Where to fish in the forest? Tree characteristics and contiguous seagrass features predict mangrove forest quality for fishes and crustaceans

Caroline Wanjiru, Ivan Nagelkerken, Sonja Rueckert, William Harcourt, Mark Huxham* (Corresponding Author)

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Mangroves often support rich fish and crustacean communities, although faunal abundance and diversity show strong spatiotemporal variability. Consistent patterns in mangrove animal communities might be dictated by forest characteristics, by seascape context or by some combination of these factors. Predicting drivers of spatial heterogeneity in mangrove faunal communities can better support the zoning of forests for management purposes, for example by identifying sites important for fisheries nursery provision.
We sampled 14 sites within a large (4000 ha) mangrove forest in Kenya, quarterly over a period of 2 years. There were clear and consistent differences in the quality of sites for fish and crustacean abundance and diversity.
Forest characteristics (as summarised by the complexity index, CI) and seascape metrics (the presence, area and configuration of contiguous seagrass) were strong predictors of site differences. However, they showed opposite influences on dominant members of the fish and crustacean faunas, with CI correlated negatively with fishes and positively with crustaceans, and seagrass area correlated positively with fishes and negatively with crustaceans.
Synthesis and applications. Sites within the same mangrove forest exhibit consistent differences in fish and crustacean abundance. However, the fish and crustacean communities (and particularly dominant species within them) act differently in response to forest and seascape characteristics. Old growth, mature forest, set in a seascape of seagrass patches with bare sediment, was associated with highest crustacean abundance. In contrast, denser smaller trees and seascapes with larger, continuous areas of seagrass correlated better with fish abundance. Zoning for management, as mandated in new Kenyan policy, will need to consider these differences in seascape use between fish and crustaceans.
Original languageEnglish
Pages (from-to)1340-1351
Number of pages12
JournalJournal of Applied Ecology
Volume60
Issue number7
Early online date28 Apr 2023
DOIs
Publication statusPublished - Jul 2023

Bibliographical note

Acknowledgements
We thank the people of Vanga and the field team of Hamisi Kirauni, Derrick Omollo, Josphat Nguu, Sammy Kibor, Evans, Alfred Obinga, Boaz Orembo, Rashid Anam, Ben Onyango and Harith Mohamed. Derek and Maureen Moss, Earthwatch Institute and the School of Applied Sciences, Edinburgh Napier University, provided financial support for CW. Our lead author, Caroline Wanjiru, died in December 2022 and is sadly missed; this paper forms part of her legacy

Data Availability Statement

Data available from the Edinburgh Napier Repository https://doi.org/10.17869/enu.2023.3069847 (Wanjiru et al., 2023).

Keywords

  • Nursery habitat
  • ecosystem services
  • shrimp, juveniles
  • mosaic
  • East Africa
  • Complexity

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