Effects of detrital non-native and native macroalgae on the nitrogen and carbon cycling in intertidal sediments

The decay of non-native and native seaweed mixing may modify sediment biogeochemistry and organic matter transfers within benthic food webs according to their composition and biomass. The non-native species Sargassum muticum was deliberately added to the sediment of an intertidal sandflat at different biomass and mixed to the native species Ulva sp. and Fucus vesiculosus. The sediment porewater was then ¹³C and ¹⁵N enriched to test whether both detrital diversity and biomass influenced the transfer of porewater carbon and nitrogen to the sediment and to the macrofauna consumers. More ¹⁵N-nitrogen was mobilized to sediments and macrofauna when the 3-species detrital mixing was buried, probably because this mixing provided species-specific compounds such as polyphenols due to the presence of S. muticum and F. vesiculosus, as well as large amounts of nitrogen due to the presence of Ulva. Our study revealed the importance of detrital diversity and non-native seaweeds for the nitrogen cycling in the benthic food web.     

Assessment and sources of nonaromatic hydrocarbons in surface sediments of three harbors in Santa Catarina State, Brazil

Nonaromatic hydrocarbons and geochemical parameters from 17 sediment?Cwater interface samples were used to assess sources of organic matter in three harbors, located in Santa Catarina State, southern Brazil. The evaluation was based on the molar C/N/P ratios, abundance of resolved nonaromatic hydrocarbons (3.0?C25.9 ??g g^???1), unresolved complex mixture, and two indexes: the carbon preference index (CPI) and the low molecular weight to high molecular weight ratio. The results indicate that the organic matter is predominantly of terrestrial origin (C/N > 10 and CPI > 2). Variations in the total organic carbon from 0.43 to 2.98 mmol g^???1 and total phosphorus from 82.4 to 464.3 ??g g^???1 showed no clear correlation with the silt and clay fractions of the sediments possibly due to anthropogenic input. In contrast to the low level of contamination based on the acyclic hydrocarbon distribution, the results obtained from a series of geologically stable hopanes and steranes reveal the presence of less degradable petroleum derivatives.     

Environmental monitoring using surface water, river sediments, and vegetation: A case study in the Famatina Range, La Rioja, NW Argentina

This work discusses trace elements studied beneath the semiarid endorheic region of the Famatina Range (La Rioja, NW Argentina). The results obtained in 27 control sites allow the determination of five distinct geochemical patterns in the Famatina Range. Pattern 1 reflects the composition of underlying Paleozoic and Tertiary bedrock (background level: water pH, 7.5–9; specific conductance, 0.2–0.7 mS cm⁻¹), which is influenced by mineralization. Pattern 2 exhibits water pH, 6; specific conductance, 0.7 mS cm⁻¹; high contents of Cu, Cd, Rb, Zn, Sn, and Be in waters; and high contents of Cu, Cd, Zn, Pb, Cr, Sb, Ag, Be, Co, Ni, Bi, Rare Earth Elements (REE), Li, Ba, Cs, and Sr in sediments. Pattern 3 exhibits water pH, 3–4; specific conductance, 1.0 mS cm⁻¹; high contents of Pb, Co, Be, Au, As, Cr, Hg, Th, Ba, Cs, Rb, Sb, Y, Zr, REE, and Hf in waters; high contents of Cd, Zn, Mo, and As in sediments). Pattern 3 is also modified by the input of elements from a source external to the Famatina Range. Pattern 4 exhibits water pH, 7–8; specific conductance, 1.5–2.3 mS cm⁻¹; high contents of B, Li, Ba, Sr, and Zn in waters; high contents of Li, Cr, Sr, Ni, and Cs in sediments. Finally, Pattern 5 is developed on the red sandstones from De la Cuesta Formation (water pH, 8; specific conductance, 2.5–5.0 mS cm⁻¹; high contents of Sr, Mo, U, B, Li, Rb, and Hf in waters; high contents of B, Ba, Cs, Li, and Rb in sediments). The mobility of above-mentioned elements is mainly related to water pH changes and evaporation processes.     

Short Note

This study was aimed to investigate the role of two exotic bivalves ( Ruditapes philippinarum and Musculista senhousia ) on the trophic enrichment and the nutritional quality of sediments from the Sacca di Goro (northern Adriatic Sea) through manipulative experiments. The concentrations of sedimentary total organic matter, biopolymeric carbon, carbohydrates, proteins, lipids, and chlorophyll- a were determined through a 64 days-long period. The experimental setup consisted in three replicated treatments ( R. philippinarum , M. senhousia and simply sand), with treatments and time as fixed factors. All the biochemical classes showed wide fluctuation, and significant differences among treatments were detected during the experimental period. Both bivalve species played a role in sediment enrichment process. At the end of the experimental period, proteins represented the main biochemical class of organic compounds in the treatments with bivalves (48.5 and 44.5% of the biopolymeric fraction in the M. senhousia and R. philippinarum treatments, respectively), while in the control treatment they were only 32.7%. The accumulation of proteic nitrogen increased the nutritional quality of the sedimentary organic matter. Moreover, the presence of M. senhousia also enhanced the accumulation of microphytobenthic carbon.     

A temporary social parasite of tropical plant-ants improves the fitness of a myrmecophyte

Myrmecophytes offer plant-ants a nesting place in exchange for protection from their enemies, particularly defoliators. These obligate ant–plant mutualisms are common model systems for studying factors that allow horizontally transmitted mutualisms to persist since parasites of ant–myrmecophyte mutualisms exploit the rewards provided by host plants whilst providing no protection in return. In pioneer formations in French Guiana, Azteca alfari and Azteca ovaticeps are known to be mutualists of myrmecophytic Cecropia (Cecropia ants). Here, we show that Azteca andreae, whose colonies build carton nests on myrmecophytic Cecropia, is not a parasite of Azteca–Cecropia mutualisms nor is it a temporary social parasite of A. alfari; it is, however, a temporary social parasite of A. ovaticeps. Contrarily to the two mutualistic Azteca species that are only occasional predators feeding mostly on hemipteran honeydew and food bodies provided by the host trees, A. andreae workers, which also attend hemipterans, do not exploit the food bodies. Rather, they employ an effective hunting technique where the leaf margins are fringed with ambushing workers, waiting for insects to alight. As a result, the host trees’ fitness is not affected as A. andreae colonies protect their foliage better than do mutualistic Azteca species resulting in greater fruit production. Yet, contrarily to mutualistic Azteca, when host tree development does not keep pace with colony growth, A. andreae workers forage on surrounding plants; the colonies can even move to a non-Cecropia tree.     

Responses of marine benthic microalgae to elevated CO2

Increasing anthropogenic CO₂ emissions to the atmosphere are causing a rise in pCO₂ concentrations in the ocean surface and lowering pH. To predict the effects of these changes, we need to improve our understanding of the responses of marine primary producers since these drive biogeochemical cycles and profoundly affect the structure and function of benthic habitats. The effects of increasing CO₂ levels on the colonisation of artificial substrata by microalgal assemblages (periphyton) were examined across a CO₂ gradient off the volcanic island of Vulcano (NE Sicily). We show that periphyton communities altered significantly as CO₂ concentrations increased. CO₂ enrichment caused significant increases in chlorophyll a concentrations and in diatom abundance although we did not detect any changes in cyanobacteria. SEM analysis revealed major shifts in diatom assemblage composition as CO₂ levels increased. The responses of benthic microalgae to rising anthropogenic CO₂ emissions are likely to have significant ecological ramifications for coastal systems.     

The costs and benefits of working with one's spouse: A two‐sample examination of spousal support,work–family conflict,and emotional exhaustion in work‐linked relationships

Although the prevalence of employees working within the same workplace or occupation with their spouse has increased, relatively little research has examined their experiences. On the basis of the boundary and conservation of resources (COR) theories, we argue that higher levels of work–family role integration among work‐linked couples will lead to higher levels of spousal support resources and lower levels of work–family conflict. This will, in turn, lead to lower emotional exhaustion among employees in a work‐linked relationship. Among two samples of employees in a variety of occupations, we found that being in a work‐linked relationship was associated with both higher spousal instrumental support as well as different forms of work–family conflict. The interaction between spousal support and work–family conflict was associated with emotional exhaustion. We discuss the implications of these findings for boundary and COR theories in terms of movement of resources across work–family boundaries and resource relevance in the strain process. Copyright © 2011 John Wiley & Sons, Ltd.     

Optimization of tourism impacts within protected areas by means of genetic algorithms

The search for a balance between nature conservation and tourism development within protected areas is becoming an increasingly multifaceted problem worldwide, as outlined by an increasing number of authors and highlighted at several international events. Since it is unlikely that all management objectives will reach their optimum values simultaneously, an optimization approach is required to meet multiple, conflicting goals and to obtain an overall trade-off in terms of the conceived objectives.     

产业联盟透视 关于中外产业联盟问题的10个答问

国内外产业联盟的形成和发展,原因在于经济全球化、高新技术特别是信息技术的快速发展。联盟按照自愿、平等、互利原则建立,这种组织形式有利于成员间的资源整合,有利于新技术的研发、统一标准、开拓全球市场,使联盟成员在市场竞争中获得更多的优势。联盟的发展需要有明确的定位,坚持战略性、市场化、互利性原则。目前安防行业成立的产业联盟,本质上是企业联盟。在企业家探索、实践产业联盟之际,我们对产业联盟的来龙去脉、对联盟的定位和功能进行了梳理,目的是抛砖引玉,希望大家对产业联盟、企业联盟有一个相对全面、直观的解读。