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

Abstract

Multiple anthropogenic disturbances to bacterial diversity have been investigated in coastal ecosystems, in which temporal variability in the bacterioplankton community has been considered a ubiquitous process. However, far less is known about the temporal dynamics of a bacterioplankton community responding to pollution disturbances such as toxic metals. We used coastal water microcosms perturbed with 0, 10, 100, and 1,000 g liter ؊1 of cadmium (Cd) for 2 weeks to investigate temporal variability, Cd-induced patterns, and their interaction in the coastal bacterioplankton community and to reveal whether the bacterial community structure would reflect the Cd gradient in a temporally varying system. Our results showed that the bacterioplankton community structure shifted along the Cd gradient consistently after a 4-day incubation, although it exhibited some resistance to Cd at low concentration (10 g liter ؊1 ). A process akin to an arms race between temporal variability and Cd exposure was observed, and the temporal variability overwhelmed Cd-induced patterns in the bacterial community. The temporal succession of the bacterial community was correlated with pH, dissolved oxygen, NO 3 ؊ -N, NO 2 ؊ -N, PO 4 3؊ -P, dissolved organic carbon, and chlorophyll a, and each of these parameters contributed more to community variance than Cd did. However, elevated Cd levels did decrease the temporal turnover rate of community. Furthermore, key taxa, affiliated to the families Flavobacteriaceae, Rhodobacteraceae, Erythrobacteraceae, Piscirickettsiaceae, and Alteromonadaceae, showed a high frequency of being associated with Cd levels during 2 weeks. This study provides direct evidence that specific Cd-induced patterns in bacterioplankton communities exist in highly varying manipulated coastal systems. Future investigations on an ecosystem scale across longer temporal scales are needed to validate the observed pattern. In the last decades, heavy metal concentrations have increased significantly, reaching up to several mg liter Ϫ1 , in seriously polluted estuaries or harbors (1, 2) as a consequence of industrial discharge and river outflows. Cadmium (Cd) is one of the most toxic metals frequently detected in the coastal areas of China, and its presence exceeds the permissible environmental limit in several bays, including Bohai Bay and Jiaozhou Bay (3, 4), which can harm human health via seafood consumption because of its accumulative and carcinogenic properties (3,5,6). 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.The resp...

Cadmium Exposure-Sedum alfredii Planting Interactions Shape the Bacterial Community in the Hyperaccumulator Plant Rhizosphere

“…In this study, on the basis of plant presence, the increase of Cd pollution further altered the soil bacterial community structure (Fig. 4), which is in line with results from a previous study focusing on the response of bacterial community to Cd in coastal water microcosms (44). The gradually increasing divergence of bacterial community assemblage along the Cd gradient between HE rhizosphere and other samples indicated the interactions between root system and Cd exposure that occurred during the phytoextraction of Cd pollution by HE S. alfredii.…”

“…6A). The stable correlation of these taxa with Cd suggests a possible ecological role of them in response to Cd exposure in soils (44). Even so, they are not likely key players in Cd hyperaccumulation in HE S. alfredii, since they are not specifically localized to the HE rhizosphere.…”

Prokaryotic Community Structure Driven by Salinity and Ionic Concentrations in Plateau Lakes of the Tibetan Plateau

“…4; see also Table S5 in the supplemental material). In agreement with our findings, many previous studies have shown that pH and the DO concentration are major drivers of microbial community distributions in various ecosystems (22,(81)(82)(83)(84)(85)(86). pH has been described to be a master variable that integrates the physiochemical status of aquatic ecosystems (87).…”

“…5). The unexplained variation may result from ecologically neutral processes of diversification (93) and factors not measured in this study that are known to affect prokaryotic community structures, including the dissolved organic carbon concentration (86,94,95) and the chlorophyll a concentration (4,94,96).…”

Bacterial biogeography in the coastal waters of northern Zhejiang, East China Sea is highly controlled by spatially structured environmental gradients

“…Various studies have identified a wide range of biotic and abiotic factors influencing the diversity of marine bacterioplankton such as salinity (Lozupone and Knight, ), temperature (Lindh et al ., ), trophic status (Fodelianakis et al ., ), oxygen (Wright et al ., ), heavy metal (Wang et al ., ), depth (Fortunato et al ., ), upwelling (Nelson et al ., ), geographic location (Lear et al ., ), phytoplankton bloom (Niu et al ., ) and grazing pressure (Jürgens and Matz, ). However, knowledge on variability of bacterial community composition (BCC) and diversity across multiple environmental gradients in coastal water area is scarce.…”