Clara Lord

Femtosecond laser ablation ICP-MS measurement of otolith Sr:Ca and Ba:Ca composition reveal differential use of freshwater habitats for three amphidromous Sicyopterus (Teleostei: Gobioidei: Sicydiinae) species

The use of freshwater habitats was examined in three amphidromous goby species of the genus Sicyopterus using otolith microchemistry. Two species were endemic to either New Caledonia or Vanuatu whilst the other was widely distributed. Depositional patterns of strontium (Sr) and barium (Ba) in the otolith of adults were analysed with femtosecond laser ablation inductively coupled plasma mass spectrometry (ICP-MS). The Sr:Ca and Ba:Ca results uncovered three different adult behaviours within the freshwater habitat. Some fishes stayed in elevated locations (square profile); others undertook back-and-forth migrations between higher and lower reaches (up-and-down profile), and finally, others stayed in the lower reaches (constant profile). The consequences of these movements to larval survival or competition for food and territory are discussed. This work brings new knowledge on amphidromous behaviour, and it highlights the necessity of multi-elemental analysis to study amphidromy in freshwater systems.

Tropical and temperate freshwater amphidromy: a comparison between life history characteristics of Sicydiinae, ayu, sculpins and galaxiids

Amphidromy is a distinctive form of diadromy, but differences in the life histories of tropical and temperate amphidromous fishes suggest that there are two types of freshwater amphidromy. The life histories of Sicydiinae gobies, ayu (Plecoglossus altivelis), Japanese sculpins (Cottus) and galaxiids (Galaxiidae), suggest that the Sicydiinae are representatives of tropical freshwater amphidromy, whereas ayu, sculpins and galaxiids are representatives of temperate freshwater amphidromy. The Sicydiine larval stage may be required to occur in the ocean for all species, but ayu, sculpins and galaxiids have landlocked or fluvial forms with larvae that do not need to enter the ocean for larval feeding and growth. This suggests that Sicydiine larvae have a high oceanic dependency whereas ayu, sculpins and galaxiid larvae have a low oceanic dependency. Freshwater amphidromous fish in tropical and temperate zones appear to have developed two different strategies in the evolution of their life histories. It is likely that the evolutionary direction of the larval stage of tropical amphidromy is to remain in the sea and that of temperate amphidromy is towards having the ability to remain in freshwater if needed. Tropical and temperate amphidromy appear to be biologically informative categories and evaluations of this hypothesis will facilitate better understanding of the various forms of amphidromy in the future.

Otolith shape analysis for three Sicyopterus (Teleostei: Gobioidei: Sicydiinae) species from New Caledonia and Vanuatu

Otolith shape analysis has been used in a number of studies as an inexpensive and powerful method for categorising fish in individual stocks. Elliptical Fourier analysis was used on three different amphidromous Sicyopterus species. Sicyopterus lagocephalus is a widespread species while the other two have a limited distribution area, Sicyopterus aiensis being endemic to Vanuatu, and Sicyopterus sarasini to New Caledonia. Both endemics live in sympatry with the widespread species. The otolith shape of all fish sampled was a clear species differentiator, thereby demonstrating that otolith shape is species-specific. At an intraspecific level there are different river populations within samples from Vanuatu, indicating a western group and an eastern “central” group.These results are congruent both for the endemic species, S. aiensis and for the cosmopolitan species. Finally, we found that, for S. lagocephalus, the cosmopolitan species, New Caledonian samples are close to western Vanuatu samples, the latter two being well differentiated from the eastern “central” Vanuatu samples. The explanation for these results may lay either in the influence of environmental factors on the otolith shape, or in the influence of common early life history thus reflecting genetic factors, or a combination of both.

Threatened fishes of the world: Sicyopterus sarasini Weber & de Beaufort, 1915 (Gobiidae)

Common name: “Sicyoptere de Sarasin” or “Lochon”. Conservation status: critically endangered. Identification: D1 VI, D2 I + 10, A I + 10, C 11–14, P 17–19, LL 45–65. Maximum standard length: 15 cm (Watson et al. 2000) (Illustration by Clara Lord). Distribution: Endemic to New Caledonia. Inventories between 1995 and 2000 by MNHN found it in 17 catchment areas in South Province (Marquet et al. 2003); February 2007 inventory found it only in four (Kwatea, Trou Bleu, Nera and Barendeu Rivers). Abundance: Largely relictual. Best-preserved populations in Trou Bleu and Barendeu Rivers. “Cote Oubliee” populations suspected in good health. Habitat and ecology: Strictly lives in rivers with peridotite beds, in clear, well-oxygenated water (current speed 30–80 cm·s) 20–40 cm deep, on pebbles or rocks; adheres to substrate with sucker-like pelvic fins. Scrapes diatoms and algal food off substrate (Marquet et al. 2003). Reproduction: Amphidromous. Spawns in rivers. River current carries planktonic larvae to sea. Several months later, they return to rivers where they metamorphose into juveniles (Keith 2003), and climb up waterfalls with their sucker, colonising upper streams. Threats: River physical deterioration and water pollution from nickel mining and deforestation. Silt deposits on rocks prevent algal growth, eliminating predominant food source; also prevents fish adhesion to rocks, thus decreasing access to headwater habitats and spawning ground availability. Conservation actions: No legal protection or conservation activity. Conservation recommendations: Inventory and monitoring of remaining stock. Study Environ Biol Fish (2008) 83:169–170 DOI 10.1007/s10641-007-9311-9

Threatened fishes of the world: Protogobius attiti Watson & Pöllabauer, 1998 (Rhyacichthyidae)

tus: Critically endangered. Identification: D1 VIIVIII, D2 I+8, A I+8, C 13-16, P 18-19, LL 30-32. Body subcylindrical and slightly compressed, head slightly pointed and sub-inferior mouth. Lateral line scales ctenoid; lateral line is complete from head to hypural base. Predorsal medium line has 10–12 scales, generally ctenoid. Five to six scales in transverse back series. The belly has cycloid anterior scales and ctenoid scales behind the anus. Snout and preopercule naked. Sixteen to twenty one scales on the operculum. Seven scales in zigzag series. Jaws with conical teeth, generally curved, 5–6 rows anteriorly and 1–2 rows laterally. Males and females have similar colorations: the body is speckled with red-orange and white dots on the back and flanks, the belly is greyish; the flanks have a line of black dots coming from the operculum to the base of the caudal fin. Pectoral, pelvic, anal and caudal fins are hyaline to pinkish. The female has a black dot and a red dot, both fringed by a white line, on the upper part of the first dorsal fin. Totally black male specimens also exist, with a golden line on the flanks. Size up to 80 mm (Marquet et al. 2003). Distribution: The Rhyacichthyidae family includes two genera (Protogobius and Rhyacichthys) and three species. Two of them occur in New Caledonia (Keith 2002). The genus Protogobius is endemic of South Province, New Caledonia and is one of the most primitive gobies known to date. The species is currently known from nine streams. The first specimens have been found in two rivers: the Fausse Yaté River and the Trou Bleu River. Abundance: The populations found in the nine streams are more or less dynamic, and sometimes relictual. The best preserved populations are found in the Pourina and Ni rivers, located on the Côte oubliée (Forgotten Coast), where the catchment area should be entirely protected. Habitat and ecology: Protogobius attiti prefers clear, well-oxygenated streams on peridotite gravel and rock substrate. It prefers regions with overhanging vegetation in slower areas of swift streams. Rocks and gravel are usually coated with detritus. When threatened, P. attiti dives into the substrate with its eyes, mouth and first dorsal fin above the gravel. Protogobius attiti is carnivorous and feeds principally C. Lord (&) Æ P. Keith Département Milieux et Peuplements Aquatiques, Muséum national d’Histoire naturelle, CP 26, 43, rue Cuvier, 75231 Paris cedex 05, France e-mail: claralord@mnhn.fr Environ Biol Fish (2006) 77:101–102 DOI 10.1007/s10641-006-9060-1