Correlative evidence for competition between fucus serratus and the introduced chlorophyte codium fragile subsp. fragile on the southwest coast of Norway

The distribution of Codium fragile subsp. fragile and the native canopy-forming alga Fucusserratus was recorded at 51 sites in a 20 km long, sheltered region on the southwest coast of Norway. The purpose of the study was to examine if these species are potentially competing and how their distributions are related to wave-exposure and substrate. Codium fragile subsp. fragile was patchily distributed, a pattern which appears to have been sustained over time since its introduction to this area. It was almost always observed growing below mean low water, in the low intertidal and shallow subtidal. Both substrate type and wave-exposure influenced the vertical distribution of C. fragile subsp. fragile; growth occurred higher on the shore at sheltered sites and deeper in the subtidal on stony substrate. Its vertical range of growth overlapped with that of F. serratus and, when C. fragile subsp. fragile was abundant, F. serratus tended to grow higher on the shore and at lower abundances. This suggests that C. fragile subsp. fragile is affecting F. serratus in this area through competition, but only in the lower portion of the fucoid’s vertical range and only at sites favorable for its own growth with regard to shelter and substrate.publishedVersio

Oral health and quality of life among people with severe or long-term mental illness: A call for interprofessional collaboration

People with severe or long-term mental illness (SMI) have poorer oral health than the general population has, but little is known about how, to what extent, and in what ways oral health problems affect daily functioning, quality of life and well-being among people in this patient group. The present study investigated oral health and oral health-related quality of life for persons with SMI in Norway. The longitudinal clinical study targeted SMI patients with their age- and gender-matched control patients at a public dental clinic in Norway. SMI patients were recruited from an ambulatory team within community mental health services. Clinical examinations followed the WHO criteria. We used a validated Oral Impact on Daily Performance (OIDP) instrument to assess oral health-related quality of life (OHRQoL). The prevalence of oral impact (OIDP > 0) was 77% among SMI patients and 22% among the controls. More than 60% of the SMI patients reported difficulties showing their teeth without embarrassment, compared to 5.5% of the controls. The results suggest that shame is a key factor inhibiting patients faced with the need for dental treatment. Collaboration between dental and mental health professionals is therefore essential for this patient group to enjoy dignified oral health and quality of life.publishedVersio

Improving Salmonid Monitoring by Nocturnal Counting in Rivers

Accurate abundance estimates are crucial for evidence-based fisheries management. In rivers, drift dive counting and electrofishing are commonly used for quantifying fish abundance. However, the likelihood that fish are detected by these counting methods is affected by a range of factors, with substantial potential implications for the outcomes. Fish behavior and distribution also differs with light intensity, yet diel variation in abundance estimates produced by common enumeration methods has received little attention. Here, we present a comparison of diurnal and nocturnal counts of the landlocked population of Atlantic Salmon Salmo salar, known as “småblank,” and Brown Trout Salmo trutta in a Norwegian river. Six drift dive transects and 12 electrofishing sites were surveyed at day and night in early autumn. During drift dives, småblank were exclusively observed at night. Brown Trout were observed by snorkelers both day and night but in significantly higher numbers at night (six times more Brown Trout per 100 m at night versus in the day). Catch per unit effort of backpack electrofishing was significantly higher at night than at daytime for both småblank and Brown Trout older than age 0 (202% and 108% higher, respectively). We argue that differences in drift dive counts were mainly caused by fish hiding in the substrate during the day and being more active at night, resulting in diel differences in detection rate. Further studies are needed to determine whether differences in electrofishing catches were caused by diel fish migrations or higher catchability at night.publishedVersio

Safety assessment of the functional feed additive phenylcapsaicin in a commercial broiler diet

Introduction: Intestinal colonisation of Salmonella is a major concern in the poultry industry, and a low dose of the high-purity synthetic capsaicin analogue phenylcapsaicin (PheCap) has the potential to be a phytobiotic alternative to antibiotics in reducing floor Salmonella in commercial broiler chicken houses. In this study we present the first safety assessment of PheCap at doses relevant for the poultry industry. Methods: In a completely randomized block design, Ross 308 male broilers were offered feed containing 0, 10, 15, or 150 mg PheCap/kg. Growth rates, mortality, haematology, clinical chemistry, foot pad lesions, litter quality and gross pathological examination of organs and tissues were evaluated for signs of toxicity over a two-phase, 35-day growth period. Results: No differences in feed intake and broiler growth were found, with broilers in the control group having the highest mortality. There was a statistically significant increase in the European Production Efficiency Factor (EPEF) for the 10 (p = 0.02) and 15 mg PheCap/kg feed (p = 0.003) treatment doses. No dose dependent adverse effects were found for any of the treatment doses. The No Observed Adverse Effect Level (NOAEL) of PheCap is probably higher than that of the highest weekly averaged daily intake of 36.3 mg/kg BW/day observed in the present study. Conclusions: The inclusion of PheCap in broiler feed at doses relevant for the commercial poultry industry is assumed not have any negative effects on broiler health.publishedVersio

Effects of habitat enrichment and food availability on the foraging behaviour of juvenile Atlantic Cod (Gadus morhua L)

The environment can play an important role in shaping how an animal behaves, and how well the animal performs in a particular environment can be influenced by early experiences. The tradition of releasing captive-reared juveniles into the wild in an effort to strengthen wild fish populations has often had little success owing to high post-release mortality. Fish reared under standard hatchery conditions are provided with fewer stimuli and they receive excess quantities of pellet food that are easy to handle and consume. Captive reared fish therefore appear to be under-stimulated and overfed. Several studies have demonstrated that simple structural enrichment in the rearing facilities promotes flexible behaviour compared to fish reared in plain, standard hatchery tanks. Less attention has been given to the effects of the diet. Here we use a cross-factored design to test the relative role of food ration and spatial enrichment on foraging behaviour. Our results show that fish from enriched environments, regardless of previous food-ration size, were more reluctant to start feeding on the first day in a novel arena. On day two and three, however, fish with prior experience of a low food ration showed greater foraging activity and efficiency than fish fed on full rations. On the second and third day, prior experience with enrichment was less important. We discuss how early feeding experience in combination with structural enrichment may contribute in producing fish that are better suited for release into the wild.publishedVersio

Ontogenetic Change in Behavioral Responses to Structural Enrichment From Fry to Parr in Juvenile Atlantic Salmon (Salmo salar L.)

Enrichment is widely used as a tool for studying how changes in environment affect animal behavior. Here, we report an experimental study investigating if behaviors shaped by stimuli from environmental enrichment depending on the stage animals are exposed to enrichment. We used juvenile Atlantic salmon (Salmo salar) in their first autumn. This is a species commonly reared for conservation purposes. Previous work has shown that environmental enrichment had no effect on long-term survival when the fry stage (smaller than 70 mm) was released, but that if late parr stages (larger than 70 mm) are released, enrichment is reported to have a positive effect on smolt migration survival. Here, we explored the effect of enrichment at two different stages of development. Both stages were reared and treated for 7 weeks (fry at 11–18 weeks and parr at 24–31 weeks after hatching) before tested for behavior. Responses known to be associated with exploratory behavior, activity, and stress coping were quantified by testing 18-week-old fry and 31-week-old parr in a six-chamber maze on 7 successive days after rearing in structurally enriched (plastic plants and tubes) or plain impoverished rearing environments. The data show that Atlantic salmon are sensitive to stimuli from structural enrichment when they are parr, but not when in the fry stage. Parr deprived of enrichment (control treatment) were reluctant to start exploring the maze, and when they did, they spent a longer time frozen than enriched parr, suggesting that deprivation of enrichment at this life can be stressful. Our data suggest that structural enrichment could have the potential to improve welfare for salmonids in captivity and for survival of released juvenile salmon if structural enrichment is provided at the parr stage and the fish reared for conservation are released at the parr stage.publishedVersio

Feeding Hotspots and Distribution of Fin and Humpback Whales in the Norwegian Sea From 2013 to 2018.

Fin whales (Balaenoptera physalus) and humpback whales (Megaptera novaeangliae) are commonly found in the Norwegian Sea during the summer months. Records from around 1995 to 2004 show that their distribution patterns were mainly associated with those of macro-zooplankton. More recent studies conducted from 2009 to 2012 demonstrate marked shifts, with fin whale distribution related to pelagic fish distribution, decreasing densities of humpbacks, and increased densities of toothed whales. During the same period, historically large abundances of pelagic planktivorous fish in the Norwegian Sea were reported. The goals of this study were to examine the summer distribution of fin and humpback whales from 2013 to 2018 and to assess the potential association between distribution and environmental impact factors. Results suggest a pronounced northerly shift in distribution for both species, a feeding hotspot for fin whales at the shelf area between Svalbard and Norway, and one near Bear Island for humpback whales. Fin whale distribution was associated with that of blue whiting (Micromesistius poutassou) and capelin (Mallotus villosus), whereas humpback whale distribution was associated with that of euphausiids (Meganyctiphanes norvegica, Thysanoessa longicaudata, and Thysanoessa inermis), capelin, and herring (Clupea harengus). However, a significant negative spatial correlation was found between whale occurrence and the widely expanding population of northeast Atlantic mackerel (Scomber scombrus). The results of this study suggest that the prey composition of fin and humpback whales in recent years contain a large proportion of fish. The apparent northerly shift in the distribution of these whale species is largely determined by the availability of prey, but it likely is also impacted by direct or indirect interspecific interactions, especially with killer whales (Orcinus orca). Such large-scale pronounced changes in distribution seem to confirm a high degree of plasticity in fin and humpback whale feeding in the Norwegian Sea.publishedVersio

グンキモノガタリ ニオケル オンリョウ

担当教員: 久保勇(人文社会科学研究科)平成21年度(2009)教養コア科目授業C(芸術と文化)授業コード:G14C1510

Empirical Support for Optimal Virulence in a Castrating Parasite

The trade-off hypothesis for the evolution of virulence predicts that parasite transmission stage production and host exploitation are balanced such that lifetime transmission success (LTS) is maximised. However, the experimental evidence for this prediction is weak, mainly because LTS, which indicates parasite fitness, has been difficult to measure. For castrating parasites, this simple model has been modified to take into account that parasites convert host reproductive resources into transmission stages. Parasites that kill the host too early will hardly benefit from these resources, while postponing the killing of the host results in diminished returns. As predicted from optimality models, a parasite inducing castration should therefore castrate early, but show intermediate levels of virulence, where virulence is measured as time to host killing. We studied virulence in an experimental system where a bacterial parasite castrates its host and produces spores that are not released until after host death. This permits estimating the LTS of the parasite, which can then be related to its virulence. We exposed replicate individual Daphnia magna (Crustacea) of one host clone to the same amount of bacterial spores and followed individuals until their death. We found that the parasite shows strong variation in the time to kill its host and that transmission stage production peaks at an intermediate level of virulence. A further experiment tested for the genetic basis of variation in virulence by comparing survival curves of daphniids infected with parasite spores obtained from early killing versus late killing infections. Hosts infected with early killer spores had a significantly higher death rate as compared to those infected with late killers, indicating that variation in time to death was at least in part caused by genetic differences among parasites. We speculate that the clear peak in lifetime reproductive success at intermediate killing times may be caused by the exceptionally strong physiological trade-off between host and parasite reproduction. This is the first experimental study to demonstrate that the production of propagules is highest at intermediate levels of virulence and that parasite genetic variability is available to drive the evolution of virulence in this system