EPPO Global Database

Invasion risks posed by the aquarium trade on the Great Lakes and consequences for the EPPO region

In North America, a study was undertaken on the introduction of non-indigenous species into the Great Lakes by the aquaculture industry. This pathway has been implicated in 6% of all documented invasions in the Great Lakes (10 animal and plant species). The aquarium hobby is indeed extremely popular in North America, with over 10% of households possessing ornamental fish.

A set of animal and plant species provided by the aquarium trade and fish markets was collected through surveys in 20 aquarium and pet stores located in close proximity to Lake Erie and Lake Ontario. It was assumed that these species, normally only intended for aquarium use, may be transferred to unintended habitats such as the freshwaters of the Great Lakes by human release.

Survivorship of these species has been assessed according to the following criteria:

overwintering ability from vegetative reproductive parts (turions, overwintering buds),
temperature tolerance of the vegetative parts of the plant to determine whether they could survive harsh winter climates,
history of invasion elsewhere in the world,
“propagule pressure”, measured by the number of individuals released, which is considered to be correlated with establishment success. Based on the assumption that popular species have more opportunities to be released, species present in less than 20% of the shops surveyed were arbitrarily considered as having a low chance of establishing populations, while those species present in 20% or more of the stores were classified as high risk invaders.

The species are listed with information on the percentage occurrence in shops, the area of origin of the species, their known behaviour of invasiveness elsewhere in the world, their probability of establishment in the Great Lakes (according to the criteria previously described). Species listed below are considered as having the potential to overwinter in the Great Lakes region. Whether they are traded or present in the wild in the EPPO region is indicated in the last column.

(%) store	Species	Area of origin	Invasion elsewhere	Prob. of establish. in Great Lakes	Trade and presence in the EPPO region
20	Cabomba caroliniana (Cabombaceae) (EPPO List of IAS)	S-Am.	Aquarium escape in N-Am., established in Connecticut,  New York, Maryland, Oregon, Australia	Has already invaded	Traded and established in GB, HU, NL
35	Egeria densa (Hydrocharitaceae) (EPPO List of IAS)	Cosm.	N-Am.	High	Traded and established in AT, BE, CH, DE, ES, FR, GB, IT, NL
30	Ceratophyllum demersum (Ceratophyllaceae)	Cosm., unclear	Hawaii, Australia, New Zealand	Native	Traded and native in the EPPO region
25	Hygrophila polysperma (Lentibulariaceae)	India, Malaysia	Established in Florida, Texas, Virginia	High	Traded, not established in the wild in the EPPO region
25	Myriophyllum aquaticum (Haloragaceae) (EPPO List of IAS)	S-Am.	Introduced in N-Am. through aquarium trade, established in Northern California	High	Traded and established in BE, DE, FR, GB, NL, PL,
10	Myriophyllum heterophyllum (Haloragaceae)	East coast of N-Am.	Spreading through New-England state	Low	Traded and established in AT, ES, GB

The following species are not considered as having the potential to overwinter in the Great Lakes region:

(%) store	Species	Area of origin	Invasion elsewhere	Trade and presence in the EPPO region
20	Anubias sp. (Araceae)	W-Af.	/	Traded but not mentioned in the wild
20	Chamaedorea elegans (Arecaceae)	C-Am.	/	Not mentioned
30	Crinum thaianum (Amaryllidaceae)	Thailand	/	Traded but not mentioned in the wild
40	Echinodorus amazonicus (Alismataceae)	Trop. S-Am.	/	Traded but not mentioned in the wild
20	Echinodorus osiris (Alismataceae)	Brazil	/	Not mentioned
30	Eichhornia crassipes (Pontederiaceae)	S-Am.	Tropical and subtropical regions	Traded and naturalized in ES, IL, PT, RU
20	Hygrophila difformis (Acanthaceae)	India, Malaysia	Australia	Traded, but not mentioned in the wild
25	Ludwigia sp. (Onagraceae) (EPPO List of IAS)	S-Am.	Temperate Europe	Traded and naturalized in BE, CH, ES, FR, IT, NL, PT
25	Microsorium pteropus (Polypodiaceae)	SE-As, tropics	/	Traded, not mentioned in the wild
25	Nymphoides aquatica (Menyanthaceae)	N-Am.	/	Not mentioned
20	Pilea cadierei (Urticaceae)	Indochina, Viet-Nam	/	Not mentioned
20	Pistia stratiotes (Araceae)	Trop. and subtrop. areas	Cambodia, China, Philippines, Hawaii, etc.	Traded and naturalized in ES
20	Rotala indica (Lythraceae)	Asia	Serious weed of rice in Afghanistan, Japan, Korea, Philippines, Taiwan. Troublesome in the USA	Traded, present in IT but has not spread since 1986
30	Vallisneria americana (Hydrocharitaceae)	N-Am.	/	Traded, not mentioned in the wild

In order to use this information for the EPPO region, the EPPO Secretariat has done a CLIMEX study comparing Toronto and the EPPO region. The following countries situated in Northern-Central Europe presented 70% of climate similarity with Toronto: Austria, Finland, north-eastern France, Germany, the Netherlands, Norway, Poland, Sweden, Switzerland, Russia and Ukraine. Species considered to have the potential to overwinter in the Great Lakes region may have the same ability in those European countries. Cabomba caroliniana (EPPO List of IAS), Myriophyllum heterophyllum, Eichhornia crassipes and Pistia stratiotes are already present in the wild in the EPPO region and could therefore present a risk and require further investigation. Hygrophila polysperma and Hygrophila difformis are not known to occur in the EPPO region but are frequently imported as aquatic plants (see EPPO RS 2007/016). Rotala indica is present in rice cultivation in Piemonte region in Italy, but it has not spread since 1986 and is therefore not considered as a priority (Desfayes, 2005).

Sources

Desfayes M (2005) Données floristiques pour le Piémont et ses rizières, et pour la Lombardie voisine: plantes aquatiques et palustres. Rivista Piemontese di Storia Naturale 26, 73-100.

Rixon CAM, Duggan IC, Bergeron NMN, Ricciardi A, Macisaac HJ (2005) Invasion risks posed by the aquarium trade and live fish markets on the Laurentian Great Lakes. Biodiversity and Conservation 14, 1365-1381.