| dc.description.abstract |
Similar to natural rivers, manmade inlets connect inland runoff to the ocean. Port
Everglades Inlet (PEI) is a busy cargo and cruise ship port in South Florida, which
can act as a source of pollution to surrounding beaches and offshore coral reefs.
Understanding the composition and fluctuations of bacterioplankton communities ("microbiomes")
in major port inlets is important due to potential impacts on surrounding environments.
We hypothesize seasonal microbial fluctuations, which were profiled by high throughput
16S rRNA amplicon sequencing and analysis.Surface water samples were collected every
week for one year. A total of four samples per month, two from each sampling location,
were used for statistical analysis creating a high sampling frequency and finer sampling
scale than previous inlet microbiome studies. We observed significant differences
in community alpha diversity between months and seasons. Analysis of composition of
microbiomes (ANCOM) tests were run in QIIME 2 at genus level taxonomic classification
to determine which genera were differentially abundant between seasons and months.
Beta diversity results yielded significant differences in PEI community composition
in regard to month, season, water temperature, and salinity. Analysis of potentially
pathogenic genera showed presence of Staphylococcus and Streptococcus. However, statistical
analysis indicated that these organisms were not present in significantly high abundances
throughout the year or between seasons.Significant differences in alpha diversity
were observed when comparing microbial communities with respect to time. This observation
stems from the high community evenness and low community richness in August. This
indicates that only a few organisms dominated the community during this month. August
had lower than average rainfall levels for a wet season, which may have contributed
to less runoff, and fewer bacterial groups introduced into the port surface waters.
Bacterioplankton beta diversity differed significantly by month, season, water temperature,
and salinity. The 2013-2014 dry season (October-April), was warmer and wetter than
historical averages. This may have driven significant differences in beta diversity.
Increased nitrogen and phosphorous concentrations were observed in these dry season
months, possibly creating favorable bacterial growth conditions. Potentially pathogenic
genera were present in the PEI. However their relatively low, non-significant abundance
levels highlight their relatively low risk for public health concerns. This study
represents the first to sample a large port at this sampling scale and sequencing
depth. These data can help establish the inlet microbial community baseline and supplement
the vital monitoring of local marine and recreational environments, all the more poignant
in context of local reef disease outbreaks and worldwide coral reef collapse in wake
of a harsh 2014-16 El Niño event.
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