Seascape configuration influences connectivity of reef fish assemblages
(English)In: Biological Conservation, ISSN 0006-3207, E-ISSN 1873-2917Article in journal (Refereed) Submitted
Shallow-water habitats within tropical seascapes are intimately connected through ontogenetic and/or feeding migrations of fish. Knowledge on connectivity in the Indo-Pacific region is however sparse. Landscape ecology has been suggested as a useful approach when studying seascape connectivity. In this study, we examine the influence of habitat connectivity on reef fish assemblages in shallow-water habitats surrounding Zanzibar (Tanzania), using a seascape approach. We tested the relationships between a set of landscape and habitat variables and fish diversity and density for different functional groups and life stages. Habitat data was collected at scales ranging from 1m to >2km using aerial photography and ground-truthing. Fish data was collected using a standardised point census method. Furthermore, semi-structured interviews with 127 fishers in the bay were conducted to account for different fishing activity. We show that coral reefs in a complex seascape of Zanzibar are connected to seagrass beds through migration of fish. Habitat connectivity of seagrass and seagrass/coral mix within a 750m radius of coral reefs had a positive influence on fish abundances in the functional group of invertebrate feeders/piscivores, especially within the family Lutjanidae and Lethrinidae. Within-patch seagrass cover had a positive influence on nursery species. Depth also had a positive influence on fish assemblages, highlighting the importance of considering a third dimension, not accounted for in terrestrial studies. Generally, fishing activity between sites did neither influence species richness nor abundance, except for the abundance of juvenile parrotfish. We demonstrate that a landscape ecology approach, combining connectivity and habitat variables, is important for understanding and managing the tropical seascape, although it must be applied at relevant scales, habitat metrics and seascape configurations to fully capture ecological connectivity.
Research subject Marine Ecotoxicology
IdentifiersURN: urn:nbn:se:su:diva-75187OAI: oai:DiVA.org:su-75187DiVA: diva2:515886
Submitted article part of dissertation.2012-04-162012-04-112015-10-02Bibliographically approved