Category: Reports

Reports

Moist diet for farmed fish

Published:

01/02/2009

Authors:

Jón Örn Pálsson

Supported by:

AVS Fisheries Research Fund. Preliminary project (S 034‐05)

Moist diet for farmed fish

Gellyfeed is a synonym for a two-stage production process of aquaculture feed. The method was developed with the aim of reducing storage costs and producing strong feed pellets. Studies confirm that long-term leaching of raw materials and storage impairs the quality of proteins and renders the raw material unsuitable for wet feed production. The maximum shelf life of fish raw material in a strong alkaline state is 14 days. The method can be useful for killing bacteria, viruses and parasites. Options for storage of raw materials for wet feed production are freezing and digestion processing. The production of wet feed from by-products that occur in the northern Westfjords can be a promising option. The legislation of the European Economic Area does not prohibit the use of by-products from wild cod in feed for farmed cod.

Gellyfeed is a name of a two-step production process of moist diet for farmed fish. The process is developed to reduce the cost of preserving by-products and to make a physical strong pellet. Research confirms that alkaline preserved raw material and longtime storing damage the protein quality and make the raw material not suitable for use in moist diet. Maximum storing time of alkaline preserved by ‐ products is 14 days. The process can be practical for eliminating harm from bacteria, viruses or parasites. The alternative methods for storing by ‐ products are freezing or silage production. Moist diet produced from by ‐ products from the northern region of the Westfjords in Iceland seems to be economically promising option. The legislation from the European Union does not forbid using by-products from wild cod as a raw material in production of moist diet.

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Reports

Development of analytical methods for food imaging - Use of imaging to assess spinal defects immediately at the larval stage of cod farming / Development of analytical methods - The use of image analysis for detection of spinal deformities of fish larvae

Published:

01/01/2009

Authors:

Jónína Þ Jóhannsdóttir, Rut Hermannsdóttir, Rannveig Björnsdóttir

Supported by:

Matvælasetur Háskólinn á Akureyri

Development of analytical methods for food imaging - Use of imaging to assess spinal defects immediately at the larval stage of cod farming / Development of analytical methods - The use of image analysis for detection of spinal deformities of fish larvae

Research has shown that there is a great difference in the quality of food according to its origin and different treatment, and therefore it is important to be able to monitor the quality of processed raw materials and food in the easiest and most reliable way. Imaging is a very interesting option that can provide information that is accessible and shows well the structure of tissues and the effect of different factors on the composition and properties of products. Various defects are common problems in cod farming and it is believed that this can, among other things, limit growth potential and cause increased losses. Skeletal defects such as skulls do not appear until the later stages of larval rearing and it is therefore important to develop an easy method of diagnosis earlier in the process. Imaging of cod and halibut larvae was based on a staining method with a double staining solution in which bones and cartilage are stained (Alazarin red and Alcian blue). Various versions were tested during the adaptation of the method, which proved necessary in order to get the clearest picture of the appearance of the spine. It turned out to be best to dye over a longer period of time (overnight), but the bleaching time needs to be extended from the original method description to reduce the color in the flesh. The results indicate that imaging is a good way to assess the quality of larvae and it is best to stain only the bones as cartilage in the fins and face can shade the upper part of the spine.

Research reveal variable quality of food products, depending on the origin, processing and other treatment of the product. Hence, it is considered of importance to be able to easily monitor the quality of the raw material. Image analysis is considered an interesting choice of analytical method which allows detection of tissue structures and analysis of the effects of various factors on tissue structure and various quality parameters. Various deformities are commonly observed in aquacultured fish and may limit growth and contribute to reduced survival. Spinal deformities do not appear until late during the larval stages and therefore it is important to develop an accessible method for early detection of these deformities. Cod and halibut larvae were analyzed using image analysis following double staining of bone and cartilage (Alazarin red and Alcian blue). Various adjustments of the method were tested in order to get a clear view of the spinal cord. The most successful results were obtained when staining was carried out overnight and the bleaching time extended in order to minimize staining of the flesh. The results indicate that image analysis using staining is practical for detection of spinal deformities of fish larvae. The most successful results were obtained using staining of only the bone tissue as staining of the cartilage as well would predominate the uppermost part of the spine.

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Reports

Fishing, sorting, processing and markets for mackerel caught by pelagic vessels. Markaður / Fishing, grading, pre ‐ processing, processing and marketing of mackerel products catches by pelagic vessels. Markets

Published:

01/01/2009

Authors:

Ragnheiður Sveinþórsdóttir

Supported by:

AVS

Fishing, sorting, processing and markets for mackerel caught by pelagic vessels. Markaður / Fishing, grading, pre ‐ processing, processing and marketing of mackerel products catches by pelagic vessels. Markets

The aim of this project is to study the fishing of pelagic fishing vessels for mackerel in Icelandic waters, make formal measurements, come up with solutions on how to sort the mackerel from other fish on board and how to process it in freezer vessels. The equipment options necessary for the processing will be analyzed, and markets for mackerel caught in Icelandic waters will also be explored according to the seasons. In this section, markets for mackerel products are described. The main exporters and main buyers are covered. The two largest exporting nations are also deepening their exports in terms of products and prices.

The objective of this project is to examine mackerel fishing on Icelandic fishing grounds, perform geometrician measurements, find the best solution for grading the mackerel by size and species on board and how to process it in freezer vessels. Analyze what kind of technology is necessary. Moreover, to examine the markets for mackerel caught on Icelandic fishing grounds during the summer. In this part requirements analysis was carried out about what is needed to process mackerel on board vessels caught during summertime on Icelandic fishing grounds. In this section the focus is on markets for mackerel products. The focus is on exporters and buyers and also more about exports and prices at the two biggest export nations for mackerel products.

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Reports

Thermal Performance of Corrugated Plastic Boxes and Expanded Polystyrene Boxes

Published:

01/01/2009

Authors:

Björn Margeirsson, Sigurjón Arason, Halldór Pálsson

Supported by:

EU ‐ project Chill on (project no. FP6‐016333‐2), AVS Research Fund, TÞS Research Fund and University of Iceland Research Fund

Contact

Sigurjón Arason

Chief Engineer

sigurjon.arason@matis.is

Thermal Performance of Corrugated Plastic Boxes and Expanded Polystyrene Boxes

Experiments were performed on the insulation value of two types of packaging for fresh fish fillets: 1) Corrugated plastic box (CP) and 2) Foam plastic box (EPS). The variable temperature around the packages was controlled in the experimental cold rooms and the temperature development outside and inside the packages was monitored with thermometers. Both individual boxes and whole pallets of boxes were examined, as well as the cooling capacity of ice mats, which are sometimes placed on top of boxes for transport from manufacturer to buyer. The cooling mats (ice mats) proved to be very effective in protecting the fish fillets from heat stress. Furthermore, the results showed the superior thermal insulation of the foam plastic box over the corrugated plastic box regardless of the use of cooling mats. In fact, the difference in insulation value is even more visible when using cooling mats. Experiments with fully stacked pallets of fish boxes (approximately 300 kg per pallet) showed that the average temperature rise of fillets can be double for a corrugated plastic box with a foam plastic box, provided that the surrounding air is 10 ° C hot and has considerable movement. Finally, it was shown that several hours. fluctuations in air temperature around an entire fishing board can cause a very uneven heat distribution within the position on the board.  

Experiments were carried out to compare the thermal performance of two different types of packaging for fresh fish fillets: 1) Corrugated plastic (CP) and 2) Expanded Polystyrene (EPS) boxes. The boxes containing fresh fillets were affected with dynamic thermal loads in air climate chambers. Meanwhile, the fillet temperature was monitored with temperature loggers. Both free standing boxes and whole pallets were affected with dynamic thermal loads in the study and the chilling effect of frozen cooling mats was studied by using them in some of the boxes. The frozen cooling mats proved very efficient for protecting fresh fish fillets against temperature abuse. Furthermore, the results show that the insulating performance of EPS is significantly better than of CP, independent of the usage of cooling mats. The difference in insulating performance between the two packaging types is actually exaggerated when cooling mats are used. The experiments with whole pallets revealed that the mean fillet temperature rise for a whole 300 kg fish pallet can be twofold using CP compared to using EPS, given that the movement of surrounding air is considerable and its temperature is 10 ° C. Finally, it was shown that in dynamic temperature conditions, the temperature distribution in a whole pallet of fish fillets can be far from homogeneous.

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Reports

Comparison of microstructure between farmed and wild cod

Published:

01/12/2008

Authors:

Valur Norðri Gunnlaugsson, Guðrún Anna Finnbogadóttir

Supported by:

AVS R26-06 / AVS R&D Fund of Ministry of Fisheries in Iceland

Contact

Valur Norðri Gunnlaugsson

Research Group Leader

valur@matis.is

Comparison of microstructure between farmed and wild cod

The aim of this project was to build up knowledge through image analysis to facilitate the processing and product development of farmed cod. In the project "Future cod", imaging revealed remarkable results where a large difference was found in the structure of the flesh in wild cod and farmed cod. The purpose of this project was to examine this difference in more detail and try to find reasons for it. The results of the project confirmed this large difference in intercellular space, as had been seen before, but it was only seen in samples taken from live fish. There was little difference in pre-rigor samples taken, whether farmed or wild. After post-rigor, only wild fish were sampled, as the processing properties of farmed cod were weak after freezing. It was found that the extracellular space increased again in wild fish during death. Numerous other measurements were made on these samples in step 4 of this project and a close connection could be seen with the results for the proportion of intercellular cells in these samples. The mobility of water molecules was lower in wild cod muscles, which was consistent with the greater intercellular space than in farmed fish. On the other hand, the water content of the wild cod was higher. The results indicated that the structure and properties of the muscle were quite different in these groups. The research was part of the project "Processing and quality control of farmed cod, more specifically a summary for work component 3.

In previous project there was much difference in gap between cells samples from wild and farmed cod. In this project phase the aim was to confirm this difference and try to identify the reason for it. The results showed a difference in microstructure between wild cod and farmed one, when samples were taken from live fish. This difference was not a distinct, when samples from pre-rigor and post rigor fish where analyzed. In project phase 4 these samples where used for number of measurement. The results from the microstructure analysis were in harmony with results from measurement of water content and water mobility.

Report closed until December 2011 / Report closed until December 2011

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Reports

Comparison of wild and farmed cod muscle characteristics

Published:

01/12/2008

Authors:

Valur Norðri Gunnlaugsson, Guðrún Anna Finnbogadóttir, María Guðjónsdóttir, Kolbrún Sveinsdóttir, Hannes Magnússon, Kristján Jóakimsson, Kristín Anna Þórarinsdóttir, Sigurjón Arason

Supported by:

AVS R26-06 / AVS R&D Fund of Ministry of Fisheries in Iceland

Contact

Valur Norðri Gunnlaugsson

Research Group Leader

valur@matis.is

Comparison of wild and farmed cod muscle characteristics

The aim of the project was to make a comparison of the properties of cod products made from wild cod before and after dead-freezing and farmed cod before dead-freezing. Also experiment with storage in sludge, ice spray on brine and supercooling (-2.4 ° C) on farmed fish to investigate how the properties of the flesh change with different treatment. Mortality stiffness had a significant effect on weight gain and salt uptake during injection and storage. The uptake of pre-rigor samples was rather low while the uptake of post-rigor wild cod was significant. The pre-rigor fish had less than 5% uptake after pickling, while the wild post-rigor had almost 9% uptake. A similar pattern was seen after injection, where the longest uptake was obtained in wild post-rigor fish or 16.5%. The salinity of most samples ranged from 0.3-0.4%. No significant difference was observed between unsalted samples. In the saline-salted groups, there was only salt uptake in wild cod that was injected after death. On the other hand, salt intake in fish injected before death was insignificant and applied to both wild and farmed cod. The water content was higher in wild cod compared to farmed cod and also spray salting led to a higher water content. Measurements from NMR measurements indicated that there was a difference in the mobility of water molecules and the possible location of water, but this can affect the water - holding properties of the muscle. The fish fillets generally performed well in traditional quality assessments, whether they were injected fillets or untreated fillets. Discharges did not increase as much during the storage period as expected, although considerable discharges were made into the pre- and wild post on the thirteenth day of storage. In previous experiments, the color of farmed fish products has been very white, despite the fact that they have become unusable. On the other hand, yellow cod products turn yellow with shelf life. The results of this experiment did not confirm this difference between farmed cod and wild cod.

There was a great difference in the sensory properties of farmed cod and wild cod after boiling, primarily in texture where wild groups were much thicker, more mushy and softer. Breeding groups had a meaty mouth effect, were more gummy and stuttering, in addition to having a sweeter taste and a much more meaty taste and smell. Storage temperature generally had the effect of producing earlier symptoms of damage in products stored at + 1 ° C compared to -2.4 ° C. The shelf life of farmed cod stored at -2.4 ° C was at least 5 days longer than that of a comparable group stored at + 1 ° C. The effect of storage temperature was also observed in the number of microorganisms, which together with the injection salting led to a larger number of microorganisms. However, there was little difference in products in terms of whether processing took place before or after death solidification. The research was part of the project "Processing and quality control of farmed cod, more specifically a summary for work components 2 and 4.

Production of farmed cod is increasing rapidly, but quality appraisals show that farmed cod has different characteristic from wild cod. These different characteristics make traditional production methods not suitable for farmed cod and therefore it is necessary to analyze those characteristics and adjust production methods especially for farmed cod. Matis ohf has been involved in farmed cod research from its foundation and the company built its foundation on the work which was done by its predecessors. The aim of this project was to look at these different characteristics between farmed and wild cod, pre and post rigor. The aim was also to do experiments with injection of brine and superchilling (-2.4 ° C) and detect the impact of different methods. NMR was used to analyze difference in longitudinal relaxation time (T1), between the samples, farmed cod had lower values for T1 than wild one. Therefore the mobility of water indicates difference in structure between the samples. High levels of glycogen are usually found in farmed cod which results in sharp fall of pH after slaughter. This low pH affects texture, because of collagen degradation which results in gap formation. The low pH also affects water holding capacity of the farmed cod. Measurements have shown higher pH in wild cod and this difference continues through low temperature storage. Texture measurements after 2 days storage indicates that farmed cod is lower in firmness than wild one, regardless of whether the fish is filleted pre- or post rigor. Sensory panels have also detected difference between wild and farmed cod. Wild cod is more tender and mushier, while the farmed one has more meaty texture, is more rubbery and has a clammy texture. Also the farmed fish has sweeter taste and more meaty taste and smell. Farmed cod is different from wild cod in many aspects. Therefore it is necessary to know those aspects and adjust processes especially for production of consumer goods from farmed cod.

Report closed until December 2011 / Report closed until December 2011

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Reports

Comparison of farmed and wild cod fillets during light salting

Published:

01/12/2008

Authors:

Valur Norðri Gunnlaugsson, Guðrún Anna Finnbogadóttir, María Guðjónsdóttir, Kolbrún Sveinsdóttir, Kristján Jóakimsson, Sigurjón Arason

Supported by:

AVS Fisheries Research Fund, Rannís Technology Development Fund

Contact

Valur Norðri Gunnlaugsson

Research Group Leader

valur@matis.is

Comparison of farmed and wild cod fillets during light salting

The aim was to go through the processing process of lightly salted products made from wild cod after freezing and farmed cod before freezing, from filleting to consumers. This basic information was to be used to formulate new processing and transport processes for the export of lightly salted farmed fish products to southern Europe. There was a significant difference between the characteristics of pre-rigor cod farming and wild post-rigor cod during spraying and pickling. The uptake of brine was much higher in wild cod, but the farmed fish picked up a small amount of brine, which resulted in a small weight gain and low salt content. This large difference in salt uptake affected most of the variables examined, such as the water content and sensory properties of fillets. The difference was mainly in the texture factors, as the wild cod generally had a softer, juicier and softer texture, as it was more watery. The shelf life of farmed fish was longer. The main conclusion was that farmed fish products have different properties than wild fish products, but not worse. However, the timing of processing makes light salting difficult. If pre-rigor fish is salted immediately after filleting, death stiffness counteracts salt absorption. Therefore, traditional processes in the processing of wild post-rigor fish can not be transferred to prerigor volcanic fish. The research was part of the project "Processing and quality control of farmed cod, more specifically a summary for work component 5.

The aim of this part of this project was to look at the process of lightly salted cod, both from wild catch and farmed cod. To gather information from the processing part and try to improve the process and adjust the process to farmed cod. The results from this phase of the project strongly indicate that there is a big difference between farmed and wild cod when we look at physical properties. After injection and brine salting of the cod the wild cod had gained much weight while the farmed one did not gain any weight and therefore had low salt content. This difference in brine uptake resulted in difference between the sample groups in almost every research segment of this phase. The wild cod had more salt content and therefore more water content which resulted in more tender, softer and juicer fillets. It is obvious that those products are of different nature and farmed cod might not be suitable for the salting process because of limited brine uptake. However, despite the low salt content of the farmed cod, the fillets had better shelf life than the wild cod. The farmed cod has other characteristics than wild catch, and those characteristics have to be utilized in processing and production of consumer goods.

Report closed until December 2011 / Report closed until December 2011

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Reports

Comparison of properties of farmed cod and wild cod in loose freezing / Effects of freezing on muscle properties of wild and farmed cod fillets

Published:

01/12/2008

Authors:

Valur Norðri Gunnlaugsson, María Guðjónsdóttir, Guðrún Anna Finnbogadóttir, Kristján Jóakimsson, Sigurjón Arason

Supported by:

AVS R26-06 / AVS R&D Fund of Ministry of Fisheries in Iceland

Contact

Valur Norðri Gunnlaugsson

Research Group Leader

valur@matis.is

Comparison of properties of farmed cod and wild cod in loose freezing / Effects of freezing on muscle properties of wild and farmed cod fillets

A comparison was made of the effects of freezing on different cod fillets. The raw material was farmed pre rigor cod and wild pre and post rigor cod. It was also investigated how fillets sprayed with brine came out of the freezer. The results showed that freezing did not in any way reduce the quality of these products. They performed well in quality assessment, emissions did not increase in samples and there was little or no change in the chemical content of these samples. The products all came out well from the freezing, whether it was farmed fish or wild fish and what treatment he received during the slaughter process.

The research was part of the project "Processing and quality control of farmed cod, more specifically a summary for work component 6.

In this project phase the aim was to look at effect of freezing on cod fillets from wild and farmed cod in different rigor stages. The goal was also to evaluate effects of brine injecting on the quality of the product after freezing and thawing. The results indicated that the freezing process did not affect the quality of those products. The quality assessment and chemical measurements did not indicate negative changes during freezing and thawing. All the samples got good results, both farmed and wild cod samples and the brine injection did not affect the quality of frozen products.

Report closed until December 2011 / Report closed until December 2011

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Reports

Bioactive products in the production of halibut and cod larvae / Bioactive products in production of halibut and cod larvae

Published:

01/12/2008

Authors:

Jónína Þ. Jóhannsdóttir, Rannveig Björnsdóttir, Eydís Elva Þórarinsdóttir, Kristjana Hákonardóttir, Laufey Hrólfsdóttir

Supported by:

AVS, Matvælasetur HA

Bioactive products in the production of halibut and cod larvae / Bioactive products in production of halibut and cod larvae

The aim of the project was to find ways to improve the survival and quality of cod and halibut larvae and to use environmentally friendly methods. The aim was also to open up the possibility of utilizing saithe peptides that could increase the value of saithe. The results of a previous project in halibut farming were promising and indicated that it was most convenient to treat larvae with peptides through feed animals, in addition to which it was necessary to further investigate the concentration of treatment. In connection with the project, new facilities for animal husbandry have been developed and set up at Fiskey hf. for research into the different treatments of feed animals and thus contribute to increased stability in the production of halibut juveniles. Repeated experiments with bioactive substances in the cultivation of equidae have been carried out and they seemed to tolerate a certain concentration of the substances. The main results of experiments in the early stages of cod farming indicate that treatment with saithe peptides results in good growth, noticeably faster development of internal organs and a much lower incidence of larval defects. However, it is clear that the effects of different levels of treatment need to be further investigated. There is strong evidence that IgM and lysozyme are present in cod larvae soon after hatching or much earlier than previously claimed, and that treatment appeared to stimulate their production. Treatment with saithe peptides does not appear to affect the bacterial flora of larvae, but a specific species composition was detected in the gastrointestinal tract of larvae in pots where larval survival and quality were optimal. This gives evidence that a certain species composition of bacterial flora is favorable for cod larvae.

The main goal of this project was to increase viability and quality of cod and halibut larvae before and during the first feeding period by using bioactive products. The aim was also to increase the exploitation and value of pollock. The findings of previous projects in halibut culture were promising and indicated that treating live feed is a suitable method to carry bioactive products to the larval intestines during first feeding but the intensities of treatment needed to be further investigated. New facilities have been developed in relation to the project for research in the live feed culture at Fiskey Ltd. to promote increased stability in the production of halibut fingerlings. Repeated experiments have been conducted in the culture of rotifers and results indicate good tolerance towards treatment with bioactive products in certain intensities. The overall results of the project indicated that pollock peptides may promote increased growth and quality of cod larvae during first feeding. The results also indicate the presence of IgM and lysozyme early post hatching, but it has not been observed in cod larvae of this size before. Furthermore, results also indicate that hydrolysates from pollock can stimulate the production of these factors in cod larvae. Treatment using pollock peptides, did not affect the bacterial community structure of live feed or cod larvae, however a similar structure was observed in larvae from the most successful production units different from other tanks. The results therefore indicate a bacterial community structure that may be preferable to the cod larvae.

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Reports

Biodiversity in hot springs at Þeistareykir and Gjástykki / Biodiversity in hot springs at Þeistareykir and Gjástykki

Published:

01/12/2008

Authors:

Sólveig K. Pétursdóttir, Snædís Huld Björnsdóttir, Sólveig Ólafsdóttir, Guðmundur Óli Hreggviðsson

Supported by:

Þeistareykir ehf

Contact

Guðmundur Óli Hreggviðsson

Strategic Scientist

gudmundo@matis.is

Biodiversity in hot springs at Þeistareykir and Gjástykki / Biodiversity in hot springs at Þeistareykir and Gjástykki

The project was part of an environmental assessment for the planned geothermal utilization and involved a study of the ecosystem in the hot springs at Þeistareykir and Gjástykki. A total of 27 samples were taken. Temperatures and acidity at the sampling points ranged from 33-96 ° C to pH 1.9-8.6. The species composition of the micro-organisms and their proportions were determined by nucleic acid amplification and sequencing of the 16S rRNA species-determining gene using bacterial and antimicrobial markers. A total of 21 bacteria and / or ancient bacteria were detected in 21 samples. DNA sequences were classified into species according to 98% affinities and compared with Genbank sequences for species analysis. In acidic hot springs at Þeistareykir, species within the bacterial assemblages β-, δ-, and γ-Proteobacteria and Aquificae were most common, especially acidic and / or primitive species that use sulfur and iron compounds and bind CO2. In vapors in lava caves at Þeistareykir at higher acidity levels (pH 6.7-8.6), the species Acidobacteria, Actinobacteria, Chloroflexi and Deinococcus-Thermus were prominent. Deinococcus-Thermus and Verrucomicrobium were the most common in samples from the hot springs in Gjástykki (pH 4.4-6.9). Many of these species are non-primitive. Ancient bacteria were found mainly in acidic areas at Þeistareykir, and in all samples from Gjástykki, but not in steam eyes in lava at Þeistareykir, as the acidity level is higher there. Species within the Crenarchaeota group were found in all of these samples, but species within the Euryarchaeota were bound to samples from the surface formations and acid soils. Most ancient bacteria can live primitive life. Biodiversity (Nt / Nmax) bacteria was most often between 1-3 and 1-2 among ancient bacteria. These low values are typical of peripheral ecosystems, where one species is in a very high proportion. Numerous new species were found in the samples, especially bacteria in steam eyes in lava at Þeistareykir and in hot springs in Gjástykki. Also, species of Euryarchaeota within ancient bacteria often showed a low kinship percentage and are therefore considered new species.

Due to future plans for utilizing the geothermal power at Þeistareykir and Gjástykki, an environmental assessment of the biodiversity in hot springs from these sites was carried out. A total of 27 samples were taken from various sites at temperatures of 33-96 ° C and pH 1.9-8.6. The species composition and ratios of thermophiles were estimated by PCR and sequencing of the 16S rRNA genes using bacterial and archaeal primers. Microbial species were detected in 21 samples. DNA sequences were grouped at the 98% similarity species level and compared with available sequences in Genbank for species determination. Species belonging to the bacterial phyla of β-, δ-, and γ-Proteobacteria and Aquificae were dominating in samples from the solfatara fields of Þeistareykir. These were mainly acidophiles and autotrophs capable of utilizing sulfur- and iron compounds and fixing CO2. A totally different pattern of species composition was observed in samples from fumaroles at the lava fields of Þeistareykir at higher pH (6,7-8,6) than in the solfataras. These were mainly Acidobacteria, Actinobacteria, Chloroflexi and DeinococcusThermus. In Gjástykki, (pH 4.4-6.9) Deinococcus-Thermus and Verrucomicrobium sp. were dominating. These are mainly heterotrophs. Archeal species were found as well in the solfatara fields at Þeistareykir and also in hot springs at Gjástykki, but not in the high pH fumaroles at Þeistareykir lava fields. Species from the Crenarchaeota group were found in the samples, but species belonging to the Euryarchaeota group were only detected in solfatara soil samples and sulfur / iron precipitates. These were mainly autotrophs. Biodiversity (Nt / Nmax) was calculated for all samples and estimated at 1-3 among the Bacteria and 1-2 among the Archaea. These low values are typical for extreme environments where one species is highly dominating. Many novel species were found in the samples, especially in soil from fumaroles at the lava field at Þeistareykir and in hot springs at Gjástykki. Euryarchaeal species within the Archaea domain often showed low similarity to known species and most likely represent new species.

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