Salt sensitivity of the morphometry of Artemia franciscana during development: A demonstration of 3-D critical windows

Abstract

A 3-D conceptual framework of “critical windows” was used to examine if morphometry of Artemia franciscana is altered by salinity exposure during certain key periods of development. A. franciscana were hatched at 20 ppt (designated control salinity) and were then exposed to 10, 30, 40 or 50 ppt either chronically (day 1-15) or only on days 1-6, 7-9, 10-12 or 13-15. On day 15, maturity was assessed and morphometric characteristics, including mass, total body length, tail length and width, length of the third swimming appendage and eye diameter, were measured. Maturation and morphometry on day 15 were influenced by exposure window and salinity dose. A. franciscana were generally larger following exposure to 10 and 40 ppt during day 1-6 and 7-9 when compared to day 10-12 and 13-15, in part due to a higher percentage of mature individuals. Exposure to different salinities on day 1-6 produced the greatest differences in morphometry, and thus day 1-6 appears to be a period in development when A. franciscana is particularly sensitive to salinity. Viewing the developmental window as three-dimensional allowed more effective visualization of the complex interactions between exposure window, stressor dose and the magnitude of morphometric changes in A. franciscana.