- Scientific name: Gammarus pseudolimnaeus
- Species of Greatest Conservation Need (MA State Wildlife Action Plan)
- Special Concern (MA Endangered Species Act)
Description
Smith, D.G. 1984. Selected freshwater invertebrates proposed for special concern status in Massachusetts, Part II. Mass. Dept. of Env. Qual. Engineering, Div. of Wat. Pollut. Control. Westborough, MA
The northern spring amphipod is a laterally compressed, many segmented, freshwater crustacean that looks like a small, flat shrimp. It is uniformly dark, and mature specimens can reach 11-18 mm (0.43-0.70 inches) in length (Bousfield 1958, Bell 1971, Hynes and Harper 1972). Its head has two pairs of antennae and a pair of eyes and is fused with the first of seven thoracic segments. Each thoracic segment, as well as the six abdominal segments, has a pair of legs and/or gills that aid in respiration and locomotion.
Amphipods in the genus Gammarus are similar to this species. Gammarus fasciatus is most similar and identification guides sufficiently illustrate the differences among these species (Smith 2000).
Life cycle and behavior
Several studies have investigated the life history of the northern spring amphipod, and those available have been done on populations outside Massachusetts. These studies found that the life cycle of this species ranges from 9-16 months (Bousfield 1958, Hynes and Harper 1972, Waters 1981, Miller 1982). Reproduction begins in late winter and early spring and peaks from April to June. Eggs are brooded for three to four weeks with young starting to appear in late March or early April. Reproductive activity continues through the summer, ceasing by mid fall. As with other amphipods this species is a detritivore, feeding on decaying organic matter including leaf litter.
In general, amphipods aggregate in large numbers and remain hidden in organic debris or among beds of aquatic vegetation. All appendages are used to aid locomotion, and some specifically aid in swimming by providing a thrusting force, while others flex outward to bend the body, allowing for a sideswimming movement. It is for this reason that amphipods are given the name “sideswimmers” or scuds (Smith 2001). Amphipods react negatively to light and so tend to be more active at night.
Distribution and abundance
The northern spring amphipod ranges west to the Great Lakes region south to Oklahoma, with Massachusetts representing its eastern range limit. In Massachusetts, the species occurs within several headwater streams of tributaries to the Housatonic River in southwestern Massachusetts. Recorded abundances range from tens to thousands of individuals of both sexes and life stages.
The status of the northern spring amphipod in Massachusetts remains unclear. It is found in a restricted area characterized by carbonate-rich springs, a habitat that is rare in Massachusetts. It is listed under the Massachusetts Endangered Species Act as a Species of Special Concern. All listed species are protected from killing, collecting, possessing, or sale and from activities that would destroy habitat and thus directly or indirectly cause mortality or disrupt critical behaviors. In addition, listed animals are specifically protected from activities that disrupt nesting, breeding, feeding, or migration.
Habitat
In Massachusetts, the northern spring amphipod has only been found in vegetated, calcium-rich springs and spring-fed streams that flow through the swampy lowlands of the western drainages of the Housatonic River basin (Smith 1997). However, throughout its range it inhabits a variety of aquatic habitats with an affinity toward springs and spring-fed streams. This species can be found in cool, hard waters that are high in carbonate from the associated bedrock and is occasionally found in outlet streams (D.G. Smith, personal communication 2003).
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Low gradient, headwater stream habitat in southwestern Massachusetts suitable for northern spring amphipod.
Threats
The northern spring amphipod lives in clear, unpolluted headwater streams. Riparian and watershed development, sedimentation, nonnative riparian plant species, streamflow alteration from surface or groundwater withdrawal, and groundwater contamination from pollutants are a potential threat to this species. Further, climate change may threaten the habitat of this species by reducing water availability during prolonged drought events.
Conservation
Survey and monitoring
The last targeted survey effort for this species was in the late 1990s. As such, effort is needed to evaluate its historical distribution. Surveys should also reserve effort to target potentially suitable spring-fed, hardwater streams in other tributaries to the Housatonic or Hoosic Rivers.
Monitoring efforts are recommended at least every 5 years or as needed (e.g., in response to potential disturbance or stressor events) at its historical sites.
Management
Protection of northern spring amphipod habitat is critical for species persistence in Massachusetts. Since the species known distribution is from only a handful of sites, new development and forestry cuts of riparian areas should be limited to prevent alteration of sediment and flow regimes. Prevention and control of invasive riparian plant species may also be warranted to preserve leaf litter composition and quality for species consumption.
Research needs
Surveys should continue to target historical but also identify new carbonate springs and streams to better understand its distribution, relative abundance, and habitat requirements in Massachusetts. Physical surveys coupled with eDNA collections could improve species detection, assuming species DNA markers are developed. Further, research is also needed to assess northern spring amphipods’ habitat and species risk to climate change projections, including prolonged drought, as its habitat is groundwater dominated.
References
Bell, R.T. 1971. Handbook of the Malacostraca of Vermont and neighboring regions. Zoology Department University of Vermont. Burlington, VT. 65 pp.
Bousfield, E. 1958. Fresh-water amphipod crustaceans of glaciated North America. Canadian Field Naturalist 72: 55-113.
Hynes, H.B.N., and F. Harper. 1972. The life histories of Gammarus lacustris and Gammarus pseudolimnaeus in southern Ontario. Crustaceana, Suppl 3. Studies on Peracarida: 329-341.
Miller, S.A. 1982. The life history of Gammarus pseudolimnaeus Bousfield in a central Wisconsin stream (Amphipoda: Gammaridae). Crustaceana 43: 89-99.
Smith, D.G. 1997. An annotated checklist of Malacostracans (Crustacea) inhabiting southern New England fresh waters. Journal of Freshwater Ecology 12 (2): 217-223.
Smith, D.G. 2000. Keys to the Freshwater Macroinvertebrates of southern New England. Published by author. Sunderland, MA. 243 pp.
Smith, D.G. 2001. Pennak’s Freshwater Invertebrates of the United States: Porifera to Crustacea. Wiley and Son’s Inc., NY. 638 pp.
Waters, T.F. 1981. Seasonal patterns in production and drift of Gammarus pseudolimnaeus in Valley Creek, Minnesota. Ecology 62 (6): 1458-1466.
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| Date published: | March 7, 2025 |
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