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Research article - Peer-reviewed, 2020

Thresholds in seascape connectivity: the spatial arrangement of nursery habitats structure fish communities on nearby reefs

Berkstrom, C.; Eggertsen, L.; Goodell, W.; Cordeiro, C. A. M. M.; Lucena, M. B.; Gustafsson, R.; Bandeira, S.; Jiddawi, N.; Ferreira, C. E. L.

Abstract

Ecosystems are linked by the movement of organisms across habitat boundaries and the arrangement of habitat patches can affect species abundance and composition. In tropical seascapes many coral reef fishes settle in adjacent habitats and undergo ontogenetic habitat shifts to coral reefs as they grow. Few studies have attempted to measure at what distances from nursery habitats these fish migrations (connectivity) cease to exist and how the abundance, biomass and proportion of nursery species change on coral reefs along distance gradients away from nursery areas. The present study examines seascape spatial arrangement, including distances between habitats, and its consequences on connectivity within a tropical seascape in Mozambique using a seascape ecology approach. Fish and habitat surveys were undertaken in 2016/2017 and a thematic habitat map was created in ArcGIS, where cover and distances between habitat patches were calculated. Distance to mangroves and seagrasses were significant predictors for abundance and biomass of most nursery species. The proportions of nursery species were highest in the south of the archipelago, where mangroves were present and decreased with distance to nurseries (mangroves and seagrasses). Some nursery species were absent on reef sites farthest from nursery habitats, at 80 km from mangroves and at 12 km from seagrass habitats. The proportion of nursery/non-nursery snapper and parrotfish species, as well as abundance and biomass of seagrass nursery species abruptly declined at 8 km from seagrass habitats, indicating a threshold distance at which migrations may cease. Additionally, reefs isolated by large stretches of sand and deep water had very low abundances of several nursery species despite being within moderate distances from nursery habitats. This highlights the importance of considering the matrix (sand and deep water) as barriers for fish migration.

Keywords

coral reef; fish migrations; habitat configuration; habitat connectivity; habitat shifts; landscape ecology; ontogenetic

Published in

Ecography
2020, volume: 43, number: 6, pages: 882-896
Publisher: WILEY

Authors' information

Stockholm University
Swedish University of Agricultural Sciences, Department of Aquatic Resources
Eggertsen, L.
Univ Fed Rio de Janeiro
Goodell, W.
Univ Hawaii
Cordeiro, C. A. M. M.
Univ Fed Fluminense
Lucena, M. B.
Univ Fed Fluminense
Gustafsson, R.
Stockholm Univ
Bandeira, S.
Eduardo Mondlane Univ
Jiddawi, N.
Univ Dar Es Salaam
Ferreira, C. E. L.
Univ Fed Fluminense

Sustainable Development Goals

SDG14 Life below water

UKÄ Subject classification

Ecology

Publication Identifiers

DOI: https://doi.org/10.1111/ecog.04868

URI (permanent link to this page)

https://res.slu.se/id/publ/105030