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Experimental tests of priority effects and light availability on relative performance of Myriophyllum spicatum and Elodea nuttallii propagules in artificial stream channels.

Zefferman EP - PLoS ONE (2015)

Bottom Line: Native priority did not significantly affect growth rate or survival of M. spicatum, possibly because of unexpectedly poor growth of the E. nuttallii planted early.This study suggests that altering light levels could be effective in reducing growth of an invasive macrophyte, and for changing the competitive balance between a native and a non-native species in the establishment phase.Further investigations into the use of priority effects and resource alteration for submersed macrophyte management are warranted, given their mixed results in other (limited) studies.

View Article: PubMed Central - PubMed

Affiliation: Department of Plant Sciences and Graduate Group in Ecology, University of California Davis, Davis, California, United States of America.

ABSTRACT
Submersed macrophytes have important ecological functions in many streams, but fostering growth of beneficial native species while suppressing weedy invasives may be challenging. Two approaches commonly used in management of terrestrial plant communities may be useful in this context: (1) altering resource availability and (2) establishing desirable species before weeds can invade (priority effects). However, these approaches are rarely used in aquatic systems, despite widespread need for sustainable solutions to aquatic weed problems. In artificial stream channels in California, USA, I conducted experiments with asexual propagules of non-native invasive Myriophyllum spicatum (Eurasian watermilfoil) and native Elodea nuttallii (western waterweed) to address the questions: (1) How does light availability affect relative performance of the two species?; (2) Does planting the native earlier than the invasive decrease survival or growth rate of the invasive?; and (3) Do light level and priority effects interact? The relative performance between E. nuttallii and M. spicatum had an interesting and unexpected pattern: M. spicatum had higher growth rates than E. nuttallii in the zero and medium shade levels, but had similar performance in the low and high shade levels. This pattern is most likely the result of E. nutallii's sensitivity to both very low and very high light, and M. spicatum's sensitivity to very low light only. Native priority did not significantly affect growth rate or survival of M. spicatum, possibly because of unexpectedly poor growth of the E. nuttallii planted early. This study suggests that altering light levels could be effective in reducing growth of an invasive macrophyte, and for changing the competitive balance between a native and a non-native species in the establishment phase. Further investigations into the use of priority effects and resource alteration for submersed macrophyte management are warranted, given their mixed results in other (limited) studies.

No MeSH data available.


Related in: MedlinePlus

Boxplots comparing RGR of M. spicatum and E. nuttallii planted concurrently across shade levels.Box edges mark the 1st and 3rd quartile, and the median is shown with a dark line. Whiskers extend to a maximum of 1.5 x interquartile range outward, and values beyond this are indicated by circles. Diamonds show the mean of each shade level*species combination. Asterisks indicate significant differences (p < 0.05) in pairwise t-tests between species, and “NS” indicates non-significant differences.
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pone.0120248.g002: Boxplots comparing RGR of M. spicatum and E. nuttallii planted concurrently across shade levels.Box edges mark the 1st and 3rd quartile, and the median is shown with a dark line. Whiskers extend to a maximum of 1.5 x interquartile range outward, and values beyond this are indicated by circles. Diamonds show the mean of each shade level*species combination. Asterisks indicate significant differences (p < 0.05) in pairwise t-tests between species, and “NS” indicates non-significant differences.

Mentions: Plot level survival was 100% for both species in the concurrent treatment. Overall, M. spicatum had higher RGR than E. nuttallii (significant species effect). Shade had a significant effect on RGR, but these differences across shade levels did not differ significantly between the two species (no significant species x shade interaction) (Table 3A, Fig. 2). The mean RGR of E. nuttallii in the concurrent treatment was highest in the low shade level, intermediate in the zero and medium shade levels, and lowest in the high shade level—41.1% lower than the low shade level (Fig. 2). However, Tukey means comparisons for E. nuttallii in the concurrent treatment only show a significant difference in RGR in the high shade level compared to the zero (p = 0.022) and low shade levels (p = 0.0004).


Experimental tests of priority effects and light availability on relative performance of Myriophyllum spicatum and Elodea nuttallii propagules in artificial stream channels.

Zefferman EP - PLoS ONE (2015)

Boxplots comparing RGR of M. spicatum and E. nuttallii planted concurrently across shade levels.Box edges mark the 1st and 3rd quartile, and the median is shown with a dark line. Whiskers extend to a maximum of 1.5 x interquartile range outward, and values beyond this are indicated by circles. Diamonds show the mean of each shade level*species combination. Asterisks indicate significant differences (p < 0.05) in pairwise t-tests between species, and “NS” indicates non-significant differences.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4366179&req=5

pone.0120248.g002: Boxplots comparing RGR of M. spicatum and E. nuttallii planted concurrently across shade levels.Box edges mark the 1st and 3rd quartile, and the median is shown with a dark line. Whiskers extend to a maximum of 1.5 x interquartile range outward, and values beyond this are indicated by circles. Diamonds show the mean of each shade level*species combination. Asterisks indicate significant differences (p < 0.05) in pairwise t-tests between species, and “NS” indicates non-significant differences.
Mentions: Plot level survival was 100% for both species in the concurrent treatment. Overall, M. spicatum had higher RGR than E. nuttallii (significant species effect). Shade had a significant effect on RGR, but these differences across shade levels did not differ significantly between the two species (no significant species x shade interaction) (Table 3A, Fig. 2). The mean RGR of E. nuttallii in the concurrent treatment was highest in the low shade level, intermediate in the zero and medium shade levels, and lowest in the high shade level—41.1% lower than the low shade level (Fig. 2). However, Tukey means comparisons for E. nuttallii in the concurrent treatment only show a significant difference in RGR in the high shade level compared to the zero (p = 0.022) and low shade levels (p = 0.0004).

Bottom Line: Native priority did not significantly affect growth rate or survival of M. spicatum, possibly because of unexpectedly poor growth of the E. nuttallii planted early.This study suggests that altering light levels could be effective in reducing growth of an invasive macrophyte, and for changing the competitive balance between a native and a non-native species in the establishment phase.Further investigations into the use of priority effects and resource alteration for submersed macrophyte management are warranted, given their mixed results in other (limited) studies.

View Article: PubMed Central - PubMed

Affiliation: Department of Plant Sciences and Graduate Group in Ecology, University of California Davis, Davis, California, United States of America.

ABSTRACT
Submersed macrophytes have important ecological functions in many streams, but fostering growth of beneficial native species while suppressing weedy invasives may be challenging. Two approaches commonly used in management of terrestrial plant communities may be useful in this context: (1) altering resource availability and (2) establishing desirable species before weeds can invade (priority effects). However, these approaches are rarely used in aquatic systems, despite widespread need for sustainable solutions to aquatic weed problems. In artificial stream channels in California, USA, I conducted experiments with asexual propagules of non-native invasive Myriophyllum spicatum (Eurasian watermilfoil) and native Elodea nuttallii (western waterweed) to address the questions: (1) How does light availability affect relative performance of the two species?; (2) Does planting the native earlier than the invasive decrease survival or growth rate of the invasive?; and (3) Do light level and priority effects interact? The relative performance between E. nuttallii and M. spicatum had an interesting and unexpected pattern: M. spicatum had higher growth rates than E. nuttallii in the zero and medium shade levels, but had similar performance in the low and high shade levels. This pattern is most likely the result of E. nutallii's sensitivity to both very low and very high light, and M. spicatum's sensitivity to very low light only. Native priority did not significantly affect growth rate or survival of M. spicatum, possibly because of unexpectedly poor growth of the E. nuttallii planted early. This study suggests that altering light levels could be effective in reducing growth of an invasive macrophyte, and for changing the competitive balance between a native and a non-native species in the establishment phase. Further investigations into the use of priority effects and resource alteration for submersed macrophyte management are warranted, given their mixed results in other (limited) studies.

No MeSH data available.


Related in: MedlinePlus