scholarly journals The jellification of north temperate lakes

2015 ◽  
Vol 282 (1798) ◽  
pp. 20142449 ◽  
Author(s):  
Adam Jeziorski ◽  
Andrew J. Tanentzap ◽  
Norman D. Yan ◽  
Andrew M. Paterson ◽  
Michelle E. Palmer ◽  
...  
Keyword(s):  
Western Europe ◽  
Phosphorus Content ◽  
Bythotrephes Longimanus ◽  
Water Users ◽  
Jelly Coat ◽  
Softwater Lakes ◽  
North Temperate Lakes ◽  
Cladoceran Zooplankton ◽  
Zooplankton Communities

Calcium (Ca) concentrations are decreasing in softwater lakes across eastern North America and western Europe. Using long-term contemporary and palaeo-environmental field data, we show that this is precipitating a dramatic change in Canadian lakes: the replacement of previously dominant pelagic herbivores (Ca-rich Daphnia species) by Holopedium glacialis , a jelly-clad, Ca-poor competitor. In some lakes, this transformation is being facilitated by increases in macro-invertebrate predation, both from native ( Chaoborus spp . ) and introduced ( Bythotrephes longimanus ) zooplanktivores, to which Holopedium , with its jelly coat, is relatively invulnerable. Greater representation by Holopedium within cladoceran zooplankton communities will reduce nutrient transfer through food webs, given their lower phosphorus content relative to daphniids, and greater absolute abundances may pose long-term problems to water users. The dominance of jelly-clad zooplankton will likely persist while lakewater Ca levels remain low.

Implications of long-term dynamics of fish and zooplankton communities for among-lake comparisons

2006 ◽  
Vol 63 (8) ◽  
pp. 1812-1821 ◽  
Author(s):  
Julian D Olden ◽  
Olaf P Jensen ◽  
M Jake Vander Zanden
Keyword(s):  
Species Composition ◽  
Community Composition ◽  
Temporal Stability ◽  
Habitat Characteristics ◽  
Implicit Assumption ◽  
Lake Area ◽  
Data Set ◽  
North Temperate Lakes ◽  
Zooplankton Communities

Understanding the environmental determinants of lake community composition has been a central pursuit in freshwater ecology. Previous studies have defined community composition based on temporally limited surveys, with the implicit assumption that interannual variation is negligible compared with among-lake variability. Using a long-term data set for fish and zooplankton communities in five north temperate lakes (Wisconsin, USA), we found that interannual, within-lake similarity in species composition (a measure of temporal stability in community composition) generally exceeded community similarity among lakes. Despite these differences, however, the strength of community–environment relationships were found to range widely (2%–99% explained variation) depending on the choice of single-year sample used in the analysis, a result of high temporal coherence in limnological and biological characteristics. Perhaps of greatest concern, interannual similarity in species composition showed consistent relationships with habitat variables commonly used to explain community differences among lakes. Decreasing lake area and shoreline perimeter (indicative of lower habitat heterogeneity) and seepage lakes were associated with low interannual similarity in community composition, thus confounding the ability to differentiate among lake communities according to their habitat characteristics. In light of our results, we offer a number of explicit recommendations for the selection and analysis of community data in future cross-lake studies.

scholarly journals Long‐term variability and trends in meteorological droughts in Western Europe (1851–2018)

2020 ◽  
Author(s):  
Sergio M. Vicente‐Serrano ◽  
Fernando Domínguez‐Castro ◽  
Conor Murphy ◽  
Jamie Hannaford ◽  
Fergus Reig ◽  
...  
Keyword(s):  
Western Europe ◽  
Meteorological Droughts

Changes in the crustacean communities of Lakes Michigan, Huron, and Erie following the invasion of the predatory cladoceran Bythotrephes longimanus

2004 ◽  
Vol 61 (11) ◽  
pp. 2111-2125 ◽  
Author(s):  
Richard P Barbiero ◽  
Marc L Tuchman
Keyword(s):  
Zooplankton Community ◽  
Crustacean Zooplankton ◽  
Bythotrephes Longimanus ◽  
Zooplankton Community Structure ◽  
Cladoceran Species ◽  
Invertebrate Predators ◽  
Predatory Cladoceran ◽  
Leptodora Kindti ◽  
Escape Responses ◽  
Zooplankton Communities

The crustacean zooplankton communities in Lakes Michigan and Huron and the central and eastern basins of Lake Erie have shown substantial, persistent changes since the invasion of the predatory cladoceran Bythotrephes in the mid-1980s. A number of cladoceran species have declined dramatically since the invasion, including Eubosmina coregoni, Holopedium gibberum, Daphnia retrocurva, Daphnia pulicaria, and Leptodora kindti, and overall species richness has decreased as a result. Copepods have been relatively unaffected, with the notable exception of Meso cyclops edax, which has virtually disappeared from the lakes. These species shifts have for the most part been consistent and equally pronounced across all three lakes. Responses of crustacean species to the Bythotrephes invasion do not appear to be solely a consequence of size, and it is likely that other factors, e.g., morphology, vertical distribution, or escape responses, are important determinants of vulnerability to predation. Our results indicate that invertebrate predators in general, and invasive ones in particular, can have pronounced, lasting effects on zooplankton community structure.

Cost determination and sustainable financing for rural water services in sub-Saharan Africa

Water Policy ◽  
2007 ◽  
Vol 9 (4) ◽  
pp. 373-391 ◽  
Author(s):  
Peter A. Harvey
Keyword(s):  
Sub Saharan Africa ◽  
Water Services ◽  
Innovative Strategies ◽  
Water Users ◽  
Sub Saharan ◽  
The Cost ◽  
National Governments ◽  
Cost Determination ◽  
Sustainable Financing

Access to safe, sufficient and affordable water in rural Africa will not increase unless sustainable financing strategies are developed which ensure the sustainability of existing water services. There is a strong need for international donors and national governments to confront the true costs associated with sustained service provision in order to develop practicable long-term financing mechanisms. This paper presents a systematic approach that can be applied to determine the overall cost of service delivery based on respective cost estimates for operation and maintenance, institutional support, and rehabilitation and expansion. This can then be used to develop a tariff hierarchy which clearly indicates the cost to water users of different levels of cost recovery, and which can be used as a planning tool for implementing agencies. Community financing mechanisms to ensure sustained payment of tariffs must be matched to specific communities and their economic characteristics; a blanket approach is unlikely to function effectively. Innovative strategies are also needed to ensure that the rural poor are adequately served, for which a realistic, targeted and transparent approach to subsidy is required.

Transformations of Identity and Society in Anglo-Saxon Essex

2019 ◽  
Author(s):  
Alexander Mirrington
Keyword(s):  
North Sea ◽  
North Atlantic ◽  
Western Europe ◽  
Anglo Saxon ◽  
Early Medieval ◽  
Cultural Affiliation ◽  
Profound Influence ◽  
North Western

Transformations of Identity and Society in Anglo-Saxon Essex: A Case Study of an Early Medieval North Atlantic Community presents the results of a comprehensive archaeological study of early medieval Essex (c.AD 400-1066). This region provides an important case study for examining coastal societies of north-western Europe. Drawing on a wealth of new data, the author demonstrates the profound influence of maritime contacts on changing expressions of cultural affiliation. It is argued that this Continental orientation reflects Essex’s longterm engagement with the emergent, dynamic North Sea network. The wide chronological focus and inclusive dataset enables long-term socio-economic continuity and transformation to be revealed. These include major new insights into the construction of group identity in Essex between the 5th and 11th centuries and the identification of several previously unknown sites of exchange. The presentation also includes the first full archaeological study of Essex under ‘Viking’ rule.

scholarly journals Long-Term Changes in Summer Zooplankton Communities of the Western Chukchi Sea, 1945–2012

Oceanography ◽  
2015 ◽  
Vol 28 (3) ◽  
pp. 100-115 ◽  
Author(s):  
Elizaveta Ershova ◽  
Russell Hopcroft ◽  
Ksenia Kosobokova ◽  
Kohei Matsuno ◽  
R. John Nelson ◽  
...  
Keyword(s):  
Chukchi Sea ◽  
Long Term Changes ◽  
Zooplankton Communities

scholarly journals High frequency Barium profiles in shells of the Great Scallop <i>Pecten maximus</i>: a methodical long-term and multi-site survey in Western Europe

2008 ◽  
Vol 5 (5) ◽  
pp. 3665-3698 ◽  
Author(s):  
A. Barats ◽  
D. Amouroux ◽  
L. Chauvaud ◽  
C. Pécheyran ◽  
A. Lorrain ◽  
...  
Keyword(s):  
High Frequency ◽  
Western Europe ◽  
Pecten Maximus ◽  
Coastal Environments ◽  
Great Scallop ◽  
Site Survey ◽  
Scallop Shells ◽  
Bay Of Brest ◽  
Long Term Survey

Abstract. Skeletal barium/calcium ([Ba]/[Ca])shell ratios were measured every third daily striae in 39 flat valves of the Great Scallop Pecten maximus (2-year old; 3 shells/year) collected in temperate coastal environments of Western Europe. Variations of ([Ba]/[Ca])shell ratio were first demonstrated reproducible for several scallop individuals from the same population, over a 7-year period (1998–2004), and from different coastal environments in France (42–49° N). As in previous studies, ([Ba]/[Ca])shell profiles exhibited a background ratio punctuated by transient maxima occurring in summer. Background partition coefficient (DBa=0.11±0.03, in 2000) was similar to that previously reported in P. maximus shells (DBa=0.18), suggesting a direct shell uptake of dissolved seawater Ba (Gillikin et al., 2008). Special attention was then dedicated to the complete monitoring of high resolution ([Ba]/[Ca])shell profiles in bivalve shells (7 years, Bay of Brest) to better constrain environmental processes influencing both the occurrence and the amplitude of summer peaks. In 2000, seawater Ba analyses underlined significant particulate Ba inputs at the seawater interface (SWI) during ([Ba]/[Ca])shell peak events. These Ba inputs are suggested to be subsequent to and rather induced by a pelagic biogenic process. The long term survey revealed first that archived Ba within the shell cannot be used as a direct paleo productivity tracer, and second that complex pelagic/benthic processes in the Ba cycle are responsible of particulate Ba inputs to the SWI, subsequently taken up by the bivalve and recorded as higher ([Ba]/[Ca])shell ratios. When these processes will be better constrained, high frequency observations of Ba in scallop shells would provide new insights into filter feeding dynamics and into Ba biogeochemistry in coastal environments.

scholarly journals Motivations behind individuals’ energy efficiency investments and daily energy-saving behavior: The case of China

2021 ◽  
Author(s):  
J. K. Perret ◽  
V. Udalov ◽  
N. Fabisch
Keyword(s):  
Energy Efficiency ◽  
Energy Saving ◽  
Western Europe ◽  
Peer Pressure ◽  
China Policy ◽  
Beijing Area ◽  
Daily Energy ◽  
Sociocultural Background ◽  
The Impact

AbstractThe impact of environmental motivations on the individual’s decisions regarding investments in energy efficiency and the adoption of energy-saving habits are analyzed for a representative sample of Chinese inhabitants from the larger Beijing area, replicating a comparative study on Western Europe. For the considered type of energy efficiency investments and daily energy-saving activities similarities and discrepancies between the two regions are discussed in regard to their sociocultural background as well as governmental regulations. The study provides empirical evidence that for Chinese environmental issues if all only play a tertiary role after monetary and regulatory incentives. The findings could suggest that in China policy programs aimed at raising environmental awareness and forming pro-environmental motivations might not lead to an increase in energy efficiency investments and daily energy-saving activities and the Chinese government’s interests in this regard might be better served by implementing corresponding incentives via regulations. In the long-term. However, social peer pressure might affect a change in the Chinese mentality.

Market Power and Market Failure The Decline of the European Fertilizer Industry and the Expansion of Norsk Hydro

2008 ◽  
Vol 9 (1) ◽  
pp. 70-95 ◽  
Author(s):  
Einar Lie
Keyword(s):  
Western Europe ◽  
Market Failure ◽  
Cost Structure ◽  
Organizational Capabilities ◽  
Main Argument ◽  
Norsk Hydro ◽  
Fertilizer Industry ◽  
Market Shares ◽  
The Stability

During the 1980s, the fertilizer industry in Western Europe underwent some radical changes. Reduced profitability and overcapacity forced a number of smaller producers to close down, and most of the major firms in the business either withdrew from the market or reduced their capacity. The exception was the Norwegian industrial conglomerate Norsk Hydro, which expanded rapidly and established itself as the largest producer in Europe and later globally.The article discusses the strategy behind Hydro's expansion in relation to the changing structure of the fertilizer market, which historically was characterized by tacit and explicit agreements on prices and market shares between the major producers. Hydro's strategy and growth are analyzed in relation to some theoretical contributions from the study of transnationalisation of enterprises. A main argument is that Hydro's expansion was not driven by advantages in cost structure or organizational capabilities, nor did the expansion create such advantages. The Norwegian company expanded in foreignmarkets partly because it had less to lose from a counterattack than competitors in largermarkets and partly because of strategic disadvantages. Contrary to most of its large European competitors, Hydro failed to identify the long term threats to the stability and profitability of the Western European market.

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