Parity and disparity between two Chama oysters: the reproductive biology of the Indo‐Pacific C. pacifica Broderip, invasive to the Mediterranean Sea; and C. savignyi Lamy, indigenous to the Red Sea

Abstract

The Indo‐Pacific oyster Chama pacifica Broderip, 1835 (Mollusca, Bivalvia, Chamidae) is rarely found in the Northern Red Sea reefs of Eilat (Gulf of Aqaba), where it is outnumbered by its indigenous congener, Chama savignyi Lamy, 1921. The influx of Eritrean biota from the Red Sea into the Mediterranean Sea via the Suez Canal has led to the formation of massive Chama oyster beds along the Eastern Mediterranean shore. However, unlike the Northern Red Sea, the Eastern Mediterranean Chama beds are dominated by C. pacifica oysters, whereas C. savignyi is absent from this region. In an attempt to understand this difference in their respective distribution, the reproductive biology of both species was compared. Histological analysis of the male and female gonads, monitored monthly from March 2009 to August 2010 in both regions, revealed a similar reproductive cycle, comprising six stages: onset of gametogenesis, advanced gametogenesis, ripe, ready to spawn, spent and sexual rest. Female gonads demonstrated an additional, seventh stage – restoration, coinciding with inferred spawning of ripe gametes. Both species were found to be dioecious spawners, with a single, annual, temperature‐dependent inferred spawning period. Chama pacifica was found to reproduce efficiently in maximal Mediterranean seawater temperatures not experienced by the Northern Red Sea Chama populations. This study demonstrates the high invasive potential of an oyster species despite its rarity in its source region.

The gill microbiota of invasive and indigenous Spondylus oysters from the Mediterranean Sea and northern Red Sea

“…The spiny oyster Spondylus spinosus Schreibers, 1793, is a Lessepsian migrant that was first documented in the Eastern Mediterranean Sea (hereafter EMS) in 1988 (Mienis et al ., ), and has since expanded its distribution north‐west to Turkey (Çeviker and Albayrak, ; Katsanevakis et al ., ; Crocetta et al ., ; Shabtay et al ., ). Along the Israeli Mediterranean coast S. spinosus forms dense beds together with another invasive oyster, Chama pacifica , dwelling on sandstone and artificial structures at a depth of 2–40 m (Mienis et al ., ; Zurel et al ., ; Shabtay et al ., ). Although S. spinosus is highly abundant along the Israeli Mediterranean coast, it is extremely scarce in Eilat, Gulf of Aqaba, northern Red Sea (hereafter NRS), which is probably the northernmost edge of its native distribution (Shabtay, ; Shabtay et al ., ).…”

What guides invasion success? Ecological correlates of arrival, establishment and spread of Red Sea bivalves in the Mediterranean Sea

“…The increase in the proportion of extratropical species is also evident at later invasion stages. Low winter seawater temperatures in the eastern Mediterranean are one of the main factors limiting the survival and reproductive success of Red Sea immigrants (Rilov & Galil, 2009;Zurel et al, 2012), although high summer extremes may be detrimental as well (Belmaker et al, 2013). Similarly, fish species experiencing a broader range of temperatures in their native range are more likely to enter the Mediterranean Sea (Belmaker et al, 2013) and have greater rates of subsequent dispersal (Ben Rais Lasram et al, 2008).…”

“…Taxonomic identity and distribution of Lessepsian bivalves in the Mediterranean Sea is well documented (Gofas & Zenetos, 2003;Zenetos et al, 2010;Tzomos et al, 2012), and our knowledge about the ecology and biology of selected species is continuously expanding (e.g. Rilov et al, 2004;Zurel et al, 2012). Nonetheless, the strong focus of previous studies on just a few of the most conspicuous immigrants (reviewed by Safriel, 2013) is hindering our ability to understand the dynamics of the entire invasion process.…”

Invading bivalves replaced native Mediterranean bivalves, with little effect on the local benthic community

“…Several invading bivalves dominate local communities in the Levantine basin and may have replaced native bivalves (Zurel et al 2012 ; Rilov 2013 ; Crocetta et al 2013 ). The pearl oyster, Pinctada radiata (Leach, 1814; family Margaritidae) was one of the first invasive mollusks recorded in the Mediterranean (first observed in 1874) and became abundant in the Levantine basin (Galil 2008 ) with evidence of spreading into the western Mediterranean basin (Kersting and Hendriks 2021 ).…”