Drivers of zooplankton community composition in a novel ecosystem: Hawai'i mangroves as a case study.
Management of established non-native plants is challenging because removal is expensive and can produce negative consequences, yet establishment can create novel ecosystems. Red mangrove propagules were introduced to Moloka'i, Hawai'i, in 1902 to mitigate the effects of soil erosion and have since spread along the coast and to adjacent islands creating novel habitat. We compared zooplankton communities between novel mangrove and historical non-mangrove habitat both within fishponds and along open coastline to examine environmental factors, including mangrove presence, affecting zooplankton community composition. Community composition patterns were driven by lunar cycle and site characteristics, including fishpond structure, mangrove and open-coast shoreline length, percent of mangrove shoreline length, total percent mangrove leaf carbon and upstream watershed disturbance. Our findings indicate that during the tropical summer reproductive season, non-native mangroves support diversity, richness and community composition similar to non-mangrove areas, though some widespread taxa have lower abundance, and some rare taxa are more abundant in mangroves. Additionally, fishpond zooplankton community structure is significantly different from open-coast areas, indicating fishponds, themselves, create novel habitat. Synthesis and application. In the face of declining fisheries, threatened reef habitat and changing climatic conditions, non-native mangroves may provide, rather than impede, zooplankton habitat availability in novel locations.