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Material properties of euphausiids and other zooplankton from the Bering Sea
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Image of FIG. 1.
FIG. 1.

Cruise trackline (solid line) of the NOAA Ship Oscar Dyson from 20 June to 9 July 2008. Methot trawl locations are identified (filled circles) and numbered. Bathymetry contours (dotted lines) are shown for 50, 100, 200, and 2000 m.

Image of FIG. 2.
FIG. 2.

Representative photographs of taxa collected and measured for their material properties. Top row (from left to right): euphausiid, copepod, amphipod, and chaetognath. Bottom row (from left to right): fish larvae, gastropod, jellyfish, and squid.

Image of FIG. 3.
FIG. 3.

Species composition of euphausiids caught in Methot trawls that were measured for their physical (length) or material properties.

Image of FIG. 4.
FIG. 4.

Length-frequency distributions for all euphausiids (upper left), T. inermis (upper right), T. raschii (lower left), and T. spinifera (lower right).

Image of FIG. 5.
FIG. 5.

Density contrast of each zooplankton taxon. The lower line of the box represents the quartile, the thick black line is the median, and the upper line of the box is the quartile while the whiskers are the maximum and minimum values. Circles represent outliers. The zooplankton taxa are all fluid like and subsequently have lower values of . Euphausiids have the largest range in values while jellyfish (data from two species combined) have the smallest range in values.

Image of FIG. 6.
FIG. 6.

Pairwise scatter plots of and animal density as a function of location for all euphausiids.

Image of FIG. 7.
FIG. 7.

Pairwise scatter plots for ambient salinity, water density, temperature, and animal length against g. Location, salinity, and water density are components of PCI and location, temperature and animal length are components of PC2. Although the relationship is weak, as PCI increases so does . On the contrary, as PC2 increases, decreases.

Image of FIG. 8.
FIG. 8.

Density contrast for T. inermis and T. raschii for each MT. Overall values are lower for the East region (MT01, 02, 03, 04) compared to the West (MT05, 06, 07, 08, 09).

Image of FIG. 9.
FIG. 9.

Density contrast as a function of animal length for all euphausiids , T. inermis , T. raschii , and T. spinifera . There is a large range in values for all animal lengths. A linear regression showed that there is little correlation between the two variables for all euphausiids and each species. All species: ; ; T. inermis: ; ; T. raschii: ; , and T. spinifera: ; .

Image of FIG. 10.
FIG. 10.

Density contrast distributions for different euphausiid species between the East (MT01, MT02, MT03, MT04) and West (MT05, MT06, MT07, MT08, MT09) locations. Density contrast was significantly different between the western and eastern sample sites for euphausiids .

Image of FIG. 11.
FIG. 11.

Chlorophyll-a integrated over the water column varied with Methot trawl location. Sites in the western region (MTs 5 and higher) had lower levels of chl-a than eastern sites (MTs 4 and lower).

Image of FIG. 12.
FIG. 12.

Amphipod density contrast was weakly correlated with animal length. Amphipods from Methot trawl 05 were split between small and large animals, whereas animals from Methot trawl 08 were almost all large animals. The large animals showed a greater range in values. Density contrast was significantly different between the small and large amphipods (t-test, ). Results from a linear regression showed that and .


Generic image for table

Mean and standard deviation (sd) of material properties, physical features, and environmental variables for euphausiids at each MT. Density contrast values are presented for all euphausiid species combined as well as for each individual species. The sd for all water density measurements was negligible . The average volume fraction of the chamber used for the measurements is also reported for each MT.

Generic image for table

Average water column properties for MT stations, based on nearby CTD casts. No data were available for MT03 and MT06.

Generic image for table

Range, mean, and standard deviation (sd) of animal length, density contrast , and sound speed contrast for different zooplankton taxa; regardless of location. The number of animals measured (n) for from each taxon is also presented along with the number of animal groups (nn) for which was measured. The volume fraction of animals relative to the chamber used for the measurements is averaged for each zooplankton taxon. Data presented for Chrysaora melanaster is from pieces of their bell, not the whole animal.


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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Material properties of euphausiids and other zooplankton from the Bering Sea