Pathogenic bacteria significantly increased under oxygen depletion in coastal waters: A continuous observation in the central Bohai Sea

Abstract

The spread of pathogenic bacteria in coastal waters endangers the health of the local people and jeopardizes the safety of the marine environment. However, their dynamics during seasonal hypoxia in the Bohai Sea (BHS) have not been studied. Here, pathogenic bacteria were detected from the 16S rRNA gene sequencing database and were used to explore their dynamics and driving factors with the progressively deoxygenating in the BHS. Our results showed that pathogenic bacteria were detected in all samples, accounting for 0.13 to 24.65% of the total number of prokaryotic sequences in each sample. Pathogenic Proteobacteria was dominated in all samples, followed by Firmicutes, Actinobacteria, Tenericutes, and Bacteroidetes, etc. β-diversity analysis showed that pathogenic bacteria are highly temporally heterogeneous and regulated by environmental factors. According to RDA analysis, these variations may be influenced by salinity, ammonia, DO, phosphate, silicate, and Chl a. Additionally, pathogenic bacteria in surface water and hypoxia zone were found to be significantly separated in August. The vertical distribution of pathogenic bacterial communities is influenced by several variables, including DO and nutrition. It is noteworthy that the hypoxia zones increase the abundance of certain pathogenic genera, especially Vibrio and Arcobacter, and the stability of the pathogenic bacterial community increased from May to August. These phenomena indicate that the central Bohai Sea is threatened by an increasingly serious pathogenic community from May to August. And the developing hypoxia zone in the future may intensify this phenomenon and pose a more serious threat to human health. This study provides new insight into the changes of pathogenic bacteria in aquatic ecosystems and may help to make effective policies to control the spread of pathogenic bacteria.

First screening of bacteria assemblages associated with the marine polychaete Melinna palmata Grube, 1870 and adjacent sediments

“…These microorganisms' interactions with environmental parameters serve as indicators that reflect the function and structure of marine ecosystems, as highlighted in previous studies (Boucher et al, 2006). For instance, the community structure and dynamics of bacteria belonging to Proteobacteria, Firmicutes, and Actinobacteriota phyla appeared to be affected by various factors such as salinity, dissolved oxygen, ammonia, phosphate and silicate concentrations (Guo et al, 2022b). Although variations in microbial community can be substantial across different habitat types, primarily due to the impact of environmental gradients (Martiny et al, 2006), some studies suggested consistency in community composition across similar habitats, regardless of geographical distance (Lauber et al, 2009).…”

Reviews and syntheses: Biological Indicators of Oxygen Stress in Water Breathing Animals

“…Disease/Parasites: Under low oxygen conditions, some parasitic and microbial infections can become more common or severe, affecting both individuals and populations. Certain types of pathogenic bacteria start to grow under low-oxygen conditions, increasing organisms' likelihood of exposure (Guo et al, 2022). In addition, low-oxygen effects on host immune responses are common.…”

Characterization of Opportunistic Pathogenic Multi-Drug Resistant Bacteria Isolated from Marine Coastal Water in Jazan, Saudi Arabia

“…The growth of pathogenic bacteria in marine water is influenced by various aspects, including temperature, pH value, dissolved oxygen, and salinity. Moreover, higher concentrations of nutrients in association with suspended matter have been recorded to boost the persistence of pathogenic bacteria in coastal marine water [10,11]. The excessive use of antibiotics has led to the reduction of susceptible pathogenic bacteria and the increment of resistant populations against multiple antibiotics.…”