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Accurate methods to track changes in lake productivity through time and space are critical to fisheries management. Chlorophyll a is the most widely studied proxy for ecosystem primary production and has been the topic of many studies. The main sources of chlorophyll a measurements are ship-based measures or multi-spectral satellite data. Autonomous underwater vehicles can survey large spatial extents approaching the scale of satellite data, but with the accuracy of ship-based water sampling methods. We use several statistical measures to compare measures of chlorophyll a collected in Lake Michigan with spatiotemporally matched satellite-derived measures of chlorophyll a from the MODIS Aqua multi-spectral sensor using NASA's OC3 and the Great Lakes Fit algorithms. Our findings show a near one to one relationship between AUV data and both satellite-derived data sets when the AUV data are coarsened to the resolution of the satellite data. A comparison of satellite-based chlorophyll a to AUV-derived chlorophyll summarized in discrete water depth bins suggested that, based on decreasing coefficients of determination, satellite estimates of chlorophyll accounted for the most variability in chlorophyll a concentrations in the upper 10 m of the water column, even though satellite sensors may detect past this depth.

The recent proliferation of icebergs in the Southern Ocean and the chemical and biological enrichment recently identified in the surrounding water raise the question of whether these icebergs are major contributors to drawdown of CO2 and the export of organic carbon to the deep ocean. The Lagrangian sediment trap (LST) was developed to measure the carbon export associated with these free-drifting icebergs. The core of the LST is a neutrally buoyant Sounding Oceanographic Lagrangian Observer (SOLO) float ( Davis et al., 2001 ) that contains a variable-buoyancy engine, enabling it to sink to a set depth (600 m for the iceberg study), drift at that depth, then resurface on preset time intervals. Four sediment-trap funnels and opening/closing sample cups mounted around each SOLO float collect sinking particulate matter. Additionally, an upward-looking acoustic system mounted on the float detects the presence of ice cover above. In March/April 2009, three LSTs were deployed in the NW Weddell Sea for a total of five successful missions. Four of these LST deployments were made near or under a large iceberg. The fifth deployment was made at a control site 74 km from the nearest large iceberg. Sinking particulate matter was collected on each deployment. Despite the high-risk nature of the deployments, the LSTs successfully sampled particulate matter beneath drifting icebergs.

Ship-based observations of free-drifting icebergs are hindered by the dangers of calving ice. To improve the efficacy and safety of these studies, new unmanned aerial vehicles (UAVs) were developed and then deployed in the Southern Ocean. These inexpensive UAVs were launched and recovered from a ship by scientific personal with a few weeks of flight training. The UAVs sent real-time video back to the ship, allowing researchers to observe conditions in regions of the icebergs not visible from the ship. In addition, the UAVs dropped newly developed global positioning system (GPS) tracking tags, permitting researchers to record the precise position of the icebergs over time. The position reports received from the tags show that the motion of free-drifting icebergs changes rapidly and is a complex combination of both translation and rotation.

A commercially available, small (less than 100-kg), remotely operated vehicle (ROV) was modified to image and sample the marine ecosystem surrounding free-drifting icebergs east of the Antarctic Peninsula during three field expeditions in 2005, 2008 and 2009. Modifications included fitting the vehicle with an accessory tool sled, additional thrusters, flotation and significant changes to internal wiring to support a wide array of sensors and samplers. The ROV was re-configured aboard the R/V Nathaniel B. Palmer to perform either general exploration and biological sampling (Bio dives) or water sampling (Chemistry dives). In-situ sensors and a suction sampler were used for Bio dives while a suction pump and hose were fastened along the full length of the ROV tether to enable continuous water sampling adjacent to each iceberg during Chemistry-dives. Details of the ROV system are presented along with a discussion of the 18 dives that explored the sides and bottoms of six different icebergs during the 2009 field expedition.