Depauperate seed banks in urban tropical seagrass meadows
Glendon Hong Ming Ong A , Samantha Lai B , Siti Maryam Yaakub
C D and Peter Todd B
+ Author Affiliations
- Author Affiliations
A NTU Food Technology Centre, 50 Nanyang Avenue, N1.2-B3-27, Singapore 639798, Republic of Singapore.
B Experimental Marine Ecology Laboratory, Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Block S3, Level 2, Singapore 117543, Republic of Singapore.
C Ecological Habitats and Processes Department, DHI Water & Environment (S) Pte Ltd, 2 Venture Drive, #18–18, Vision Exchange, Singapore 608526, Republic of Singapore.
D Corresponding author. Email: smj@dhigroup.com
Marine and Freshwater Research 71(8) 935-941 https://doi.org/10.1071/MF19204
Submitted: 2 June 2019 Accepted: 21 May 2020 Published: 17 July 2020
Abstract
Seagrasses need to be resilient if they are to persist in the long term. Being able to build up a dormant seed bank in sediments is a key strategy that some species employ to regenerate from large-scale degradation. Much of the research on seed banks has focussed on temperate species, and little is known regarding the status of seed banks in tropical meadows. In the present study, we examined the seed bank status of three common seagrass species at six sites in Singapore and attempted to identify potential drivers of seed abundance. Our results indicated depauperate seed banks with few species setting viable seed and low seed densities. Halophila ovalis seeds were found at four sites and Halodule uninervis seeds at two sites, but Cymodocea rotundata seeds were absent from all six sites. Whereas H. ovalis seed viability ranged from 20% to 68.8%, none of the H. uninervis seeds was viable. Halophila ovalis seed densities (33–334 m–2) were much higher than those of H. uninervis (9–21 m–2). Of the variables examined, only H. ovalis cover was positively correlated with the number of seeds. Our study has highlighted the vulnerability of seagrass meadows in Singapore’s urban waters to future disturbances.
Additional keywords: Cymodocea rotundata, dispersal, germination, Halodule uninervis, Halophila ovalis, sexual reproduction.
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