DOI: 10.7280/d1v70g
title: Newport Bay water quality and eelgrass bed stability

description: Eelgrass (Zostera spp.) is a marine flowering plant found in coastal
 regions worldwide and provides critical habitat, nutrient cycling, and
 shoreline buffering to ecosystems. Populations are declining in many of
 these regions due to the negative impacts poor water quality has on light
 availability and photosynthesis. The Lower Newport Bay (LNB) in Southern
 California is a heavily developed recreational harbor and estuarine
 habitat supporting species from varying taxa, including eelgrass. To
 understand the impact water quality has on eelgrass persistence in LNB, we
 selected four sites with long-term stable eelgrass populations and four
 sites with transitional eelgrass populations to collect weekly
 measurements of weather conditions, light availability, and water quality
 parameters. Through repeated measure ANOVAs using date as a between
 factor, we found that stable eelgrass beds had significantly higher light
 availability, dissolved oxygen concentrations, and bluer water on the
 Forel-Ule scale. We fit a linear mixed effect model using the log of
 turbidity, log of chlorophyll, and log of eelgrass bed depth as fixed
 effects with depth nested in site as random effects, found it to be the
 best fit model using AIC (Akaike Information Criterion), and found that
 depth and turbidity are significant predictors of light availability.
 These results indicate that turbidity, rather than chlorophyll
 concentration, has a greater impact on light availability and eelgrass
 health in LNB. This pilot project provides a foundation for future
 research and recommendations for eelgrass conservation in LNB, and
 suggests that runoff contributing to higher turbidity may be a leading
 cause of unhealthy eelgrass beds.
description: Data collection was performed from kayaks,
 with relevant tide and weather data recorded from observations in the
 field and corroborated by online sources. Field equipment included a
 Photosynthetically Active Radiation (PAR) sensor, YSI® Pro20 dissolved
 oxygen probe, salinity pen, depth finder, and secchi disk with an attached
 data logger (HOBO). In the lab, turbidity of collected water samples was
 analyzed using a LaMotte® turbidity meter. Chlorophyll samples were
 collected in the field my filtering water samples through a Swinnex filter
 (GF/F Borosilicate glass microfiber 25 mm) encased in a filter holder, and
 then later  analyzed in the laboratory using the non-acidification
 extraction method for the Turner® brand fluorometer.
 After combining project and online derived datasets, analysis consisted of the investigation of relationships to test links with light availability and bed stability. We found that our results followed precedents set in the research, with light availability showing significant differences between stable and transitional eelgrass beds. In addition, other variables assessed through ANOVA's such as dissolved oxygen concentration and Forel-Ule color scale were found to have significant differences between eelgrass bed stability categories. We fit a linear mixed effect model using the log of turbidity, log of chlorophyll, and log of eelgrass bed depth as fixed effects with depth nested in site as random effects, found it to be the best fit model using AIC (Akaike Information Criterion), and found that depth and turbidity are significant predictors of light availability.
description: R Studio and R software.