Abstract Detail

Physiology

Thorhaug, Anitra [1], Yu, Shuo [2], Wu, Yunchao Wu [3], Serrao, Ester A [4], Zhang, Jingping [2], Jiang, Zhijian [2], Huang, Chi [2], Cui, Lijun [2], Huang, Xiaoping [2], Schwarz, Arthur [5], Berlyn, Graeme [6].

Enhalus acoroides seeds, fruit, genetic population dynamics in disturbed areas in Southeast Asia from Indonesia to Hainan Island.

Seagrasses are under great stress in estuarine Southeastern Tropical Asia, particularly the dominant species Enhalus acoroides, which includes a huge food-web. Estimates describe 30% decimation of regional seagrass resources. Seagrasses are higher plants, having evolved into the marine realm by different pathways from terrestrial plants via aquatic pathways. Various species retained four differing seed structures. Tropical species evolved large fleshy fruit, which while floating on currents disperse populations. The dominant Indo-Pacific tropical/subtropical seagrass is Enhalus acoroides offering services fisheries and biodiversity nursery and habitat, stabilization of sediment with massive burial of carbon, and resilience of shorelines. The fruit carrying xx.x seeds floats disperses seeds up to tens of kilometers. Seeds begin sprouting blades and roots immediately, growing vertically very rapidly, although more slowly laterally via rhizomes measured as 0.6my-1. The planted specimens growing in clear water and medium sand flower 9 months after seedphase. The flowers are found throughout the length of the blades. Enhalus in polluted waters is not prone to flower similar to Thalassia and Halodule. How are these perennial seagrass populations renewed naturally after severe disturbances when much of the expansion of seagrass is rhizomal growth (Tomlinson, 1979)? On Hainan Island, Li’an Lagoon, China, the Institute of Oceanlogy carried out a study on Enhalus’s fine-scale genetic structure to define into mechanisms for population dynamics.persistence Here, we address this question for an ecologically important seagrass species, which is subject to severe disturbance in China. The fine-scale spatial genetic structure (SGS) was measured finding statistically higher Sp at the ramet-level compared with genet-level. This indicates that clonality increases the SGS pattern for Enhalus. Significant SGS at the genet level may be explained by the aggregated dispersal of seed and pollen cohorts. The estimated gene dispersal variance suggests that dispersal-mediated sexual reproduction is more prevalent than clonal growth in study area. Flowering density of randomly-selected Enhalus measured at several sites estimated the relative frequency of sexual reproduction vs. asexual growth using spatial autocorrelation analysis to estimate the population persistence showing high clonal diversity, predicted from its high sexual reproduction density. From flowering field observations in Pacific, Atlantic, we predict on-going anthropogenic disturbances will negatively affect mating fertilization pattern as well as the SGS patterns in the future due to high frequency of morbid shoots observed creating less sexual reproduction critical to the preservation of the present sustainability. This has been presented to decision-making for future seagrass management and restoration plans.

1 - Yale University, 1359 SW 22 Terrace, Miami, FL, 33145.0, United States
2 - South China Sea Institute of Oceanology, China
3 - University of Chinese Academy of Sciences, China
4 - University of Algarve, Portugal
5 - Southwestern Adventist University, Biological Sciences, 100 W Hillcrest, Keene, TX, 76059, United States
6 - Yale University, School Of Foresty & Evironmental Studies, Marsh Hall-360 PROSPECT ST, New Haven, CT, 06511, United States

Keywords:
Seagrass reproduction
Flowers, fruit Enhalus
Enhalus genetics
Enhalus population dynamics.

Presentation Type: Oral Paper
Session: PHYS1, Physiology
Location: San Pedro 2/Starr Pass
Date: Monday, July 29th, 2019
Time: 8:15 AM
Number: PHYS1002
Abstract ID:376
Candidate for Awards:None