TY - JOUR
T1 - Microbial respiration and ecoenzyme activity in sediments from the Gulf of Mexico hypoxic zone
AU - Hill, Brian H.
AU - Elonen, Colleen M.
AU - Anderson, Leroy E.
AU - Lehrter, John C.
PY - 2014
Y1 - 2014
N2 - Sediment chemistry (total carbon [TC], total nitrogen [TN], total phosphorus [TP]), microbial respiration (dehydrogenase activity, DHA), and ecoenzyme activity (EEA) were measured in 4 zones of similarity in the northern Gulf of Mexico (GOM). DHA and EEA reflected the differences in C and N availability associated with proximity to the discharges of the Mississippi and Atchafalaya Rivers, and EEA represented the interface between microbial demands for, and environmental supplies of, nutrients. DHA was positively correlated with β-glucosidase (BG, r = 0.30), [β-N-acetyl glucosaminidase + L-leucine amino peptidase] ([NAG + LAP], 0.65), acid phosphatase (AP, 0.17), and aryl sulfatase (SULF, 0.42). EEAs were positively correlated with each other (0.34-0.76). DHA (0.22-0.33), [NAG + LAP] (0.46-0.64), and SULF (0.17-0.56) were positively correlated with TC, TN, and TP, while BG (0.58-0.60) and AP (0.50-0.58) were correlated only with TC and TN. Carbon use efficiency (CUE) and organic C decomposition rate (M), both based on ecoenzyme models, were positively correlated with TN and TC (0.43-0.46) and TC, TN, and TP (0.24-0.60), respectively. Modeled respiration (Rm), based on M, TC, and sediment bulk density, was correlated with sediment chemistry (0.17-0.90), and with DHA (0.50). All measured chemistry, DHA, EEA, and modeled decomposition parameters exhibited significant cruise, zone, and sediment depth effects, but few significant interaction effects. Structural equation modeling (SEM) revealed a causal relationship between sediment chemistry, EEA, and DHA, explaining 46% of the variance in DHA. As such, the relative activities of the functional classes of ecoenzymes are both a measure of nutrient availability and ecosystem metabolism that may be used to assess large-scale phenomena, such as regional impacts of anthropogenic disturbances.
AB - Sediment chemistry (total carbon [TC], total nitrogen [TN], total phosphorus [TP]), microbial respiration (dehydrogenase activity, DHA), and ecoenzyme activity (EEA) were measured in 4 zones of similarity in the northern Gulf of Mexico (GOM). DHA and EEA reflected the differences in C and N availability associated with proximity to the discharges of the Mississippi and Atchafalaya Rivers, and EEA represented the interface between microbial demands for, and environmental supplies of, nutrients. DHA was positively correlated with β-glucosidase (BG, r = 0.30), [β-N-acetyl glucosaminidase + L-leucine amino peptidase] ([NAG + LAP], 0.65), acid phosphatase (AP, 0.17), and aryl sulfatase (SULF, 0.42). EEAs were positively correlated with each other (0.34-0.76). DHA (0.22-0.33), [NAG + LAP] (0.46-0.64), and SULF (0.17-0.56) were positively correlated with TC, TN, and TP, while BG (0.58-0.60) and AP (0.50-0.58) were correlated only with TC and TN. Carbon use efficiency (CUE) and organic C decomposition rate (M), both based on ecoenzyme models, were positively correlated with TN and TC (0.43-0.46) and TC, TN, and TP (0.24-0.60), respectively. Modeled respiration (Rm), based on M, TC, and sediment bulk density, was correlated with sediment chemistry (0.17-0.90), and with DHA (0.50). All measured chemistry, DHA, EEA, and modeled decomposition parameters exhibited significant cruise, zone, and sediment depth effects, but few significant interaction effects. Structural equation modeling (SEM) revealed a causal relationship between sediment chemistry, EEA, and DHA, explaining 46% of the variance in DHA. As such, the relative activities of the functional classes of ecoenzymes are both a measure of nutrient availability and ecosystem metabolism that may be used to assess large-scale phenomena, such as regional impacts of anthropogenic disturbances.
KW - Ecoenzymes
KW - Gulf of Mexico
KW - Hypoxia
KW - Respiration
KW - Sediments
KW - Structural equation modeling
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U2 - 10.3354/ame01689
DO - 10.3354/ame01689
M3 - Article
AN - SCOPUS:84901332010
SN - 0948-3055
VL - 72
SP - 105
EP - 116
JO - Marine Microbial Food Webs
JF - Marine Microbial Food Webs
IS - 2
ER -