Ulf Båmstedt

Oxygen and carbon isotope ratios related to growth line patterns in skeletons of Lophelia pertusa (L) (Anthozoa, Scleractinia): Implications for determination of linear extension rate

Abstract Patterns of growth lines and the composition of stable oxygen and carbon isotopes were studied in skeletons of the deep-water scleractinian Lophelia pertusa in longitudinal and transverse sections of corallites. δ180 showed a significant, positive linear correlation with δ13C. A gradual depletion of δ180 and BC was found in the theca, both towards the corallite edge within single growth layers, and across growth layers from the theca surface. δ18O was negatively correlated with the rate of linear extension. These results indicated that isotopic fractionation in Lophelia is controlled by kinetic isotope effects. The range of δ180 was 3.5 times larger than expected for aragonite precipitating in isotopic equilibrium with ambient sea water. However, the shape of the δ180 curve along the growth axis in the septa was almost parallel with the curve of sea water temperatures. This correspondence may be caused by a relation between growth rate and temperature or other environmental variables correlated w...

Growth rate and toxicity of Prymnesium parvum and Prymnesium patelliferum(haptophyta) in response to changes in salinity, light and temperature

Abstract Toxic blooms consisting of Prymnesium parvum CARTER and Prymnesium patelliferum GREEN, HIBBERD … PIENAAR have caused variable degrees of mortality off armed fish in the Sandsfjord system, southwestern Norway annually between 1989 and 1996. Cultures of {P. parvum} and P. patelliferum were established from water samples during the bloom in the Sandsfjord system in 1993. In order to investigate possible differences in reproduction rates and autecology between the two species, growth as a function of different salinity, photon fluence rates (PFR) and temperatures of the two Norwegian strains was compared with the corresponding growth of strains of P. parvum from England and Denmark, and strains of {P. patelliferum} from Australia and England. The toxicities of the same strains grown under varying salinity, light and temperature conditions, were also compared. Maximum growth rates were generally higher in P. patelliferum than in P. parvum, but strain differences within the species varied significantly...

Coastal cod and north-east Arctic cod - do they mingle at the spawning grounds in Lofoten?

Abstract Cod (Gadus morhua L.) off northern Norway are divided into two main groups. The north-east Arctic cod (NAC) migrate southwards from the Barents Sea to the main spawning area near the Lofoten Islands on the coast off northern Norway. Coastal cod (CC) are relatively stationary, live and spawn along the entire Norwegian coast, including near the Lofoten Islands. In order to test if the two groups physically intermingle at the spawning grounds, cod were sampled by trawl and Danish seine at the traditionally important spawning grounds near the Lofoten Islands during the spawning season in 1995-97. Cod from 24 samples were examined for haemoglobin alleles, length, sex and stage of sexual maturity. The results indicate that: (I) NAC and CC did not mingle randomly. (2) However, specimens from both groups may stay simultaneously at the same local spawning ground within an area of less than 0.012 km2- (3) Distribution of NAC and CC overlapped vertically, although NAC was more abundant than CC in samples fr...

Ecological significance of individual variability in copepod bioenergetics

High interstage variability in body length and mass, reproductive state, and metabolic activity is characteristic of copepod populations from the Barents Sea and coastal waters in Sweden and Norway. The dry weight of a given copepodite stage, sampled at a given time from a homogeneous water mass, may vary by a factor of 4–5 between extreme individuals, protein and particularly lipid content being even more variable. Similarly, high variability in gut fullness and grazing rate within defined copepodite stages typically occurs at all times of the year, both when measured as in situ rate or experimentally determined rate, using homogeneous food suspensions. In accordance with this, maturation state (measured as length of gonads) and spawning (measured as rate of egg production over 24 h) are highly variable factors at the individual level. Since all these factors also influence the metabolic rate of the animals the respiratory rate (measured as ETS activity) of comparable individuals may vary by a factor of 5 or more. The results indicate that high individual variability in size and activity parameters is universal. This can not be explained by existing models of feeding behaviour, growth and development, and calls for new models, in which the nutritional history of the individual may play an important role.

Distribution and sedimentation of faecal on the Nordvestbanken shelf, northern Norway, in 1994

Abstract A close seasonal coherence between mesozooplankton and abundance of faecal pellets was encountered at Nordvestbanken, northern Norwegian shelf, in 1994. Mesozooplankton at Nordvestbanken influenced the vertical flux of organic matter by production, consumption, modification, and destruction of faecal pellets. On average, 11-37% of particulate organic, vertical carbon flux was comprised by faecal pellets. The pelagic degradation of organic matter at Nordvestbanken appears to be reduced due to the low pelagic residence time in the upper 100 m of the water column of faecal pellets ( 1.3-8.3 d). The specific seasonal sinking rates of faecal pellets (12-77 m d-1)fell well into the range of in situ and in vitro sinking rates reported in the literature for the dominating classes of faecal pellets al Nordvestbanken, i.e. from calanoid copepods and pteropods. The shape, colour, density, and degree of fragmentation of faecal pellets appears to reflect variations and changir1g preferences in the diet of mes...

Is the scyphomedusa Cyanea capillata (l.) dependent on gelatinous prey for its early development

Asbtract Newly released ephyrae ofthe scyphomedusa Cyanea capillata did not grow on either Artemia nauplii or copepod dominated mixed zooplankton, but grew with an average rate of 16.5 % day-1 (maximum of 30.6 % day-1) with a ctenophore as food. The two first food types did not generate medusae with normal development of tentacles and oral arms over a seven-week period, whereas the ctenophore food did. We suggest that availability of gelatinous prey for newly released ephyrae is a bottleneck in the development, making constraints on the population succession and at least partly explaining inter-annual variations in abundance of C. capillata.

Ecobiochemical studies on the deep-water pelagic community of Korsfjorden, Western Norway. Adenine nucleotides in zooplankton

Adenine nucleotides of zooplankton were extracted from freeze-dried individuals killed in liquid nitrogen. 96% of the ATP in frozen samples stored at-26°C degraded to AMP in 8 days, while ATP was stable for the same period in freeze-dried samples. A strong metabolic stress caused by capturing the animals was evidenced by a marked lowering of the energy charge [(ATP)+1/2(ADP)/(ATP)+(ADP)+(AMP)], the natural level of energy charge being restored in about 24 h. The concentration of ATP showed no significant correlation with the dry weight of the individuals of a species nor with the mean dry weight of the species. The ATP concentration showed marked seasonal changes with increasing values during periods of reproduction, which is assumed to reflect an inheretn seasonal rhythm in the metabolism. ATP cannot be used as a general estimator of metabolism as it did not reflect differences in metabolic activity between different-sized individuals or species. The mean energy charge for 13 species was 0.7.

Sensor Networking in Aquatic Environments - Experiences and New Challenges

In this paper we present the design and implemen tation of a small-scale marine sensor network. The network monitors the temperature in the Baltic Sea on different heights from the water surface down to the bottom. Unlike many other wireless sensor networks, this network contains both a wired and a wireless part. One of the major challenges is that the network is hard to access after its deployment and hence both hard- and software must be robust and reliable. We also present the design of an advanced buoy system featuring a diving unit that achieves a better vertical resolution and discuss remaining challenges of sensor networking in aquatic environments.

Impacts of elevated terrestrial nutrient loads and temperature on pelagic food-web efficiency and fish production

Both temperature and terrestrial organic matter have strong impacts on aquatic food-web dynamics and production. Temperature affects vital rates of all organisms, and terrestrial organic matter can act both as an energy source for lower trophic levels, while simultaneously reducing light availability for autotrophic production. As climate change predictions for the Baltic Sea and elsewhere suggest increases in both terrestrial matter runoff and increases in temperature, we studied the effects on pelagic food-web dynamics and food-web efficiency in a plausible future scenario with respect to these abiotic variables in a large-scale mesocosm experiment. Total basal (phytoplankton plus bacterial) production was slightly reduced when only increasing temperatures, but was otherwise similar across all other treatments. Separate increases in nutrient loads and temperature decreased the ratio of autotrophic:heterotrophic production, but the combined treatment of elevated temperature and terrestrial nutrient loads increased both fish production and food-web efficiency. CDOM: Chl a ratios strongly indicated that terrestrial and not autotrophic carbon was the main energy source in these food webs and our results also showed that zooplankton biomass was positively correlated with increased bacterial production. Concomitantly, biomass of the dominant calanoid copepod Acartia sp. increased as an effect of increased temperature. As the combined effects of increased temperature and terrestrial organic nutrient loads were required to increase zooplankton abundance and fish production, conclusions about effects of climate change on food-web dynamics and fish production must be based on realistic combinations of several abiotic factors. Moreover, our results question established notions on the net inefficiency of heterotrophic carbon transfer to the top of the food web.

Mass occurrence of the physonect siphonophore Apolemia uvaria (Lesueur) in Norwegian waters

Abstract At the end of November 1997 salmon farmers in Hordaland County on the coast of western Norway reported mass occurrence of an unknown animal that caused severe lesions and death of fishes. The organism was identified as the physonect siphonophore Apolemia uvaria. A survey of reported sightings (Fig. 1) shows that the species ranged from Gullmarsfjorden on the Swedish west coast to Finnmark in northern Norway. The first known observation from Scandinavia was from Kosterfjorden in western Sweden in early November. After news about death of farmed salmon was first made public by radio, television and newspapers in the last part of November, additional reports arrived almost concomitantly from sites all along the coast (see reports in Havbruksrevyen, internet: http:// www.intrafish.no). Based on problems reported by salmon farmers it seemed that the abundance of siphonophores along the mid-Norway coast decreased after mid December (Karl Tangen, pers. commn). In mid December we made a field survey from...