Benthic Habitat Mapping
To learn more about the biological and physical resources in our shallow coastal waters, the seafloor mapping program is collecting fine-scale bathymetry and sonar data, information on sediment grain size, water column parameters, and marine invertebrate community samples. Together, these data create a detailed benthic habitat map that can provide a baseline for long-term monitoring or a “before” picture in case of major storm or pollution events.
What does BENTHIC mean?
Benthos comes from the Greek word for “depth of the sea” and refers to the community of animals and plants that live on, in or near the bottom of the sea. The word is now used for both marine and fresh water environments. Benthos encompasses all depths, from tide pools to the continental shelf down to abyssal depths.
What is CMECS?
To make our maps comparable on a national and international level, we use CMECS; the Coastal and Marine Ecological Classification Standard. CMECS is a framework used to organize information gathered about oceans and coasts using four components: the water column component (currents and tides, water temperature and various features of water chemistry), the substrate component (grain size and organic content of sediment), the geoform component (acoustic data), and the biotic component (flora and fauna).
Most animals we find in our grab samples are invertebrates. To learn more about these spineless creatures, check out our invertebrate gallery.
How are samples collected?
To collect benthic invertebrates, we use Van Veen grabs and Ponar grabs. The grab is lowered from the boat until it hits the seafloor. As the line is pulled in again the grab automatically closes and the sample is brought on board. From this sample we can get information on grain size and organic content of the sediment and, once we are back at the lab, look for benthic invertebrates living in and on the seafloor. While we collect sediment samples we also collect data on water chemistry (like pH, salinity, dissolved oxygen,…) with a mulitparameter water quality detector. We also attach cameras to our equipment to collect visual data of the seafloor and the area surrounding the sample site. All samples are taken back to the lab for analysis.
How are samples analyzed in the lab?
Our invertebrate samples get rinsed through a 1mm mesh sieve and then transfer to big glass jars. We add ethanol to the sample to keep the animals from decomposing. We also add Rose Bengal; a stain that attaches to anything that was alive at the time of collection and colors it pink.
Once a sample is properly stained, the next step is to “pick” through it. Our great volunteers carefully sift through each sample, scoop by scoop, and look for pink stained invertebrates which they collect in little vials. Staff scientists then count and identify each individual using a dissecting microscope. So far we have identified more than 239000 individuals belonging to more than 300 different species!