Principal Investigator: Russell Brainard (PIFSC)
Co-Principal Investigators: Erin Oleson, Thomas Oliver, Pollyanna Fisher-Pool (PIFSC)
External Collaborators: Marc Lammers (Hawaii Institute of Marine Biology), Simone Baumann-Pickering (Scripps Institution of Oceanography Acoustic Ecology Laboratory)


Project title

Acoustic monitoring of recovery and resilience of coral reef ecosystems

Research Objectives

Our research objectives for this project will primarily address the following two NMFS-identified Research Topics to support understanding, analyses, and management of protected species (ESA-­listed corals and cetaceans) and ocean soundscapes: Topic #2) ocean soundscapes and their natural and anthropogenic components, including characterizing levels and trends in ocean noise and Topic #5) species biology through the use of acoustic techniques.

Reef soundscapes are filled with meaningful sounds that help us monitor and understand ecological processes. The use of sound for communication and perception of the environment is essential for numerous marine taxa such as crustaceans, fish, and cetaceans that produce repeated and identifiable sounds within a variety of behavioral contexts (Lammers and Munger, 2016). On Hawaiian reefs, approximately half of all fish are believed to be soniferous (Tricas and Boyle, 2014). Alpheid snapping shrimp and herbivore grazing are also common sounds on most reefs (Lammers et al. 2008). Particular levels, intensities, and patterns of sound correlate with a range of meaningful reef parameters including total fish density (notably parrotfish and damselfish), diversity, and trophic complexity, coral cover and substrate composition, coral and overall benthic diversity, (Kennedy et al. 2010). Coral reef soundscapes are increasingly being described (Staaterman et al. 2014, Kaplan et al. 2015, Radford et al. 2014, Nedelec et al. 2015, Bertucci et al. 2016) and documented to be an important attractant for the pelagic larvae of corals, crustaceans, and reef fish to find suitable habitats for settlement and as indicator of predator avoidance for juvenile fishes (Simpson et al. 2004, Vermeij et al. 2010, Leis and Lockett 2005, Montgomery et al. 2006, Radford et al. 2011). Snapping shrimp noise, which dominates reef soundscapes and varies spatially and temporally depending on physical variables, natural cycles, environmental events (Lammers et al. 2006 & 2008, Watanabe et al. 2002), may be the primary sounds attracting larval fish (Simpson et al. 2008).

Soundtrap and EAR

Rapid changes in the soundscapes in the ocean, including from the effects of ocean acidification (Hester et al. 2008), may have negative impacts on reef communities over time by disrupting or masking biologically­-relevant sounds, with the potential to affect spawning, larval settlement, and other ecologically important processes. In addition, recent work suggests that noise from small vessels may increase the predation risk for some reef fish (Simpson et al. 2016). Consequently, robust measures of soundscapes are needed in order to compare the acoustic ecology of coral reefs across space and time. Such measures have the potential to dramatically improve our understanding of long-­term ecological processes on coral reefs, especially when integrated with other measures of reef and environmental conditions. All of these parameters are likely to change over the timescale of recovery for heavily impacted reef sites like those at Howland, Baker, and Jarvis.

We will acquire year-long soundscape characterizations in both shallow water coral reef ecosystems at Jarvis, Howland, and Baker Islands and in deep­-water at Howland Island. The shallow water soundscape characterizations will assist PIFSC efforts to better understand resilience and recovery processes of the coral communities devastated by the 2015-2016 mass coral mortality event at these 3 remote insular ecosystems. Being removed from other anthropogenic stressors, these remote island locations provide a unique opportunity to learn more about natural mechanisms and processes of recovery from events as severe as 2015-2016 mass mortality. Such an understanding could be helpful in developing recovery plans in the coral reef habitats of the other 18 ESA­-listed corals around the globe. As outlined above, many coral reef associated species use environmental acoustic cues to identify reef locations for settlement and successful recruitment (Mann et al. 2007, Vermeij et al. 2010, Piercy et al. 2014, Kaplan & Mooney, 2016). Monitoring these acoustic settlement cues during the current coral recruitment and recovery phase will improve our understanding of how important these acoustic cues are in maintaining resilient reefs. The proposed acoustic measurements will also detect and document potential unpermitted vessels visiting these marine national monuments.

Deep-water acoustic monitoring at Howland Island will provide a record of cetacean occurrence, seasonality, and relative abundance at this remote equatorial site. Howland Island has never been surveyed for cetaceans, and the impact of the recent El Nino events on the cetacean fauna is unknown. Unfortunately, there is no baseline for cetacean occurrence in this region, but trends in cetacean occurrence, and the mesopelagic soundscape can be compared to reef soundscapes to evaluate relationships between these connected systems.

Significance

The extreme nature of the 2015-2016 coral bleaching event at Jarvis, Howland, and Baker Islands provides an unprecedented opportunity to use passive acoustics to continually monitor reef recovery processes and improve our understanding of reef resilience and the ability of ESA-­listed corals to recover and survive in the face of climate change. The combination of deep­-water monitoring at Howland Island will provide a more complete assessment of the connection with the pelagic ecosystem and provide the first assessment of cetacean populations in this remote region.


                        Soundtrap and EAR 2