Diets of deep-sea macrourid fishes in the western Mediterranean

Abstract

The feeding habits of the 4 most abundant macrourids that occur on the deep slope of the Catalan Sea (western Mediterranean) were examined for the first time for the Mediterranean at depths between 1000 and 2250 m. Diets of Chalinura mediterranea, Coryphaenoides guentheri, Coelorhynchus labiatus and Trachyrhynchus trachyrhynchus were analysed for 2 seasons (summer and autumn) and/or 3 different bathymetric strata. Coryphaenoides guentheri was the most euryphagous and T. trachyrhynchus the least. Chalinura mediterranea, Coelorhynchus labiatus and T. trachyrhynchus has a benthopelagic diet, whilst Coryphaenoides guentheri has a benthic diet. Coelorhynchus labiatus has a slight preference for bathybenthic prey (polychaetes, gammaridean amphipods) whereas Chalinura mediterranea and T. trachyrhynchus display a preference for bathypelagic prey (calanoid copepods, mysids). Chalinura mediterranea and Coryphaenoides guentheri have bathymetric differences in diet marked by the capture of different prey-items and also by a greater vacuity, a greater consumption of prey and a greater diversity at 1800 to 2250 m. A greater diversity in the diet is found in the Mediterranean populations of Chalinura mediterranea, Coryphaenoides guentheri and Coelorhynchus labiatus than in the Atlantic populations; this is probably an adaptation to the faunal paucity of the Mediterranean deep sea. General affinities among the diets of all macrourids are also analysed. The apparent coincidence between the diets of Chalinura mediterranea and T. trachyrhynchus could explain the bathymetric segregation of their respectives niches. Coelorhynchus labiatus, whose habitat width lies within those of the other 3 macrourids, has a dietary overlap intermediate to those of the other 3 macrourids. Ecological separation is maintained by a combination of differential depth distribution and feeding habits.KEY WORDS: Chalinura mediterranea · Coryphaenoides guentheri · Macrouridae · Feeding ecology · Western Mediterranean · Deep-sea ecology Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 234: [215][216][217][218][219][220][221][222][223][224][225][226][227][228] 2002 alimentary canal have been given by Morales-Nin (1990), Stefanescu et al. (1992b), Carrassón & Matallanas (1994) and Massutí et al. (1995). Diets of macrourids for depth ranges of 200 to 800 m have been studied by Macpherson (1979Macpherson ( , 1981, and some generic data on the diet of 1 specimen of Coryphaenoides guentheri and 1 Chalinura mediterranea from a depth of more than 2400 m have been reported by Geistdoerfer (1978). Apart from these 2 observations, no studies have been carried out on the diet of macrourids below a depth of 1000 m in the Mediterranean. In demersal deep-sea fishes in the western Mediterranean, a different behaviour in depth-size trends has been found compared to that in Atlantic waters; at the same time, a significant size reduction in Mediterranean populations of many species (among them the macrourids) has been...

Deep-water fish assemblages in the Mediterranean Sea

“…In the opinion of these authors, the high activity and the long range foraging needed in an unpredictable food environment would exclude or drastically limit the smaller groups of crustaceans. Jones et al (2003) recorded only the caridean shrimp Acanthephyra eximia and the macrourid C. mediterranea below 4000 m, indicating that the presence of these two species at depths at which the other species were absent might be due to a combination of their small size and mobility as well as their opportunistic and euryphagic feeding strategy (Cartes and Maynou, 1998;Carrassón and Matallanas, 2002).…”

“…Hureau et al, 1979;Haedrich et al, 1980;Gordon, 1984a, 1984b;Carrassón and Matallanas, 1990;Mahaut et al, 1990;Carrassón et al, 1992;Merrett and Haedrich, 1997;Carrassón and Matallanas, 2001). In addition, a degree of overlapping between these two extreme trophic strategies seems to be found in other species belonging to the Macrouridae, Moridae and Bythitidae families, which feed on food occurring within the benthic boundary and at the bottom interface (Isaacs and Schwartzlose, 1975;Geistdoerfer, 1978;Macpherson, 1979;Gordon, 1984a, 1984b;Carrassón and Matallanas, 1990;Mahaut et al, 1990;Carrassón and Matallanas, 2002). According to these studies, the present results would indicate that: 1) the differences in the ichthyofauna structure between the Balearic Sea and the Ionian Sea are more marked on the upper and middle slope than on the lower slope; and 2) in the Mediterranean lower slope assemblage, which is very little diversified, several life styles coexist: the smaller and medium sized species feeding mainly on benthopelagic plankton or strictly benthic organisms are widespread throughout the basin as typical species of food-limited assemblages; the large car-nivorous species, roaming a vast area searching for randomly occurring large food items, seem to be differently distributed between the Balearic and Ionian Sea.…”

Feeding habits of <i>Cataetyx alleni</i> (Pisces: Bythitidae) in the deep western Mediterranean

“…Polyacanthonotus rissoanus and Coryphaenoides guentheri), also preying on infauna, occur in the Catalan Sea. Both species, euryphagous with a diet based on small-size organisms (Carrassón and Matallanas, 2002), probably contribute to the disappearance of Cataetyx alleni below 1851 m. A clear inverse relationship is observed between the abundance of Cataetyx alleni and Polyacanthonotus rissoanus in the environment and its trophic overlap.…”

“…We identified thirty-nine categories of prey items from the stomachs containing food (Table 1). Of all the demersal species of fish in the Catalan sea below a depth of 1000 m, it has the highest dietary diversity (Table 1), together with the macrourids (Carrassón and Matallanas, 1998, 2001, 2002Carrassón et al, 1992Carrassón et al, , 1997.…”

Parasitisation by Bathycreadium elongatum ­(Digenea, Opecoelidae) in pyloric caeca of Trachyrincus scabrus (Teleostei, Macrouridae)

“…This apparent seasonality of the development of the parasite in the host does not correspond with the constant nature of hydrographic factors, such as temperature and salinity (about 13°C and 38.4, respectively) of deeper waters in the Mediterranean Sea from 200 m downwards (Salat & Cruzado 1981). T. scabrus tends to live close to the bottom unlike other macrourid species (Massutí et al 1995, Carrassón & Matallanas 2002. Therefore, seasonality in the life cycle of this parasite could be associated with a higher abundance of the intermediary hosts such as crustaceans.…”