Science Inventory

Development of threshold values for a seagrass epiphyte indicator of nutrient enrichment in coastal systems.

Citation:

Nelson, Walt. Development of threshold values for a seagrass epiphyte indicator of nutrient enrichment in coastal systems. Pacific Estuarine Research Society, Coos Bay, OR, March 16 - 18, 2017.

Impact/Purpose:

An extensive review of seagrass epiphyte literature was conducted to determine whether, and under what conditions, seagrass epiphyte metrics could be used as a potential indicator for nutrient impacts in estuarine ecosystems. Location-specific modifying factors (grazing pressure, seagrass species) that cause variation in response patterns are the greatest challenge to regional scale applicability of threshold values. This abstract contributes to SSWR 4.02B.

Description:

Epiphytes on seagrasses have been studied for more than 50 years, and proposed as an indicator of anthropogenic nutrient enrichment for over 30 years. Epiphytes have been correlated with seagrass declines, causally related to nutrient additions in both field and mesocosm experiments, and have quantifiable impacts on light available to host plants. An extensive review of seagrass epiphyte literature was conducted to determine whether seagrass epiphyte metrics can be used as a biological indicator for nutrient impacts. While a wide variety of epiphyte metrics have been used by authors, epiphyte biomass as biomass per unit seagrass biomass may be the most effective epiphyte indicator. Regression analyses of epiphyte versus seagrass response metrics were used to estimate values representing potential thresholds for environmental concern. Median epiphyte loads associated with 25 and 50% reduction in seagrass biomass, density and productivity are proposed as potential thresholds. Location-specific modifying factors (grazing pressure, seagrass species) that cause variation in response patterns are the greatest challenge to regional scale applicability of threshold values.

Record Details:

Record Type: DOCUMENT (PRESENTATION/SLIDE)
Product Published Date: 03/18/2017
Record Last Revised: 03/22/2017
OMB Category: Other
Record ID: 335802

Organization:

U.S. ENVIRONMENTAL PROTECTION AGENCY

OFFICE OF RESEARCH AND DEVELOPMENT

NATIONAL HEALTH AND ENVIRONMENTAL EFFECTS RESEARCH LABORATORY

WESTERN ECOLOGY DIVISION

PACIFIC COASTAL ECOLOGY BRANCH