Plankton food web dynamics and storm events in Kaneohe Bay
This research is funded by UH SeaGrant (2012 – 2014 omnibus).
Investigators: Erica Goetze (PI), Petra Lenz (co-I), Karen Selph (co-I).
Recent studies report changing rainfall patterns for the Hawaiian Islands in association with global climate change, with lower precipitation expected within the next century. Because storm runoff delivers nutrients to the coastal ocean, changing rainfall patterns around the Islands are likely to strongly influence the plankton dynamics in Hawaii’s coastal ecosystems. The planktonic community within Kaneohe Bay, Hawaii’s largest coastal embayment, responds strongly to storm perturbations at the base of the food web, but little is known about how these changes propagate up to higher trophic levels. In addition, prior research on zooplankton in this system has focused on the larger organisms, and the dominant, but small-bodied metazoans (cyclopoid copepods, copepod nauplii) remain under-studied. In this research, we will investigate the trophic role of these small metazoan grazers in order to understand how carbon flows through intermediate trophic levels in the food web. In order to assess how their functional role may change with declining nutrient delivery to the Bay, we will investigate their feeding ecology during both background (non-storm) conditions and following two large storm events.A combination of novel molecular and conventional techniques will be used to study the trophic ecology of these small grazers. Naupliar feeding rates will be estimated in grazing experiments, and combined with field sampling of pico – to microplankton prey populations, and molecular enumeration of nauplii in field samples. Cyclopoid feeding rates will be investigated in grazing experiments on mixed prey assemblages and in targeted studies on naupliar predation. Through the use of novel molecular tools and monospecific laboratory cultures we will be able to estimate the grazing impact of these small metazoans at the species level. These small zooplankton are the dominant prey for many reef-associated fish and invertebrates, and understanding their population dynamics is therefore important. Our work also will provide insights into the ecological impacts of coastal storms and climate change on the plankton community in Kaneohe Bay.
Graduate student Michelle Jungbluth has been working hard on this project, and her MSc thesis research was completed within this system.