Joseph D. Germano

Towards a greater understanding of pattern, scale and process in marine benthic systems: a picture is worth a thousand worms

Historically, advances in our knowledge of benthic community structure and functioning have necessarily relied upon destructive sampling devices (grabs, cores, anchor dredges, etc.) that lose valuable contextual information in the process of sampling. In the last 40 years, instrumentation capable of measuring dynamic events and/or processes within and immediately above the seafloor has been developed that facilitates the collection of ecological information. Of these, both acoustic and optical imaging devices have played a significant role in revealing much about the physiology and behaviour of, and interactions between benthic species, and the sedimentary habitat in which they reside. While a number of reviews have separately considered the methodological and technical aspects of imaging technologies, the collective contribution that imaging has made to benthic ecology has received less attention. In this short review, we attempt to highlight key instances over the last 40 years where either acoustic or optical-based imaging techniques have provided new ecological insights and information about fine-grained sedimentary environments. In so doing, we focus on the ecological advances that have formed the precursor to current research efforts and introduce some of the latest revelations from appropriate and emerging imaging applications.

Plan-view photos, benthic grabs, and sediment-profile images: using complementary techniques to assess response to seafloor disturbance.

A monitoring survey was conducted in July 2005 at the Rhode Island Sound Disposal Site (RISDS) as part of the Disposal Area Monitoring System (DAMOS) program. The survey included the collection of sediment-profile and plan-view images, and benthic biology grabs. Each of these techniques provides a different, yet complementary perspective on benthic community conditions. These complementary techniques aided in the assessment of the benthic recovery process within RISDS following the placement of dredged material from the Providence River and Harbor Maintenance Dredging Project (PRHMDP). Based on observed patterns of physical, chemical, and biological responses of seafloor environments to dredged material disposal activity it was expected that the benthic community within RISDS would be in an intermediate phase of recolonization (Stage II). Results of the 2005 RISDS survey indicated that in the six months since disposal activities at RISDS had concluded, the biological community at RISDS was recovering relatively rapidly and Stages II and III infauna were present throughout the region.

Sediment Profile Imaging: An Efficient Method of Remote Ecological Monitoring of the Seafloor (REMOTS TM SYSTEM)

The Rhoads-Cande profile photographic camera and its updated version, the video REMOTS (Remote Ecological Monitoring of the Seafloor) system, are described for in situ remote monitoring of the seafloor. These systems allow one to identify temporal and spatial changes in both the benthic fauna and physical-chemical aspects of the sedimentary environment. Image interpretation is based on a model which allows one to deduce the stage of infaunal succession from observed organism-sediment relations. The REMOTS system was developed because existing methods of obtaining ecological information are labor intensive, expensive, and data return is slow. The REMOTS system may be used for efficient monitoring of dredge-spoil activities and as a reconnaissance mapping tool for detecting change in benthic habitats in the region of outer continental shelf drilling fields.