First record of Palaemon macrodactylus Rathbun, 1902 (Decapoda, Palaemonidae) in the western Mediterranean

Abstract

The Mediterranean Sea is one of the world’s hotspots for marine bio-invasions. Most invasions are first documented based on an initial record of occasional adult captures. However, reports of larval stages could indicate that there is an adult population that is reproducing and therefore well established in the area. The spread of the oriental shrimp, Palaemon macrodactylus, from its native estuarine waters of southeast Asia to new regions worldwide is well documented. We report the first record of this species in the Mediterranean based on the presence of its larval stages in plankton samples. Decapod larvae were collected in five offshore plankton surveys performed off the Balearic Islands (western Mediterranean), and zoeae III and VI of the oriental shrimp werefound among them. Taking into account the duration of the successive developmental stages, and the hydrodynamic characteristics of the study area, these larvae were most probably spawned by adult populations not yet documented. The larvae were found in marine waters despite the fact that adults usually inhabit brackish waters. Our study is a good example of how plankton studies can help to detect larval stages of invasive species before the adult populations are detected.

Record of an established population of Palaemon macrodactylus Rathbun, 1902 (Decapoda, Palaemonidae) in the Mediterranean Sea: confirming a prediction

“…As penaeids are quite sensitive to the WSSV, some concern may arise for the farming of Marsupenaeus japonicus, carried on since 1980's in some North Adriatic lagoons, and for the fishery of the autochthonous stock of Melicertus kerathurus. Ashelby et al (2013) suggested that the oriental shrimp will likely diffuse in the near future in north-eastern Europe (Baltic Sea), southern Norway, north-western Africa, and pointed out that invasion of the Mediterranean region might already have begun (based on the larval evidence reported by Torres et al, 2012). The present data fully confirm this prediction and we can expect to see this shrimp in other Mediterranean brackish habitats in the near future.…”

“…Ashelby et al (2013) suggested the possibility that these larvae might have been released by a passing vessel during offshore ballast water exchange, instead of originating from a nearby still undetected population as hypothesized by Torres et al (2012). Photographic evidence (no specimens could be collected at that time) of the presence of P. macrodactylus in the lagoon of Sacca di Goro (northern Adriatic Sea) was provided by Rinaldi (2012).…”

“…The presence of P. macrodactylus in the western Mediterranean Sea has been inferred from the presence of a few larvae (one zoea VI in 2005, and seven zoeae III in 2010) in plankton samples collected in marine waters off Mallorca, Balearic Islands (Torres et al, 2012). Ashelby et al (2013) suggested the possibility that these larvae might have been released by a passing vessel during offshore ballast water exchange, instead of originating from a nearby still undetected population as hypothesized by Torres et al (2012).…”

Introduction of a new Indo-Pacific marine cladoceran to the Mediterranean Sea

“…This could be due to the use of a 200-μm mesh net, which does not sample effectively individuals smaller than 450 μm (Hopcroft et al, 2001). Their absence from previous studies often happens when studies do not aim at detecting allochthonous species, and the presence of such species is not noted by non-specialized taxonomists; consequently, specimens of alien species are accidentally referred to as similar congeneric native species or their juveniles (Torres et al, 2012). It is unlikely that this species entered the Mediterranean Sea via the Strait of Gibraltar through natural expansion, because P. schmackeri is primarily distributed along the western coast of the Atlantic Ocean, and to the best of our knowledge has not yet been recorded along the eastern coast of this ocean close to the Gibraltar Strait.…”

Alien species in the Mediterranean Sea by 2012. A contribution to the application of European Union’s Marine Strategy Framework Directive (MSFD). Part 2. Introduction trends and pathways

“…Decapods are the prevalent group, followed by copepods. The latest records are the shrimp Palaemon macrodactylus (Torres et al, 2012) in the WMED, and two parasitic copepods, Caligus fugu and Taeniacanthus lagocephali, caught on a Lessepsian puffer fish in the EMED (Özak et al, 2012). We have added the unusual finding of the brine shrimp Artemia franciscana in the saltworks of Margherita di Savoia, Apulia (Mura et al, 2006 (Bianchi & Morri, 1996).…”