Phosphorus and DOC availability influence the partitioning between bacterioplankton production and respiration in tidal marsh ecosystems

Abstract

Summary The organic carbon consumed by aquatic bacteria (BCC) is partitioned between bacterial production (BP) and respiration (BR), but the factors that determine BCC and its partition into BP and BR are not well understood. We explored the coupling between BR, BR and BCC, and their links to dissolved organic carbon (DOC) and nutrient availability in natural and restored tidal marshes and in the adjoining waters of Delaware Bay estuary. Labile DOC (LDOC) ranged from 3% to 22% of the DOC pool, and explained more of the variance in both BR and BCC than did bulk DOC. Bacterial growth efficiency (BGE) was highly variable (0.09–0.58), and natural Spartina alterniflora marshes had consistently higher BGE than both restoration marshes and tidal floodwaters. BGE was negatively related to the ratio of LDOC to total dissolved phosphorous, which was highest in natural marshes. The enhancement of BP observed in the marshes relative to the estuarine floodwaters had different origins: In natural marshes it was mostly due to increases in BGE, whereas in restored marshes it followed increased BCC. These results highlight the importance of P in regulating microbial metabolism in coastal areas, and the need to understand the pathways that lead to BP in these systems.

High bacterial carbon demand and low growth efficiency at a tropical hypereutrophic estuary: importance of dissolved organic matter remineralization

“…Since then, the vast majority of studies still corroborate this pattern: BGE >30% on average in more productive areas, such as upwelling and estuarine systems (ASMALA et al, 2014;NEWELL, 2012;FUENTES et al, 2012;GUENTHER et al, 2008), and BGE < 20% on average at oceanic sites (ALONSO-SÁEZ et al, 2007;DEL GIORGIO et al, 2011;LØNBORG et al, 2013;. This means that in most eutrophic systems, bacterioplankton act more as a source of organic carbon for the higher consumers.…”

“…The high variability in BP, BR, BCD and BGE, also observed in other tropical estuaries (GUENTHER et al, 2008;RAM et al, 2007), was already expected due to the high hydrodynamic complexity of this system (GUENTHER et al, 2015). Although the BP rates measured in Recife harbor were similar, on average, to other tropical and temperate estuaries (APPLE; DEL GIORGIO, 2007;NEWELL, 2012;GUENTHER et al, 2008;RAM et al, 2003), the BR rates were higher, leading to lower BGE (see Table 3). Bacterial respiration rates were more variable than BP rates and inversely correlated to BGE (see Table 2) which suggest that BGE variations are better explained by BR.…”

“…The direct correlation between BP and N-NH 4 (r=0.53; p=0.01) and the absence of correlation between BP and the N-oxidized forms (r=0.25; p=0.23) suggests a higher reliability of bacterioplankton on ammonium contents in this system. The higher BGE observed in the more productive estuarine systems is usually correlated to the nutrient availability and/or DOM quality (APPLE; DEL GIORGIO, 2007;ASMALA et al, 2014;NEWELL, 2012;GUENTHER et al, 2008) which support bacterial growth (BP) with less maintenance energy costs (BR). The DOM quality (or lability) is defined by its nutritional value (stoichiometric balanced C:N:P ratio), diagenetic state (freshly leached vs. microbial processed), as well as molecular size (low vs. high molecular weight) and shape (degree of aromaticity), irrespective of its allochthonous or autochthonous origin (AMON; BENNER, 1996;ATTERMEYER et al, 2014;GOLDMAN et al, 1987).…”

Response of Bacterioplankton Communities to Cadmium Exposure in Coastal Water Microcosms with High Temporal Variability

“…Overall, a gradual vanishing of phytoplankton biomass over time was observed, while there was a slight decrease in DO in the later stage of incubation (see Table S1 in the supplemental material). The importance of phytoplankton and DO in shaping the marine bacterioplankton community has been confirmed before (51)(52)(53), as were other driving factors here (7,16,24). Phosphate and Cd share a similar direction in shaping the bacterial community (Fig.…”

“…One of the major scientific challenges is to evaluate threats of pollution disturbances to the biodiversity. Bacterioplankton plays crucial roles in the mineralization of organic matter and nutrient cycling in marine ecosystems (7,8), and bacterioplankton community composition (BCC) quickly responds to anthropogenic disturbances such as chemical pollution, nutrient enrichment, and the introduction of antibiotics and pathogens (9). Therefore, bacterioplankton communities might be used to evaluate the ecological effect of pollution in a coastal environment.…”