Mutualistic relationships in marine angiosperms: enhanced germination of seeds by mega-herbivores

Tol, Samantha J., Jarvis, Jessie C., York, Paul H., Congdon, Bradley C., and Coles, Robert G. (2021) Mutualistic relationships in marine angiosperms: enhanced germination of seeds by mega-herbivores. Biotropica, 53 (6). pp. 1535-1545.

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Angiosperms have co-evolved with animals over thousands of years leading to an array of mutualistic relationships. Passage of plant seeds through animal intestines leads to an important mutualism providing the animal with food and the plant with seed dispersal and enhanced germination. This phenomenon is well studied in terrestrial angiosperms, but there is less research in aquatic environments. We studied the effect of gut passage in marine mega-herbivores (green sea turtles and dugongs) on seed germination for a common Australian seagrass, Zostera muelleri.

We collected fecal samples likely to contain seeds, as well as seagrass seeds from plants at two coastal seagrass meadows in the central Great Barrier Reef World Heritage Area, Australia. Seeds collected from feces and plants were subjected to germination trials across different temperature treatments: low (19°C), medium (26°C), and high (32°C). We found excreted seeds had a significantly greater germination probability (two to four times greater) and germinated significantly faster (18–61% faster) than seeds from the plant. Excreted seeds which had not germinated at the end of the experiment were significantly less likely to be viable compared with seeds taken from the plant. Seeds released from the plant have a slow germination and low germination probability compared with excreted seeds, but retain a high percentage of seed viability. Our study is the first record of marine mega-herbivores enhancing germination of Z. muelleri seeds. By transporting seeds to new locations and enhancing germination, these animals are important in seagrass resilience and connectivity among metapopulations.

Item ID: 68195
Item Type: Article (Research - C1)
ISSN: 1744-7429
Keywords: biotic dispersal, Chelonia mydas, connect, Dugong dugon, Great Barrier Reef, green sea turtle, seagrass, symbiosis
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A version of this publication was included as Chapter 4 of the following PhD thesis: Tol, Samantha (2020) Relative importance of different seagrass re-establishment strategies in tropical Queensland, Australia. PhD thesis, James Cook University, which is available Open Access in ResearchOnline@JCU. Please see the Related URLs for access.

Funders: Sea World Research and Rescue Foundation (SWR), National Environmental Science Program (NESP) Tropical Water Quality (TWQ) Hub, Australian Government Department of Agriculture, Water and the Environment, TropWATER at James Cook University (JCU)
Research Data:
Date Deposited: 14 Jul 2021 02:41
FoR Codes: 31 BIOLOGICAL SCIENCES > 3103 Ecology > 310305 Marine and estuarine ecology (incl. marine ichthyology) @ 40%
31 BIOLOGICAL SCIENCES > 3108 Plant biology > 310804 Plant developmental and reproductive biology @ 30%
41 ENVIRONMENTAL SCIENCES > 4102 Ecological applications > 410203 Ecosystem function @ 30%
SEO Codes: 18 ENVIRONMENTAL MANAGEMENT > 1805 Marine systems and management > 180501 Assessment and management of benthic marine ecosystems @ 30%
18 ENVIRONMENTAL MANAGEMENT > 1802 Coastal and estuarine systems and management > 180201 Assessment and management of coastal and estuarine ecosystems @ 70%
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