Estimating areal production of intertidal microphytobenthos based on spatio-temporal community dynamics and laboratory measurements

Abstract

In situ Microphytobenthic community dynamics were combined with laboratory measurement of predominant species by fluorescence methods to estimate the areal primary production. Field investigation of community dynamics of microphytobenthos (MPB) was conducted from August 2006 to August 2007 in intertidal flats of the Nakdong River estuary, Korea. MPB Biomass varied between 0.47 and 16.58 µg cm −3 in the surface 1 cm sediment, with two dominant diatom species, Amphora coffeaeformis and Navicula sp., occupying average 77.2 ± 14.9% of total number of MPB cells. The biomass was higher in the slightly muddy sand sites than that in the sand site, and showed different pattern of seasonal variation. The profile of vertical distribution of biomass was an exponential decrease trend with depth in sediments. The biomass proportions in the uppermost 3 mm were 57.6% and 37.8% with and without the presence of biofilm, respectively. The two dominant species were cultured in laboratory, and their photosynthetic parameters, rETR max (relative maximum electron transport rate), α (light utilization coefficient) and E k (light saturation parameter) were derived from rETR (relative ETR)-irradiance curves by Imaging-PAM (pulse amplitude modulated) fluorometry. The rETR-irradiance curves showed no significant difference of photosynthetic activities between the two species. The areal potential production ranged from 0.74 to 2.22 g C m −2 d −1 .

Functional resilience of PSII, vertical distribution and ecosystem-level estimates of subsurface microphytobenthos in estuarine tidal flats

“…Application of Eq. ( 2) also evaluated the fraction of subsurface Chl a, to our knowledge not done in previous studies which characterized cm-scale vertical profiles of Chl a in estuarine or marine sediments (Du and Chung, 2009;Weiqiu et al, 2013).…”

“…The proportion of total:subsurface MPB biomass (here quantified as C sub,total ) may be used to estimate the amount of potentially productive subsurface biomass from available surface values. Traditionally, MPB 'surface' biomass has been measured by sampling the top layers of sediment, in the range 2-10 mm (Du and Chung, 2009;Kelly et al, 2001), when studies target to measure the biomass implicated in primary productivity (Laviale et al, 2015;MacIntyre and Cullen, 1995;Serôdio et al, 2001;Taylor and Paterson, 1998). More recently, optical methods such as remote sensing, based on reflectance measurements or solar-induced fluorescence became an extensively used method to estimate Chl a concentrations and create km-scale maps of MPB biomass and annual rates of primary production (Benyoucef et al, 2014;Bouman et al, 2017;Combe et al, 2005;Daggers et al, 2018;Huete et al, 2015;Kazemipour et al, 2012;Ryu et al, 2014;van der Wal et al, 2010).…”