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ARS Home » Plains Area » Lubbock, Texas » Cropping Systems Research Laboratory » Plant Stress and Germplasm Development Research » Research » Publications at this Location » Publication #335057
Title: Subtle temperature differences may well determine who wins: a story of three submerged aquatic plant species

Author
item MILLER, MOLLY - University Of South Alabama
item Mahan, James
item SHERMAN, TIMOTHY - University Of South Alabama

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 10/10/2016
Publication Date: N/A
Citation: N/A

Interpretive Summary: Seagrasses play an important role in coastal regions. Humans have introduced non-native seagrasses into environments where they have the potential to displace native species. In this study we have used a recently developed laboratory tool to predict the invasive potential of seagrasses within an environment. The use of the tool allows use to study not only the current thermal environment but to make predictions about climate variation.

Technical Abstract: As temperatures increases globally, shifts in the distribution of plant species are expected, with unknown effects on invasive species abundance. It is then of value to understand the role increased temperature may have on invasive species. Although nonhomeothermic organisms are the mercy of environmental temperatures, their physiology is still temperature dependent, with species dependent thermal optima. By identifying the thermal optimum of a species and determining the amount of time spent annually in that optimal temperature zone, success can be predicted under different temperature regimes. Here we identify species-specific differences in the thermal optima of three submerged plants, Hydrilla verticillata, Myriophyllum spicatum, and Vallisneria neotropicalis. Utilizing a biochemical approach, activity of a key metabolic enzyme NADH malate dehydrogenase (MDH) was used to assess the thermal dependencies of Km and Vmax in each species. A Michaelis-Menten model was then employed to predict reaction velocity across a range of temperatures (10 - 40°C). The predicted reaction velocities were compared to multiyear in situ temperature data. At low temperatures (10 - 20°C), all three species had similar thermal behavior. However, at temperature > 20°C, enzyme activity H. verticillata exhibited a sharp increase to a level 2-3 times higher than M. spicatum and V. neotropicalis. H. verticillata is metabolically more competent at lower temperatures (earlier in season) allowing rapid growth earlier than other coexisting species. This data suggests that as water temperatures increase, the highly invasive H. verticillata will be favored over concurring species. Additionally, a northward expansion of the dioecious, southern biotype of this species is likely.