The effects of temperature and salinity on the blood chemistry and survival of juvenile Atlantic tarpon Megalops atlanticus.

Atlantic tarpon Megalops atlanticus are highly migratory sportfish that support recreational fisheries throughout their range. In US waters, juveniles can be found in coastal and estuarine habitats along the Gulf of Mexico and Atlantic seaboard, with temperature limiting their northern latitudinal distribution. Juveniles may overwinter in these areas during the first several years of life. Low temperatures are known to cause mortality in adults, but the challenges of temperature are less understood for juveniles. Furthermore, salinity, which can change dramatically in these habitats, may have a synergistic effect with temperature. To examine the physiological effects of temperature and salinity on juvenile tarpon, wild fish were acclimated to a range of conditions that potentially occur in the northern range of their estuarine habitats. The haematology of juvenile tarpon was examined in two salinity (≤2 and ≥30 ppt) and temperature (15 and 25°C) treatments, followed by a low-temperature tolerance test. After 2 weeks in treatment conditions, blood samples were analysed for haematocrit, pH, red blood cell concentration, haemoglobin content and plasma osmolality. Increased plasma osmolality was observed in fish at low temperature (15°C compared to 25°C) and at high salinity (≥30 ppt compared to ≤2 ppt). Blood pH was increased at 15°C compared to 25°C, with the highest pH at 15°C and low salinity. Haemoglobin, haematocrit and red blood cell concentration were higher at 25°C than 15°C, with haemoglobin lowest at 15°C and low salinity. For the low-temperature tolerance test, all fish were acclimated to 15°C for 2 weeks, then transferred to separate tanks where temperature was gradually decreased at 0.9 ± 0.1°C/h until fish lost equilibrium. Fish at low salinity lost equilibrium more rapidly (1 ppt, 12.65 ± 0.46°C) than fish at high salinity (30 ppt, 11.26 ± 0.14°C). The results indicate juvenile tarpon are susceptible to low temperature, which is exacerbated by low salinity, findings useful in the assessment of juvenile tarpon overwintering habitat.

New records of anisakid nematodes from marine fishes off New Caledonia, with descriptions of five new species of Raphidascaris (Ichthyascaris) (Nematoda, Anisakidae).

Recent examinations of anisakid nematodes (Anisakidae) from marine fishes off New Caledonia, collected in the years 2003-2008, revealed the presence of the following five new species of Raphidascaris Railliet et Henry, 1915, all belonging to the subgenus Ichthyascaris Wu, 1949: Raphidascaris (Ichthyascaris) spinicauda n. sp. from the redbelly yellowtail fusilier Caesio cuning (Caesionidae, Perciformes); Raphidascaris (Ichthyascaris) fasciati n. sp. from the blacktip grouper Epinephelus fasciatus (Serranidae, Perciformes); Raphidascaris (Ichthyascaris) nudicauda n. sp. from the brushtooth lizardfish Saurida undosquamis (Synodontidae, Aulopiformes); Raphidascaris (Ichthyascaris) euani n. sp. from the Japanese large-eye bream Gymnocranius euanus (Lethrinidae, Perciformes); and Raphidascaris (Ichthyascaris) elopsis n. sp. from the Hawaiian ladyfish Elops hawaiensis (Elopidae, Elopiformes). An additional two congeneric species, R. (I.) etelidis Moravec et Justine, 2012 and R. (I.) sillagoides (Bruce, 1990) were found in the deep-water red snapper Etelis carbunculus (new host record) and the deepwater longtail red snapper Etelis coruscans (both Lutjanidae, Perciformes), and the silver sillago Sillago sihama (Sillaginidae, Perciformes) (new host and geographical records), respectively. Two unidentified congeneric species, Raphidascaris (Ichthyascaris) sp. 1 from the trumpet emperor Lethrinus miniatus (Lethrinidae, Perciformes) and Raphidascaris (Ichthyascaris) sp. 2 from the white-spotted puffer Arothron hispidus (Tetraodontidae, Tetraodontiformes) were recorded. Moreover, two species of Hysterothylacium Ward et Magath, 1917, H. alatum Moravec et Justine, 2015 and H. epinepheli (Yamaguti, 1941), were found in the leopard coralgrouper Plectropomus leopardus (type host) and the highfin grouper Epinephelus maculatus (new host) (both Serranidae, Perciformes), respectively. This is the second finding of H. epinepheli since its original description in Japan 79 years ago. Most species are described based on light and electron microscopical studies.

TITLE: Nouvelles mentions de nématodes anisakidés de poissons marins de Nouvelle-Calédonie, avec description de cinq nouvelles espèces de Raphidascaris (Ichthyascaris) (Nematoda, Anisakidae). ABSTRACT: L'examen récent de nématodes Anisakidae de poissons marins de la Nouvelle-Calédonie, collectés dans les années 2003­2008, a révélé la présence des cinq nouvelles espèces de Raphidascaris Railliet et Henry, 1915, toutes appartenant au sous-genre Ichthyascaris Wu, 1949 : Raphidascaris (Ichthyascaris) spinicauda n. sp. chez le fusilier Caesio cuning (Caesionidae, Perciformes) ; Raphidascaris (Ichthyascaris) fasciati n. sp. chez la loche Epinephelus fasciatus (Serranidae, Perciformes) ; Raphidascaris (Ichthyascaris) nudicauda n. sp. chez le poisson-lézard Saurida undosquamis (Synodontidae, Aulopiformes) ; Raphidascaris (Ichthyascaris) euani n. sp. chez le bossu Gymnocranius euanus (Lethrinidae, Perciformes) ; et Raphidascaris (Ichthyascaris) elopsis n. sp. chez Elops hawaiensis (Elopidae, Elopiformes). Deux autres espèces congénériques, R. (I.) etelidis Moravec et Justine, 2012 et R. (I.) sillagoides (Bruce, 1990) ont été trouvées respectivement chez les vivaneaux de profondeur Etelis carbunculus (nouvel hôte) et Etelis coruscans (Lutjanidae, Perciformes) et chez Sillago sihama (Sillaginidae, Perciformes) (nouvel hôte et nouvelle mention géographique). Deux espèces congénériques non identifiées, Raphidascaris (Ichthyascaris) sp. 1 chez le bossu Lethrinus miniatus (Lethrinidae, Perciformes) et Raphidascaris (Ichthyascaris) sp. 2 chez Arothron hispidus (Tetraodontidae, Tetraodontiformes) sont signalées. De plus, deux espèces d'Hysterothylacium Ward et Magath, 1917, H. alatum Moravec et Justine, 2015 et H. epinepheli (Yamaguti, 1941), ont été trouvées chez la saumonée Plectropomus leopardus (hôte-type) et chez la loche uitoé Epinephelus maculatus (nouvel hôte) (Serranidae, Perciformes), respectivement. Il s'agit de la deuxième mention d'H. epinepheli depuis sa description originale au Japon il y a 79 ans. La plupart des espèces ont été décrites sur la base d'études au microscope optique et électronique.