Influences of salinity and shade on seedling photosynthesis and growth of two mangrove species, Rhizophora mangle and Bruguiera sexangula, introduced to Hawaii
Krauss, K.W.; Allen, J.A. (2003). Influences of salinity and shade on seedling photosynthesis and growth of two mangrove species, Rhizophora mangle and Bruguiera sexangula, introduced to Hawaii. Aquat. Bot. 77(4): 311-324. http://dx.doi.org/10.1016/j.aquabot.2003.08.004
In: Aquatic Botany. Elsevier Science: Tokyo; Oxford; New York; London; Amsterdam. ISSN 0304-3770; e-ISSN 1879-1522, more
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| Keywords |
Chemical reactions > Photochemical reactions > Photosynthesis
Chemical reactions > Photochemical reactions > Photosynthesis > Carbon fixation
Environmental effects
Environmental effects > Salinity effects
Growth rate
ISE, USA, Hawaii, Oahu I.
Mangroves
Seedlings
Shading
Taxa > Species > Introduced species
Bruguiera sexangula (Lour.) Poir. [WoRMS]; Rhizophora mangle L. [WoRMS]
Oahu Island [Marine Regions]
Marine/Coastal; Brackish water |
| Author keywords |
carbon assimilation; invasion biology; tight response curves;photosynthesis; salt sensitivity; shade tolerance; Rhizophora mangle;Brugutera sexangula |
| Abstract |
Rhizophora mangle was first introduced to Hawaii in 1902 to promote shoreline stabilization. Intertidal competition with native and introduced salt marsh species was low, and beyond the early 1920s, mangrove forests expanded rapidly. An additional mangrove species, Bruguiera sexangula, was introduced in 1922 and currently co-occurs with R. mangle in only a few stands on the north shore and windward sides of Oahu. Where the two species overlap, R. mangle, having colonized intertidal zones first, forms nearly monospecific forest stands. To determine why R. mangle remains the dominant mangrove, we initiated a greenhouse study to compare seedling growth and photosynthetic light response of both species growing at two light levels and contrasting salinity regimes (2, 10, 32 PSU). The asymptotic nature of B. sexangula's assimilation response is indicative of stomatal regulation, whereas only light level appears to regulate photosynthesis in R. mangle. Shifts in patterns of biomass allocation and physiological response indicate two contrasting strategies relative to sunlight and salinity. B. sexangula's strategy is characterized by slow growth with little variation under favorable conditions and morphological plasticity under stressful conditions, which allows for adjustments in carbon gain efficiency (morphological strategy). On the other hand, R. mangle's strategy involves faster growth under a wide range of environmental conditions with physiological enhancement of carbon assimilation (physiological strategy). Low salinity combined with reduced light, or simply low sunlight alone, appears to favor R. mangle and B. sexangula equally. High salinity places greater, but not overwhelming, stress on B. sexangula seedlings, but tends to favor R. mangle at higher light levels. |
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