Gammarus salinus

Researched By	Georgina Budd	Data Supplied By	MarLIN
Refereed by	This information is not refereed.
Taxonomy
Scientific name	Gammarus salinus	Common name	A gammarid shrimp
MCS Code	S481	Recent Synonyms	None
Phylum	Crustacea	Subphylum
Superclass		Class	Eumalacostraca
Subclass	Peracarida	Order	Amphipoda
Suborder	Gammaridea	Family	Gammaridae
Genus	Gammarus	Species	salinus
Subspecies
Additional Information	Nine other marine species of Gammarus are found around the British Isles: Gammarus locusta, Gammarus zaddachi, Gammarus oceanicus, Gammarus chevreuxi,Gammarus tigrinus, Gammarus finmarchicus, Gammarus duebeni, Gammarus insensibilis and Gammarus crinicornis (Lincoln, 1979). Accurate identification of amphipods requires a certain amount of manipulation under a microscope.
Taxonomy References	Lincoln, 1979, Hayward et al., 1996, Ruppert & Barnes, 1994, Kolding, 1981
General Biology
Growth form	Articulate	Feeding method	Herbivore, Surface deposit feeder
Mobility/Movement	Swimmer, Crawler	Environmental position	Epibenthic
Typical food types	Organic detritus and seaweed.	Habit	Free living
Bioturbator	Not relevant	Flexibility	High (>45 degrees)
Fragility	Intermediate	Size	Small(1-2cm)
Height	Insufficient information	Growth Rate	Insufficient information
Adult dispersal potential	100-1000m	Dependency	Independent
Sociability	Gregarious
Toxic/Poisonous?	No
Additional Information	Moulting Kinné (1960) found that the frequency (days - weeks) at which Gammarus salinus moulted varied with changes in temperature, the intervals being longer in males than in females. Females kept without a male showed a progressive prolongation of the intervals between moults beginning with the 3rd of 4th interval following isolation. Females kept together with males, in pairs, maintained moults at constant intervals. No differences were observed to occur in different salinities of 5, 10 and 30 psu.
Biology References	Lincoln, 1979, Kinné, 1960, Breeman & Hoeksema, 1987
Distribution and Habitat
Distribution in Britain & Ireland	On all coasts of England, Scotland and Wales in brackish-water, especially in the Humber and Severn Estuaries.
Global distribution	North-west Europe from English Channel to Baltic, some isolated reports of Gammarus salinus on the Iberian Peninsula.
Biogeographic range	Not researched	Depth range	0-10 m
Migratory	Non-migratory / Resident
Distribution Additional Information	Gammarus species are abundant estuarine animals. Spooner (1947) stated that gammarids were adaptable to various surroundings and not limited to particularly specialised ecological niches. Nor did they show gross patchiness of distribution within their habitable range, rather continuous populations occupy the entire length of estuaries, although the proportion of species represented changes from head to mouth. Furthermore, gammarids are relatively indifferent to the nature of the substratum to a remarkable degree. Provided that there is some kind of object to provide them with shelter/cover it does not matter whether the substratum is muddy or stony, the water turbid or clear and almost any kind of organic matter provides detritus upon which to feed (Spooner, 1947). The distributional range of Gammarus salinus to the south was thought to be restricted as far as the English Channel. However, Van Maren (1975) reported Gammarus salinus for the first time on the Spanish coast in 1974.
Substratum preferences	Algae, Gravel / shingle, Coarse clean sand	Physiographic preferences	Estuary
Biological zone	Upper Infralittoral, Lower Infralittoral	Wave exposure	Sheltered, Very Sheltered, Extremely Sheltered
Tidal stream strength/Water flow	Strong (3-6 kn), Moderately Strong (1-3 kn)	Salinity	Reduced (18-30 psu), Low (<18 psu)
Habitat Additional Information
AMBI Group (Borja et al., 2000)	I
Distribution References	Lincoln, 1979, JNCC, 1999, NBN, 2002, Maren van, 1975, Crothers, 1966, Spooner, 1947
Reproduction/Life History
Reproductive type	Gonochoristic	Developmental mechanism	Direct Development
Reproductive Season	Autumn to spring	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	Increases with female length
Egg/propagule size	Insufficient information	Fertilization type	Internal
Larvae/Juveniles Larval/Juvenile dispersal potential 100-1000m Larval settlement period Not relevant Duration of larval stage Not relevant
Additional Information	Leineweber (1985) sampled a population of Gammarus salinus over 15 months in the south-western Kattegat at Sangstrup Klint, Denmark and reported that Gammarus salinus most likely had two generations per year, mature females were found from late November to late July. However, in the Limfjord, Denmark, the population of Gammarus salinus was reported to only produce one generation between 1977-1978, despite the presence of egg bearing females throughout the year (Kolding & Fenchel, 1979). Juveniles were most numerous from April through to July, and in the warmer months between July and October a relatively stable population was attained. The main reproduction period occurred during the winter months, with 80% of the female population reported to be pregnant, the adult generation died in May. During reproduction, the male carries the smaller female grasped by his gnathopods, a condition known as amplexus. The animals separate briefly to permit the final preadult moult of the female. Sperm transfer is accomplished quickly; the male twists his abdomen around so that his uropods touch the female marsupium (brood pouch) and sperm are swept into the marsupium by the ventilating current created by the female. Finally the pair separate (Rupert & Barnes, 1994). The eggs are brooded within a chamber, the marsupium, beneath the thorax, formed by shelf-like plates projecting inward from the thoracic coxae. Kinné (1960) examined the effects of different temperatures and salinity on the incubation time of Gammarus salinus. At a temperature between 19-20 °C females attained sexual maturity (1st oviposition) 20-30 days after hatching; their average length (from tip of rostrum to base of telson) being 7-8 mm. Males reached maturity one or more weeks later than the females. The incubation time (period between oviposition and hatching) of the eggs depended largely on the temperature at which the females were maintained; < 14 °C incubation took over 15 days and decreased to 5 days at 20 °C. As in other amphipods Kinné (1960) found that the fecundity of females increased with length, with numbers of eggs varying in a clutch (Ruppert & Barnes, 1994).
Reproduction References	Leineweber, 1985, Kinné, 1960, Ruppert & Barnes, 1994, Kolding & Fenchel, 1979