Bermuda Atlantic Time-Series Study (BATS) Site:

Created by George Rice, Montana State University

Map of study site and research ship
The study site for the Oceanic Microbial Observatory is the Bermuda Atlantic Time-series Study (BATS) site. The BATS site is located in the northwestern Sargasso Sea approximately 80 km southeast of the island of Bermuda (left). Rendezvous with between the RV. Weatherbird II and the R.V. Oceanus at Hydrostation S in the Northwestern Sargasso Sea in June of 2005 (right). This rendezvous was designed to pass essential equipment to the operations of the R.V. Oceanus on their 23 day cruise in the Sargasso. Picture provided by C. Carlson (Oceanic Microbial Observatory)

The BATS site is characterized as being seasonally oligotrophic, and significantly influenced by regular annual patterns of temperature variability and mixing of the water column.

Graphs of nutrient mixing and temperature variability

  • The BATS time-series graph (above left) shows a regular pattern of mixing with variable layer depths (white line) extending as deep as 200 - 300 m. The graph demonstrates a significant inter-annual variability; these events resulting in periodical deep convective overturn have been shown to be extremely important to the community structure and overall biogeochemistry of the BATS site.

  • Convective overturn provides a mechanism for nutrients to be entrained into the surface waters (above right). This nutrient entrainment into the euphotic zone sets the stage for phytoplankton blooms, which occur annually in the spring, followed by a summer lull.

  • The regular annual pattern of mixing at BATS also generates a regular annual pattern of DOC production, accumulation and export out of the euphotic zone. The interaction between DOC and microbial processes, as well as the role that microbial community structure has on DOC remineralization patterns, is one of the major research focuses of the Microbial Observatory.

Monthly samplings from 0 and 200m at the BATS study site over a period of several years is starting to provide especially strong evidence for the stratification of specific bacterial groups during distinct portions of the year. In addition, infrequent deep mixing events during the stormy winter seasons provide opportunities for the temporary increase of other less-dominant bacterial groups. Observation of these patterns is followed by the generation and testing of hypotheses to explain the links between cyclic environmental conditions and adaptations in and among significant bacterial groups allowing them to exploit these changes.

Copyright on all images and material by Craig Carlson and Stephen Giovannoni 2005.