Isotopic Variation of Macroinvertebrates and Their Sources of Organic Matter Along an Estuarine Gradient

• Published in: Estuaries and coasts Vol. 43; no. 3; pp. 496 - 511
• Main Authors: Kim, Changseong, Kang, Hee Yoon, Lee, Young-Jae, Yun, Sung-Gyu, Kang, Chang-Keun
• Format: Journal Article
• Language: English
• Published: New York Springer Science + Business Media 01.05.2020; Springer US; Springer Nature B.V
• Subjects: analysis of variance; Aquatic habitats; Aquatic life; Aquatic plants; Brackishwater environment; carbon; Coastal ecology; Coastal environments; Coastal Sciences; Earth and Environmental Science; Ecology; Environment; Environmental Management; Estuaries; Food chains; Food webs; Foods; Freshwater & Marine Ecology; Freshwater plants; Isotopes; Macroinvertebrates; Marshes; mixing; nestedness; Niches; nitrogen; Nutrition; Offshore; Organic matter; Particulate organic matter; Phragmites australis; Phytobenthos; Phytoplankton; Primary production; primary productivity; riparian areas; River discharge; Salinity; Salinity effects; Salinity gradients; South Korea; Special Issue: Climate Change and Anthropogenic Change around Korean Peninsula; Stable isotopes; statistical models; Subsidies; Turbidity; Variance analysis; Water and Health; Wetlands; Zoobenthos; Zostera marina; South Korea; Trophic niche; Low-turbidity; Food web; Stable isotopes; Macrobenthos; Coastal embayment
• ISSN: 1559-2723; 1559-2731
• DOI: 10.1007/s12237-019-00543-z

Spatiotemporal patterns in the basal resources fueling the macrobenthic food web of a temperate coastal embayment subject to a low-turbidity riverine discharge (Gwangyang Bay, Korea) were evaluated using carbon and nitrogen stable isotopes. This study examined trophic links of macrobenthic food web with primary production in diverse wetland habitats along the riverine–estuarine–coastal marine continuum. δ¹³C and δ¹⁵N values of macrobenthic assemblages collected along the salinity gradient of the main channel and their putative sources of organic matter (i.e., riverine particulate organic matter (RPOM), Phragmites australis, microphytobenthos (MPB), phytoplankton, and Zostera marina) were determined. A permutational analysis of variance test showed seasonal uniformity in the isotopic niches of the macrobenthic community within different channel locations. In contrast, isotopic nestedness calculated for the microbenthic community emphasized clearly different trends in its isotopic niches among locations. The δ¹³C values of phytoplankton, suspended and sedimentary organic matter, and macrobenthic community displayed a consistently positive relationship with salinity, characterizing an important contribution of local phytoplankton to the nutrition of macrobenthic community. The isotope mixing model revealed that Phragmites-derived organic matter contributed considerably to the nutrition in the estuarine channel, whereas MPB and Zostera provided trophic subsidies to the deep bay and offshore communities. The nutritional importance of RPOM was minimal at all sites. Overall results suggest that phytoplankton production is a major nutritional contributor to the macrobenthic community in the main channel and that trapping POM originated from neighboring wetlands leads to a longitudinal isotopic niche shift in the macrobenthic community.