Search Field Guide
Advanced Search
Montana Field Guide

Montana Field Guides

Spiny Waterflea - Bythotrephes longimanus

Aquatic Invasive Species
Exotic Species (not native to Montana)

Global Rank: G5
State Rank: SNA
* (see State Rank Reason below)

Agency Status
USFWS:
USFS:
BLM:


 

External Links





State Rank Reason (see State Rank above)
A conservation status rank is not applicable because this species is not a suitable target for conservation activities as a result of being exotic or introduced.
 
General Description
Bythotrephes longimanus is a large cladoceran (zooplankton) with a long straight tail spine that is twice as long as its body and has one to three pairs of barbs. Parthenogenically produced animals have kink in middle of their spine and sexually produced animals lack the kink. This species has not been found in any Montana waterbodies yet.

Phenology
This species is most abundant in late summer and autumn.

Diagnostic Characteristics
Bythotrephes longimanus is a large cladoceran distinguished by a long straight tail spine that is twice as long as its body and has one to three pairs of barbs. Parthenogenically produced animals have kink in middle of their spine and sexually produced animals lack the kink. Bythotrephes' appearance is similar to Cercopagis pengoi, another Great Lakes invader, except Bythotrephes is larger with a more robust spine that lacks a hook at the end.

Range Comments
Native To: Northern Europe and Asia.

Nonindigenous Range: First discovered in Lake Huron in 1984; established in all of the Great Lakes by 1987 (Cullis 1988). Have since been introduced into some lakes of northern Minnesota and the Alleghany Basin of New York (USGS 2017).


Migration
This species can make diel migrations within the water column of the lakes (Straile and Halbich 2000).

Habitat
This species lives in large and small temperate lakes, can tolerate brackish water (USGS 2017).
Bythotrephes occurs in oligotrophic and mesotrophic lakes and has a lower tolerance to low dissolved oxygen concentrations than native cladocerans.

Food Habits
This species feeds on other smaller zooplankton and phytoplankton.

Ecology
Bythotrephes is found among the zooplankton in the upper water column of large and small temperate lakes, can tolerate brackish water, and is most abundant in late summer and autumn. Occurrence and density of Bythotrephes populations are apparently determined mainly by water temperature and salinity. Bythotrephes is limited to regions where water temperature ranges between 4 and 30°C and salinity values between 0.04 and 8.0‰, but it prefers temperature between 10 and 24°C and salinity between 0.04 and 0.4‰ (Grigorovich et al. 1998). Has caused a decline in the population of zooplankton as a result of predation (Vanderploeg et al. 2002); may also compete with some native species, such as perch and small crustaceans (Branstrator and Lehman 1996)

Reproductive Characteristics
Bythotrephes can reproduce asexually as well as sexually; unfertilized eggs are carried in a brood pouch, and fertilized eggs are cast off in the fall, hatching the following spring (Evans 1988).

Management
The first noticeable impact of Bythotrephes was on fisherman. The tail spines of Bythotrephes hook on fishing lines, fouling fishing gear. Has caused a decline in the population of zooplankton as a result of predation (Vanderploeg et al. 2002); may also compete with some native species, such as perch and small crustaceans (Branstrator and Lehman 1996)

Threats or Limiting Factors
Temperature appears to play a major role in determining the abundance and location of Bythotrephes in the Great Lakes, as it prefers cooler water and cannot tolerate very warm lake temperatures (Berg and Garton 1988, Garton et al. 1990, Brown and Branstrator 2004). Bythotrephes occurs in oligotrophic and mesotrophic lakes and has a lower tolerance to low dissolved oxygen concentrations than native cladocerans.

References
Login Logout
Citation for data on this website:
Spiny Waterflea — Bythotrephes longimanus.  Montana Field Guide.  .  Retrieved on , from