Pelagic larval duration of three amphidromous Sicydiinae gobies (Teleostei: Gobioidei) including widespread and endemic species

Sicydiinae species have an amphidromous life cycle during which they undergo a pelagic larval phase allowing them to disperse through the ocean and to recruit in distant island rivers. Hypotheses for the differences observed in dispersal abilities between species include the variation in pelagic larval duration (PLD). However, the implication of the PLD as a proxy for explaining the dispersal ability of a species is not clear in the Sicydiinae subfamily. In this study, otolith microstructure of three Sicydiinae species was analysed. One of these species, Sicyopus zosterophorum, has a widespread distribution in the West Pacific area, whereas the other two species, Smilosicyopus chloe and Akihito vanuatu, are endemic to New Caledonia and to Vanuatu, respectively. Deposition of the daily growth increments on the otoliths of S. zosterophorum was validated using an alizarin complexone time marking technique. We estimated the PLD for the three species by counting the number of growth increments from the core to the metamorphosis check mark, and it was shorter than the one of previous studies on Sicydiinae species. The PLD of the widespread species, S. zosterophorum (54.6 ± 5.6 days), was similar to those of the endemic species, S. chloe (53.6 ± 5.7 days) and A. vanuatu (55.4 ± 7.5 days). Here, we show that in contrast to the most diverse Sicydiinae genus, Sicyopterus, the PLD could not explain endemism, and we must take into account other elements to explain the differences observed in the distribution range.     

Insights on endemism: comparison of the duration of the marine larval phase estimated by otolith microstructural analysis of three amphidromous Sicyopterus species (Gobioidei: Sicydiinae) from Vanuatu and New Caledonia

Lord C, Brun C, Hautecœur M, Keith P. Insights on endemism: comparison of the duration of the marine larval phase estimated by otolith microstructural analysis of three amphidromous Sicyopterus species (Gobioidei: Sicydiinae) from Vanuatu and New Caledonia.
Ecology of Freshwater Fish 2010: 19: 26–38. © 2009 John Wiley & Sons A/S
Abstract –  The microstructure of otoliths of three amphidromous gobies (Sicydiinae) of the genus Sicyopterus has been analysed. One of these species, Sicyopterus lagocephalus has a widespread distribution whereas the other two are endemic ( Sicyopterus aiensis , from Vanuatu and Sicyopterus sarasini , from New Caledonia). The microstructural analysis of the otoliths showed that the duration of the marine larval phase is significantly shorter for both endemic species than for the cosmopolitan species (131 ± 3.4 days for S. lagocephalus , 79.2 ± 4.6 days for S. aiensis and 76.5 ± 3.9 days for S. sarasini ). These results led us to infer that it could be one of the factors explaining endemism. We have also improved our knowledge on the processes undergone during the marine phase by studying the growth of the otolith. This work allowed us to propose possible migration routes. These species' reproduction period has also been studied by back-calculating hatching dates. All these elements improve our understanding of the life-history traits and dispersion strategies of these species, which is crucial to implementing conservation measures in order to protect them and their environment, both threatened by anthropogenic actions.     

Pelagic larval traits of the amphidromous goby Sicyopterus lagocephalus display seasonal variations related to temperature in La Réunion Island

Amphidromous gobies represent a substantial part of freshwater fish diversity throughout islands of the Indo‐Pacific region. They display a marine pelagic phase during several months before recruiting in rivers. Understanding the relationship between larval traits and environmental conditions is a major challenge for the evaluation of a spatial scale of connectivity and populations’ dynamics, especially in a climate change context. In this study, the larval traits of Sicyopterus lagocephalus were examined and related to the sea surface temperature (SST), over three consecutive years in La Réunion Island (Mascarene archipelago). The pelagic larval duration (PLD, range from 96 to 293 days), the size‐at‐recruitment (range from 26.5 to 37 mm TL) and the larval growth rate (range from 0.112 to 0.293 mm·day^?1 TL) varied seasonally depending on hatching date. The larval growth rate was inversely correlated to the fluctuations of PLD and size. Larvae living in high sea water temperatures exhibited a faster growth, shorter PLDs and smaller sizes‐at‐recruitment than those living in cool water temperatures. The instantaneous daily growth was assessed by the study of otolith increment widths. The daily growth was not linear throughout larval life and was positively correlated to SST. We showed high amplitude of PLD periodic fluctuations (170.39 ± 43.75 days) related to temperature (12.8% PLD drop per degree), which could affect dispersal and induce intermittent connectivity between distant populations. This high plasticity of larval traits is likely to be advantageous to respond to the wide range of environmental conditions encountered throughout the species distribution range.     

Morphological changes during the transition from freshwater to sea water in an amphidromous goby,Sicyopterus lagocephalus (Pallas 1770) (Teleostei)

The widely distributed amphidromous goby Sicyopterus lagocephalus needs drastic change of habitat to fulfil its life cycle: adults live and spawn in rivers, where eggs hatch into prolarvae that have to reach the sea to acquire characteristics of planktonic larvae. Postlarvae return to rivers where they recruit and grow to the adult reproductive stage. Here, we describe the prolarval stages, namely from hatching to first contact with sea water, as well as the first marine larval stages. The observations were made under experimental conditions. We described 3 prolarval substages in freshwater (L1a–L1c). Prolarvae present a slight but visible ontogenetic development in freshwater, during which the yolk sac begins to reduce, the pigmentation increases on the body and in the eyes, and the lenses appear, although the eyes are not functional. Prolarvae need to reach the sea in a maximum of 96 h to pursue their development. Their transfer in sea water at a salinity of 36.5 induces important morphological modifications (i.e. yolk sac full absorption, appearance of pectoral fins, migration of the eyes in anterolateral position of the head, opening of mouth and anus), enabling the organisms to adapt to their new environment. This marine stage is divided into two substages: L2a corresponding to the organisation of the morphological structures adapted to the marine environment and L2b during which these morphological structures become functional. Whether it is in freshwater or sea water, the duration of the substages depends on the water temperature, but is similar for all individuals for a given temperature.     

Detection of full and limited amphidromous migratory dynamics of fish in Caribbean rivers

All native fishes living in the Caribbean island rivers are considered diadromous but few species have been validated as diadromous. In Guadeloupe (Lesser Antilles) as well as in the other tropical islands, the riverine habitats are subject to strong anthropogenic pressure due to resource modifications or dams. The management of fish biodiversity requires knowledge concerning their life history traits and behaviour that are still unknown for most species at a local scale and at the whole distribution area of the species. In a Guadeloupe river, we inferred the migratory patterns of four freshwater fishes common to Caribbean rivers by the analysis of otolith microchemistry. We found two species Eleotris perniger (Eleotridae) and Sicydium plumieri (Gobiidae) to be completely amphidromous with a marine larval phase and a freshwater adult phase. Agonostomus monticola (Mugilidae) was also found to be amphidromous in this system. The fourth species Gobiesox cephalus (Gobiesocidae) showed elemental ratios suggesting an estuarine larval phase and was defined as “limited amphidromous”. The identification of such life history traits, with limited dispersion abilities, argues for specific management measures in tropical island rivers at a basin scale for the conservation of biodiversity.     

Understanding the life histories of amphidromous fish by integrating otolith‐derived growth reconstructions,post‐larval migrations and reproductive traits

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Downstream drift of round goby (Neogobius melanostomus) and tubenose goby (Proterorhinus semilunaris) in their non‐native area

Several Ponto‐Caspian gobiid species have recently expanded their ranges in Europe and North America. This is the first study to demonstrate passive downstream dispersal (drift) of the round goby (Neogobius melanostomus) and tubenose goby (Proterorhinus semilunaris) in newly colonised areas (River Dyje, Danube basin), a factor that could play an important role in their dispersal. Drift duration (i.e. number of dates on which the species was caught) in round goby was longer than that of both native species and tubenose goby, providing a possible advantage. Size of drifting fish was restricted to a narrow range of 6–8 mm and 5–8 mm for round and tubenose goby, respectively. Drift in both species occurred almost completely during hours of darkness (<1 lux) and fish size did not vary throughout the night. In both species, drift density increased significantly during the first hour after dusk. Round goby density gradually decreased up to dawn, while tubenose goby density varied throughout the night with no clear pattern. Drift of early life stages appears to be an important phenomenon that has not received adequate attention in studies of round and tubenose goby ecology and dispersal.     

Using enriched stable isotopes of barium and magnesium to batch mark otoliths of larval golden perch (Macquaria ambigua,Richardson)

Woodcock SH, Gillanders BM, Munro AR, McGovern F, Crook DA, Sanger AC. Using enriched stable isotopes of barium and magnesium to batch mark otoliths of larval golden perch (Macquaria ambigua, Richardson). Ecology of Freshwater Fish 2011: 20: 157–165. © 2010 John Wiley & Sons A/S Abstract – Enriched stable isotope immersion techniques were used to mark the otoliths of larval golden perch (Macquaria ambigua) immediately post‐hatch. Two experiments were undertaken: the first involved rearing larvae in water enriched with three concentrations of ¹³⁷Ba for 1–5 days. Marks were produced in as little as 1 day; however, otolith isotope ratios reached equilibrium with the water in 5 days at 90 μg·l^?1. The second experiment involved rearing larvae in isotope enriched water with combinations of stable isotopes of Ba and Mg for 4 days after hatching. Seven significantly different isotopic signatures were produced using three Ba isotopes, which were reflective of the water. Only slight differences were found in otoliths of larvae that were reared in combinations of Mg isotopes, which did not reflect the water chemistry. The length of golden perch at 3 weeks of age showed that isotope immersion did not negatively affect early growth.     

Dispersal of black sea bass (Centropristis striata) larvae on the southeast U.S. continental shelf: results of a coupled vertical larval behavior – 3D circulation model

In the marine environment, pelagic dispersal is important for determining the distribution and abundance of populations, as well as providing connections among populations. Estimates of larval dispersal from spawning grounds are important to determining temporal and spatial patterns in recruitment that may have significant influences on the dynamics of the population. We present a case study of the dispersal of Centropristis striata (black sea bass) larvae on the southeast U.S. continental shelf. We use a coupled larval behavior – 3D circulation model to compare the effects of the timing and location of spawning against that of larval vertical migration on larval dispersal. Using the results of field data on larval vertical distributions, we compare the dispersal of virtual 'larvae' which have ontogenetic changes in vertical behavior with that of particles fixed near the surface and near the bottom. Larvae were released at potential spawning sites four times throughout the spawning season (February through May) for 3 yr (2002–04) and tracked for the assumed larval duration (from 27 to 37 days including the egg stage). Results indicate that adult behavior, in the form of spawning time and location, may be more important than larval vertical behavior in determining larval dispersal on the inner- and mid- continental shelves of this region.     

Migratory history of the freshwater goby Rhinogobius sp. CB in Japan

Tsunagawa T, Arai T. Migratory history of the freshwater goby Rhinogobius sp. CB in Japan. Ecology of Freshwater Fish 2011: 20: 33–41. © 2010 John Wiley & Sons A/S Abstract – The migratory histories of Rhinogobius sp. CB collected from 32 locations connected to the sea were studied by examining the strontium (Sr) and calcium (Ca) concentrations in the otoliths using X‐ray electron microprobe (EPMA) analysis. The Sr and Ca contents in the riverine water were also determined using inductively coupled plasma mass spectrometry (ICP‐MS) analysis. The Sr:Ca ratios in the riverine waters were highly different among rivers and correlated with those in the otolith outer region corresponding to the river life period. Consequently, almost all samples (159 of 160 individuals) showed a typical amphidromous life history, with one individual showing a landlocked life history. These results suggest that the clear differences of migration history in population or locality were not found in Rhinogobius sp. CB. Therefore, it was thought that Rhinogobius sp. CB most commonly had an amphidromous life history.     

Piscivory in larval perch (Perca fluviatilis): mechanisms structuring larval roach (Rutilus rutilus) cohorts

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Growth patterns of the otoliths of Stellifer rastrifer (Pisces: Sciaenidae) from the Sergipe River estuary (Sergipe, Brazil)

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Seasonal abundance and movement of the invasive round goby (Neogobius melanostomus) on rocky substrate in the Duluth–Superior Harbor of Lake Superior

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Transmission Ecology and Larval Behaviour of Camallanus cotti (Nematoda, Camallanidae) Under Aquarium Conditions

The parasitic fish nematode Camallanus cotti has been reported from a number of freshwater fish species around the world. Its wide geographical distribution seems mainly to be the result of anthropogenic dissemination due to extensive ornamental fish trade. In most reports it is assumed that C. cotti's life cycle involves cyclopoid copepods as intermediate host and various freshwater fishes as final host. However, the species' relatively frequent and persistent occurrence in aquaria worldwide strongly indicates flexibility in its life cycle, i.e. the ability to infect the final host directly. The present study has shown that under aquaria conditions, without any presence of copepods, C. cotti is able to infect various phylogenetically distant fish species directly for at least three generations. It was further shown that the infective free-living first-stage larvae may survive for more than three weeks in the host-external environment and that their host-attracting behaviour is not precluding direct transmission to the final fish host. Any treatment for C. cotti under aquaculture or aquarium conditions should be directed towards both individual infected fish hosts as well as the free-living larvae on the substrate. This revised version was published online in August 2006 with corrections to the Cover Date.     

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The effects of temperature on growth,development and settlement of northern rock sole larvae (Lepidopsetta polyxystra)

Northern rock sole (Lepidopsetta polyxystra) is a commercially important fish in the North Pacific and a focal species in understanding larval transport to nursery grounds in the Bering Sea. However, the temperature‐dependent vital rates and settlement dynamics for this species have not been described in detail. We reared northern rock sole larvae in the laboratory to measure growth, condition, development and settlement parameters across four temperatures (2, 4, 7 and 10°C). Both length and mass‐measured growth rates increased with temperature and were best described by non‐linear regression. Residuals of the length–mass relationships were positively related to temperature, indicating larval condition also increased with temperature. Larval development and settlement were largely size dependent, resulting in reduced larval stage duration and earlier settlement at higher temperatures owing to more rapid growth at elevated temperatures. However, larvae at colder temperatures were less developed at a given size, but more likely to settle at smaller sizes than larvae reared in warmer conditions. These temperature–response parameters can be used to refine current and future transport models for northern rock sole larvae under changing environmental conditions in the North Pacific.