Embedded Files
Research at GCRL Botany
Research at GCRL Botany
Distributional observations during an outbreak in 2005 by personnel with the Mississippi Department of Marine Resources (DMR) suggest that S. molesta was able to survive in salinities of up to 7 parts per thousand (ppt) in the lower Pascagoula River. The response of S. molesta to three salinity levels (0, 5, 10 ppt) was tested using chlorophyll fluorescence. The health of the plants was measured over a period of one month, using a log scale series of observation intensities (hourly, daily, weekly). Plant responses indicated an acute salinity effect after about 4-6 hours and then a gradual chronic decline. Compared to initial measurements, the final F/Fm’ dropped by 5%, 6% and 29%, while the final Fv/Fm dropped 6%, 27% and 39% in the 0, 5, and 10 ppt treatments respectively. Only plants in the 0 ppt treatment showed significant new growth. Plants in 5 ppt appeared to maintain themselves, but plants at 10 ppt all exhibited signs of severe stress and loss of color, turgor, and tissue viability after 10 days.
Figure 1: Photos of representative plants after one month at 3 salinities
Figure 2: Chlorophyll fluorescence data on stress responses measured with Pulse Amplitude Modulated fluorometer. Mean (s.e.) chlorophyll fluorescence over time in S. molesta plants exposed to three different salinities (0, 5, and 10 ppt): (a) Hourly effective quantum yield (ΔF/Fm’) on 30 leaves on day 1, (b) Hourly potential quantum yield (Fv/Fm) from 6 dark-adapted leaves on day 1, (c) Noon-time effective quantum yield (ΔF/Fm’) on 30 leaves from day 1 to day 30, (d) Noon-time potential quantum yield (Fv/Fm) from 6 dark-adapted leaves from day 1 to day 30.
Figure 3: Map of S. molesta distribution in the United States
Research Conclusions
Research Conclusions
Salvinia molesta is a species of major concern in the northern GoM.
Salinity tolerance of 5 ppt or greater could allow invasion into areas where biological control is not possible.
PAM fluorescence indicated both chronic and acute responses.
Plants are unlikely to survive in 10 ppt .
Page updated
Google Sites
Report abuse