Gammarus insensibilis

Researched By	Nicola White	Data Supplied By	MarLIN
Refereed by	Dr Martin Sheader
Taxonomy
Scientific name	Gammarus insensibilis	Common name	Lagoon sand shrimp
MCS Code	S476	Recent Synonyms	None
Phylum	Crustacea	Subphylum
Superclass		Class	Eumalacostraca
Subclass	Peracarida	Order	Amphipoda
Suborder	Gammaridea	Family	Gammaridae
Genus	Gammarus	Species	insensibilis
Subspecies
Additional Information	As the species is morphologically close to Gammarus locusta it may be under-recorded in parts of its range.
Taxonomy References	Howson & Picton, 1997, Lincoln, 1979, Sheader & Sheader, 1985, Sheader & Sheader, 1987
General Biology
Growth form	Articulate	Feeding method	Herbivore
Mobility/Movement	Swimmer, Crawler	Environmental position	Epifaunal
Typical food types	Chaetomorpha	Habit	Free living
Bioturbator	Not relevant	Flexibility	Low (10-45 degrees)
Fragility	Intermediate	Size	Small(1-2cm)
Height	Insufficient information	Growth Rate	Insufficient information
Adult dispersal potential	100-1000m	Dependency	Independent
Sociability	Solitary
Toxic/Poisonous?	No
Additional Information	This species is often found in dense populations.
Biology References
Distribution and Habitat
Distribution in Britain & Ireland	In England, distribution is restricted to the central southern coast with two isolated east coast sites. Not recorded west of Fleet in Dorset and is absent from the lagoons of Cornwall.
Global distribution	South from the English Channel along the Atlantic coasts of Europe to the Mediterranean and in the Black Sea.
Biogeographic range	Not researched	Depth range	Restricted to depth of lagoons; 2-3 m max.
Migratory	Non-migratory / Resident
Distribution Additional Information	Distribution is restricted to southern parts of England and probably represents the northern limit of the species' range. Found in Dorset, Hampshire, Sussex, Isle of Wight, Essex and Kent in the south and isolated sites in Lincolnshire and Suffolk on the east coast. The species was present in Widewater lagoon, Sussex, but has not been recorded there since 1979. Other habitat characteristics are: a regular tidal input of seawater; a small tidal range; no or low freshwater input other than rainfall; water retained at all states of the tide and at all seasons; salinity within the range 10-58 psu, usually 15-35 psu, with seasonal variation.
Substratum preferences	Mud, Muddy sand, Sandy mud	Physiographic preferences	Isolated saline water (Lagoon)
Biological zone	Lower Littoral Fringe	Wave exposure	Very Sheltered, Extremely Sheltered
Tidal stream strength/Water flow	Insufficient information	Salinity	See additional Information
Habitat Additional Information
AMBI Group (Borja et al., 2000)	I
Distribution References	Lincoln, 1979, Sheader & Sheader, 1985, Sheader & Sheader, 1987, Anonymous, 1999(s)
Reproduction/Life History
Reproductive type	Gonochoristic	Developmental mechanism	Direct Development
Reproductive Season	All year with summer peak	Reproductive Location	Insufficient information
Reproductive frequency	Annual protracted	Regeneration potential	No
Life span	<1 year	Age at reproductive maturity	<1 year
Generation time	<1 year	Fecundity	11-100
Egg/propagule size	Insufficient information	Fertilization type	Insufficient information
Larvae/Juveniles Larval/Juvenile dispersal potential Not relevant Larval settlement period Not relevant Duration of larval stage Not relevant
Additional Information	Reproduction continues throughout the year with peak reproductive activity in the warm summer months in the UK. In France, life span varies from 48 to 408 days according to the water temperature when born (Janssen et al., 1979). Those born in the winter develop 4 to 5 times slower than those born in the summer. Egg incubation time also increases with a reduction in water temperature from 7 days in summer to 50 days in winter.
Reproduction References	Janssen et al., 1979