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Marine and Freshwater Research Marine and Freshwater Research Society
Advances in the aquatic sciences
RESEARCH ARTICLE

Effects of the mangrove forest environment and tree species characteristics on fiddler crab communities

Wilmari Theron https://orcid.org/0000-0002-4283-3823 A * , Sershen A B , Nasreen Peer C and Anusha Rajkaran A
+ Author Affiliations
- Author Affiliations

A Department of Biodiversity and Conservation Biology, University of the Western Cape, Robert Sobukwe Road, Bellville 7530, South Africa.

B Institute of Natural Resources, PO Box 100396, Scottsville 3209, South Africa.

C Department of Botany and Zoology, Natural Sciences Building, Stellenbosch University, Merriman Avenue, Stellenbosch 7600, South Africa.

* Correspondence to: theronwilmari@gmail.com

Handling Editor: Kerrylee Rogers

Marine and Freshwater Research 73(11) 1283-1296 https://doi.org/10.1071/MF21309
Submitted: 20 October 2021  Accepted: 25 June 2022   Published: 5 August 2022

© 2022 The Author(s) (or their employer(s)). Published by CSIRO Publishing.

Abstract

Context: South African mangrove forests consist predominantly of three tree species wherein fiddler crabs live beneath the vegetation and act as important bioengineers.

Aims: To examine whether, and to what extent, tree morphology and forest structure affect fiddler crab communities.

Methods: Various physicochemical parameters (sediment pH, organic matter and microphytobenthos) and tree characteristics (e.g. tree density, canopy cover and importance value) were related to the abundance or presence of these crabs within eight South African mangrove-dominated estuaries by using multivariate models.

Key results: Overall, fiddler crab abundance was driven by sediment organic matter. The abundance of Austruca occidentalis was negatively correlated with sediment organic matter (C = −0.369, P = 0.013), whereas abundance of Paraleptuca chlorophthalmus was positively correlated (C = 0.115; P = 0.008). Tubuca urvillei abundance was not affected by anything. Fiddler crab presence was largely driven by sediment organic matter for all species and pneumatophore density in A. occidentalis.

Conclusions: Results indicated that mangrove tree structure influences fiddler crabs indirectly at the population level, by modulating physicochemical and biological variables.

Implications: Understanding mangrove tree and macrobenthic fauna co-existence patterns will be essential in developing climate-responsive management strategies for these species and the systems within which they occur.

Keywords: Avicennia marina, biodiversity, estuary, fiddler crabs, forest structure, microphytobenthos, sediment organic matter, South Africa.


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