Biology

Surveillance and diagnosis of parasitic Bonamia ostreae infections in flat oysters (Ostrea edulis) are prerequisites for protection and management of wild populations. In addition, reliable and non-lethal detection methods are required for selection of healthy brood oysters in aquaculture productions. Here we present a non-lethal diagnostic technique based on environmental DNA (eDNA) from water samples and demonstrate applications in laboratory trials. Forty oysters originating from Limfjorden, Denmark were kept in 30 ppt sea water in individual tanks. Water was sampled 6 days later, after which all oysters were euthanized and examined for infection, applying PCR. Four oysters (10%) were found to be infected with B. ostreae in gill and mantle tissue. eDNA purified from the water surrounding these oysters contained parasite DNA. A subsequent sampling from the field encompassed 20 oysters and 15 water samples from 5 different locations. Only one oyster turned out positive and all wate...

Epiphytic lichen and bryophyte distribution and frequency were investigated on the trunks of 145 young oak trees throughout London and surrounding counties, and compared with pollution levels and bark pH. Sixty-four lichen and four bryophyte species were recorded. Three major zones were identified: (i) two central regions with a few lichens, bryophytes absent; (ii) a surrounding region with a more diverse flora including a high cover of nitrophyte lichens; and (iii) an outer region, characterised by species absent from central London, including acidophytes. Nineteen species were correlated with nitrogen oxides and 16 with bark pH, suggesting that transport-related pollution and bark acidity influence lichen and bryophyte distribution in London today. Lichens and bryophytes are responding to factors that influence human and environmental health in London. Biomonitoring therefore has a practical role to assess the effects of measures to improve London's air quality.

Bag dette faellesfaglige undervisningsforlob ligger et onske om at lave en meningsfuld, naervaerende og maske ogsa spaendende opgave inden for naturfag som eleverne skal arbejde med. Det virker motiverende at arbejde med observationer som man selv indsamler i felten. Isaer hvis det samtidig kan bruges som indgangsvinkel til at forsta sammenhaenge i naturen eller abne ojnene for anvendelsen af de vaerktojer der laeres i fagene.

In this paper we present a prototype system for location-based guiding. A user survey has been conducted and the observations are used to support design choices. The prototype allows for both indoor and outdoor navigation at and in the vicinity of the NaturBornholm experience centre in Denmark using a combination of Bluetooth, Near Field Communication (NFC), GPS and QR codes. Bluetooth, NFC and GPS are used for location-based information and QR codes are used to convey user preferences. 

A population of Theodoxus fluviatilis L in the littoral zone of Lake Esrom was investigated from November 1977 to February 1979. The population was sampled every month in the winter period and twice during the rest of the year. Biomass was estimated as ash-free dry weight (AFDW) of the organic matter both of the soft parts of the animal and the shell itself. The relation between AFDW (c) and shell length (l) was log c ¼ 2.9509 Â log (l)À1.7120. The population comprised more than 1 year-class, which could be separated by shell length, by a narrow band on the shells and the growth of algae on the shell. The life cycle lasted 2 1 2 À 3 years. The oldest animals had a shell length of 7.0-7.5 mm. A few individuals who were estimated to be 3 1 2 years had a shell length up to 8.6 mm. Population density varied between 575 and 2115 individuals m À2 on the stony substratum. The average was 1160 individuals m À2. Mortality was low during the summer period. In winter many animals died due to the effect of ice and stormy weather on the stony substratum. Growth of the animals was estimated from the shell length. Maximum growth was observed from May to August with no growth during the winter. Egg capsules were found on the stones all year round. New capsules were found from late May to the middle of November. Most freshly laid capsules were observed in May-June and August-September. Capsules from the late summer hatched in spring and capsules laid in the spring hatched in August-September. The average annual net production for the whole population was estimated by three methods. The Allen curve method gave 1.895 AFDW m À2 , the growth-increment method gave 1.784 mg AFDW m À2 and the Hynes method 2.284 mg AFDW m À2. Corresponding estimated P/B ratios were 1.29, 1.30 and 1.57. Annual net-production of the four investigated year-classes was 16 mg AFDW m À2 year À1 for 1975, 224 mg AFDW m À2 year À1 for 1976, 1.258 mg AFDW m À2 year À1 for 1977 and 287 mg AFDW m À2 year À1 for 1978. P/B ratios for the three oldest yearclasses were, respectively, 0.32, 0.50 and 1.67. A comparison with other investigations on gastropod life cycles, reproduction and P/B ratios is made and differences discussed. Variations are correlated to temperature, and food quality and quantity.

Nitrogen (N2) fixation by moss-associated cyanobacteria is an important N source in pristine ecosystems. Previous studies have shown that moss-associated N2 fixation is sensitive to anthropogenic N pollution. However, we still lack understanding of the effects of other factors derived from anthropogenic sources, such as heavy metal pollution on N2 fixation. To test this, we collected two dominant mosses (Pleurozium schreberi and Spaghnum palustre) from a temperate bog in Denmark and assessed their N2 fixation responses to simulated heavy metal pollution by adding 5 levels (plus a control) of copper (Cu, 0–0.05 mg g dw−1) and zinc (Zn, 0–0.1 mg g dw−1). Metal concentrations in both mosses increased linearly with Cu and Zn addition, but N2 fixation activity associated with S. palustre was to a greater extent negatively affected by both Cu and Zn additions than that associated with P. schreberi. Copper additions even promoted N2 fixation in P. schreberi. Hence, the heavy metal sensitiv...