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Kristin Heggland *,****, Camilla Ottesen**, Jørgen Berge *,***
In this study we examined the demersal fish species Leatagonus decagonus (Atlantic poacher) collected form fjords around Svalbard. It is a commonly encountered species in coastal waters of Svalbard, often found on depths around 350 m. They tolerate wide temperature fluctuations and are found in waters with temperatures ranging from -1.7 to 4.4 °C. They are not however found in waters with salinities t preference outside the spawning season, giving a domination of one sex in our sampling areas. Our results suggest sexual dimorphism in size. Females were longer (10.2-15.6 cm, mean=13.2 cm) than males (10.6-13.9 cm, mean=12.1cm). Females were also heavier (4-12 gram, mean=7.4) than males (3-10 gram, mean=5.81 g). Both length and weight was significantly different between the sexes (p= 0.011 and p= 0.027, respectively). There was no significant difference in age distribution between the sexes. However, males had a wider age distribution (2-14 years) than females (3-7 years). The majority of specimens were 4-7 years old (mean = 4.9 years). Both sexes had a length-weight relationship that gave a negative isomorphic body condition, indicating energy priority towards reproduction rather than tissue growth. The females were overall larger than males with age. There was an overall differentiation in size of the liver between the sexes with males having larger liver indices than females. These results may suggest male parental care as males that watch over eggs do not get to feed much and therefore store energy in the liver for this purpose. Alternatively, females may put so much energy in the eggs that they do not have the ability to build up energy stores like the males. There was little variation in gonadosmatic index with length and age, indicating that most of our specimens were mature. Thus, both females and males are mature by the age of 4. L. decagonus produce relatively few (2'976–4'854 eggs, but at least half the eggs in each gonad were undeveloped) big and lipid rich eggs, which suggest that there is some sort of parental care. This is usually true for species with relatively low fecundity. Pelagic postlarvae found in June were big and well developed, typically for species with K-strategy.
Estelle Kilias*, Eva-Maria Nöthig*, Ilka Peeken*, Christian Wolf*, Katja Metfies*
Climate change is expected to be particularly intense in the Arctic Ocean having as well extensive consequences on Arctic pelagic ecosystems. Thus, evaluations of the impact on the base of the food web, on local phytoplankton communities, are required. Prerequisite of such an evaluation is comprehensive information about the present phytoplankton diversity and distribution. Recent investigations indicate that rising temperatures as well as freshening of surface waters in the marine environment promote a shift in the phytoplankton community towards a dominance of smaller cells. In such a scenario, picoplankton can comprise a large pool of biomass and can attain high abundances. Understanding the impact of climate related environmental change for this phytoplankton size class in the Arctic Ocean demands that we understand how environmental parameters influence their diversity, occurrence and distribution. In this perspective, samples to investigate picoplankton have been taken in the area of the “deep-sea long-term observatory HAUSGARTEN” of the Alfred-Wegener-Institute (Fram Strait) in July 2009 and analyzed by the application of ribosomal fingerprinting technology (ARISA), 18S rDNA clone libraries and Pyrosequencing. The investigation area between 2 - 6°E and 78 – 80°N is located within the frontal zone which is separating the warm and cold water masses originating from the West Spitzbergen Current and East Greenland Current, respectively. Based on the heterogeneous hydrographic condition differences in the picoplankton community according to the water masses is likely. Preliminary results on the investigation of the genetic diversity of picoplankton reflect these environmental differences. The findings reveal that the diversity within the warm water mass is higher compared to the one found in the colder water mass. Further the dominance of single species (Phaeocystis pouchetii vs. Micromonas pusilla) differs at the stations according to abiotic conditions. All in all, this study will provide a framework for a better understanding of the interactions between environmental conditions and corresponding pico-phytoplankton communities in arctic pelagic systems.
Allen B. Campeau*, Sienna Gray**, Kjersti Kjær***, Marius Næss****, Bart Peeters*****
Climate warming and associated environmental changes are occurring at a rapid rate throughout much of the Arctic region. Terrestrial ecosystems in the Arctic are highly vulnerable to these changes because of their simplicity and high sensitivity. The effects of a warming environment are thus stronger and more profound in the Arctic than in ecosystems at lower latitudes.