Dataset Information

Seasonal and interannual variability of the marine bacterioplankton community throughout the water column over ten years.

ABSTRACT: Microbial activities that affect global oceanographic and atmospheric processes happen throughout the water column, yet the long-term ecological dynamics of microbes have been studied largely in the euphotic zone and adjacent seasonally mixed depths. We investigated temporal patterns in the community structure of free-living bacteria, by sampling approximately monthly from 5?m, the deep chlorophyll maximum (?15-40?m), 150, 500 and 890?m, in San Pedro Channel (maximum depth 900?m, hypoxic below ?500?m), off the coast of Southern California. Community structure and biodiversity (inverse Simpson index) showed seasonal patterns near the surface and bottom of the water column, but not at intermediate depths. Inverse Simpson's index was highest in the winter in surface waters and in the spring at 890?m, and varied interannually at all depths. Biodiversity appeared to be driven partially by exchange of microbes between depths and was highest when communities were changing slowly over time. Meanwhile, communities from the surface through 500?m varied interannually. After accounting for seasonality, several environmental parameters co-varied with community structure at the surface and 890?m, but not at the intermediate depths. Abundant and seasonally variable groups included, at 890?m, Nitrospina, Flavobacteria and Marine Group A. Seasonality at 890?m is likely driven by variability in sinking particles, which originate in surface waters, pass transiently through the middle water column and accumulate on the seafloor where they alter the chemical environment. Seasonal subeuphotic groups are likely those whose ecology is strongly influenced by these particles. This surface-to-bottom, decade-long, study identifies seasonality and interannual variability not only of overall community structure, but also of numerous taxonomic groups and near-species level operational taxonomic units.

SUBMITTER: Cram JA

PROVIDER: S-EPMC4331575 | biostudies-literature | 2015 Mar

REPOSITORIES: biostudies-literature

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Seasonal and interannual variability of the marine bacterioplankton community throughout the water column over ten years.

Cram Jacob A JA Chow Cheryl-Emiliane T CE Sachdeva Rohan R Needham David M DM Parada Alma E AE Steele Joshua A JA Fuhrman Jed A JA

The ISME journal 20140909 3

Microbial activities that affect global oceanographic and atmospheric processes happen throughout the water column, yet the long-term ecological dynamics of microbes have been studied largely in the euphotic zone and adjacent seasonally mixed depths. We investigated temporal patterns in the community structure of free-living bacteria, by sampling approximately monthly from 5 m, the deep chlorophyll maximum (∼15-40 m), 150, 500 and 890 m, in San Pedro Channel (maximum depth 900 m, hypoxic below ∼ ...[more]

PMID: 25203836

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Project description:Understanding temporal patterns of marine mammal occurrence is useful for establishing conservation strategies. We used a 38 yr-long dataset spanning 1976 to 2013 to describe temporal patterns and trends in marine mammal strandings along a subtropical stretch of the east coast of South America. This region is influenced by a transitional zone between tropical and temperate waters and is considered an important fishing ground off Brazil. Generalized Additive Models were used to evaluate the temporal stranding patterns of the most frequently stranded species. Forty species were documented in 12,540 stranding events. Franciscana (n = 4,574), South American fur seal, (n = 3,419), South American sea lion (n = 2,049), bottlenose dolphins (n = 293) and subantarctic fur seal (n = 219) were the most frequently stranded marine mammals. The seasonality of strandings of franciscana and bottlenose dolphin coincided with periods of higher fishing effort and strandings of South American and subantarctic fur seals with post-reproductive dispersal. For South American sea lion the seasonality of strandings is associated with both fishing effort and post-reproductive dispersal. Some clear seasonal patterns were associated with occurrence of cold- (e.g. subantarctic fur seal) and warm-water (e.g. rough-toothed dolphin) species in winter and summer, respectively. Inter-annual increases in stranding rate were observed for franciscana and South American fur seal and these are likely related to increased fishing effort and population growth, respectively. For subantarctic fur seal the stranding rate showed a slight decline while for bottlenose dolphin it remained steady. No significant year to year variation in stranding rate was observed for South American sea lion. The slight decrease in frequency of temperate/polar marine mammals and the increased occurrence of subtropical/tropical species since the late 1990s might be associated with environmental changes linked to climate change. This long-term study indicates that temporal stranding patterns of marine mammals might be explained by either fishing-related or environmental factors.

Dataset Information

Seasonal and interannual variability of the marine bacterioplankton community throughout the water column over ten years.

Publications

Seasonal and interannual variability of the marine bacterioplankton community throughout the water column over ten years.

Similar Datasets

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