The ecological condition of Gulf of Mexico resources from Perdido Key to Port St. Joe, Florida: Part II near-shelf coastal resources

In 1999, the United States Environmental Protection Agency Gulf Ecology Division initiated a pilot study to assess the condition of nearshore coastal resources. Near-shelf areas associated with coastal beaches are susceptible to land based activities, but are not consistently monitored. Additionally, few or no marine water quality criteria exist for evaluating these waters. The goal of this pilot study was to assess the ecological condition of Gulf of Mexico near-shelf resources using a probability-based survey design. Data are used to generate a baseline assessment of condition in coastal nearshore areas and provide a comparative tool for evaluating future trends in condition. Water quality, sediment quality and benthic diversity data can provide a baseline assessment for managers to evaluate the potential for future problems such as nutrient over-enrichment, sediment contamination and degraded biological condition. We present results from a probability-based survey demonstration assessing near-shelf resources along the Florida panhandle.     

Low-maturity Kulthieth Formation Coal: A Possible Source of Polycyclic Aromatic Hydrocarbons in Benthic Sediment of the Northern Gulf of Alaska

The successful application of forensic geology to contamination studies involving natural systems requires identification of appropriate endmembers and an understanding of the geologic setting and processes affecting the systems. Studies attempting to delineate the background, or natural, source for hydrocarbon contamination in Gulf of Alaska (GOA) benthic sediments have invoked a number of potential sources, including seep oils, source rocks, and coal. Oil seeps have subsequently been questioned as significant sources of hydrocarbons present in benthic sediments of the GOA in part because the pattern of relative polycyclic aromatic hydrocarbon (PAH) abundance characteristic of benthic GOA sediments is inconsistent with patterns typical of weathered seep oils. Likewise, native coal has been dismissed in part because ratios of labile hydrocarbons to total organic carbon (e.g. PAH: TOC) for Bering River coal field (BRCF) sources are too low--i.e. the coals are over mature--to be consistent with GOA sediments. We present evidence here that native coal may have been prematurely dismissed, because BRCF coals do not adequately represent the geochemical signatures of coals elsewhere in the Kulthieth Formation. Contrary to previous thought, Kulthieth Formation coals east of the BRCF have much higher PAH: TOC ratios, and the patterns of labile hydrocarbons in these low thermal maturity coals suggest a possible genetic relationship between Kulthieth Formation coals and nearby oil seeps on the Sullivan anticline. Analyses of low-maturity Kulthieth Formation coal indicate the low maturity coal is a significant source of PAH. Source apportionment models that neglect this source will underestimate the contribution of native coals to the regional background hydrocarbon signature.     

江苏地表水体大型底栖无脊椎动物生物多样性状况研究

大型底栖无脊椎动物群落结构与水体水质和水生态系统健康状况关系密切,其受外界干扰后群落结构的变化趋势可以反映水体受污染的性质和程度。2008年,对江苏省主要饮用水源地,长江、京杭大运河等主要河流及太湖等重点湖泊开展底栖动物调查与评价研究,共设置调查点位154个。江苏主要饮用水源地底栖动物的物种数量为78种,主要河流发现底栖动物96种,主要湖泊底栖动物发现65种。从物种多样性指数评价结果看,主要湖泊的底栖生物多样性状况优于地表水源地和主要河流,丰富和较丰富所占比例合计达58%;主要河流的评价结果最差,丰富和较丰富所占比例合计仅达30.7%,存在11.3%物种多样性极贫乏的点位,且大部分水体底栖动物组成以耐污种为主,优势种为极耐污的霍甫水丝蚓,水质状况劣于饮用水源地和主要湖泊。     

Nitrogen versus phosphorus limitation in a subtropical coastal embayment (Moreton Bay; Australia): Implications for management

An approach combining nutrient budgets, dynamic modelling, and field observations of phytoplankton and nitrogen (N₂)-fixing Lyngbya majuscula following changes in wastewater N loads, was used to demonstrate that Moreton Bay is potentially phosphorus (P) limited. Modelling and nutrient budgeting shows that benthic N-fixation loads are high, allowing the system to overcome any potential N-limitation. Phytoplankton biomass has shown little change from 1991 to 2006 in the sections of Moreton Bay most impacted by wastewater effluents, despite a large reduction in wastewater N loads from 2000 to 2002. This is consistent with modelling that also showed no reduction in primary productivity associated with reduced N loads. Most importantly, there have been rapid increases in the occurrence of N-fixing L. majuscula in Moreton Bay as wastewater P loads have increased relative to wastewater N loads. This is also consistent with modelling. This work supports the premise that there may be fundamental differences in nutrient limitation of primary production between subtropical and temperate coastal systems due to differences in the importance of internal nitrogen sources and sinks (N-fixation and denitrification). These differences need to be recognised for optimum management of coastal systems.     

Functional Isomorphism of Ecosystems and Its Significance for Ecological Prognosis

A concept concerning the functional isomorphism of natural ecosystems as a factor modulating climatogenic changes in the soil–plant cover is proposed. On an empirical basis, production and destruction types of isomorphism are distinguished, which differ in their prevailing influence on the dynamics of zonal and regional ecosystems in the boreal and subboreal belts.     

Effects of plant diversity on greenhouse gas emissions in microcosms simulating vertical constructed wetlands with high ammonium loading

Wastewater with relatively high nitrogen concentrations is a major source of nitrous oxide (N₂O) and methane (CH₄) emissions and exerts multiple stresses on the environment. Studies have shown that plant diversity plays an important role in ecosystem functioning. However, the effects of plant species diversity on CH₄ and N₂O emissions under high ammonium (NH₄⁺-N) loading rates remain unclear. In this study, a microcosm experiment simulating vertical constructed wetlands supplied with high NH₄⁺-N water levels was established. The treatments included four species richness levels (1, 2, 3, 4) and 15 species compositions. There was no significant relationship between species richness and N₂O emissions. However, N₂O emissions were significantly reduced by specific plant species composition. Notably, the communities with the presence of Rumex japonicus L. reduced N₂O emissions by 62% compared to communities without this species. This reduction in N₂O emissions may have been a result of decreased N concentrations and increased plant biomass. CH₄ emissions did not respond to plant species richness or species identity. Overall, plant species identity surpassed species richness in lowering N₂O emissions from constructed wetlands with high NH₄⁺-N water. The results also suggest that communities with R. japonicus could achieve higher N removal and lower greenhouse gas emissions than other wetland species.     

Settlement seasonality and temporal changes in hard substrate macrozoobenthic communities of Lesina Lagoon (Apulia, Southern Adriatic Sea)

The macrofauna settling on experimental substrates was studied at two sites of the Lesina Lagoon to test its possible role in monitoring ecological variations in a brackish-water ecosystem. The community settlement was seasonally investigated on 3-month-old wooden poles; the development was monitored from 2001 to 2005. Comparisons with benthic assemblages settled on 10-yr-old poles were also performed. The main hydrological parameters were periodically measured during the study. A total of 38 species were collected. The assemblage reached the highest development in the central lagoon, showing relevant carbonate structures which supported a rich vagile fauna. Close to the sea-water inlet species richness and abundance values were lower, with the disappearance of some brackish-water species. A remarkable salinity drop during 2004 produced some faunistic changes in the assemblages, which however maintained different structures between the study sites, thus confirming macrozoobenthos as an efficient bioindicator of different environmental conditions for transition biotopes and a useful investigation tool in monitoring programmes.     

Prognosis of the impact of global climate change on zonal ecosystems of the Volga River Basin

On the basis of the GISS prognostic climatic model, landscape-ecological scenarios concerning the immediate future of the region are considered in the forms of cartographic and analytical models. These scenarios predict a growing thermoarid bioclimatic trend accompanied by a general northward displacement of zonal boundaries, with corresponding acceleration of the biological cycle and increase in the productivity of boreal forests.