INTRA-SPECIES GROUPINGS OF CHUM SALMON ONCORHYNCHUS KETA (SALMONIDAE) OF THE AMUR RIVER AND THEIR DISTRIBUTION WITHIN THE BASIN

Chum salmon in the Amur River basin are represented by two races: summer and fall ones. For the summer race, one population with specific type of spawning grounds is known, but the fall race includes three populations with different types of spawning grounds. In total, four eco-geographical groupings of the species are separated in their reproduction by geographical boundaries of geomorphological zones, as well as temporally and ecologically. Chum salmon do not spawn in the Chinese part of the Amur basin in more than 50 years. In the Russian part, the summer chum salmon spawn completely in the hyporheic waters in late July — August, the major grouping of fall chum (77.1 %) spawns in the spring waters in September-November, other two groupings spawn in the hyporheic waters of the lower Amur in September (20.4 %) and in the spring waters of the lakes near the Amur mouth in October-November (2.5 %).

Melting the secrets of gelatinisation temperature in rice

Gelatinisation temperature (GT) is one of the key traits measured in programs for breeding rice (Oryza sativa L.). It is commonly estimated by the alkali spreading value (ASV), and less commonly by differential scanning calorimetry (DSC). Using a diverse set of germplasm, it was determined that DSC values associate poorly with ASV, are not correlated with amylose content but correlate with cooking time. Rice varieties are traditionally grouped into three classes of GT based on ASV: high, intermediate and low. However, the distribution of DSC values of 4000 samples shows only two classes: high and low. Large differences in the distributions of chain lengths synthesised by starch synthase IIa (SSIIa) support the two classes as the major grouping, two haplotypes associating with each peak. Each peak of DSC values spanned 10°C. The chain length distribution of the amylopectin molecules from varieties at the upper boundary of each peak showed significantly more chains that span both the crystalline and amorphous lamellae of a cluster than varieties at the other end of that distribution. Improved varieties, classified as intermediate GT by ASV, belong to both of the classes defined by DSC, implying that some enzyme, other than SSIIa is involved in intermediate GT.

A survey of the ecology and composition of submerged aquatic snail–plant communities

A total of 305 sites were surveyed in southern Manitoba and adjacent areas for the presence of aquatic gastropods and submerged macrophytes with respect to eight water chemistry parameters. Many of the 41 gastropod species found within the study area showed significant preferences for certain parameters. Chi-square tests revealed 68 significant positive and 4 negative interspecific gastropod associations, many of which could not be correlated with net similarities or dissimilarities in significant preferences for the environmental parameters examined. The most common species did not form the most highly significant associations. Members of possible species pairs were compared with respect to their similarities in significant positive associations with other gastropods. The major groupings that emerged reflected characteristics of the habitats within which the species occurred most frequently.Chi-square tests were also conducted for possible snail–plant pairs, resulting in 161 significant positive and 31 negative associations. Many of these could not be correlated with environmental preferences. Members of possible gastropod pairs were compared with respect to their similarities in significant associations with macrophytes. The major grouping that emerged consisted of gastropods which also formed the most highly significant positive associations with macrophytes.