Abundance patterns at the invasion front: the case of Siganus luridus in Linosa (Strait of Sicily, Central Mediterranean Sea)

Abstract

Abstract. In the present study we investigated spawning of the butterfly kingfish (Gasterochisma melampus), a Scombridae species distributed in circumpolar temperate waters of the Southern Hemisphere in the Atlantic, Indian and Pacific oceans. Using data from 25 564 individuals collected by longline operations from 1987 to 1996, analysis of the gonadosomatic index, maturity based on oocyte size and the presence of hydrated eggs revealed that the spawning area was between longitude 85 and 1308W and latitude 28 and 418S in the south-east Pacific Ocean, and that the spawning season was from mid-April to mid-July. Length-frequency data suggested that larger fish arrived and spawned earlier, whereas smaller fish did so later. The species has distinctive reproductive characteristics compared with other Scombridae: it produces large hydrated eggs 1.6 mm in diameter, sea surface temperatures in the spawning area were as low as 14-188C and more than 80% of fish were female. The south-east Pacific Ocean may be the only (and is at least the major) spawning area of the species. Butterfly kingfish is a single stock that migrates to the Atlantic, Indian and Pacific oceans to feed and returns to the south-east Pacific Ocean to spawn.Additional keywords: reproductive biology.

New Mediterranean Biodiversity Records (December 2017)

“…This finding represents further evidence on the recent expansion of rabbitfishes at their invasion front (for Siganus luridus see Azzurro et al, 2017) and indicates the possible establishment of a new population of S. rivulatus in the Sicily Strait. The isopod genus Mesanthura, belonging to the superfamily Anthuroidea, currently comprises 46 described species (Poore & Schotte, 2009).…”

Range‐extending tropical herbivores increase diversity, intensity and extent of herbivory functions in temperate marine ecosystems

“…For instance, the Mediterranean Sea has extensive and productive seagrass and seaweed habitats (Sales & Ballesteros, 2012), yet hosts only two native herbivorous fish species ( Sarpa salpa and Sparisoma cretense ), which likely has eased the expansion of tropical herbivores in the region. Scarus ghobban remains uncommon in the Mediterranean Sea, but the occurrence of this species has extended from Israel to Greece (Erguden, Bayhan, Alagöz Erguden, & Altun, 2018), while the rabbitfish Siganus luridus and Siganus rivulatus have become abundant in many locations, attaining MaxS of ~100 individuals at the edge of their expansion in Linoza, Italy (Azzurro et al., 2017). The region of our study has a higher diversity, with five dominant species, but still lags far behind herbivore assemblages in the tropics with 30–100 species (Steneck, Bellwood, & Hay, 2017).…”

“…MaxN; Cappo, Harvey, Malcolm, & Speare, 2003). In addition to abundance information, MaxS can be a proxy for reproductive behaviour (Azzurro, Franzitta, Milazzo, Bariche, & Fanelli, 2017) and ecological impact, since certain species have positive correlations between school size and per capita consumption rates (Basford et al., 2016; Michael, Hyndes, Vanderklift, & Vergés, 2013). For simplicity, we report the highest MaxS and the average MaxS (MaxSm) per subregion in the text.…”

Latitudinal patterns in trophic structure of temperate reef‐associated fishes and predicted consequences of climate change

“…where the arrival of tropical species from the Red Sea is initially facilitated by the Suez Canal and where the expansion of herbivorous fish is occurring longitudinally in a western direction as this basin continues to warm (Azzurro, Franzitta, Milazzo, Bariche, & Fanelli, 2017).…”