Life cycles of Eukiefferiella claripennis (Lundbeck 1898) and Eukiefferiella minor (Edwards 1929) (Diptera: Chironomidae) in spring-fed streams of different temperatures with reference to climate change

The effect of temperature on the life cycles of two chironomid species, Eukiefferiella claripennis and Eukiefferiella minor, was studied by comparing populations from seven spring-fed streams, ranging in annual average temperatures between 5.4°C and 21.3°C. Dependent on stream, both species showed differences in their life cycles: E. claripennis was regarded univoltine in the two coldest streams, IS7 (annual average 5.4°C) and IS11 (5.3°C), and bivoltine or multivoltine in the warmer streams (ranging from 9.7°C to 21.3°C). E. claripennis developed and grew slower in the colder streams compared to the warmer ones. The winter generation in the warmer streams took longer time to complete compared to the summer generation. E. minor was bivoltine in all the streams, with no emergence during the winter in the colder streams, but in one of the warmer streams (IS6, 13.3°C) emergence was continuous throughout the year. In four streams (IS7, cold; IS6, IS5 and IS1, warm) E. minor may even have been multivoltine. There was no trend between the number of generations completed in one year and stream temperature for E. minor. The summer generation of E. minor in the cold stream IS7 produced smaller larvae compared to the winter generation. Following global warming the life cycle of E. claripennis is expected to change from univoltine to bivoltine, and could show changes in emergence pattern. E. minor on the other hand, will likely show less change in its life cycle. Changes in emergence pattern of E. minor could though be possible. doi: 10.5324/fn.v31i0.1367. Published online: 17 October 2012

Læra íslensk fyrirtæki hvert af öðru? Athugun á samleitni framleiðni á milli fyrirtækja árin 2003-2018

Umfjöllunarefni þessarar ritgerðar er framleiðni fyrirtækja og samleitni þeirra á milli. Leitast verður við að svara spurningunni hvort fyrirtæki læri hvert af öðru og þannig vaxi framleiðni hraðar í þeim fyrirtækjum sem auka við sig þekkingu samanborið við þau fyrirtæki sem fremst standa hvað varðar framleiðni. Til langs tíma er framleiðniaukning háð vexti tækniþekkingar. Þetta á við bæði um framleiðni landa og fyrirtækja. Hagfræðingarnir Nelson og Phelps settu fram líkan um vöxt tækniþekkingar sem þeir notuðu til að skýra þá krafta sem valda því að tækniþekking vex hraðar eftir því sem hún er lengra frá jafnvæginu í upphafi. Í líkani þeirra er vöxtur tækniþekkingar Harrod-hlutlaus og því er aukning tækniþekkingarinnar aukning á framleiðni vinnuafls. Í fyrirtækjum er þá um að ræða framleiðni þeirra sem þar starfa. Í rannsókninni eru notuð gögn fyrir stök fyrirtæki til að rannsaka hvort um sé að ræða samleitni þeirra á milli. Prófað er sérstaklega fyrir β-samleitni með aðhvarfsgreiningu fyrir tvö tímabil, 2003-2007 og 2008-2018. Einnig er σ-samleitni metin út frá dreifingu framleiðni á hvern starfsmann. Þetta er greint hjá átta mismunandi atvinnugreinum. Niðurstöður gefa okkur vísbendingar um að σ-samleitni hafi verið til staðar þegar meðalframleiðni minnkar á árunum eftir 2007. Niðurstöður aðhvarfsgreininganna benda til þess að á báðum tímabilum hafi β-samleitni verið í öllum þeim atvinnugreinum sem skoðaðar voru. Áhrifin voru sterkari á fyrra tímabilinu en því seinna. Þessar niðurstöður benda til þess að fyrirtæki læri hvert af öðru og auki þannig framleiðni sína

Integrating ecosystem services into conservation strategies for freshwater and marine habitats: a review

Over the last two decades, there has been increasing public and political recognition of society's dependency upon natural habitat complexity and ecological processes to sustain provision of crucial ecosystem services, ranging from supplying potable water through to climate regulation. How has the ecosystem-services perspective been integrated into strategies for aquatic habitat conservation?Literature on conservation of diverse freshwater and marine habitats was reviewed to assess the extent to which past and current strategies specifically targeted ecosystem services, and considered ecosystem functions, potential trade-offs and social issues when formulating protection measures for conserving aquatic habitats.Surprisingly few published examples exist where comprehensive assessment of ecosystem services supported development of conservation plans. Seldom were aquatic habitat conservation objectives framed in terms of balancing trade-offs, assessing social values and evaluating suites of ecosystem services under different strategies. Time frames for achieving these objectives were also rarely specified. There was no evidence for fundamental differences between marine and freshwater habitats with respect to their ecosystem services that should be considered when setting targets for their conservation.When an ecosystem-service perspective is used for setting objectives in aquatic habitat conservation, the following actions are recommended: (1) explicitly listing and evaluating full suites of ecosystem services to be conserved; (2) identifying current and future potential trade-offs arising from conservation; (3) specifying time frames within which particular strategies might protect or enhance desired services; and (4) predicting how different proposed strategies might affect each ecosystem function, service flow and public benefit.This approach will help ensure that less-apparent ecosystem services (e.g. regulating, supporting) and their associated ecosystem functions receive adequate recognition and protection in aquatic conservation of freshwater and marine habitats. However, conservation objectives should not focus solely on protecting or enhancing ecosystem services but complement current strategies targeting biodiversity and other conservation goals

Impacts of warming on the structure and functioning of aquatic communities: Indivudual- to ecosystem-level responses

Environmental warming is predicted to rise dramatically over the next century, yet few studies have investigated its effects in natural, multi-species systems. We present data collated over an 8-year period from a catchment of geothermally heated streams in Iceland, which acts as a natural experiment on the effects of warming across different organisational levels and spatiotemporal scales. Body sizes and population biomasses of individual species responded strongly to temperature, with some providing evidence to support temperature size rules. Macroinvertebrate and meiofaunal community composition also changed dramatically across the thermal gradient. Interactions within the warm streams in particular were characterised by food chains linking algae to snails to the apex predator, brown trout These chains were missing from the colder systems, where snails were replaced by much smaller herbivores and invertebrate omnivores were the top predators. Trout were also subsidised by terrestrial invertebrate prey, which could have an effect analogous to apparent competition within the aquatic prey assemblage. Top-down effects by snails on diatoms were stronger in the warmer streams, which could account for a shallowing of mass-abundance slopes across the community. This may indicate reduced energy transfer efficiency from resources to consumers in the warmer systems and/or a change in predator-prey mass ratios. All the ecosystem process rates investigated increased with temperature, but with differing thermal sensitivities, with important implications for overall ecosystem functioning (e.g. creating potential imbalances in elemental fluxes). Ecosystem respiration rose rapidly with temperature, leading to increased heterotrophy. There were also indications that food web stability may be lower in the warmer streams

Glacier shrinkage driving global changes in downstream systems

Glaciers cover ∼10% of the Earth’s land surface, but they are shrinking rapidly across most parts of the world, leading to cascading impacts on downstream systems. Glaciers impart unique footprints on river flow at times when other water sources are low. Changes in river hydrology and morphology caused by climate-induced glacier loss are projected to be the greatest of any hydrological system, with major implications for riverine and near-shore marine environments. Here, we synthesize current evidence of how glacier shrinkage will alter hydrological regimes, sediment transport, and biogeochemical and contaminant fluxes from rivers to oceans. This will profoundly influence the natural environment, including many facets of biodiversity, and the ecosystem services that glacier-fed rivers provide to humans, particularly provision of water for agriculture, hydropower, and consumption. We conclude that human society must plan adaptation and mitigation measures for the full breadth of impacts in all affected regions caused by glacier shrinkage