A recent publication in Marine Ecology Progress (Marine Ecology Progress, 2013 V.480, pp 39-56) sheds more light on the complex process of diel zooplankton migration. A recent graduate of the UVic’s School of Earth and Ocean Sciences, Dr. Mei Sato has completed extensive analysis of the zooplankton diel vertical migration patterns using chlorophyll and echo-sounder data collected by DFO and VENUS, respectively, in Saanich Inlet. Her research was focused on understanding the second order drivers of the diel migration timing. The first order signal is the seasonal variation due to changes in the length of day-light hours (Image: the hour-glass shape of the slice), while the second order terms look into environmental factors that impact behavior of the species that are integral part of the food web.
Dr. Mei Sato’s analysis shows that there are subtle variations to the time of ascent and decent during the year, which might be attributed to both food supply and zooplankton life-cycle (body size). Other factors include variations in the presence of predators and prey competition. Some factors, such as lunar cycles and the possible influence of full moons were statistically ruled out.
Mei successfully defended her Ph.D. thesis in early May 2013.
Reference: Sato M., Dower J., Dewey, R. 2013. Second-order seasonal variability in diel vertical migration timing of euphausiids in a coastal inlet. Marine Ecology Progress Series 480: 39-56, DOI:10.3354/meps10215.
UBC oceanographer Dr. Mark Halverson has been making use of VENUS Coastal Ocean Dynamics Applications Radar (“CODAR”) data from the Strait of Georgia in his research. His analysis revealed an abrupt cutoff in data availability to the south of the coverage area, rather than the gradual fall-off with distance from the two antennae one would expect from purely physical considerations.
Subsequent investigation revealed an overly-restrictive software setting that has since been modified. All ocean-current data going back to the commissioning of the VENUS CODAR array in August 2012 has been reprocessed, extending the coverage of the array southward by about 3 km.
This animated figure shows the coverage area before and after the reprocessing. Thanks go to Dr. Halverson for pointing out this anomaly, allowing us to improve our product. Our users are not mere customers, but active collaborators in the VENUS mission to provide data to the oceanographic community.
Learn more about the VENUS CODAR array at our About the Data page and view the latest CODAR ocean-current data on the VENUS website.
Image 1: Power spectral densities over the range 10–1600 Hz using 5-min averages. (a) Complete dataset: 14 December 2011 to 30 April 2012. (b) Exceptional ship signature: 23–24 February 2012. Note the difference in dynamic range between (a) and (b).
There is currently a lack of consensus over how to average local shipping noise levels to assess the impact of such noise on marine life. Using data collected between Dec. 2011 and Apr. 2012 from an Ocean Sonics low frequency hydrophone that was deployed at the VENUS Strait of Georgia East site, this publication assesses various methods for averaging local shipping noise levels. The conclusion from this assessment is that mean sound pressure levels averaged in linear space are most relevant for determining the cumulative impact on marine life (Image-2).
Reference:
Merchant N.D., Blondel P., Dakin D.T., Dorocicz J. 2012. Averaging underwater noise levels for environmental assessment of shipping. The Journal of the Acoustical Society of America, 132(4), pp. EL343-EL349.
For a year, the VENUS camera photographed the same area of seafloor in Saanich Inlet. A recent paper has examined the response of the benthic animals to changing levels of oxygen. Only a few species cope with hypoxia but the high numbers suggest that food availability and refuge from oxygen-starved predators is a good strategy for some. The research predicts marked changes on the continental shelf with growing “dead zones”.
See:
Matabos M., Tunnicliffe V., Juniper S.K., Dean C. 2012. A year in hypoxia: epibenthic community responses to severe oxygen deficit at a subsea observatory in a coastal inlet. PLoS ONE 7(9): e45626. DOI:10.1371/journal.pone.0045626.
A group of researchers have successfully identified a new dinoflagellate species. Part of the large group of eukaryotes (approx. 1555 species), the new species has distinct morphological characteristics and was named Archaeperidinium saanichi sp.nov. after Saanich Inlet, the place where, using a VENUS sediment trap, Dr. Vera Pospelova and her MSc student – Andrea Price collected samples and conducted their research that led to a publication in Marine Micropaleontology (see reference below).
The image shows cyst (left) and motile (right) stages of the new species
Reference:
Mertens K.N., Yamaguchi A., Kawami H., Ribeiro S., Leander B.S., Price A.M., Pospelova V., Ellegaard M., Matsuoka K. 2012. Archaeperidinium saanichi sp. nov.: A new species based on morphological variation of cyst and theca within the Archaeperidinium minutum Jörgensen 1912 species complex. Marine Micropaleontology, Volumes 96–97, December 2012, pp. 48-62, ISSN 0377-8398, DOI:10.1016/j.marmicro.2012.08.002.
On May 28-29 international group of researchers gather at the Institute of Ocean Sciences to share knowledge and discuss research opportunities in Saanich Inlet as a model hypoxia ecosystem. To learn more about the symposium and see the scientific program, visit the 2012 Saanich Inlet Symposium.
On February 15 & 16, the Department of Fisheries and Oceans held the annual meeting to assess the State of the Ocean for 2011. We recently submitted our fourth contribution to this important and broad-reaching document. Included in this report are the three CTD time series from our three Node locations, Saanich Inlet, and Strait of Georgia Central and East, available from our State of the Ocean page. The Saanich Inlet time series is now over 6 years long, and reveals weekly, monthly, annual and inter-annual variations. Of key note for 2011 was the relatively mild spring and slightly cooler summer, which resulted in a prolonged melting of the large coastal snow pack and a prolonged Fraser River freshet, and the capturing of May and June dense water in-flows at the SoG Central site.
VENUS 2011 State of the Ocean Report (PDF)
VENUS State of the Ocean Reports from previous years
VENUS State of the Ocean page
Studying biorhythms in Saanich Inlet is an ongoing research project supported by the VENUS network. Following the initial deployment and analysis of results, published in Sensors (Aguzzi et al. 2011), the group of international collaborators is now using a seafloor camera (DISCo) that features a more developed control interface. The interface can automate the process of turning the lights on and taking imagery. The camera schedule is set to take 4 images every 30 min 24/7 which allows researchers to observe and assess changes in the environment as they occur.
Saanich Inlet is home to two species that are new to science: an anemone that lives at 100m depth remains to be described (Synhalcurias n.sp.) while the white sea squirt was described several years ago as Bathypera feminalba. The name means “White Lady” – reflecting the white colour and the location in Saanich Inlet where it was collected: White Lady Rocks.
For the past four years, the Paleoenvironmental Laboratory of Dr. Vera Pospelova (University of Victoria, SEOS) has been involved in continuous monitoring program of fossilizable phytoplankton in Saanich Inlet, British Columbia. Part of the phytoplankton sampling for the research program is done using a sediment trap deployed on the VENUS network. Controlled over the Internet, the sediment trap is an example of interactive instrument installed on the cabled ocean observatory that allows researchers changing instrument settings and monitor status of their experiment over the web.
In this image: Brightfield photomicrograph of diatoms Ditylum brightwelli and one toxic dinoflagellate Dinophysis acuminata collected from a VENUS Strait of Georgia research site. (Oct 2, 2011).
