Contribution of nanoprotists to metazooplankton diet in a mesocosm experiment in the coastal northern Baltic

Grazing by a metazooplankton community on nanoprotists <10µm was studied four times during a 21 day enclosure experimentcarried out off the SW coast of Finland in late summer. Duringthe study, the pelagic community was manipulated through nutrientenrichment (N + P) and through predation by stickleback fry.Grazing experiments were conducted in the laboratory using 5µm prefiltered, ³H-labelled nanoplankton as tracer food. Grazing by mesozooplankton (Meso) and metazaan microplankton(Micro), screened through 140 and 100 µm mesh, was studied.Owing to enrichment effects and weak predation control by fish,the biomass of Meso and Micro increased during the study peridMeso biomass consisted mostly of the copepod Eurytemora affinisand the cladoceran Bosmina longispims maritima, and Micro biomassof copepod nauplii NIII–NVI. The community clearance rateof Meso usually exceeded that of Micro when feeding on nanoprotistsThe opposite was found for the biomass-smc clearance rate, revealingnanoprotists to be a more important f d source for Micro thanfor Meso. Metazmplankton were not able to control nanoprotists,because Meso and Micro were estimated to remove on average 4and 2% of nanoprotowan biomass daily. When integrated throughthe study period, grazing on nanoprotists could meet 5 and 17%of the carbon need for Meso and Micro, 3 and 12% of their productionbeing estimated to consist of bacterial carbon transferred bynanoprotists Micro were estimated to be more closely Linkedto the microbial food web than Meso, suggesting that the trophicpusition of copepods changes slightly during their maturationfrom nauphi to larger copepodites. ¹ Present address: Department of Ecology and Systematics, Divkionof Hydrobiology, University of Helsinki, FIN-00014, Helsinki,Finland     

Distributions,life cycles and hybridization of two Mysis relicta group species (Crustacea: Mysida) in the northern Baltic Sea and Lake Båven

We used electrophoretically identified material to assess the geographical distributions, life cycles and interspecific hybridization of two sibling species of the Mysis relicta species group (sp. I and sp. II) in the northern Baltic region. In the Gulf of Finland, sp. I prevails in inshore waters and sp. II in the open sea; the distributions overlap in the outer archipelago zone. In the Gulf of Bothnia, only sp. II was found in the southern part (Bothnian Sea), whereas the two species coexist throughout the northerly Bothnian Bay. Both the local and large-scale distributions are salinity-related, but salinity alone does not explain the differences. The two species exhibit different patterns of geographical variation in their life histories. In strict sympatry in the north they have identical two-year life cycles with winter breeding. Further south (Gulf of Finland), sp. I exhibits a predominantly one-year winter-breeding cycle, whereas sp. II breeds throughout the year. The patterns comply with the concept of a great phenotypic flexibility and environmental control of life history characteristics in the Mysis relicta group, and make a contrast to the stable life cycle of the congeneric M. mixta. F1 hybrids between the two M. relicta group species were found at a low frequency (0.6%) in the Bothnian Bay, but not in other areas of sympatry. This revised version was published online in July 2006 with corrections to the Cover Date.     

Environmental impacts of wooden,plastic, and wood-polymer composite pallet: a life cycle assessment approach

Purpose

Waste recycling is one of the essential tools for the European Union’s transition towards a circular economy. One of the possibilities for recycling wood and plastic waste is to utilise it to produce composite product. This study analyses the environmental impacts of producing composite pallets made of wood and plastic waste from construction and demolition activities in Finland. It also compares these impacts with conventional wooden and plastic pallets made of virgin materials.

Methods

Two different life cycle assessment methods were used: attributional life cycle assessment and consequential life cycle assessment. In both of the life cycle assessment studies, 1000 trips were considered as the functional unit. Furthermore, end-of-life allocation formula such as 0:100 with a credit system had been used in this study. This study also used sensitivity analysis and normalisation calculation to determine the best performing pallet.

Result and discussion

In the attributional cradle-to-grave life cycle assessment, wood-polymer composite pallets had the lowest environmental impact in abiotic depletion potential (fossil), acidification potential, eutrophication potential, global warming potential (including biogenic carbon), global warming potential (including biogenic carbon) with indirect land-use change, and ozone depletion potential. In contrast, wooden pallets showed the lowest impact on global warming potential (excluding biogenic carbon). In the consequential life cycle assessment, wood-polymer composite pallets showed the best environmental impact in all impact categories. In both attributional and consequential life cycle assessments, plastic pallet had the maximum impact. The sensitivity analysis and normalisation calculation showed that wood-polymer composite pallets can be a better choice over plastic and wooden pallet.

Conclusions

The overall results of the pallets depends on the methodological approach of the LCA. However, it can be concluded that the wood-polymer composite pallet can be a better choice over the plastic pallet and, in most cases, over the wooden pallet. This study will be of use to the pallet industry and relevant stakeholders.