Linkage Between Mangrove Seedling Colonization, Sediment Traits, and Nitrogen Input

Abstract

Mangroves around the world settle along coasts and estuaries, where they usually encounter aquaculture effluent that causes eutrophication and regulates the nitrogen cycle in their ecosystems. Moreover, the physical–chemical features of sediment in mangrove habitats might be altered by coastal wind, waves, and currents more frequently under the condition of increasing extreme climatic events. These events affect the process of colonization/regeneration of mangroves. To study how exogenous nitrogen input and sediment texture affect root system establishment of mangrove propagules and the early growth of seedlings, in turn, we set up a mesocosm experiment to explore the morphological and physiological responses of the root system of two mangroves, i.e., Kandelia obovata and Sonneratia apetala. We found that the root morphological features of mangrove seedlings mostly showed significant differences across the sediment texture treatment; K. obovata seedlings were more intensively influenced than S. apetala seedlings. It could be ascribed that the roots of K. obovata seedlings were more sensitive to sediment texture than S. apetala seedlings. Conversely, the treatment of exogenous nitrogen input showed a slighter even non-significant influence on the root features of mangrove seedlings. These results suggest that the seedlings of S. apetala and K. obovata performed similarly. In estuaries and coasts featuring eutrophication and various sediment textures, the conservation and restoration of mangroves should consider these conditions to ensure the sustainable development of mangroves.

A biogeographical approach to characterizing the climatic, physical and geomorphic niche of the most widely distributed mangrove species,Avicennia marina

“…The sediment accreted in mangrove forests is mostly of terrigenous origin and arrives in tidal waters. Sediment accretion rates in mangroves rarely exceed 10 mm year −1 (Krauss et al, 2014), and there are many examples of the impacts of excessively high sediment loads on mangroves, ranging from reduced tree vigour to the death of some species (Fagherazzi et al, 2017; He et al, 2022). We find that A .…”

Recruitment and mortality of Rhizophora mangle L. seedlings in the Tropical Southwestern Atlantic mangrove

“…Studies of seedling population dynamics are fundamental for understanding the ecological processes in mangroves colonized by this species, and can be applied globally, given the ecological and genetic proximity between the species (Tomlinson, 1986;Francisco et al, 2018). New-individual recruitment and mortality rates in R. mangle are widely variable across ontogeneticstages (Ellison and Farnsworth, 1993;Kock, 1997;Padilla et al, 2004;Proffitt and Travis, 2010;Goldberg and Heine, 2017;Simpson et al, 2017) and the early mangrove seedling establishment and development are regulated by intrinsic characteristics and environmental variables (He et al, 2022). Sloey et al (2022) highlight the importance of recognizing that the causes of mortality vary according to the ontogenetic stages depending on species, geographic location, and interactions between species, and the relative influence of environmental drivers may shift throughout a species' ontogeny.…”