Monthly Archives: August 2016

Smith lab and colleagues present an autonomous approach to measure coral reef net calcification and production rates

Assessment of net community production and calcification of a coral reef using a boundary layer approach

Abstract: Coral reefs are threatened worldwide, and there is a need to develop new approaches to monitor reef health under natural conditions. Because simultaneous measurements of net community production (NCP) and net community calcification (NCC) are used as important indicators of reef health, tools are needed to assess them in situ. Here, we present the Benthic Ecosystem and Acidification Measurement System (BEAMS), to provide the first fully autonomous approach capable of sustained, simultaneous measurements of reef NCP and NCC under undisturbed, natural conditions on timescales ranging from tens of minutes to weeks. BEAMS combines the chemical and velocity gradient in the benthic boundary layer to quantify flux from the benthos for a variety of parameters to measure NCP and NCC. Here, BEAMS was used to measure these rates from two different sites with different benthic communities on the western reef terrace at Palmyra Atoll for two weeks in September, 2014. Measurements were made every ∼15 minutes. The trends in metabolic rates were consistent with the benthic communities between the two sites with one dominated by fleshy organisms and the other dominated by calcifiers (degraded and healthy reefs, respectively). This demonstrates the potential utility of BEAMS as a reef health monitoring tool. NCP and NCC were tightly coupled on timescales of minutes to days, and light was the primary driver for the variability of daily integrated metabolic rates. No correlation between CO2 levels and daily integrated NCC was observed, indicating that NCC at these sites were not significantly affected by CO2.

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New publication from Smith lab & colleagues: Meet the Benthic Underwater Microscope (BUM)

Underwater microscopy for in situ studies of benthic ecosystems

Abstract: Microscopic-scale processes significantly influence benthic marine ecosystems such as coral reefs and kelp forests. Due to the ocean’s complex and dynamic nature, it is most informative to study these processes in the natural environment yet it is inherently difficult. Here we present a system capable of non-invasively imaging seafloor environments and organisms in situ at nearly micrometre resolution. We overcome the challenges of underwater microscopy through the use of a long working distance microscopic objective, an electrically tunable lens and focused reflectance illumination. The diver-deployed instrument permits studies of both spatial and temporal processes such as the algal colonization and overgrowth of bleaching corals, as well as coral polyp behaviour and interspecific competition. By enabling in situ observations at previously unattainable scales, this instrument can provide important new insights into micro-scale processes in benthic ecosystems that shape observed patterns at much larger scales.

See more info & some great videos here!

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scripps oceanography uc san diego