Friday, November 23, 2007:
Critters and SCINI
For those of you waiting for news on the latest progress with SCINI, you'll have to be patient because this update will discuss the other major component of the project. Dr’ Kim’s past research in Antarctica has focused on benthic community changes (critters living in and on the seafloor) resulting from human activities in the Antarctic. Detecting benthic community change requires years of patient and focused sampling so long term data sets can be compiled and analyzed. Read on for a taste of what the marine biologists do when sampling for community change in the Antarctic.
(continued...)
This project is sampling the sea floor around McMurdo Station where human impacts are expected and reference locations far from McMurdo where human impacts are expected to be minimal. So what kind of impacts are we talking about? Any time people occupy a location for an extended period of time, wastes are generated. This includes things like trash, used fuel and lubricants, human wastes and a wide variety of construction materials. McMurdo’s long history of activity dates back to 1901, and over the years and phases of development at the station, waste disposal policies were not always as environmentally responsible as they are today. This was primarily due to the extreme logistical difficulty and cost of transporting waste back out of Antarctica. Ocean disposal was common in the past and today we still find extensive evidence of waste products on the ocean bottom. Because the environment is so cold here, waste products degrade very slowly, forcing biological communities to contend with these conditions for many years. Some species are tolerant and can adapt to contaminated conditions while others are very sensitive and unable to adapt. This often leads to an increase of the tolerant species and a decline in the sensitive species. Increases and decreases of even a few species can lead to major changes in the entire community due to the interdependency of species in this harsh environment. Detecting changes in community structure and tracking those changes over time allows us to assess the magnitude of the human impacts around McMurdo and the rate at which communities are recovering now that effective waste management has been implemented. Dr. Kim and her colleagues began monitoring benthic communities around McMurdo in 1988 so those data sets are now invaluable when assessing human impacts and long term change around McMurdo. The current project will add three years of benthic community assessment to the existing data and will serve to further expand our understanding of long term change in Polar regions.
Benthic community sampling under the ice is extremely difficult because of the effort and cost of drilling multiple holes through the ice. Small ROVs like SCINI can’t perform all the needed sampling and large ROVs with manipulator arms capable of collecting all the samples are typically too large to fit through ice holes. That means divers are still the most effective sediment sampling tool in this environment. It leads to some pretty cold fingers, toes and lips but each trip under the ice amazes us in some new way. Getting to see and study these communities is a marine biologist’s dream so I for one hope that we are never able to completely automate sampling with ROVs.
We collect three types of samples at each study location: infaunal cores, digital photographs and video transects.
Six infaunal cores about the size of a coffee can are pressed into the sediment and then capped (not easy with big gloves on) so they can be transported to the surface.
In the lab, sieving the sediment through a fine screen separates the critters from the sediment and allows for easier preservation and handling.
A microscope is then used to do the taxonomic identification and counting of the various species in the sample. Infaunal core sampling is used primarily for identifying small species such as polychaete worms, crustaceans and bryozoans that can be found living in or on the sediment in relatively high numbers.
Next, ten underwater digital photos are taken at each location in such a way that the image captures 1 square meter of seafloor. These images are then analyzed to do area counts of larger species like nemertean worms, urchins and anemones that the cores don’t effectively capture.
A final sampling effort involves taking underwater digital video along three ten meter long by one meter wide transects of sea floor. These video images are then analyzed to identify and count larger and more mobile species such as sponges, pycnogonids (sea spiders), large isopods and nudibranchs along the transect.
Each of these sampling efforts yields a list of species and their average abundances within the sample area. By combining the species counts from each of the three sampling techniques we can develop a basic community structure for the location we are interested in. In short we simply are trying to determine what animals live at a location and the relative density of those animals. Tracking that information over multiple years at many locations helps us understand whether the communities are changing and whether the communities are healthy or impacted. That in turn allows us to associate human activities with community changes so that we can better mange the unique resources in Antarctica.
So what ties SCINI and benthic community assessments together in this project? Divers in the Antarctic are restricted to shallow water (<130 feet) by physiological limitations and U.S. policy. We also need a three to four foot hole to dive through. That combination prohibits the exploration of vast areas of the sea floor deeper than 130 feet. SCINI however requires a small ice hole so it can be deployed with much less effort and costs and eventually should be able to reach depths of several thousand feet. Its high resolution video allows us to observe and quantify at least a portion of the community at much greater depths than previously possible and its navigation capabilities allow us to build more accurate maps of each sampling location. This gives us complimentary sampling techniques that actually broaden the information we can collect and expands the depth range over which we can sample. It’s a great combination of old and new technologies that will give us better insights to marine life under the ice.
(continued...)
This project is sampling the sea floor around McMurdo Station where human impacts are expected and reference locations far from McMurdo where human impacts are expected to be minimal. So what kind of impacts are we talking about? Any time people occupy a location for an extended period of time, wastes are generated. This includes things like trash, used fuel and lubricants, human wastes and a wide variety of construction materials. McMurdo’s long history of activity dates back to 1901, and over the years and phases of development at the station, waste disposal policies were not always as environmentally responsible as they are today. This was primarily due to the extreme logistical difficulty and cost of transporting waste back out of Antarctica. Ocean disposal was common in the past and today we still find extensive evidence of waste products on the ocean bottom. Because the environment is so cold here, waste products degrade very slowly, forcing biological communities to contend with these conditions for many years. Some species are tolerant and can adapt to contaminated conditions while others are very sensitive and unable to adapt. This often leads to an increase of the tolerant species and a decline in the sensitive species. Increases and decreases of even a few species can lead to major changes in the entire community due to the interdependency of species in this harsh environment. Detecting changes in community structure and tracking those changes over time allows us to assess the magnitude of the human impacts around McMurdo and the rate at which communities are recovering now that effective waste management has been implemented. Dr. Kim and her colleagues began monitoring benthic communities around McMurdo in 1988 so those data sets are now invaluable when assessing human impacts and long term change around McMurdo. The current project will add three years of benthic community assessment to the existing data and will serve to further expand our understanding of long term change in Polar regions.
Benthic community sampling under the ice is extremely difficult because of the effort and cost of drilling multiple holes through the ice. Small ROVs like SCINI can’t perform all the needed sampling and large ROVs with manipulator arms capable of collecting all the samples are typically too large to fit through ice holes. That means divers are still the most effective sediment sampling tool in this environment. It leads to some pretty cold fingers, toes and lips but each trip under the ice amazes us in some new way. Getting to see and study these communities is a marine biologist’s dream so I for one hope that we are never able to completely automate sampling with ROVs.
We collect three types of samples at each study location: infaunal cores, digital photographs and video transects.
Six infaunal cores about the size of a coffee can are pressed into the sediment and then capped (not easy with big gloves on) so they can be transported to the surface.
In the lab, sieving the sediment through a fine screen separates the critters from the sediment and allows for easier preservation and handling.
A microscope is then used to do the taxonomic identification and counting of the various species in the sample. Infaunal core sampling is used primarily for identifying small species such as polychaete worms, crustaceans and bryozoans that can be found living in or on the sediment in relatively high numbers.
Next, ten underwater digital photos are taken at each location in such a way that the image captures 1 square meter of seafloor. These images are then analyzed to do area counts of larger species like nemertean worms, urchins and anemones that the cores don’t effectively capture.
A final sampling effort involves taking underwater digital video along three ten meter long by one meter wide transects of sea floor. These video images are then analyzed to identify and count larger and more mobile species such as sponges, pycnogonids (sea spiders), large isopods and nudibranchs along the transect.
Each of these sampling efforts yields a list of species and their average abundances within the sample area. By combining the species counts from each of the three sampling techniques we can develop a basic community structure for the location we are interested in. In short we simply are trying to determine what animals live at a location and the relative density of those animals. Tracking that information over multiple years at many locations helps us understand whether the communities are changing and whether the communities are healthy or impacted. That in turn allows us to associate human activities with community changes so that we can better mange the unique resources in Antarctica.
So what ties SCINI and benthic community assessments together in this project? Divers in the Antarctic are restricted to shallow water (<130 feet) by physiological limitations and U.S. policy. We also need a three to four foot hole to dive through. That combination prohibits the exploration of vast areas of the sea floor deeper than 130 feet. SCINI however requires a small ice hole so it can be deployed with much less effort and costs and eventually should be able to reach depths of several thousand feet. Its high resolution video allows us to observe and quantify at least a portion of the community at much greater depths than previously possible and its navigation capabilities allow us to build more accurate maps of each sampling location. This gives us complimentary sampling techniques that actually broaden the information we can collect and expands the depth range over which we can sample. It’s a great combination of old and new technologies that will give us better insights to marine life under the ice.
Comments:
Are you sampling for diatoms (had to ask!)? I know Sarah Spaulding did a survey of freshwater diatoms in the dry valley areas, but are there marine diatoms, and are you looking at them?
Hi Vera - we are not sampling for diatoms in this project but there are marine diatoms here. Some folks have taken a look at the sediment and ice diatom communities. Interestingly there is a very diverse microbial community that lives on the surface of the frazile ice (the crystals forming under the thick surface ice). It is poorly studied so now you have a new research project to pursue!
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