Pacific Island Network marine water quality monitoring protocol: version 2.0

Raikow, David; Kozar, Kelly; McCutcheon, Amanda; Farahi, Anne

doi:10.36967/2300648

The National Park Service established the Inventory and Monitoring Division (IMD) in order to monitor physical, chemical, and biological elements and processes of ecosystems that represent overall ecosystem health within parks. Water quality is widely used as an indicator of aquatic resource condition and was identified as a high priority vital sign by the Pacific Island Network (PACN). The objectives of this protocol are to collect high-quality spatial and time-series data on the water quality in the marine areas of PACN parks, to analyze these data, and to communicate spatial and temporal patterns of water quality parameters, including statistically identifiable trends, in briefing statements, reports, and publications. These data inform natural resource management decisions made in the face of environmental threats, such as climate change, chemical and microbial contamination, ocean acidification, nutrient enrichment, invasive species, shoreline erosion, and sedimentation. This protocol revision follows guidance set forth by IMD and evaluates recommendations put forth in prior marine water quality trend reporting (Raikow et al. 2021). It is a substantive change to the marine portion of the PACN water quality protocol version 1 (Jones et al., “Protocol,” 2011). Here we revise sampling design and field methods based on trend and power analyses of data collected from 2008 to 2015 and conduct a full scientific review of the marine portion of the original water quality protocol. Methods were modified to improve understanding of landscape-level influences on nearshore water quality, cull redundant sampling, and increase program efficiency, while still meeting or exceeding the original goals of the monitoring protocol. Specific changes include the following: The objectives have been modified by specifying the magnitude of change the sampling design must be able to detect within 10 years and removing the goal of establishing ranges for water quality parameter values Total dissolved nitrogen, total dissolved phosphorus, and nitrate + nitrite are clearly identified as primary analytes Sampling no longer occurs at “near-bottom” depths Sampling no longer occurs at temporary/random sites Sampling will occur twice a year instead of four times per year New fixed sites have been added to improve spatial coverage and monitor submarine groundwater discharge and river discharge Sampling will occur during ebb tide when possible Sampling high river discharge events will occur when possible Sampling at the actual sea floor will occur during annual benthic surveys Sample sites are established within the marine areas of Kaloko-Honokōhau National Historical Park (KAHO), Kalaupapa National Historical Park (KALA), War in the Pacific National Historical Park (WAPA), and National Park of American Samoa (NPSA). Water quality parameters monitored at each site include total dissolved phosphorus (TDP), total dissolved nitrogen (TDN), nitrate + nitrite, pH, temperature, dissolved oxygen, total algae (chlorophyll), turbidity, and specific conductance (salinity). Water sampling methods remain unchanged from the previous protocol; three replicate surface water samples consisting of independent grabs are collected at each site, water samples are filtered for analysis of dissolved nutrients and are kept on ice in a dark container until returning to offices, where they are immediately frozen, and stored under these conditions until they are sent to a lab for analysis. Data will be managed under standard operating protocols (SOPs) that ensure data entered into databases are verified for accuracy and certified as scientifically valid after completing established quality assurance and control procedures. Data are published into the public domain and reported to parks via trend reports and briefing statements. Trend reports will be published approximately once every 10 years (or sooner if warranted) and peer-reviewed. These reports will generally consist of an introduction; methods; analyses, including linear mixed models, Mann-Kendall analyses, spatial analyses, results; and a discussion that will include interpretation of results, management implications, and suggested improvements to protocol methods, if applicable. Briefing reports are intended to provide annual updates of marine water quality data to parks but will not contain statistical analyses or interpretation of results as found in trend reports. Operational reviews and updates to SOPs will be conducted annually.

Pacific Island Network marine water quality monitoring protocol: version 2.0

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