First record of the invasive medusa Blackfordia virginica (Hydrozoa: Leptomedusae) in the Río de la Plata estuary, Argentina-Uruguay

Abstract

Blackfordia virginica is a well-known invasive medusa inhabiting estuarine areas. It was recently detected in northern Argentina, constituting the first record of invasive hydromedusa for the Argentine Sea. In this work more than 1,500 plankton samples in the southwestern Atlantic Ocean (34-55º S) from 1983 to 2000 were analyzed. More than 5,000 specimens per sample of B. virginica were found in Río de la Plata estuary for the first time in February 2000. This river is one of the large waterways of South America with an intense nautical traffic and several exotic species has been recorded here, mainly due to trans-oceanic shipping traffic. It is important to point out that we found medusae of both sexes (therefore this species could be introduced in either the medusa or the polyp stages or both), different size classes (including very small juveniles) and maturation stages, and in such high numbers that would suggest local reproduction. For this reason the recent finding of this hydromedusa could represent the starting point of an successful introduction.

Abundance, seasonal patterns and diet of the non-native jellyfish Blackfordia virginica in a Portuguese estuary

“…The bell size diameter registered in the Portuguese estuaries is therefore higher than the 10 mm measured in other estuaries (Mills & Sommer, 1995;Genzano et al, 2006). ind./m 3 in Río de la Plata estuary, Argentina-Uruguay (mesh size not referred by the authors) (Genzano et al 2006); 10.6 ind./m 3 in Babitonga estuary, Brazil (mesh size 300 µm) (Bardi & Marques, 2009) and 2.7x10 -2 and 2.5x10 -2 ind./m 3 in Antonina Bay, Brazil (mesh size 500 µm) (Nogueira Jr.& De Oliveira, 2006). Direct comparison of densities among these studies would be impractical as different or unknown mesh sizes were used to collect medusae.…”

Ecological insights into the polyp stage of non-native hydrozoans in the San Francisco Estuary

“…Each of our study species has now been identified on several continents (Kramp 1961;Paranaguá 1963;Denayer 1973;Santhakumari et al 1997;Folino 2000;Buecher et al 2005;Genzano et al 2006;Bardi and Marques 2009). While some findings from this study can be applied to these systems, a continued effort to study the poorly understood polyp stage is necessary to develop predictive tools for bloom formation, ecological impact, and management decisions, as well as to determine sites vulnerable to future invasions.…”

Low genetic diversity of the putatively introduced, brackish water hydrozoan,Blackfordia virginica(Leptothecata: Blackfordiidae), throughout the United States, with a new record for Lake Pontchartrain, Louisiana

“…An alternative hypothesis is that B. virginica is native to Virginia, where it was first collected and subsequently introduced to the Black Sea (Leppäkoski et al 2009). Internationally, B. virginica has also been reported in the Cananeia, Guaratuba, and Babitonga Bays, Brazil (Bardi & Marques 2009), Argentina and Uruguay (Genzano et al 2006), Mexico (Álvarez Silva et al 2003), Portugal and Spain (Chicaro et al 2009), the Caspian Sea, which boarders Azerbaijan, Iran, Kazakhstan, Russia and Turkmenistan, (Leppäkoski et al 2009), the Loire estuary in France, the Mira estuary in Portugal, Nova Scotia, Canada (Moore 1987), Lake Belona in Romania, the South China Sea and East China Sea in the Fujian Province (Zhang 1982, Lin & Zhang 1990, and the Ganges and Vasishta Godvari estuaries in India (Sastry & Chandramohan 1989). No genetic studies have thus far been carried out to address the dynamics of any population of B. virginica.…”