Sea warming and fish distribution: the case of the small pelagic fish, Sardinella aurita, in the western Mediterranean

Abstract

This study analyses the temporal and spatial changes in abundance and distribution of the warm water species round sardinella (Sardinella aurita) in the western Mediterranean over the last decades in relation to sea water temperature. In the western Mediterranean basin , a significant positive relationship was found between round sardinella landings and temperature anomalies. Along a latitudinal gradient off the Mediterranean Iberian coast (1989)(1990)(1991)(1992)(1993)(1994)(1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004), a gradual increase in species abundance was observed from south to north, with a certain time lag going northwards, associated with the increase in sea water temperature. The abundance of round sardinella in the two warmest and southernmost areas was positively and significantly correlated with sea surface temperature registered during the start of gonad maturation the previous year. In addition, the positive relationship established between water temperature and abundance of round sardinella in the coldest and northernmost study area demonstrates that there is a temperature limit for the distribution of this species in the western Mediterranean. In addition, this study analyses round sardinella larvae distribution and abundance in the summers of 2003 and 2004, and conducts a comparison with the situation 20 years ago (summer 1983). Results show a marked increase in larval abundance during the last decades and the present appearance of larvae in the northernmost study areas, where they did not occur 20 years ago. This indicates the successful reproduction of round sardinella in the northern part of the Mediterranean, where the species has expanded, confirming its establishment in the area.

Temperature induced disease in the starfish Astropecten jonstoni

“…Several long-term records suggest that Mediterranean Sea surface temperatures have increased in the last decades. Along the Mediterranean coast of Spain sea surface temperatures are clearly higher after 1994 than in the preceding decades to 1950 (Sabaté et al, 2006). Also in the Gulf of Marseille abnormally long periods of high water temperatures have been measured in the last few years (Salat & Pascual, 2002).…”

“…Lawrence, 2004;Sabaté, 2006;Ward et al, 2007;Webster, 2007). A majority of these studies deal with mass mortalities observed in different coral species and other sessile invertebrates (Perez et al, 2000;Kushmaro et al, 2001;Boyett et al, 2007;Remily & Richardson, 2006;Ward et al, 2007).…”

Exploiting the closest productive area: geographical segregation of foraging grounds in a critically endangered seabird

“…In fact, the western Mediterranean is characterised by a latitudinal gradient in chl a and SST values of oceanic waters (i.e. more productive and cooler in the Gulf of Lions than in Cape Palos), whereas coastal waters show productivity hotspots in Cape Creus, Ebro Delta and Cape La Nao (Sabatés et al 2006, Bellido et al 2008, Gordoa et al 2008. Moreover, SI values of other marine top predators also show overall latitudinal gradients explained by the exploitation of different water masses along the Southern Ocean, showing increasing negative δ…”

Temporal and along-shelf distribution of the larval fish assemblage at Gran Canaria, Canary Islands

“…Both ecosystems have neritic and oceanic species in their larval community structure (Sabatés et al, 1990;Somarakis et al, 2002;Isari et al, 2008), but their presence during the year is completely different. Sardinella aurita and Hygophum hygomii are summer spawners in the Mediterranean Sea (Goodyear et al, 1972;Olivar and Palomera, 1994;Sabatés et al, 2006), while their larvae are present during the whole year off Gran Canaria (Bécognée et al, 2006). Similarly, Scomber colias is a summer spawner in the Mediterranean (Sabatés, 1990), but it only reproduces during winter in the Canaries (Lorenzo and Pajuelo, 1996).…”