Shrimp food

This paper review is complimentary to my previous blog post. The Marty et al. (2010) study updated the distribution of Hemimysis in the Great Lakes, described the physical characteristics of sampled Hemimysis communities using length-weight relationships, interpreted variations in stable isotopes (carbon and nitrogen) in relation to food web dynamics, and described the temporal dynamics of Hemimysis within a food web with respect to food sources and trophic position.

Fig. 3 Linear regressions predicting wet (top)
 and dry (bottom) weight (mg) based on
body length (mm). Black circles Lake
Ontario, clear circles Lake Erie, and
black triangles Lake Michigan.

 

Highlights:

They produced a great weight, length regression (Figure 3).

They found that Hemimysis can feed on multiple carbon sources including pelagic and littoral autochthonous and terrestrial carbon. The isotopic signatures ranged from -24.5‰ to -30.2‰ and 12.2 to 15.0‰ for carbon and nitrogen respectively for individuals sampled on a single date and location in Lake Erie.

The amount of variation in signatures suggest an extremely variable diet. This makes it hard to determine specific food web impacts of this new invasive.





I thought the nitrogen and carbon relationship (Figure 4) was great. This suggests that Hemimysis feed on littoral and pelagic algal sources and as an individual moves from pelagic to littoral sources, their trophic position decreases. This could increase connectivity between littoral and pelagic food webs when consumed by predators from higher trophic levels.



Fig. 4 δ¹⁵N vs. δ¹³C of individual
Hemimysis  from Lake Erie (‰) (top)
and residuals of the δ¹⁵N/δ¹³C
relationship vs. C:N ratios of
Hemimysis.



Final thought:

This was an extremely interesting study. The authors tackled a lot of essential questions surrounding the biology of Hemimysis anomala. It is a good start in piecing together possible impacts on the Great Lakes ecosystem.

Reference:
Marty, J., Bowen, K., Koops, M.A. (2010) Distribution and ecology of Hemimysis anomala, the latest invader of the Great Lakes basin. Hydrobiologia 647(1): 71-80.