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Vol. 54, 2015
Meiofaunal
communities in a tropical seagrass bed and adjacent unvegetated
sediments with note on sufficient sample size for determining local
diversity indices
Jian-Xiang Liao1,*,
Hsin-Ming Yeh2, and Hin-Kiu Mok1
1Department of Oceanography, National Sun Yat-sen University, Lienhai Road 70, Kaohsiung 80424, Taiwan
2Coastal and Offshore Resources Research Center, Fisheries Research Institute, Yugang North 3rd Road 6, Kaohsiung 80672, Taiwan
Abstract
Background: Seagrass
beds are highly diverse and productive marine habitats for many
associated organisms in nearshore coastal waters. The differences in
abundance, diversity, and community structure of benthic invertebrates
between seagrass beds and adjacent unvegetated sediments have been
stated, whereas most studies are primarily focused on macrofauna or
based on a comparatively long distance, i.e., more than 10 m. The
present study is designed to test if the community structures of
meiofauna, especially the free-living nematodes, differ between
seagrass beds and adjacent unvegetated sediments on a meter scale.
Results: There are 21 meiofaunal taxa and 63 nematode genera that have been identified from a tropical seagrass bed of Thalassia hemprichii
in Ludao, Taiwan. Although the compositions of higher meiofaunal taxa
are undistinguished, according to correspondence analysis, the
assemblages of nematode genera differ substantially between the
seagrass bed and unvegetated sediments. Regarding the nematodes,
approximately 50% of genera are restricted to the seagrass bed whereas
6% are restricted to unvegetated sediments, which indicate both
habitats possessing distinct infaunas. The number of replicates for
reasonable estimation of the local diversity index is calculated by the
randomization technique. For local seagrass beds, only a single core is
sufficient for reliably estimating meiofaunal diversity, but at least
three cores or a sample size of 300 individuals is needed for the
nematode community.
Conclusions: Nematode
assemblages provide more particular differences between seagrass and
unvegetated habitats than meiofaunal communities on small spatial
scales. Both seagrass beds and adjacent unvegetated sediments harbor
specific meiofaunal communities, and hence, the conservation strategy
for seagrass should also consider the peripheral bare area of seagrass
beds.
Key words: Meiobenthos; Thalassia hemprichii; Community composition; Marine nematode; Randomization; Diversity index.
*Correspondence: E-mail: jianxiangliao@gmail.com
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