Origin, composition and quality of suspended particulate organic matter in relation to freshwater inflow in a South Texas estuary

Abstract

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Influence of Major Storm Events on the Quantity and Composition of Particulate Organic Matter and the Phytoplankton Community in a Subtropical Estuary, Texas

“…Riverine δ 13 C-DIC can drive down the estuarine δ 13 C-POC through uptake and fixation by estuarine phytoplankton (Figure 4B; Fogel et al, 1992). Delivery of freshwater phytoplankton from the rivers to the bay may also have contributed to the lower δ 13 C signal that we observed (δ 13 C = −31.4 , Lebreton et al, 2016). While depleted δ 13 C values in river water are often attributed to C3 plant contributions from the surrounding terrestrial landscape, this is not a viable explanation in this system because POM in the Mission and Aransas rivers becomes enriched in δ 13 C-POC during storm flow conditions (δ 13 C = −22 to −20 , Mooney and McClelland, 2012).…”

“…Freshwater discharge into the MAE has been variable over the past decade; multi-year droughts with very low baseflows are interspersed with large storm events occurring at high frequency for many months at a time, as seen during the study period (Figure 2A) and in previous studies (Mooney and McClelland, 2012;Bruesewitz et al, 2013;Lebreton et al, 2016). These sporadic freshwater inflows significantly influence system-wide salinity, with a decreasing degree of influence along the inshore to offshore transect ( Figure 2B).…”

“…Compared to more "traditional" estuarine models, the MAE is often nutrient limited due to the lack of inorganic nutrient influx related to low runoff and river discharge (Mooney and McClelland, 2012;Bruesewitz et al, 2013). Episodic high freshwater inflows to the MAE significantly impact POM source and concentration (Mooney and McClelland, 2012;Lebreton et al, 2016), yet it remains unclear how storm events affect phytoplankton communities in the MAE. Phytoplankton communities in the MAE have not been systematically characterized, but in this region, chromophytes, haptophytes, pelagophytes, and dinoflagellates generally are the dominant species (Qian et al, 1996).…”

“…As an ideal model for subtropical regions, the microtidal Mission-Aransas Estuary (MAE) is located on the western edge of the Gulf of Mexico in south Texas, with a strong episodic nature of precipitation and resulting freshwater inflow events (Mooney and McClelland, 2012;Bruesewitz et al, 2013;Lebreton et al, 2016). Compared to more "traditional" estuarine models, the MAE is often nutrient limited due to the lack of inorganic nutrient influx related to low runoff and river discharge (Mooney and McClelland, 2012;Bruesewitz et al, 2013).…”

Socio-Economic Implications of Drought in the Agricultural Sector and the State Economy

“…For instance, Venkataramana et al [12] projected multi-year droughts in the late 21st century to occur across the state, with the worst droughts anticipated in El Paso. Effects of severe drought conditions on dissolved organic matter and ecosystems have been estimated by Miller and Shank [13], Acosta-Martinez et al [14], Lebreton et al [15], and Schwantes et al [16]. Specifically, the 2011 drought has accounted for considerable losses in agricultural production of $7.62 billion in Texas (not including timber production) [1,2,17].…”