Impacts of exotic mangroves and mangrove control on tide pool fish assemblages

Abstract

Fish were sampled from tide pools in Hawaii to determine how exotic mangroves Rhizophora mangle and the use of herbicides to chemically eradicate them are impacting tide pool fish assemblages. Ecological parameters were compared among mangrove-invaded, native vegetated, and non-vegetated tide pools before and after mangroves had been chemically eradicated. Native fish densities were higher than exotic fish densities in all treatments, were dominated by flagtails Kuhlia xenura, did not differ among treatments, and 1 yr after herbicidial eradication of mangroves, were greater than or equal to pre-control densities. Exotic fish densities did not differ between mangrove and native vegetated tide pools, were dominated by mollies Poecilia sp., were significantly lower in non-vegetated vs. vegetated pools, and did not differ before and after mangrove eradication. Significantly smaller native flagtails and exotic mollies were present in mangrove tide pools than in all other treatments. Our data suggests that exotic mangroves in Hawaii are not having an adverse effect on native fish assemblages in tide pools, and may actually provide nursery habitat for native and exotic fish. Furthermore, the presence of vegetation and not its origin may be more influential on exotic fish assemblages. Finally, our data suggests that if chemical eradication of mangroves negatively affected tide pool fish assemblages, those effects are short-lived. Future studies should attempt to quantify the ecological value of native versus exotic vegetation in supporting native (or exotic) fish assemblages.

Citation

MacKenzie, Richard A.; Kryss, Cailtin L. 2013. Impacts of exotic mangroves and mangrove control on tide pool fish assemblages. Marine Ecological Progress Series. 472:219-237.