Munin: Institutt for arktisk og marin biologi

Parasite communities of two three-spined stickleback (Gasterosteus aculeatus) populations : effects of a local-scale host introduction?

Jakobsen, Jonas (Master thesis; Mastergradsoppgave, Nov-2011)

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Spatial and temporal variation in abundance of willow ptarmigan Lagopus lagopus and rock ptarmigan Lagopus muta in Finnmark county, Norway : evaluation of methods for population monitoring

Bolstad, Johannes (Master thesis; Mastergradsoppgave, 15-May-2010)

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Abstract:

Abstract: Sustainable harvesting requires reliable quantitative estimates of pre-harvesting population size, however, within low management budgets, good quality predictions are often difficult to obtain. For the popular game species willow ptarmigan (Lagopus lagopus) estimates of population density or relative indices are often obtained from line transect surveys, however, the quality of estimates could be sensitive to low sampling effort. Additional ptarmigan population data is hunting statistics, but the potential lack of convergence between population density and hunting bag remains a concern. The sympatric rock ptarmigan (Lagopus muta) is commonly given much less management attention, and the species is often arbitrarily expected to show synchronised dynamics with willow ptarmigan. In this paper we evaluate different population indices obtained from willow ptarmigan line transects surveys in late summer, and catch reports of subsistence snare trapping in late winter, and specifically assess these indices’ ability to predict subsequent ptarmigan hunting bags in eight municipalities in northernmost Norway. We use line transect data from 6–7 years of varying monitoring effort, snare trapping data from between 6 and 12 years in different municipalities, and hunting statistics from 7–8 years in all municipalities. Generalised linear mixed-effect models indicated that only crude predictions of the subsequent willow ptarmigan hunting bags could be made from the line transect estimates under the current management regime. The snare trapping index made only a minor improvement of the prediction, and although the potential effects varied between municipalities, its inclusion as a predictor is not generally recommended in future ptarmigan management. The rock ptarmigan hunting bags could not be predicted by any of the available pre-harvesting indices. Variance component analyses revealed pronounced lack of systematic variation in all indices for both ptarmigan species, consequently any prediction of subsequent hunting bag outcome, should be highly conservative. Although we did not find clear tendencies of better predictions in municipalities with higher line transect effort, we suspect that the monitoring effort needed to provide useful pre-harvest indices is highly underestimated in the current management regime. Potentially unknown ptarmigan population processes and an elevated hunting pressure, should encourage management to increase, knowledge-based ptarmigan monitoring in the future. Key words: willow ptarmigan; rock ptarmigan; sustainable harvesting; population density indices; line transect; snare trapping statistics; hunting statistics; population dynamics; population monitoring; game management; arctic ecosystems; Finnmark; Norway.

URI:

http://hdl.handle.net/10037/3781

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thesis.pdf (7.149Mb)

Abstract:	With petroleum exploration and development expanding in the Arctic (AMAP, 2007) there is a need to obtain additional information on the ecotoxicology of Arctic organisms. Here we perform 192 hr laboratory exposure experiments on the keystone Arctic zooplankton species, Calanus finmarchicus. We trace the accumulation and depuration of two polycyclic aromatic hydrocarbons (PAHs): phenanthrene and benzo[a]pyrene (B[a]P) using 14C labeled PAH compounds. Copepods were not fed during the experiment, limiting uptake to diffusion processes alone. The lighter PAH compound, phenanthrene, accumulated rapidly in C. finmarchicus, reaching steady state within 96 h. The heavier PAH compound, B[a]P, accumulated more slowly and steady state was not reached within the 192 h exposure period. As expected, the bioconcentration factor (BCF) for B[a]P was higher than for phenanthrene in accordance with a higher octanol/water partition coefficient for B[a]P (log Kow = 6.04) compared to phenanthrene (log Kow = 4.53). However, for both compounds, log BCF was lower than log Kow that may indicate active biotransformation and excretion of the selected PAH compounds. These findings on the bio-uptake kinetics for petroleum hydrocarbons are essential for evaluating the potential consequences of an oil spill in the Arctic.
Description:	This is the submitted manuscript version of the paper. This paper is part of Louise Kiel Jensen's doctoral thesis, which is available in Munin at http://hdl.handle.net/10037/3794
URI:	http://hdl.handle.net/10037/3802

Abstract:	Temporal dynamics of the microbial food web in the Barents Sea and adjacent water masses in the European Arctic are to a large extent unknown. Seasonal variation in stocks and production rates of heterotrophic bacteria and phototrophic and heterotrophic picoplankton and nanoflagellates was investigated in the upper 50 m of the highlatitude Kongsfjorden, Svalbard, during six field campaigns between March and December 2006. Heterotrophic bacteria, picoplankton and nanoflagellates contributed to ecosystem structure and function in all seasons. Activity within the microbial food web peaked during spring bloom in April, parallel to low abundances of mesozooplankton. In the nutrient-limited post-bloom scenario, an efficient microbial loop, fuelled by dissolved organic carbon from abundant mesozooplankton feeding on phytoplankton and protozooplankton, facilitated maximum integrated primary production rates. A tight microbial food web consisting of heterotrophic bacteria and phototrophic and heterotrophic picoplankton and nanoflagellates was found in the stratified water masses encountered in July and September. Microbial stocks and rates were low but persistent under winter conditions. Seasonal comparisons of microbial biomass and production revealed that structure and function of the microbial food web were fundamentally different during the spring bloom when compared with other seasons. While the microbial food web was in a regenerative mode most of the time, during the spring bloom, a microbial transfer mode represented a trophic link for organic carbon in time and space. The microbial food web’s ability to fill different functional roles in periods dominated by new and regenerated production may enhance the ecological flexibility of pelagic ecosystems in the present era of climate change.
Description:	This article is part of Lena Seuthe's doctoral thesis, which is available in Munin at http://hdl.handle.net/10037/3777
URI:	http://hdl.handle.net/10037/3779

Abstract:	The composition and ecological role of ciliates and dinoflagellates were investigated at one station in Kongsfjorden, Svalbard, during six consecutive field campaigns between March and December 2006. Total ciliate and dinoflagellate abundance mirrored the seasonal progression of phytoplankton, peaking with 5.8 9 104 cells l-1 in April at an average chlorophyll a concentration of 10 lg l-1. Dinoflagellates were more abundant than ciliates, dominated by small athecates. Among ciliates, aloricate oligotrichs dominated the assemblage. A large fraction ([60%) of ciliates and dinoflagellates contained chloroplasts in spring and summer. The biomass of the purely heterotrophic fraction of the ciliate and dinoflagellate community (protozooplankton) was with 14 lg C l-1 highest in conjunction with the phytoplankton spring bloom in April. Growth experiments revealed similar specific growth rates for heterotrophic ciliates and dinoflagellates (\0–0.8 d-1). Food availability may have controlled the protozooplankton assemblage in winter, while copepods may have exerted a strong control during the post-bloom period. Calculations of the potential grazing rates of the protozooplankton indicated its ability to control or heavily impact the phytoplankton stocks at most times. The results show that ciliates and dinoflagellates were an important component of the pelagic food web in Kongsfjorden and need to be taken into account when discussing the fate of phytoplankton and biogeochemical cycling in Arctic marine ecosystems.
Description:	This paper is part of Lena Seuthe's doctoral thesis, which is available in Munin at http://hdl.handle.net/10037/3777
URI:	http://hdl.handle.net/10037/3778

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