国家地区对于草地生态系统对于全球性氮沉降增加响应进行了较全面的研究，对于分布广泛的欧亚大陆草原研究相对不足。 本文研究选择对于欧亚大陆草原较具代表性的成熟羊草草原群落及该群落的退化类型为研究对象，从1999年开始，在这两类群落中选取地形相对平缓均一，植被组成一致的地段设置了施肥小区并进行持续氮素添加实验。本文研究了成熟和退化羊草草原群落物种功能特性与土壤微生物量C、N、P对氮素添加响应。 羊草群落中6种主要植物的地上生物量、种群密度、比叶面积、叶氮和叶绿素含量对于氮素添加响应以及各指标之间相关关系的分析表明：比叶面积、基于质量的叶片含氮量和叶绿素含量、叶绿素a和叶绿素b的比值等叶片水平上物种功能特性间的相互作用，共同影响和决定了种群密度和地上生物量对氮素添加的响应。羊草通过提高比叶面积、叶片叶绿素含量和含氮量、种群密度及个体生物量等多重调节功能对氮素添加做出响应。西伯利亚羽茅主要通过提高比叶面积、单位质量叶片的叶绿素含量和含氮量，以及株丛生物量，使其在群落占据优势。大针茅和冰草在提高比叶面积、叶片叶绿素含量和含氮量的调节能力相对较低，种群密度沿氮素添加梯度显著降低。黄囊苔草只能通过提高叶片叶绿素含量和含氮量对氮素添加做出响应，其叶绿素a与叶绿素b的比值沿氮素添加梯度逐渐降低，种群密度和地上生物量也显著降低。糙隐子草的叶绿素a与叶绿素b比值沿氮素添加梯度显著降低，但由于糙隐子草具有较高的SLA，且对叶绿素、叶片含氮量的调节能力较强，氮素添加处理没有对其种群密度和地上生物量产生显著的影响。上述结果支持Tilman的光资源竞争假说和Knops等的物种替代假说。 成熟和退化羊草群落土壤微生物量、土壤有机碳、全氮、全磷、速效氮、pH以及凋落物碳、氮、磷含量的测定结果表明：（1）成熟羊草群落表层土壤微生物量碳、氮、磷含量均随氮素添加量的增加而降低;退化羊草群落表层土壤微生物量碳、氮、磷含量沿氮素梯度表现出先增加而后降低的趋势;相关分析的结果显示各群落土壤微生物量碳、氮、磷均与土壤pH呈显著的正相关。（2）微生物量碳、氮、磷含量均随土层深度的增加而下将;而对照的微生物量碳、氮、磷含量则与土壤有机质含量呈显著正相关。（3）年度间降水量差异对土壤微生物量碳、氮、磷具有较大影响。综合上述研究结果，我们认为成熟羊草群落土壤微生物生长不受氮素限制，但退化群落不同;氮素添加导致的土壤酸化作用可能是两类群落表层土壤微生物量下降的主要因素，且这种影响主要集中在0-10cm的表层土壤;表层土壤微生物量碳、氮、磷对氮素添加的响应可能还受到其它因子（如生长季降水量）的影响;深层土壤微生物量较低主要是由于土壤有机质含量较低的缘故。

Soil quality of Bhilwara District (Rajasthan) in relation to pisciculture

The present paper deals with the physico-chemical data of 13 rainfed and drainable dry bundhs of Bhilwara District (India). All the dry bundhs studied showed a slightly alkaline pH ranging from 7.5 to 8.5. Electrical conductivity ranged from 2 to 8 millimhos/cm. Organic carbon in sediment fluctuated from 0.30 to 0.75%. Nitrogen, phosphate and potassium levels were fairly good, at 30 to 50 and 24 to 36 mg/100 g of soil respectively. Based on these data it was inferred that these dry bundhs were highly productive and suitable for freshwater fish culture.

Effect of some environmental factors on the acute toxicity of deltamethrin to common carp: a laboratory study under aerobic condition

The toxicity of xenobiotic in aquatic ecosystems is influenced by many factors such as ambient temperature, water hardness, pond soil type, etc. In the present study, it was observed that air temperature, water hardness and soil sediment have profound influence on the toxicity of deltamethrin to common carp fry (ay. length 3.5 ± 0.5 cm, ay. weight 0.58 ± 0.25 g); 96h LC(sub)50 values for common carp at 38.07 ± 2.20°C maximum and 27.86 ± 1.22°C minimum air temperature in soft and very hard water were 0.102 and 0.495 µg lˉ¹, respectively. This value had increased significantly to 2.37 and 3.02 µg at 30.55 ± 1.21°C maximum and 26.04 ± 0.61°C minimum air temperature, respectively. When sediment was included, 96h LC(sub)50 at 38.07°C maximum temperature in very hard water was 1.808 µg 1ˉ¹ and this had increased to 8.073 µg 1ˉ¹ when tested at 30.55°C maximum temperature. Due to the 7.5°C increase in maximum and 1.7°C in minimum temperature, toxicity increased significantly. Lower toxicity in very hard water in comparison to soft water may be due to the lower solubility of deltarnethrin and high level of calcium. Adsorption reaction of deltamethrin with clay, humus, FeOOH, MnOOH and particulate organic carbon, and complexation reaction with dissolved organic carbon were responsible for the lowered toxicity in the experiment with sediment. Exposure time had no significant effect on acute toxicity of deltamethrin.