The Laminariaceae off North Shapinsay: Changes from 1947 to 1953

Four sublittoral surveys, off the north coast of the islandof Shapinsay, Orkney, have been completed in May 1947, July1951, July 1952, and July 1953. The calculated quantity of seaweed from 1 to 6 fathoms was 34,000tons during the initial survey of May 1947 after a comparativelymild winter and before the period when bad weather brings aboutthe loss of large quantities of the previous year's growth oflaminaria fronds. The three resurveys were completed after this. The quantity of seaweed in July 1951 was 10,000 tons, and inJuly 1952 a further reduction was found, bringing down the quantityto 6,000 tons. In July 1953 the quantity had partially recovered,reaching 7,000 tons. The increase was reflected more in theseaweed cover than in density. Between 1952 and 1953 the weightof individual plants had decreased but the number of plantsper unit area was greater, which, combined with an increasein the area of seabed covered, made an overall gain in quantity.Laminaria saccharina maintained its dominance in this area throughoutthe period 1947–53.     

NUTRITIONAL REQUIREMENTS OF ACETOBACTER SPECIES: INORGANIC AMMONIUM SALTS AS SOURCES OF NITROGEN

SUMMARY: Forty-six strains of Acetobacter , representing twenty species, have been compared on the basis of their respective abilities to proliferate in two defined inorganic media, in which either glucose or ethanol was the sole source of carbon and energy. Twenty-three strains, representing eleven species, grew in either inorganic medium when glucose was present and nine of these strains, representing five species, could grow also in either inorganic medium when ethanol was present. The remaining twenty-three strains, representing eleven species, failed to grow in either medium with either glucose or ethanol. Three organisms grew better with ethanol than with glucose and three were inhibited by ethanol in the presence of glucose.     

Soil salinity is correlated with a decline in 13C discrimination in leaves of Atriplex species

Abstract A dune-swale-dune transect in north-eastern South Australia with a regular covering of saltbush (Atriplex vesicaria and Atriplex stipitata) was studied. The transect topography was surveyed, as were the Δ (discrimination against ¹³C in CO₂) of the saltbush plants, and the electrical conductivity and chloride profiles of the soil. Increasing soil salinity, surveyed as electromagnetic (EM) soil conductivity, correlated with a decrease in A composition in the leaves of the C4 Atriplex species. No such correlation occurred with the whole plant. Further, the Δ of foliage was more variable than the Δ of whole plants. The Δ of foliage was higher than that of corresponding stems. We suggest that soil conductivity measured in this way is a meaningful assessment of plant growth conditions, and that further study will demonstrate its scope for incorporation into field studies of native plants at a quantitative level.     

Sexually transmitted disease in a promiscuous insect, Adalia bipunctata

Abstract.

• 1 Sexually transmitted diseases (STDs) have rarely been reported in insects and other invertebrates. The majority of those reported involve organisms where sexual transmission is augmented by either vertical (i.e. inherited) transmission, or horizontal transmission, independent of host sexual activity.
• 2 We here demonstrate the existence of an STD in the coccinellid beetle Adalia bipunctata. This species bears a parasitic mite of the genus Coccipolipus. We show that, like many other podapolipid mites, this mite is transmitted between host individuals at a high rate during copulation. It also appears to be transmitted at a low rate between non-copulating individuals.
• 3 We show that infected female A.bipunctata produced eggs at a reduced rate, and that the eggs produced by infected females have highly decreased viability. However, no effect of infection upon host longevity was observed.
• 4 The results are discussed in relation to the incidences of sexually transmitted disease in invertebrates in general, the causes of disease symptoms, and the importance of this disease in the evolution of A.bipunctata.