A five-day cruise using the research vessel Connecticut (RV CT) and the Kraken2 (K2) ROV was conducted from May 19-23rd, shortly after the RV CT/SEABOSS cruise. The mission visited 12 of the sample blocks and sites that were identified as being inadequately sampled by the SEABOSS system. This determination was based primarily upon the nature of the substrate being too hard and topographically complex to sample with the SEABOSS. The drift-mode sampling approach of the SEABOSS did not allow extended imaging of the rougher boulder/ledge habitats. The K2 ROV, conversely, is ideally suited to stopping and imaging the vertical surfaces of boulder habitats with great detail with its powerful zoom cameras (both hi-definition video and high resolution digital still). In addition a survey of a previously unidentified wreck site discovered by the SEABOSS was attempted. However, low visibility and high currents precluded adequate documentation of this site. The K2 collected over 30 hours of hi-definition digital video (~2 terabytes) and 412 down-looking and 2050 forward-looking digital still images that will be analyzed over the next year to assess the sites’ community structure and biodiversity.

Map depicting the locations of the Kraken2 ROV Spring 2018 dive sites. The red boundary illustrates the extent of the Phase II area.

The K2 ROV cruise revealed some of the most complex terrain observed in the Sound to date.  To see an example video, click on this link: https://youtu.be/XKVNCYrSJwo

 

The Long Island Sound Cable Fund Habitat Mapping initiative has entered Phase II that is focused on the eastern Long Island Sound area. The LISMaRC was planning field operations in this area for sediment, ecological and physical oceanography characterization in the August-September timeframe. However, delays in the delivery of the RV Connecticut from the shipyard pushed the schedule back into late fall. The available ship time allowed for the conduct of at-sea operations from November 28^th – December 3^rd.   This timeframe allowed for sampling of approximately one-third of the Phase II area and the remainder of the sampling will be conducted in May, 2018. The Fall 2017 cruise was conducted by scientists from the Universities of Connecticut and New Haven and the US Geological Survey’s Woods Hole Marine and Coastal Science Center.

This was the first cruise on the newly stretched (from 76’ to 90’) RV Connecticut that provided more laboratory and berthing space to better accommodate research activities and additional scientists and students. The cruise utilized the US Geological Survey’s SEABOSS (Seafloor Benthic Observation and Sampling System) to both collect sediment samples and image the seafloor using video and still imagery.

The squares represent sample blocks, wherein three individual sediment samples were collected and one photo/video transect of up to 500 meters was conducted. The circles represent sample sites where a single sediment grab was collected and a transect conducted. The sampling areas were chosen based upon the detailed backscatter maps generated by earlier multibeam sonar surveys by the National Oceanic and Atmospheric Administration’s Office of Coast Survey. The backscatter is a measure of the strength of the return of an acoustic pulse generated by the sonar system, which in turn provides a proxy indicator of the nature of the seafloor, with hard bottoms returning a lot of the sound and represented by lighter shades and soft bottoms absorbing more of the sound appearing darker.

The cruise involved SEABOSS operations during the daylight 12-hour period with physical oceanographic sampling comprised of acoustic Doppler current profiler (ADCP) and conductivity, temperature and depth (CTD) sampling across depth gradients in some of the shallow areas of the Phase II area. The figure below illustrates several of the areas sampled to characterize the physical oceanographic conditions, with the ship’s tracks (red) illustrating the repeated ADCP surveys over the 12 hour evening watch and the circles indicating the locations where repeated CTD profiles were collected to provide detailed data on the temperature and salinity at these locations. This survey protocol will provide important data on the physical strength of the currents and four-dimensional structure of the water column in these poorly sampled shallow areas of the Sound.