Palaemon elegans (rock shrimp)
- Summary of Invasiveness
- Taxonomic Tree
- Notes on Taxonomy and Nomenclature
- Distribution Table
- History of Introduction and Spread
- Risk of Introduction
- Habitat List
- Biology and Ecology
- Water Tolerances
- Natural enemies
- Notes on Natural Enemies
- Means of Movement and Dispersal
- Pathway Causes
- Pathway Vectors
- Impact Summary
- Environmental Impact
- Risk and Impact Factors
- Uses List
- Similarities to Other Species/Conditions
- Prevention and Control
- Gaps in Knowledge/Research Needs
- Links to Websites
- Distribution Maps
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PicturesTop of page
IdentityTop of page
Preferred Scientific Name
- Palaemon elegans Rathke, 1837
Preferred Common Name
- rock shrimp
Other Scientific Names
- Leander squilla Kemp, 1910
- Leander squilla var. elegans de Man, 1915
- Leander squilla var. intermedia de Man, 1915
International Common Names
- English: common prawn
Local Common Names
- Croatia: jadranska kozica
- France: crevette bouquet
- Germany: Kleine Felsengarnele
- Italy: gamberetto
- Netherlands: gewone steurgarnaal
- Poland: krewetka atlantycka
- Portugal: camarão de poça
- Spain: quisquilla
Summary of InvasivenessTop of page
P. elegans is a euryhaline species that is native to the Atlantic and Mediterranean (including the Black Sea) coasts of Europe, ranging from Norway to South Africa. It inhabits intertidal areas, lagoons and estuaries, forming very abundant populations in vegetated places. It was also accidentally introduced to the Aral and Caspian lakes in the 1950s. Very recently it has colonized the Baltic Sea, spreading by 2003 as far as the Gulf of Finland. Recent reports show that the species has completely replaced the native P. adspersus, from many suitable habitats along the southern Baltic coast and colonized some coastal lagoons, devoid of palaemonid shrimp before. The vector of its introduction remains unknown so it is unclear whether P. elegans should be treated as an invasive alien species posing a threat to local biodiversity, or if it is simply enriching the biodiversity through the natural extension of its range from the Atlantic coast.
Taxonomic TreeTop of page
- Domain: Eukaryota
- Kingdom: Metazoa
- Phylum: Arthropoda
- Subphylum: Crustacea
- Class: Malacostraca
- Subclass: Eumalacostraca
- Order: Decapoda
- Suborder: Natantia
- Unknown: Palaeomonoidea
- Family: Palaemonidae
- Genus: Palaemon
- Species: Palaemon elegans
Notes on Taxonomy and NomenclatureTop of page
Some misunderstanding on the distribution of Palaemon elegans in the Baltic Sea arises from confusing this species in literature with Palaemon adspersus, due to use of its old synonymic name by some authors. For example, Balss (1926), cites P. elegans under its old name Leander squilla (Linnaeus, 1758). According to Opinion 564 of the International Commission of Zoological Nomenclature (Holthuis, 1988), the name Cancer squilla described by Linnaeus (1758: 632, 1761: 495-496) belongs in reality to Palaemon adspersus Rathke, 1837 (syn. Leander adspersus). The latter name was conserved by the Commission, through suppression of the specific name squilla Linnaeus. In fact, in the cited work of Balss (1926) the information on the species distribution in Baltic concerns only Leander squilla var. typical, that was later included in P. adspersus; the other variety mentioned by Balss (1926), L.s. var. elegans Rathke, 1837 was later raised to species level as Palaemon elegans. Holthuis (1949, 1950) gave more detailed explanation behind the taxonomic changes and stated that former reports of P. elegans (Balls, 1926; Schellenberg, 1928) in the Baltic Sea were mistakes which resulted from confusing this species with P. adspersus. In conclusion, all the older data may be attributed to P. adspersus or, at least, the occurrence of P. elegans in the Baltic at that time was highly doubtful (Grabowski, 2006).
DescriptionTop of page
The maximum length of P. elegans is 63 mm. Its rostrum is strongly expanded ventrally, straight or very slightly upwardly curved with seven to nine dorsal teeth and with two to four (most often three) ventral teeth. The tip of the rostrum is often bifid. Three or rarely two dorsal teeth are placed behind the posterior edge of the orbit. Ventral side of the rostrum with a single row of setae. Antenules triramous, shorter ramus of the outer flagellum stout and fused to the longer ramus for about 50-60% of its length. Third maxilliped about 0.5 x length of scaphocerite, exopod present. Mandible with incisor and molar process, and two segmented palp. Sixth abdominal segment with a protuberance just above the posterolateral marginal spine. Carapace and abdomen usually with a black colour transverse striped pattern. Legs with yellow and blue bands. However, the colouration may differ depending on the habitat – in turbid waters the pattern is likely to fade away almost completely. Detailed illustrated descriptions were provided by Smaldon (1993) and by Gonzales-Ortegon and Cuesta (2006).
DistributionTop of page
This euryhaline marine species inhabits vegetated areas (Dalla Via, 1985) and is widely distributed in European coastal waters from the Black and Mediterranean seas to the North Sea and the Atlantic shores of Norway. As introduced unintentionally it occurs also in the Aral and Caspian lakes. It has also colonized the Baltic Sea as far east as the Gulf of Finland.
Distribution TableTop of page
The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.
|Continent/Country/Region||Distribution||Last Reported||Origin||First Reported||Invasive||Reference||Notes|
|Atlantic, Eastern Central||Widespread||Native||Not invasive||González-Ortegón and Cuesta, 2006|
|Atlantic, Northeast||Widespread||Native||Not invasive||González-Ortegón and Cuesta, 2006|
|Atlantic, Southeast||Widespread||Native||Not invasive||González-Ortegón and Cuesta, 2006|
|Mediterranean and Black Sea||Widespread||Native||Not invasive||d'Udekem d'Acoz, 1999|
|Azerbaijan||Absent, intercepted only||Introduced||Dore and Frimodt, 1987; d'Udekem d'Acoz, 1999|
|Georgia (Republic of)||Absent, intercepted only||Introduced||Not invasive||d'Udekem d'Acoz, 1999|
|Iran||Absent, intercepted only||Introduced||Dore and Frimodt, 1987; d'Udekem d'Acoz, 1999|
|Israel||Present||Native||Not invasive||Holthuis and Gottlies, 1958; d'Udekem d'Acoz, 1999|
|Kazakhstan||Absent, intercepted only||Introduced||Dore and Frimodt, 1987; d'Udekem d'Acoz, 1999|
|Lebanon||Present||Native||Not invasive||Holthuis and Gottlies, 1958; d'Udekem d'Acoz, 1999|
|Syria||Present||Native||Not invasive||Holthuis and Gottlies, 1958; d'Udekem d'Acoz, 1999|
|Turkey||Present||Native||Not invasive||Holthuis and Gottlies, 1958; d'Udekem d'Acoz, 1999|
|Turkmenistan||Present||Introduced||Dore and Frimodt, 1987; d'Udekem d'Acoz, 1999|
|Uzbekistan||Present||Introduced||Dore and Frimodt, 1987; d'Udekem d'Acoz, 1999|
|Algeria||Present||Native||Not invasive||Dore and Frimodt, 1987|
|Cameroon||Present||Native||Not invasive||Dore and Frimodt, 1987|
|Egypt||Present||Native||Not invasive||Holthuis and Gottlies, 1958|
|Gabon||Present||Native||Not invasive||Dore and Frimodt, 1987|
|Gambia||Present||Native||Not invasive||Dore and Frimodt, 1987|
|Ghana||Present||Native||Not invasive||Dore and Frimodt, 1987|
|Guinea-Bissau||Present||Native||Not invasive||Dore and Frimodt, 1987|
|Libya||Present||Native||Not invasive||d'Udekem d'Acoz, 1999|
|Mauritania||Present||Native||Not invasive||Dore and Frimodt, 1987|
|Mayotte||Present||Native||Not invasive||d'Udekem d'Acoz, 1999|
|Morocco||Present||Native||Not invasive||d'Udekem d'Acoz, 1999|
|Namibia||Present||Native||d'Udekem d'Acoz, 1999; González-Ortegón and Cuesta, 2006|
|Nigeria||Present||Native||Not invasive||Dore and Frimodt, 1987|
|Sao Tome and Principe||Present||Native||Not invasive||Dore and Frimodt, 1987|
|Senegal||Present||Native||Not invasive||Dore and Frimodt, 1987|
|-Canary Islands||Present||Native||Not invasive||d'Udekem d'Acoz, 1999|
|Togo||Present||Native||Not invasive||Dore and Frimodt, 1987|
|Tunisia||Present||Native||Not invasive||Dore and Frimodt, 1987|
|Western Sahara||Present||Native||Not invasive||Dore and Frimodt, 1987|
|USA||Present||Present based on regional distribution.|
|-Massachusetts||Present||Sea Grant College Program MIT, 2010||Over 70 shrimp collected at Hawthorne and at nearby Palmer's Cove Yacht Club|
|Albania||Present||Native||Not invasive||d'Udekem d'Acoz, 1999|
|Belgium||Present||Native||Not invasive||Müller, 2004|
|Bosnia-Hercegovina||Present||Native||Not invasive||d'Udekem d'Acoz, 1999|
|Bulgaria||Present||Native||Not invasive||d'Udekem d'Acoz, 1999|
|Croatia||Present||Native||Not invasive||d'Udekem d'Acoz, 1999|
|Cyprus||Present||Native||Not invasive||d'Udekem d'Acoz, 1999|
|Denmark||Present||Native||Not invasive||Köhn and Gosselck, 1989|
|Finland||Present||Introduced||Invasive||Lavikainen and Laine, 2004|
|France||Present||Native||Not invasive||d'Udekem d'Acoz, 1999|
|-Corsica||Present||Native||Not invasive||d'Udekem d'Acoz, 1999|
|Germany||Present||Native||Invasive||Köhn and Gosselck, 1989|
|Gibraltar||Present||Native||Not invasive||d'Udekem d'Acoz, 1999|
|Greece||Present||Native||Not invasive||d'Udekem d'Acoz, 1999|
|Ireland||Present||Native||Not invasive||d'Udekem d'Acoz, 1999|
|Italy||Present||Native||Not invasive||d'Udekem d'Acoz, 1999|
|Malta||Present||Native||Not invasive||d'Udekem d'Acoz, 1999|
|Monaco||Present||Native||Not invasive||d'Udekem d'Acoz, 1999|
|Netherlands||Present||Native||Not invasive||d'Udekem d'Acoz, 1999|
|Norway||Present||Native||Not invasive||González-Ortegón and Cuesta, 2006|
|Portugal||Present||Native||Not invasive||d'Udekem d'Acoz, 1999|
|-Azores||Present||Native||Not invasive||d'Udekem d'Acoz, 1999|
|-Madeira||Not invasive||d'Udekem d'Acoz, 1999|
|Romania||Present||Native||Not invasive||d'Udekem d'Acoz, 1999|
|Serbia||Present||Native||Not invasive||d'Udekem d'Acoz, 1999|
|Slovenia||Present||Native||Not invasive||d'Udekem d'Acoz, 1999|
|Spain||Present||CAB ABSTRACTS Data Mining 2001; d'Udekem d'Acoz, 1999|
|Sweden||Present||Invasive||d'Udekem d'Acoz, 1999|
|UK||Present||Native||Not invasive||d'Udekem d'Acoz, 1999|
|-Channel Islands||Present||Native||Not invasive||d'Udekem d'Acoz, 1999|
|Ukraine||Present||Native||Not invasive||Zentkevich, 1963|
|Yugoslavia (Serbia and Montenegro)||Present||Native||Not invasive||d'Udekem d'Acoz, 1999|
History of Introduction and SpreadTop of page
During the first half of twentieth century it was accidentally introduced to the Aral and Caspian lakes (Zentkevich, 1963). Grabowski (2006) noted that in some publications (Janas et al., 2004) it was erroneously reported, based on data from Balss (1926), that this species was present from the southern Baltic and had ranged from Kiel to the Gulf of Gdansk since the 1920s. In fact, these data concerned another species – P. adspersus Rathke, 1837.The distribution of P. elegans in the Baltic was, until recently, limited to its westernmost part. The species was reported sporadically only from Wismarer Bucht (Köhn and Gosselck, 1989). In the eastern and southern Baltic the species was found first in 2002 in the Arkona Basin (Zettler, 2002) and in Poland in the Gulf of Gdansk (Janas et al., 2004). However, Grabowski (2006) indicated that P. elegans was present on the Polish Baltic coast at least since 2000 (records from the Martwa Wisla (Dead Vistula)).
Currently, the species is the most abundant palaemonid shrimp along the Polish Baltic coast. It also inhabits the Szczecin Lagoon and the Vistula deltaic system including the Vistula Lagoon (Jazdzewski et al., 2005; Grabowski 2006). In 2003, the species was already found in the Gulf of Finland (Kekkonen, 2003; Lavikainen and Laine, 2004). According to the suppositions of Köhn and Gosselck (1989), the larval stages of P. elegans were transported occasionally to the Baltic Sea in ballast waters. These authors reported that ovigerous females did not occur in German Baltic waters and concluded that this species was not reproducing there. Grabowski et al. (2005) observed ovigerous females and postlarval stages of all sizes in the Bay of Puck and along the open Baltic coast in Poland. In many places, it replaced completely native P. adspersus, while in others it dominated the palaemonid communities (Grabowski 2006). Köhn and Gosselck (1989) hypothesised that P. elegans could have been be introduced to German waters through ballast waters; however, there are no data available to either prove or disprove this assumption. Thus, it is still not clear if P. elegans should be treated as an introduced, invasive alien species that poses a threat to local biodiversity, or if it is simply enriching biodiversity through the natural extension of its range from the Atlantic coast.
Risk of IntroductionTop of page
The case of P. elegans may be another example in a long list of successful colonization known in the Baltic Sea (Leppäkoski and Olenin, 2000; Leppäkoski, 2004). With no doubt the species has become a permanent and important element of the Baltic fauna. In many places it replaced the native P. adspersus, and in the others it dominates the palaemonid communities. However, a question arises whether P. elegans should be treated as an introduced invasive, non-native being a threat for the local biodiversity, or simply as enriching this biodiversity through a natural range extension. The shrimp occurs along the Atlantic coasts of Europe and it may naturally penetrate into the brackish waters of the Baltic Sea similar to the European shore crab, Carcinus maenas,observed sporadically in the Eastern Baltic. On the other hand, Köhn and Gosselck (1989) hypothesised that P. elegans could be introduced through shipping (ballast waters). It is highly probable as there are numerous cases of decapod crustaceans spread, enhanced and accelerated by human activity (Rodriguez and Suarez, 2001). Ballast waters offer by no means the most effective mechanism for the introduction of exotic species (Carlton, 1985; Gollasch, 2002). It has been assessed that each day there are 3-4 thousand marine species transported worldwide (Carlton and Geller, 1993). Decapod planctonic larvae are also known to migrate this way (Chu et al., 1997) and examples of such kind of decapod introductions are known from Europe (Rodriguez and Suarez, 2001), in fact the authors discuss also this way of dispersal for the already mentioned crab, Carcinus maenas. Furthermore, P.elegans was side-introduced with mullet species to the seas of the former USSR (Zentkevitch, 1963), however this option is unlikely in the Baltic as there is no data on such fishery activity in the area. Further spread of this species by natural dispersal is suspected in the Baltic Sea (to the slightly brackish Gulf of Bothnia). It is also possible that with ballast waters it will be transferred to coastal waters and estuaries of North America or the Far East.
HabitatTop of page
The species occurs in shallow littoral zone, on muddy or sandy bottom where it is primarily associated with vegated areas, such as Zostera meadows or stony and rocky places overgrown with algae. Also, it produces highly abundant populations in reed zone in lagoons or estuaries (Dalla Via, 1985; Grabowski, 2006).
Habitat ListTop of page
|Benthic zone||Principal habitat||Natural|
|Inshore marine||Principal habitat||Natural|
Biology and EcologyTop of page
For information on the genetics of this species please see Porter et al. (2005).
The species breeds from April to September, in favourable conditions females may produce two broods per year. As in all palaemonids, the eggs are protected by females and remain attached to her pleopods until the planctonic larva hatches. Then it undergoes typical development with variable number of zoeal stages recorded (from six to nine). The larva changes lifestyle to benthic in megalope (post-larval) stage. The species life cycle was studied by Fincham,(1977) and the identification key to larval stages was provided by Fincham and Williamson (1978).
Physiology and Phenology
The species is known to accumulate cadmium in its tissues (White and Rainbow, 1986).
P. elegans is omnivorous, feeding predominantly on algae, small crustaceans and foraminiferans.
The species forms communities with other palaemonid shrimp species living in the same habitat types, such as Palaemon adspersus, P. serratus, P. longirostris and Palaemonetes varians (Grabowski, 2006).
It is a euryhaline species, occurring both in brackish and marine waters.
Water TolerancesTop of page
|Parameter||Minimum Value||Maximum Value||Typical Value||Status||Life Stage||Notes|
|Depth (m b.s.l.)||0.2||5||Optimum|
|Salinity (part per thousand)||5||25||Optimum||1-40 tolerated|
|Water temperature (ºC temperature)||20||Optimum||5-31 tolerated|
Natural enemiesTop of page
|Natural enemy||Type||Life stages||Specificity||References||Biological control in||Biological control on|
|Aggregata eberthi||Parasite||Adult||not specific|
|Aggregata octopiana||Parasite||Adult||not specific|
Notes on Natural EnemiesTop of page
Natural enemies of this species may include various aquatic birds (eg. ducks, seagulls, herons, waders) and predatory fish (eg. Zoarces viviparus, Neogobius melanostomus, Gymnocephalus cernuus, Platichthys spp., Gadus morhua), however no detailed studies are available so far (Gruszka and Wiecaszek, 2004). Arias et al. (1998) reported two species of coccidian parasites of the genus Aggregata using P. elegans as intermediate hosts in Spanish waters.
Means of Movement and DispersalTop of page Natural Dispersal (Non-Biotic)
On the local scale, in the Baltic Sea, the species is extending its range probably through natural dispersal mechanisms. Its larval stages (zoea) lead planctonic life and may be carried with sea currents. In the Baltic inshore waters the currents are associated with wind action. Adult individuals leading benthic life are able to swim short distances and colonise neighbouring patches of suitable habitats.
Köhn and Gosselck,(1989) hypothesised that P. elegans could be introduced through shipping (ballast waters). Zenkevich (1963) reported that it was side-introduced with mullet species to the Caspian and Aral seas of the former USSR.
Pathway CausesTop of page
Pathway VectorsTop of page
Impact SummaryTop of page
|Economic/livelihood||Positive and negative|
|Environment (generally)||Positive and negative|
Environmental ImpactTop of page
Impact on Biodiversity
Risk and Impact FactorsTop of page Invasiveness
- Proved invasive outside its native range
- Has a broad native range
- Abundant in its native range
- Capable of securing and ingesting a wide range of food
- Highly mobile locally
- Fast growing
- Has high reproductive potential
- Altered trophic level
- Modification of natural benthic communities
- Reduced native biodiversity
- Threat to/ loss of native species
- Competition - monopolizing resources
- Highly likely to be transported internationally accidentally
- Difficult to identify/detect in the field
- Difficult/costly to control
Uses ListTop of page
Animal feed, fodder, forage
- Laboratory use
- Research model
- Sport (hunting, shooting, fishing, racing)
Similarities to Other Species/ConditionsTop of page
Due to its very characteristic colour pattern the species is relatively easy to identify in the field. However, if the animals are not well coloured, confusion with other Palaemon (eg. P. adspersus, P. longirostris, P. serratus) or Palaemonetes (P. turcorum, P. varians, P. zariquieyi) species is possible. In such cases other morphological features, visible under stereomicrocope, have to be used. Detailed, well illustrated identification keys are provided by Smaldon (1993) and by Gonzales-Ortegon and Cuesta (2006).
Prevention and ControlTop of page
Eradication or control of this species is most probably not possible due to the animals small size, abundance, habitats and similarity to related native species.
Gaps in Knowledge/Research NeedsTop of page
As the problem of P. elegans invasiveness has been raised just recently there are still many gaps in knowledge. Particularly, further studies upon mechanisms and vectors of its spread are needed, as well as the impact on local benthic communities and place in the food chain.
ReferencesTop of page
Fincham AA, 1977. Larval development of British prawns and shrimps (Crustacea: Decapoda: Natantia). Laboratory methods and a review of Palaemon (Paleander) elegans Rathke 1837. Bulletin of the British Museum (Natural History) (Zoology), 32:1-28.
González-Ortegón E; Cuesta JA, 2006. An illustrated key to species of Palaemon and Palaemonetes (Crustacea: Decapoda: Caridea) from European waters, including the alien species Palaemon macrodactylus. Journal of Marine Biology Association United Kingdom, 86(1):93-102.
Holthuis LB, 1950. The Decapoda of the Siboga Expedition. Part X. The Palaemonidae collected by the Siboga and Snellius expeditions, with remarks on other species. Part I: Subfamily Palaemoninae. Siboga Expedition, 39(a9):1-268.
Holthuis LB; Gottlies E, 1958. An annotated list of Decapod Crustacea of the Mediterranean Coast of Israel, with an appendix listing the Decapoda of the Eastern Mediterranean. Bulletin of the Research Council of Israel:1-126.
Jazdzewski K; Konopacka A; Grabowski M, 2005. Native and alien malacostracan Crustacea along the Polish Baltic Sea coast in the twentieth century. Oceanological & Hydrobiological Studies, 24(suppl. 1/2005):195-208.
Lapinska E; Szaniawska A, 2006. Environmental preferences of Crangon crangon (Linnaeus, 1758), Palaemon adspersus Rathke, 1837 and Palaemon elegans Rathke, 1837 in the littoral zone of the Gulf of Gdansk. Crustaceana, 79(6):649-662.
Leppäkoski E, 2004. Living in a sea of exotics - the Baltic case. Aquatic Invasions in the Black, Caspian, and Mediterranean Seas, 35:237-255. [NATO Science Series IV, Earth and Environmental Sciences.]
Schellenberg A, 1928. [English title not supplied]. (Krebstiere oder Crustacea II: Decapoda, Zehnfuesser) In: Tierwelt Deutschlands und der angrenzenden Meersteile nach ihern Merkmalen und nach ihrer Lebenweise, Jena, Germany [ed. by Dahl F] Jena, Germany: Verlag von Gustav Fischer, 32-142.
ContributorsTop of page
06/02/08 Original text by:
Michal Grabowski, University of Lodz, Dept Invertebrate Zoology & Hydrobiology, Banacha 12/16, 90-237 Lodz, Poland
Distribution MapsTop of page
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