More notes about PK shrimp (Palaemonetes kadiakensis, also P.kadiakensis). There are 3 species of grass shrimp that superficially look like PK: P.pugio(41-100F), P.vulgaris & P.paludosus (41F-95F). Reported lethal temperature range for the species is in ( ). There is probably a good reason that these other 3 species have not expanded their distribution range into the North Central US and the reason could be due cold tolerence. I could not find the lower lethal temperature for PK. Close examination of specific body structures separate these 4 species.
Grass shrimp are reported to often retreat to the sediment zone or area during winter. Often this is probably due to lack of small leafy plant habitat during winter. This winter behavior could make them very vulnerable to panfish predation especially if the pond has an abundance of panfish. Water temperature of the sediment zone can be 40-41F depending on various pond conditions. My experience with PK shrimp is they will live in a winter aerated pond where the majority of the water column temperature can be 36F-39F. The less the pond is aerated during winter the closer the water column temperature will be to 39F. Mississippi Rv water temperature during Jan or Feb could be 33-34F for the first study below.
Advanced reading:
Upper Mississippi Study - Ohio Shrimp and PK shrimp.
http://www.umesc.usgs.gov/field_stations/fs5/staff/amn_shrimp.pdfP.pugio
http://www.amnh.org/learn-teach/young-na...aemonetes-pugio 
