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Hydrozoan species richness in the M editerranean S ea: past and present
Author(s) -
Gravili Cinzia,
Camillo Cristina Gioia,
Piraino Stefano,
Boero Ferdinando
Publication year - 2013
Publication title -
marine ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.668
H-Index - 58
eISSN - 1439-0485
pISSN - 0173-9565
DOI - 10.1111/maec.12023
Subject(s) - species richness , extinction (optical mineralogy) , range (aeronautics) , taxon , ecology , biology , fauna , introduced species , biodiversity , geography , paleontology , materials science , composite material
The M editerranean hydrozoan fauna ( S iphonophora excluded) comprises 400 species; most (68%) occur in the A tlantic O cean, 20% are endemic to the M editerranean, 8% are of I ndo‐ P acific origin, and 4% are non‐classifiable. There are 69 nonindigenous ( NIS ) species in the basin: 44% of these are casual (recorded just one or very few times), 28% established (widely recorded in the basin), 6% invasive (established NIS that are able rapidly or largely to disseminate away from the area of initial introduction, having a noticeable impact on the recipient community), and 22% questionable (of doubtful taxonomic status). Entry through the S uez Canal and range expansion through the G ibraltar S trait, often enhanced by ship traffic, appear to be the main processes for recent species introductions, but uncertainties remain for many NIS . Species additions immediately result in larger local or regional species pools, but the newcomers might impact on populations of native species, altering extinction probabilities. A more reliable evaluation of the species pool can be accomplished by adding new species when they enter the taxonomic record ( i.e . the records of any taxon in all types of literature), and by removing species that have not been found for a ‘reasonable’ time ( e.g . several decades). Of the 400 non‐siphonophoran hydrozoan species known to occur in the M editerranean S ea, positive records in the last 10 years are available for 156 species (39%), whereas records of the remaining 244 species are older than a decade: 67 species have not been recorded for 41 years, 13 for 31–40 years, 79 for 21–30 years, and 85 for 11–20 years.