Bioacoustic monitoring: Urgent challenges and opportunities on the MesoAmerican Reef System

The MesoAmerican Reef (MAR) and the Great Barrier Reef (GBR) are the two largest reef systems in the world yet MAR lags far behind in research and recognition. GBR has over ten times more research published than MAR, and this disparity has been consistent across decades. GBR benefits from a high level of global familiarity, whereas MAR suffers from name confusions, press errors, and absence from pop culture. MAR has few research syntheses. MAR research studies tend to be focused on one sub-region, and are mostly conducted at sites located away from human density, and thus away from where major human impacts are occurring. MAR research also lacks technological and methods standardization. The Mesoamerican Reef Report Card monitoring program is a big step toward summation, standardization, and long-term datasets, but has poor temporal resolution. MAR, unlike GBR, is transboundary, stretching along the coasts of Mexico, Belize, Guatemala, and Honduras. This characteristic complicates data collection and management. Language and cultural differences are also factors. While controversial concerns about the death of GBR are discussed, the status of MAR is difficult to assess given the paucity of information, and environmental, social, and economic policies are being formulated that could have devastating consequences. Millions of people depend on MAR directly, plus many more indirectly, whether or not they are aware of it. As development along MAR accelerates, pivotal management decisions are being made `in the dark.'Substantial baseline data collection for MAR is urgently needed, and Marine Passive Acoustic Monitoring (MPAM) presents an ideal opportunity. MPAM has many advantages. MPAM has excellent coverage over time, with night recordings as good as daytime, and the ability to record in inclement weather and across seasons. The cost of a hydrophone system is in the low to mid $1000s, minimal, especially considering the autonomy of the systems. MPAM is also minimally invasive. It uses autonomous instruments that require little human/boat presence. This reduces cost and interference with results and the surrounding environment. The large amounts of good quality data that are needed, quickly and cheaply, must be broadly applicable to serve as a platform for other research projects. MPAM captures biotic sounds from animals including crustaceans, fish, and marine mammals, as well as abiotic sounds from weather and hydrodynamic conditions. MPAM pairs well with visual survey and other sporadic monitoring methods, filling in the temporal resolution. MPAM has the potential to provide many levels of assessment, not only species identification and abundance data, but also ecosystem health data at the soundscape pattern level.The ongoing localized MPAM program on the northern MAR has developed the necessary methodology to be expanded to cover the entire reef. Initiated in 2005, recordings have been collected since 2010 at four sites - Isla Contoy, Isla Mujeres, Punta Nizuc, and Manchones. Much initial work was required before any sounds were recorded, to assess needs, confer with stakeholders, build trust and partnerships, educate about sound and acoustic monitoring, negotiate permissions and scheduling, renegotiate when personnel and politics changed, seek funding, and overcome deployment complications. Research methods were developed and standardized. Hydrophone systems (Ecological Acoustic Recorders; Loggerhead Snaps) were deployed semi-continuously, recording 30 seconds every 15 minutes. Deployment periods varied, but include over a year of data for every site, and sometimes concurrent data collection across several sites, providing opportunities for comparison. Data analysis methods were focused on soundscape characterization, and include playback and spectral analysis. Major research findings thus far include more frequent and diverse fish calls at night versus during the day, and patterns and prevalence of boat motor noise. Most important is the development of the necessary methods and structure, including cross-disciplinary science-art strategies, to conduct scientific monitoring in MAR environment.Expansion of this MPAM program to full coverage of MAR is urgent, realistic, and has the ability to bring transformative conservation and science presence and recognition to the region. Globally, both recording methods and analysis methods for MPAM have yet to be standardized. The early stage is actually a strength for its use on MAR, since rather than investing in learning and following guidelines that are already established, investments can be made in advancements in acoustic methods that contribute to international standards development and collaborations and get scientific recognition for MAR. Finding synergies with other early stage technologies could also enhance the methods and impact. Marine and hydrokinetic energy could reduce the limitations of battery power, enhance the ability to achieve continuity and easy access to the data, and gain MAR even broader recognition. Expansion of MPAM to the entire MAR would vastly increase available MAR data, and with it the potential for appropriately informed economic, social, and environmental decisions. Beyond scientific circles and regional value, methods and programs implemented on MAR could achieve global attention and impact.