BIOTIC

BIOTIC Species Information for Neomysis integer

Researched by

Georgina Budd

Data supplied by

MarLIN

Refereed by

This information is not refereed.

Taxonomy

Scientific name

Neomysis integer

Common name

An opossum shrimp

MCS Code

S76

Recent Synonyms

None

Phylum

Crustacea

Subphylum

Superclass

Class

Eumalacostraca

Subclass

Peracarida

Order

Mysidacea

Suborder

Mysida

Family

Mysidae

Genus

Neomysis

Species

integer

Subspecies

Additional Information

The species seems to be particularly susceptible to injury, causing atypical morphology which may lead to misidentification (Hayward & Ryland, 1995). Synonyms of Mysis or Neomysis vulgaris were in use in the early and continental literature, though Tattersall & Tattersall (1951) considered the specific integer (Leach) to have priority (Parker, 1979).

Taxonomy References

Hayward & Ryland, 1995b, Makings, 1977, Mauchline, 1980, Tattersall & Tattersall, 1951, Parker, 1979, Barnes, 1994,

General Biology

Growth form

Articulate

Feeding method

Active suspension feeder

Mobility/Movement

Swimmer
Crawler

Environmental position

Epibenthic
Pelagic

Typical food types

Detritus, diatoms, filamentous algae and small crustaceans.

Habit

Free living

Bioturbator

Not relevant

Flexibility

High (>45 degrees)

Fragility

Intermediate

Size

Small(1-2cm)

Height

Not relevant

Growth Rate

1-2 mm/month

Adult dispersal potential

100-1000m

Dependency

Independent

Sociability

Gregarious

Toxic/Poisonous?

General Biology Additional Information

Growth rate
In mature adults from the Ythan Estuary, Scotland, growth rate was recorded to be 1-2 mm per month in the field, which followed a rapid period of growth, of 4-5 mm per month in the summer juveniles (Astthorsson, 1980). The winter generation had a growth rate of 3-4 mm monthly for juveniles and about 1 mm per month for mature adults. During the winter there was a period of about 3 months when growth ceased (Astthorsson & Ralph, 1984).
Swimming behaviour
Neomysis integer performs a diel vertical migration, rising towards the surface waters during the night and returning to the deeper waters at daylight where it remains throughout the day (Hough & Naylor, 1992). Normal diurnal light levels are inhibitory and produce a negatively phototactic response in most species; the 24 hour cycle of change in ambient light intensity is the dominant factor controlling the diel vertical migration of mysids, such as Neomysis integer (Mauchline, 1980).
Maintenance of position
As a pelagic organism, Neomysis integer faces the problem of retaining its position within the estuarine environment, against conditions of net seaward transport (Hough & Naylor, 1992). In general, there are three main controls of the positioning of pelagic invertebrate populations in estuarine systems: reproductive compensation of seaward losses (a relatively large number of juveniles are produced per brood, behavioural adaptations (alterations in swimming activity at different tidal phases) and hydrodynamic process (distribution directly related to patterns of water circulation) (Schlacher & Wooldridge, 1994).
In laboratory experiments, Hough & Naylor (1992) found Neomysis integer to have an endogenously controlled circa-tidal swimming activity, with peak swimming activity expressed during the ebb tide. In the investigation of the significance of its endogenously controlled ebb tide swimming, Hough & Naylor (1992) observed Neomysis integer to demonstrate rheotaxic behaviour. Typically on the ebb tide in the Conway Estuary, shallow pools of isolated water are left as the tide ebbs. Aggregations of Neomysis integer in imminent risk of stranding initially headed into the current, but as the water level dropped, and before a pool was completely cut off, the species swam with the current draining from the pool and entered the stream before finally re-orientating and swimming into the current. Hough & Naylor (1992) suggested that such rheotaxic behaviour coupled a continuous ebb-phased swimming rhythm, may be of importance in the avoidance of stranding on the shore at low tide.
Maximum swimming speed by the mysid is also important, since it dictates in which flow velocities the species can maintain its position. Specimens studied by Roast et al. (1998b) from the East Looe River Estuary (Cornwall) tolerated current velocities of 6 and 9 cm s^-1, a few could swim at speeds of up to 27cm s^-1, but was not sustainable for more than a few seconds. Roast et al. (1998b) found the swimming speeds of Neomysis integer correlated well with the distribution of the species in the East Looe River Estuary, where mysids were found consistently in slower moving water (<15 cm s^-1) and were absent in faster flowing water (>20 cm s^-1). Roast et al. (1998b) stated that if swimming speed is an important factor in the position maintenance of the species, it is likely to be beneficial for the mysid to utilize any available shelter in order to conserve energy. In experimental conditions, Roast et al. (1998b) observed Neomysis integer to attach themselves to the substratum, thereby entering the boundary layer where lower velocity flows are experienced. This corresponds with field studies, for instance in the Conway Estuary, North Wales, Neomysis integer was always caught in greatest abundance in near-bottom plankton samples (Hough & Naylor, 1992). On the ebb tide, during flood and high-tide periods in the Ythan Estuary, Scotland, the species was concentrated in a band toward the moving tide edge where flows were typically lower. Also on the ebb tide and at low tide the species aggregated in shallower water and in the lee of rocks and macroalgal clumps where water flow rates were less than 10 cm/sec (Lawrie et al.,1999). Shallow burrowing into the sediment is also a common means of position maintenance in moving waters, and is a common behaviour of mysids inhabiting areas subject to tidal disturbance (Roast et al., 1998b).

Biology References

Makings, 1977, Mauchline, 1980, Tattersall & Tattersall, 1951, Mauchline, 1971, Astthorsson, 1980, Hough & Naylor, 1992, Lawrie et al., 1999, Barnes et al., 1979, Astthorsson & Ralph, 1984, Schlacher & Wooldridge, 1994, Roast et al., 1998b,

Distribution and Habitat

Distribution in Britain & Ireland

Records indicate Neomysis integer to have a widespread, but patchy distribution on all British and Irish coasts in locations of lowered salinity, usually estuaries or brackish water enclosures.

Global distribution

Distributed from Artic Norway to the Atlantic coast of Spain.

Biogeographic range

Not researched

Depth range

5-10 m

Migratory

Non-migratory / Resident

Distribution Additional Information

Salinity tolerance
Neomysis integer is a euryhaline species normally found in locations with salinities in the range 0.5 - 20 psu. However, it may be found more rarely in adjacent isolated waters of salinities greater than 20 psu, and in freshwaters. For instance, Neomysis integer adapted successfully to the transition from brackish lagoon to freshwater lagoon in the case of Loch Mor Barvas, Isle of Lewis, Scotland (Barnes, 1994).

Substratum preferences

Coarse clean sand
Gravel / shingle
Water column (pelagic)

Physiographic preferences

Sealoch
Estuary
Isolated saline water (Lagoon)

Biological zone

Upper Infralittoral
Lower Infralittoral

Wave exposure

Sheltered
Very Sheltered

Tidal stream strength/Water flow

Strong (3-6 kn)
Moderately Strong (1-3 kn)

Salinity

Low (<18 psu)
Reduced (18-30 psu)

Habitat Preferences Additional Information

Distribution References

Hayward & Ryland, 1995b, Makings, 1977, Parker, 1979, JNCC, 1999, Barnes, 1994, Parker & West, 1979,

Reproduction/Life History

Reproductive type

Gonochoristic

Developmental mechanism

Ovoviviparous

Reproductive Season

Spring to Autumn

Reproductive Location

As adult

Reproductive frequency

Annual protracted

Regeneration potential

Life span

<1 year

Age at reproductive maturity

<1 year

Generation time

<1 year

Fecundity

Up to ca 50

Egg/propagule size

Insufficient information

Fertilization type

Insufficient information

Larvae/Juveniles
Larval/Juvenile dispersal potential	100-1000m	Larval settlement period	Not relevant
Duration of larval stage	Not relevant

Reproduction Preferences Additional Information

The life history and biology of Neomysis integer differs slightly between localities (Mees et al., 1994; Astthorsson, 1980; Parker & West, 1979; Mauchline, 1971; Ralph, 1965; Kinne, 1955; Vorstman, 1951). Apparently the local environmental factors, especially temperature, have an influential role in determining the duration of the breeding season and the number of generations produced per year. Typically there are three generations per year.
For instance, in a population from Loch Etive, studied by Mauchline (1971), the over-wintering members consisted predominantly of juveniles and immature males and females. Once mature they began an intensive period of breeding in the spring. The spring generation matured rapidly and bred during late June and early July, which consequently produced a third generation in the autumn. These intensive periods of breeding were set against a background of continuous breeding throughout the year, so that discrete generations were not evident, but modal age groups within the population could be traced over weeks, or in the case of the over-wintering population, a few months.
However, outside periods of intensive breeding the recruitment rate was lower: < 1% of females carried eggs and broods were smaller. Brood size in mysid shrimps has been found to be related to female body length and season (Mauchline, 1971). A winter brood of Neomysis integer from Loch Etive consisted of between 10-25 juveniles compared to 20-50 in the summer.
In contrast, to the population of Neomysis integer from Loch Etive, a population from the Ythan estuary on the east coast of Scotland studied by Astthorsson (1980), produced only two generations per year with a complete cessation of breeding during winter. Temperature differences between the two locations were implicated as the Ythan estuary had a much lower summer maximum temperature than Loch Etive (17°C cf. 20°C; Leach, 1971; Gage, 1974).

Reproduction References

Makings, 1977, Mauchline, 1971, Astthorsson, 1980, Vorstman, 1951, Ralph, 1965, Parker & West, 1979, Kinne, 1955, Mees et al., 1994, Gage, 1974, Leach, 1971,