Acartia tonsa (Dana, 1848)

COMPILED BY: Anastasija Zaiko
CITATION OF THIS ENTRY: Zaiko A. 2004. Acartia tonsa. In: Baltic Sea Alien Species Database. S. Olenin, E. Leppakoski and D. Daunys (eds.).
INTERNET: http://www.ku.lt/nemo/mainnemo.html

TAXONOMY

Acartia tonsa - dorsal view (magnification 80). INTERNET: http://homepage.mac.com/a.shiroza/plankton/bwttf/ acartia_dorsal80_e.html	Acartia tonsa - lateral view (magnification 80). INTERNET: http://homepage.mac.com/a.shiroza/plankton/bwttf/ acartia_lateral80_e.html

IDENTIFICATION

• Diagnosis:

The body is elongated, slender. Typical lengths: 0.9-1.5 mm ( Bradford-Grieve et al. 1999).
Female. The abdomen of the female is very short, somewhat shorter than ¼ of cephalothorax that has rounded posterior margins. The abdomen is armed with thin bundles of hairs on the sides of the anal segment. The first antennae reach the middle of the genital segment.The distal segment of the fifth pair of female's podites has a rounded projection on the inner margin. The apical seta is coarsely serrated at the distal end, it is almost equal in length to the lateral seta. 
Male. The lateral part of the genital segment has bundles of short setae. The caudal branches are asymmetrical, with bundles of setae on the inner margin. The fifth pair of the male's podites is markedly asymmetrical, uniramous. The third segment of the right podite has a large inner projection. The forth segment is elongated, curved, armed with thin long setae. Basipodite (left) has a large projection (Kurashova 2002).

INTRODUCTION AND DISTRIBUTION

• First record from the Baltic Sea (year, area, reference):

Year ­ 1925
Reference - Segerstrale 1957

• Established:

in the entire Baltic Sea ­ Yes
in the area of primary introduction ­ Yes

• Origin of the species:

Acartia tonsa is a widely spread species: Indian Ocean, Malay Archipelago, Cayenne, Atlantic and Pacific coasts of the North and South Americas, Black, Azov and Mediterranean Seas (Kurashova 2002). Its distribution could be influenced by shipping as it occurs in estuarine sites of less than 33 ‰ salinity, which are also of higher temperatures than off-shore waters and provide the temperatures required for reproduction. This species produces diapause eggs which may have helped with transport in ballast waters (Eno et al. 1997).

• Distribution in Baltic Sea:

The species is distributed in the Baltic Sea - up to the Gulf of Finland. It is being observed in the Gulf of Bothnia, Gulf of Finland, Gulf of Riga, Kattegat and Belt Sea, Odra Lagoon.

• General characteristics:

Salinity range. Acartia tonsa has a broad salinity tolerance (0 – 70 ppt) (Buchanan 2002, Lance 1995, Luczkovich 2000). The euryhalinity of A. tonsa was experimentally confirmed, although it was demonstrated that this species shows high mortalities if the instantaneous change in salinity is greater than 10-15. Other complementary experiments were undertaken to define the maximum and minimum values of salinity on which this species could survive. The maximum
salinity was 72, and the minimum was lower than 1. The optimal adaptation was found between 15 and 22 (Cervetto et al. 1999). Also it was defined that adult females of the species show increased oxygen requirements when the salinity of the surrounding sea water is lowered (Lance 1995).
Temperature. Temperature is the factor that controls the geographical distribution of A. tonsa: the reproduction rate is low under 10 ºC. This species dominates in summer and autumn in warm waters in the upper layers at 0-20 m. For example, in the Baltic Sea mass development of A. tonsa occur in June-September at the temperature 16-17 ºC and salinity 4-5 PSU (Gomoiu et al. 2002).
Tolerance to pollution. Acartia tonsa is used as a test organism for different chemicals suspected to interfere with hormone systems, are used as positive controls (Ole 1999). A 3-month microcosm study held in Tampa Bay, Florida showed that A. tonsa eggs were nonviable in all treatments with added two types of fuels after only a few weeks of incubation, as evidenced by a marked decline in the abundance of nauplii (Suderman, Markus 2002).

THE ROLE IN THE BALTIC SEA ECOSYSTEM

Acartia tonsa may substitute native planktonic copepods (Gomoiu et al. 2002). As specific studyies have shown A. tonsa in the Baltic Sea area became numerically dominant in native communities. The reproduction potential of this species is high: it is known to develop in mass abundance, e.g., up to 10,000 ind m-3 (Gomoiu et al. 2002, Leppäkoski et al., 2002). Multiplying such density by the filtering rate of these animals shows that they are capable of recycling the entire water column in just 10 days (Arnold 1984).
Concerning its high abundances and grazing abilities this copepod can serve as a potential biological control of algal blooms (Roman et al. 2002). It also can change energy/matter flows between pelagic and benthic compartments and modify trophic structure of invaded ecosystems (Leppäkoski et al., 2002).
As some experimental studies refer that high levels of PSP toxin can be accumulated in copepod grazers such as Acartia tonsa, supporting the hypothesis that zooplankton may serve as PSP toxin vectors to higher trophic levels (Teegarden, Cembella 1996).

 

REFERENCES

1. Arnold Ch.L. 1984. Basic Processes Affecting Suspended Sediment Load in the River. Coastal processes of of the lower Hudson river. Conference Proceedings March 1984: http://nsgd.gso.uri.edu/nyext/nyext/nyextw84001.pdf
2. Bradford-Grieve J. M., Markhaseva E. L., Rocha C. E. F. and Abiahy B. 1999. Copepoda. In: Ed. D. Boltovskoy. South Atlantic Zooplankton. Leiden, Backhuys Publishers: 869-1098.
3. Buchanan C. 2002. Chlorophyll A Criteria. Chesapeake Bay Program: http://www.chesapeakebay.net/
4. Cervetto G., Gaudy R., Pagano, M. 1999. Influence of salinity on the distribution of Acartia tonsa (Copepoda, Calanoida). Journal of Experimental Marine Biology and Ecology. Elsevier Science Inc., 239 (1): 33-45.
5. Eno N. C., Clark R. A., Sanderson W. G. (eds.) 1997. Non-native marine species in British waters: a review and directory. JNCC, Peterbourough: 152 p.
6. Gomoiu M.T., Alexandrov B., Shadrin N., Zaitsev Y. 2002. The Black Sea - a recipient, donor and transit area for alien species. In: Leppakoski E., Gollasch S. and Olenin S.(eds), Invasive Aquatic species of Europe – distribution impacts and management. Kluwer Academic Publishers, Dordrecht, Boston, London: 341-350.
7. Kurashova E.K. 2002. Acartia tonsa Dana 1848. In: Biodiversity Database prepared in the framework of the Caspian Environment Programme: http://www.caspianenvironment.org/biodb/
8. Lance J. 1995. Respiration and osmotic behaviour of the copepod Acartia tonsa in diluted sea water. Comparative Biochemistry and Physiology. Elsevier Science Inc., 14 (1):155-165.
9. Leppakoski E., Gollasch S., Olenin S. 2002. The Baltic Sea - a field laboratory for invasion biology. In: Leppakoski E., Gollasch S. and Olenin S.(eds), Invasive Aquatic species of Europe – distribution impacts and management. Kluwer Academic Publishers, Dordrecht, Boston, London: 253-259.
10. Luczkovich J.J. 2000. Estuarine ecology: http://drjoe.biology.ecu.edu/estuary/chapter8.html
11. Ole K. 1999. Effects of Xenohormones on Crustaceans (1996 -1999). Research Report. Department of Environmental Science and Engineering. Lyngby, Denmark: 106p.
12. Roman M.R., Adolf H., Gustafson D., Jester D., Spear A., Zhang X., Barnett A., Reauhg M. 2002. Ingestion of the Dinoflagellates, Pfiesteria, Piscicida and Prorocentrum minimum by the calanoid copepod Acartia tonsa. PC01 Harmful Algal Blooms. Aquatic Sciences Meeting, Albuquerque 2001. American Society of Limnology and Oceanography: http://www.aslo.org/albuquerque2001/191.html
13. Segerstrale S.G. 1957. Baltic Sea. In: Hedgpeth J.W. (ed.) Treatise on Marine Ecology and Paleoecology I. Ecology. Geol. Soc. Am. Mem. 67: 751-800.
14. Suderman B.L., Markus N.H. 2002. The effects of Orimulsion and Fuel Oil #6 on the hatching success of copepod resting eggs in the seabed of Tampa Bay, Florida. Environmental pollution. Elsevier Science Ltd., 120(3): 787-795.
15. Teegarden G.J., Cembella A. D. 1996. Grazing of toxic dinoflagellates, Alexandrium spp., by adult copepods of coastal Maine: Implications for the fate of paralytic shellfish toxins in marine food webs. Journal of Experimental Marine Biology and Ecology. Elsevier Science B.V, 196 (1-2): 145-176.