There are increasing concerns that human activities promote the development of natural diseases in aquatic organisms. Of these, diseases concerning small cetaceans have received increasing attention. Most studies have focused on dead animals and provided information on pathogens, contaminant exposure and probable causes of death. However, our understanding of diseases in living populations, particularly with respect to prevalence during the lives of individuals, and for whole populations in different years, remains limited. This study was designed to provide such information on epidermal lesions (abnormalities not directly attributable to physical trauma that may indicate disease) in a wild population of bottlenose dolphins Tursiops truncatus. An 8 yr time series of photographs of 82 free-ranging dolphins from NE Scotland was used to investigate the occurrence and dynamics of epidermal lesions in 7 age classes of young dolphins (from their 1st to their 7th summer of life) and for an adult group. Lesions were found at high prevalence (90 to 100%) in both young and adult dolphins, with 1st-summer calves having the lowest levels. Lesions of different appearance showed 2 patterns of occurrence, either being restricted to young individuals or becoming more common with age. When severity was compared between calves (in their 2nd summer of life) born in 8 different years, a significant decline over time was observed (p < 0.005). Comparison of this change with environmental and anthropogenic factors may help identify which factors may be promoting the ubiquitous epidermal lesions in these dolphins.

Tobacco (Nicotiana tabacum L.) is subject to modification of chemical characteristics by alteration of production practices. If a suitable product can be provided for the tobacco manufacturers, utilizing the once‐over harvest approach, a much simpler and relatively less expensive harvesting machine could be developed and production costs could be markedly reduced. Normal and once‐over methods of harvesting flue‐cured tobacco were evaluated for effects on the chemical characteristics of cured leaves. All plants were topped to 12, 16, or 20 leaves per plant. Stalk position data were compared within the three topping heights. Lesser percentages of total N and total N‐soluble and a lower pH were evident in leaves grown in 1968 than those produced in 1969. As topping height was increased from 12 to 20 leaves per plant, percentages of total N, total N‐soluble, nicotine, and water‐soluble acids in the leaves decreased, while reducing sugars increased. These chemical changes were attributed to utilization of equivalent amounts of nitrogen for the development of greater number of leaves. Higher concentrations of total N, total N‐soluble, nicotine, and water‐soluble acids were recorded for leaves harvested by the normal method than when all leaves were removed in one harvest. Undoubtedly, overmature bottom leaves and immature top leaves, associated with the once‐over method, influenced the average chemical composition for the whole plant. The nitrogenous constituents and water soluble acids increasel in leaves from bottom to top stalk positions except for percent alpha amino nitrogen. The pH of leaves decreased from bottom to top stalk positions. Overmature bottom and immature top leaves from the once‐over harvest contributed to difference in chemical composition of leaves at the upper and the lower stalk positions. When all leaves were harvested at one time, only bottom and top leaves appeared to be different in chemical composition from those presently being used by the tobacco trades.

The optimum in mechanized harvesting of flue‐cured tobacco (Nicotiana tabacum L.) may involve the removal of all leaves in one operation. Field experiments were conducted during the 1968 and 1969 growing seasons to evaluate 12, 16, and 20 leaf topping heights and normal and once‐over harvesting methods for yield, value, and price of flue‐cured tobacco. A separate analysis was utilized to determine stalk position effects within the three topping heights. A significant year effect and its interactions, probably resulting from excess water received in 1968, were noted. The tobacco from the normal harvest method had a greater yield, value, and price than that harvested by the once‐over method, resulting from overmature bottom and immature top leaves, both of which cause lower dry matter yields and a lower price/45.2 kg. The high‐topped plants produced the greatest yield but the lowest price, reflecting greater amounts of lowervalued tobacco from the bottom and top leaves. Yield was lowest at the lower stalk positions, increased to a maximum near the middle stalk positions, and then decreased at the upper stalk positions. Price was at a maximum at the lower‐middle stalk position and decreased in both directions. Leaves harvested by the once‐over method were lower in yield and price at the lower and upper stalk positions as compared to leaves harvested by the normal method. Disregarding the extreme lower and upper stalk positions, the once‐over harvest method resulted in leaves that were comparable to those harvested by the normal method.

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