Daily age, growth rate, and pelagic larval duration of commercially important snapper species in Abrolhos National Marine Park.

The age and daily growth of fish are registered through the deposition of increments in their otoliths, which are concretions formed by the precipitation of substances present in the endolymphatic fluid, mainly calcium carbonate (CaCO3). Faced with the need to fill some of the gaps in the knowledge on the occurrence and duration of the initial stages of snapper species' life cycles in the Abrolhos Bank, this study aimed to describe the growth rates, age, and period of pelagic larval duration (PLD) of three snapper species during the larval pre-settlement phase, in the Abrolhos Bank region. The post-larvae were captured using light traps. Otoliths were removed from 117 samples of snapper species; however, only 69 were viable for age estimation, of which 15 were Lutjanus analis, 25 were Lutjanus jocu, and 29 were Lutjanus synagris. Together, the samples presented individuals with total lengths ranging from 16.14 to 24.76 mm and ages from 21 to 39 days. Settlement marks were found for all three species, and the average PLD was ~25 days. The somatic growth of the snapper species was positively correlated with otolith growth. L. jocu presented the greatest daily growth compared to the other species. The three species use the Abrolhos Bank as a larval settlement site, demonstrating plasticity by using different habitats throughout their lives.

Testing assumptions underlying cabezon (Scorpaenichthys marmoratus) otolith microstructure analysis using wild-caught juveniles and opportunistic rearing of eggs and larvae.

Otolith microstructure analysis provides critical biological and ecological information about the early life history of fishes. This information is particularly important to interpret and predict population dynamics for socio-economically important fisheries species; nonetheless, several key assumptions underpin the use of otolith techniques. The authors validated the use of this analysis for cabezon (Scorpaenichthys marmoratus; Ayres, 1854), a long-lived, large-bodied cottid constituent of nearshore fisheries from Baja California, Mexico, to Alaska, USA. To test three critical assumptions, the authors coupled otolith and morphometric analyses from an opportunistic rearing study of cabezon eggs and larvae with a long-term time series of juvenile cabezon field collections. The authors confirmed the daily otolith increment deposition in laboratory-reared larvae, identified the timing of first otolith increment deposition and examined the relationship between otolith growth and somatic growth in field-collected juveniles, validating the use of otolith microstructure analysis in biological and ecological interpretations of early life-history traits for this species. The findings of this study also indicated that the absorption of yolk-sac reserves, and likely the transition to exogenous feeding, plays an important role in regulating otolith increment deposition. Finally, the authors found within-brood size-at-age variation, which may be an advantage for young fish in prey-limited environments.

Hydrological connectivity drives longitudinal movement of endangered endemic Chilean darter Percilia irwini (Eigenmann, 1927).

Movement is a fundamental aspect of fish ecology, and it therefore represents an important trait to monitor for the management and conservation of fish populations. This is especially true for small benthic fish, as they often inhabit part of the catchment where their movement may be restricted by alterations to river connectivity due to human activity. Still, the movement of these small benthic fish remains poorly understood, partly because of their small size and their cryptic nature. This applies to Percilia irwini, an endangered small darter native to the south-central region of Chile. Its habitat has been affected by the presence of large hydroelectric dams and is currently threatened by the construction of several others. In this study, the authors investigated movement patterns of P. irwini from populations inhabiting different parts of the Biobío catchment, with different levels of connectivity due to natural and/or human-induced features. The authors combined chronological clustering with random forest classification to reconstruct lifelong movements from multi-elemental otolith microchemistry transects. The majority of the movements detected occurred in an undisturbed part of the catchment. These were directional upstream movements occurring between capture sites from the lower and the middle reaches of the river, representing a distance of nearly 30 km, a distance much larger than previously thought. Nonetheless, in the part of the catchment where connectivity was affected by human activity, no such movements were identified. This study shows that connectivity alteration could impede naturally occurring movement and further threaten the resilience of populations of P. irwini. Furthermore, the results presented are used to discuss advantages and disadvantages of microchemistry analysis for studying movement of small benthic fish.

White mullet Mugil curema population structure from Mexico and Brazil revealed by otolith chemistry.

The white mullet Mugil curema supports several fisheries in the neotropical region; nevertheless, the population structure is still elusive. The aim of this study was to assess the presence of adult management units and nursery areas from five sampling sites throughout the Gulf of Mexico and northern Brazil using otolith microchemistry. The Li/Ca, Na/Ca, Mn/Ca, Sr/Ca, Ba/Ca and Pb/Ca ratios were measured in otolith core (juvenile stage) and edge (adult stage) (N = 131) using laser ablation-inductively coupled plasma-mass spectrometry. Several ratios were significantly different between sampling sites for core and edge (P < 0.05). For otolith edge, permutational multivariate analysis of variance showed significant differences (P < 0.05) between all sampling sites from Mexico (except between Mecoacán and Tamiahua, P > 0.05) and between Mexico (pooled samples) and Brazil. Quadratic discriminant analyses showed jackknifed classification higher in the edge (66.6% and 99.5% for Mexico and Brazil plus Mexico, respectively) than in the core (46.3% and 76.5% Mexico and Brazil plus Mexico, respectively). The two cluster analyses based on the core microchemistry (Mexico and Brazil plus Mexico) produced three main clusters, which did not coincide with catchment areas. These results support the segregation of the M. curema adult life stages among several sampling sites from Mexico and Brazil; moreover, core analysis suggested that the nursery areas did not correspond to the capture sites or adults stocks.

Functional evaluation and testing of a newly developed Teleost's Fish Otolith derived biocomposite coating for healthcare.

Polymers such as polycaprolactone (PCL) possess biodegradability, biocompatibility and affinity with other organic media that makes them suitable for biomedical applications. In this work, a novel biocomposite coating was synthesised by mixing PCL with layers of calcium phosphate (hydroxyapatite, brushite and monetite) from a biomineral called otolith extracted from Teleost fish (Plagioscion Squamosissimus) and multiwalled carbon nanotubes in different concentrations (0.5, 1.0 and 1.5 g/L). The biocomposite coating was deposited on an osteosynthesis material Ti6Al4V by spin coating and various tests such as Fourier transformation infrared spectroscopy (FTIR), Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), scratch tests, MTT reduction cytotoxicity, HOS cell bioactivity (human osteosarcoma) by alkaline phosphatase (ALP) and fluorescence microscopy were performed to comprehensively evaluate the newly developed biocoating. It was found that an increase in the concentration of carbon nanotube induced microstructural phase changes of calcium phosphate (CP) leading to the formation of brushite, monetite and hydroxyapatite. While we discovered that an increase in the concentration of carbon nanotube generally improves the adhesion of the coating with the substrate, a certain threshold exists such that the best deposition surfaces were obtained as PCL/CP/CNT 0.0 g/L and PCL/CP/CNT 0.5 g/L.

Life history of northern Gulf of Mexico Warsaw grouper Hyporthodus nigritus inferred from otolith radiocarbon analysis.

Warsaw grouper, Hyporthodus nigritus, is a western Atlantic Ocean species typically found at depths between 55 and 525 m. It is listed as a species of concern by the U.S. National Marine Fisheries Service and as near threatened by the International Union for the Conservation of Nature. However, little information exists on the species' life history in the northern Gulf of Mexico (nGOM) and its stock status in that region is currently unknown. Age of nGOM Warsaw grouper was investigated via opaque zone counts in otolith thin sections (max age = 61 y), and then the bomb 14C chronometer was employed to validate the accuracy of age estimates. Otolith cores (n = 14) were analyzed with accelerator mass spectrometry and resulting Δ14C values overlain on a loess regression computed for a regional coral and known-age red snapper Δ14C time series. Residual analysis between predicted Δ14C values from the loess regression versus Warsaw grouper otolith core Δ14C values indicated no significant difference in the two data series. Therefore, the accuracy of otolith-based aging was validated, which enabled growth and longevity estimates to be made for nGOM Warsaw grouper. Dissolved inorganic carbon (DIC) Δ14C values collected from the nGOM support the inference that juvenile Warsaw grouper occur in shelf waters (<200 m) since DIC Δ14C values in this depth range are enriched in 14C and similar to the Δ14C values from otolith cores. A Bayesian model was fit to fishery-dependent age composition data and produced von Bertalanffy growth function parameters of L∞ = 1,533 mm, k = 0.14 y-1, and t0 = 1.82 y. Fishing mortality also was estimated in the model, which resulted in a ratio of fishing to natural mortality of 5.1:1. Overall, study results indicate Warsaw grouper is a long-lived species that is estimated to have experienced significant overfishing in the nGOM, with the age of most landed fish being <10 y.

Coastal zone use and migratory behaviour of the southern population of Mugil liza in Brazil.

We analysed the ratios Sr:Ca and Ba:Ca in the otoliths of 55 adults of the southern population of Mugil liza in Brazil (Paraná to Rio Grande do Sul) to investigate its coastal zone use and migratory behaviour. All individual M. liza analysed had Sr:Ca and Ba:Ca values indicating that their birth was in the marine environment, which is consistent with the southern population migration to spawn in the ocean,. Juveniles exhibited at least three coastal use and recruitment strategies (contingents): the majority (89%) of M. liza juveniles migrated toward brackish water. They entered the estuary before completing the first year of life (64%) or after (25%) their first year of life. The remaining 11% did not appear to enter brackish or freshwater water as a nursery or at any point in their life cycle. Some adults returned to the estuary after spawning in the ocean but others (of both sexes) never returned to the estuary after spawning, remaining in the marine environment. The pattern of juvenile habitat use in the Brazilian southern population of M. liza seems to be recurrent throughout the extent of its distribution as a consequence of the reproductive spawning aggregation behaviour, which mixes all contingents (with marine or estuarine preferences).

Reconstructing reef fish communities using fish otoliths in coral reef sediments.

Little is known about long-term changes in coral reef fish communities. Here we present a new technique that leverages fish otoliths in reef sediments to reconstruct coral reef fish communities. We found over 5,400 otoliths in 169 modern and mid-Holocene bulk samples from Caribbean Panama and Dominican Republic mid-Holocene and modern reefs, demonstrating otoliths are abundant in reef sediments. With a specially-built reference collection, we were able to assign over 4,400 otoliths to one of 56 taxa (35 families) though mostly at genus and family level. Many otoliths were from juvenile fishes for which identification is challenging. Richness (by rarefaction) of otolith assemblages was slightly higher in modern than mid-Holocene reefs, but further analyses are required to elucidate the underlying causes. We compared the living fish communities, sampled using icthyocide, with the sediment otolith assemblages on four reefs finding the otolith assemblages faithfully capture the general composition of the living fish communities. Radiocarbon dating performed directly on the otoliths suggests that relatively little mixing of sediment layers particularly on actively accreting branching coral reefs. All otolith assemblages were strongly dominated by small, fast-turnover fish taxa and juvenile individuals, and our exploration on taxonomy, functional ecology and taphonomy lead us to the conclusion that intense predation is likely the most important process for otolith accumulation in reef sediments. We conclude that otolith assemblages in modern and fossil reef sediments can provide a powerful tool to explore ecological changes in reef fish communities over time and space.

Leave forever or return home? The case of the whitemouth croaker Micropogonias furnieri in coastal systems of southeastern Brazil indicated by otolith microchemistry.

Movements of coastal fish species between estuarine systems (rearing grounds) and adjacent platforms (spawning grounds) are complex and can be influenced by multiple biotic and abiotic factors associated with the life cycle of each species. Understanding fish movement patterns between these habitats is crucial for sustainable management of these resources. We aimed to identify movement patterns of the whitemouth croaker Micropogonias furnieri, an important fishery resource along the southeastern Brazilian coast, through characterization of elemental concentration profiles in otoliths. Signal intensity ratios of Sr86:Ca43 and Ba138:Ca43, measured by a Laser ablation inductively coupled to a plasma mass spectrometry (LA-ICPMS), were analysed. Juveniles and adults fish from three semi-enclosed systems (two bays and one coastal lagoon) and adults from nine adjacent coastal areas were examined. Three main behavioural patterns were identified: 1) Marine Migrant, with a unique and definitive movement from the estuarine area towards the adjacent platform when adult; 2) Estuarine Visitor, with movements from the estuarine area towards the adjacent platform when adult but also performing excursions back to the estuarine areas and back again to the adjacent platform; and 3) Nearshore Resident, with occurrence in the adjacent coastal areas that are influenced by estuarine systems. Estuarine areas with large sea connections (e.g., bays) favour more frequent fish entrances and exits compared with coastal lagoons that have a narrow sea connection. The high eurioic condition and capacity related to adapting to different environmental conditions were detected in this study for M. furnieri, a likely strategy to maintain variation in life histories and successfully adapt to coastal marine systems.

Mn2+ concentrations in coastal fish otoliths: understanding environmental and biological influences from EPR.

The Mn2+ concentrations in the sagittae otoliths of 12 fish families (and 19 species) that co-occur in a coastal area of southeastern Brazil (~21°S) were quantified using electron paramagnetic resonance (EPR). Inferences were made about the relationship between fish habitat and trace element incorporation. Inferences were made on the relationship between trace element concentration and otolith shape. The differences in Mn2+ concentrations among the species suggest that habitat (and feeding habits) might drive the incorporation of this trace element into fish otoliths, with higher values in bottom-associated fish species than in surface-associated species. In surface-associated fish species, the correlation between trace element concentrations and otolith shape was stronger than in bottom-associated species. Thus, while the Mn bioavailability in a fish's habitat, especially from feeding resources, is a local driving influence of trace element incorporation in sagittae otoliths, species-specific requirements also have an influence. Quantitative EPR is a non-destructive technique that is very useful when the available samples cannot be damaged, like with otolith collections.

Associations between metal exposure and lesion formation in offshore Gulf of Mexico fishes collected after the Deepwater Horizon oil spill.

The objectives of this study were to: (1) examine patterns of short- and long-term metal exposure within the otoliths of six offshore fish species in varying states of health, as indicated by the presence of external skin lesions, and (2) determine if there was a change in otolith metal concentrations concurrent with the Deepwater Horizon (DWH) oil spill. Otoliths collected from 2011 to 2013 in the Gulf of Mexico (GOM) were analyzed for a suite of trace metals known to be associated with DWH oil. We found that lesioned fish often had elevated levels of otolith 60Ni and 64Zn before, during, and after the DWH oil spill. In addition, metal exposure varied according to species-specific life history patterns. These findings indicate that lesioned individuals were exposed to a persistent source of trace-metals in the GoM prior to the oil spill.

Spatial and temporal variability in the otolith chemistry of the Brazilian snapper Lutjanus alexandrei from estuarine and coastal environments.

Otolith chemistry of juvenile and adult individuals of the Brazilian snapper Lutjanus alexandrei was measured to assess the utility of natural markers for investigating individual movements. Individuals were collected over a 3-year period (2010-2012) along the north-eastern coast of Brazil from both estuarine (juvenile to sub-adult stages) and coastal (sub-adult to adult stages) areas. Six elements ((7) Li, (24) Mg, (55) Mn, (59) Co, (88) Sr and (137) Ba) were measured in sectioned otoliths of L. alexandrei using laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS). Edge composition analysis indicated that element:Ca ratios in the otoliths of juvenile and sub-adult L. alexandrei from estuaries were not significantly different among the three consecutive years (2010, 2011 and 2012), suggesting that physicochemical conditions within the nursery area investigated were temporally stable. Similarly, apart from two elements (Ba and Co), element:Ca ratios for larger L. alexandrei inhabiting coastal waters were also similar. In contrast, otolith chemistry of similar sized L. alexandrei from estuarine and coastal areas was significantly different (based on recently accreted material). Otolith Mn:Ca and Ba:Ca were both significantly higher for L. alexandrei collected in estuaries compared to fish from adjacent coastal reefs, while the opposite trend was observed for Sr:Ca. Given the pronounced differences in otolith chemistry between estuarine and coastal areas, element:Ca transects were constructed from the core to margin of the otoliths for adults (age 7+ years) collected on reefs to determine the timing of movement (ontogenetic migration) from estuarine to coastal areas. Based on observed patterns of decline for both Mn:Ca and Ba:Ca, it appears that L. alexandrei begin the move to more coastal habitats (i.e. lower element:Ca ratios) after age 2 years. The patterns observed for this species highlight the importance of conserving connectivity between coastal habitats to maintain sustainable fish stocks exploited by artisanal fisheries.

Identification of nurseries areas of juvenile Prochilodus lineatus (Valenciennes, 1836) (Characiformes: Prochilodontidae) by scale and otolith morphometry and microchemistry

The streaked prochilod Prochilodus lineatus (Valenciennes) is a commercially freshwater species from South America, distributed in the Plata basin. In the present work the morphometry (circularity, rectangularity, form factor, OL/OW and ellipticity indices) and chemistry (Sr:Ca, Ba:Ca, Zn:Ca) of lapilli otolith, and geometric morphometry of scales of streaked prochilod juveniles, in two sites in the Plata basin (Uruguay River and Estrella Wetland), were compared to determine if they are area-specific and to identify possible breeding areas. Otolith Ba:Ca ratios was 0.017±0.003 mmol/mol for Uruguay River while for Estrella Wetland individuals was bellow the detection limits. Zn:Ca ratios tended to be higher for the latter (0.03±0.002 mmol/mol). Significantly high circularity and low rectangularity values were obtained for Estrella Wetland otoliths (p < 0.05), while no significant differences for form factor, OL/OW and ellipticity were observed between sampling sites. Considering all scale geometric morphometry variables, discriminant analysis showed a good percentage of classification of individuals (90.5% for Estrella Wetland and 85.7 % for Uruguay River). These results indicate that the otolith microchemisty and morphometry (circularity and rectangularity indices) and scale morphometry are good markers of habitat and represent a potential tool for identification of streaked prochilod nursery areas.(AU)

El sábalo Prochilodus lineatus (Valenciennes) es una especie de importancia comercial de agua dulce de Sudamérica, distribuida en la cuenca del Plata. En este trabajo se comparó la morfometría (índices de circularidad, rectangularidad, factor de forma, OL/OW y elipticidad) y microquímica (Sr:Ca, Ba:Ca y Zn:Ca) del otolito lapilli, y la morfometría geométrica de las escamas de sábalos juveniles capturados en dos sitios de la cuenca del Plata (Río Uruguay y bañado la Estrella), para determinar si existen diferencias área-especificas e identificar posibles sitios de cría. La relación Ba:Ca del otolito fue 0.017±0.003 mmol/mol para el río Uruguay mientras que estuvo por debajo del límite de detección para los individuos del bañado la Estrella. La relación Zn:Ca tendió a ser más alta en el bañado la Estrella (0.03±0.002 mmol/mol). Se obtuvieron valores significativamente altos de circularidad y bajos de rectangularidad para el bañado la Estrella (p < 0.05), mientras que no se hallaron diferencias para el factor de forma, OL/OW y elipticidad. Considerando la morfometría geométrica de las escamas, el análisis discriminante mostró buenos porcentajes de clasificación (90.5% para el bañado la Estrella y 85.7 % para el Río Uruguay). Estos resultados indican que la microquímica y morfometría del otolito (índices de rectangularidad y circularidad) y la morfometría de las escamas son buenos marcadores de hábitat y representan una herramienta potencial para la identificación de sitios de cría del sábalo.(AU)

Identification of nurseries areas of juvenile Prochilodus lineatus (Valenciennes, 1836) (Characiformes: Prochilodontidae) by scale and otolith morphometry and microchemistry

The streaked prochilod Prochilodus lineatus (Valenciennes) is a commercially freshwater species from South America, distributed in the Plata basin. In the present work the morphometry (circularity, rectangularity, form factor, OL/OW and ellipticity indices) and chemistry (Sr:Ca, Ba:Ca, Zn:Ca) of lapilli otolith, and geometric morphometry of scales of streaked prochilod juveniles, in two sites in the Plata basin (Uruguay River and Estrella Wetland), were compared to determine if they are area-specific and to identify possible breeding areas. Otolith Ba:Ca ratios was 0.017±0.003 mmol/mol for Uruguay River while for Estrella Wetland individuals was bellow the detection limits. Zn:Ca ratios tended to be higher for the latter (0.03±0.002 mmol/mol). Significantly high circularity and low rectangularity values were obtained for Estrella Wetland otoliths (p < 0.05), while no significant differences for form factor, OL/OW and ellipticity were observed between sampling sites. Considering all scale geometric morphometry variables, discriminant analysis showed a good percentage of classification of individuals (90.5% for Estrella Wetland and 85.7 % for Uruguay River). These results indicate that the otolith microchemisty and morphometry (circularity and rectangularity indices) and scale morphometry are good markers of habitat and represent a potential tool for identification of streaked prochilod nursery areas.(AU)

El sábalo Prochilodus lineatus (Valenciennes) es una especie de importancia comercial de agua dulce de Sudamérica, distribuida en la cuenca del Plata. En este trabajo se comparó la morfometría (índices de circularidad, rectangularidad, factor de forma, OL/OW y elipticidad) y microquímica (Sr:Ca, Ba:Ca y Zn:Ca) del otolito lapilli, y la morfometría geométrica de las escamas de sábalos juveniles capturados en dos sitios de la cuenca del Plata (Río Uruguay y bañado la Estrella), para determinar si existen diferencias área-especificas e identificar posibles sitios de cría. La relación Ba:Ca del otolito fue 0.017±0.003 mmol/mol para el río Uruguay mientras que estuvo por debajo del límite de detección para los individuos del bañado la Estrella. La relación Zn:Ca tendió a ser más alta en el bañado la Estrella (0.03±0.002 mmol/mol). Se obtuvieron valores significativamente altos de circularidad y bajos de rectangularidad para el bañado la Estrella (p < 0.05), mientras que no se hallaron diferencias para el factor de forma, OL/OW y elipticidad. Considerando la morfometría geométrica de las escamas, el análisis discriminante mostró buenos porcentajes de clasificación (90.5% para el bañado la Estrella y 85.7 % para el Río Uruguay). Estos resultados indican que la microquímica y morfometría del otolito (índices de rectangularidad y circularidad) y la morfometría de las escamas son buenos marcadores de hábitat y representan una herramienta potencial para la identificación de sitios de cría del sábalo.(AU)

Is otolith microchemistry (Sr: Ca and Ba:Ca ratios) useful to identify Mugil curema populations in the southeastern Caribbean Sea?

The aim of the present study was to evaluate the potential use of otolith microchemistry (Sr:Ca and Ba:Ca ratios) to identify silver mullet, Mugil curema, populations in Southeastern Caribbean Sea. Fish samples were collected in 7 areas of Nueva Esparta State (Venezuela). The otolith Sr:Ca and Ba:Ca ratios and water Sr:Ca were determined (by ICP-OES and EDTA volumetric method). Otoliths Sr:Ca and Ba:Ca ratios and Sr:Ca partition coefficient of mullets in Cubagua island (south of the State) were significantly different from ratios in La Guardia (north of the State). A discriminant analysis of otolith Sr:Ca and Ba:Ca ratios separated Cubagua Island from La Guardia values. These results suggest the existence of different mullet groups in the Southeastern Caribbean Sea. For this, the simultaneous use of Sr:Ca and Ba:Ca ratios could be a potential tool to identify populations in the study area.

Is otolith microchemistry (Sr: Ca and Ba:Ca ratios) useful to identify Mugil curema populations in the southeastern Caribbean Sea? / A microquímica do otólito é um indicador do habitat de Mugil curema no sudeste do Mar Caribenho?

Abstract The aim of the present study was to evaluate the potential use of otolith microchemistry (Sr:Ca and Ba:Ca ratios) to identify silver mullet, Mugil curema, populations in Southeastern Caribbean Sea. Fish samples were collected in 7 areas of Nueva Esparta State (Venezuela). The otolith Sr:Ca and Ba:Ca ratios and water Sr:Ca were determined (by ICP-OES and EDTA volumetric method). Otoliths Sr:Ca and Ba:Ca ratios and Sr:Ca partition coefficient of mullets in Cubagua island (south of the State) were significantly different from ratios in La Guardia (north of the State). A discriminant analysis of otolith Sr:Ca and Ba:Ca ratios separated Cubagua Island from La Guardia values. These results suggest the existence of different mullet groups in the Southeastern Caribbean Sea. For this, the simultaneous use of Sr:Ca and Ba:Ca ratios could be a potential tool to identify populations in the study area.

Resumo O objetivo do presente estudo foi avaliar o potencial uso da microquímica do otólito (razões Sr:Ca e Ba:Ca) para identificar distintas populações de tainha, Mugil curema, no sudeste do mar caribenho. Os peixes foram coletados em 7 áreas do estado de Nueva Esparta (Venezuela). As razões Sr:Ca e Ba:Ca do otólito e a razão Sr:Ca da água foram determinadas (pelo ICP-OES e EDTA método volumétrico). As razões de Sr:Ca e Ba:Ca dos otólitos e o coeficiente de partição das tainhas da Ilha Cubagua (sul do estado) foram significativamente diferentes das razões de La Guardia (norte do estado). A análise discriminante das razões de Sr:Ca e Ba:Ca dos otólitos separa os valores da Ilha Cubagua e de La Guardia. Estes resultados sugerem a existência de diferentes grupos de Mugil curema no sudeste do mar Caribenho e que o uso simultâneo das razões Sr:Ca e Ba:Ca poderiam ser uma potencial ferramenta para identificar as populações da área de estudo.

Is otolith microchemistry (Sr: Ca and Ba:Ca ratios) useful to identify Mugil curema populations in the southeastern Caribbean Sea? / A microquímica do otólito é um indicador do habitat de Mugil curema no sudeste do Mar Caribenho?

The aim of the present study was to evaluate the potential use of otolith microchemistry (Sr:Ca and Ba:Ca ratios) to identify silver mullet, Mugil curema, populations in Southeastern Caribbean Sea. Fish samples were collected in 7 areas of Nueva Esparta State (Venezuela). The otolith Sr:Ca and Ba:Ca ratios and water Sr:Ca were determined (by ICP-OES and EDTA volumetric method). Otoliths Sr:Ca and Ba:Ca ratios and Sr:Ca partition coefficient of mullets in Cubagua island (south of the State) were significantly different from ratios in La Guardia (north of the State). A discriminant analysis of otolith Sr:Ca and Ba:Ca ratios separated Cubagua Island from La Guardia values. These results suggest the existence of different mullet groups in the Southeastern Caribbean Sea. For this, the simultaneous use of Sr:Ca and Ba:Ca ratios could be a potential tool to identify populations in the study area.(AU)

O objetivo do presente estudo foi avaliar o potencial uso da microquímica do otólito (razões Sr:Ca e Ba:Ca) para identificar distintas populações de tainha, Mugil curema, no sudeste do mar caribenho. Os peixes foram coletados em 7 áreas do estado de Nueva Esparta (Venezuela). As razões Sr:Ca e Ba:Ca do otólito e a razão Sr:Ca da água foram determinadas (pelo ICP-OES e EDTA método volumétrico). As razões de Sr:Ca e Ba:Ca dos otólitos e o coeficiente de partição das tainhas da Ilha Cubagua (sul do estado) foram significativamente diferentes das razões de La Guardia (norte do estado). A análise discriminante das razões de Sr:Ca e Ba:Ca dos otólitos separa os valores da Ilha Cubagua e de La Guardia. Estes resultados sugerem a existência de diferentes grupos de Mugil curema no sudeste do mar Caribenho e que o uso simultâneo das razões Sr:Ca e Ba:Ca poderiam ser uma potencial ferramenta para identificar as populações da área de estudo.(AU)

Variation in habitat use along the freshwater-marine continuum by grey mullet Mugil cephalus at the southern limits of its distribution.

In this study, habitat use by Mugil cephalus was investigated in the waters of the west coast of the North Island of New Zealand by analysing microchemical composition of otoliths (laser-ablation inductively coupled plasma mass spectrometry) obtained from individuals from commercial fish stocks and research surveys. Results of this study show that M. cephalus at the southern limits of its distribution display highly flexible migratory behaviour with extensive use of freshwater and brackish habitats, potentially enabling them to maximize foraging opportunities. Mugil cephalus can tolerate a wide range of salinities and can therefore utilize higher productivity areas, such as estuaries and eutrophic riverine lakes. Finally, M. cephalus populations across a range of climates and latitudes appear to differ in the extent to which they utilize freshwater and brackish habitats, possibly with increasing penetration of fresh waters with increasing latitude.

Use of otolith strontium: calcium and zinc:calcium ratios as an indicator of the habitat of Percophis brasiliensis Quoy & Gaimard, 1825 in the southwestern Atlantic Ocean

We evaluate the simultaneous use of Sr: Ca and Zn: Ca ratios of the sagitta otolith as a potential indicator of the habitat of Percophis brasiliensis along a latitudinal gradient in the southwestern Atlantic Ocean (34-42ºS and 51-67ºW), in order to reliably identify fish stocks. Fish were collected in three sampling sites: Argentine-Uruguayan Common Fishing Zone (AUCFZ), El Rincón (ER) and San Matías Gulf (SMG). The otolith Sr:Ca and Zn:Ca ratios were determined by ICP-OES and EDTA volumetric method. The otolith Sr:Ca ratio was similar in the three sampling sites, while the Zn:Ca ratio was significantly higher in AUCFZ than in ER and SMG for all age groups. The discriminant analysis showed an association between the otolith Sr:Ca and Zn:Ca ratios from ER and SMG. Present results suggest the potential occurrence of two fish stocks of P. brasiliensis in the study area.

Evaluamos el uso simultáneo de las relaciones Sr:Ca y Zn:Ca de los otolitos sagittae como un potencial indicador de hábitat de Percophis brasiliensis a lo largo de un gradiente longitudinal el Atlántico sudoccidental (34-42ºS - 51-67ºW) con el fin de contribuir a la identificación de los stocks pesqueros. Los peces fueron capturados en tres sitios de muestreo: Zona Común de Pesca Argentina-Uruguaya (ZCPAU), El Rincón (ER) y el Golfo San Matías (GSM). Las relaciones Sr:Ca y Zn:Ca se determinaron por ICP-OES y por titulación con EDTA. La relación Sr:Ca fue similar en los tres sitios de muestreo. La relación Zn:Ca fue mayor en la ZCPAU que en las demás areas (ER y GSM) para todos los rangos de edad. El análisis discriminante mostró una asociación entre las relaciones Sr:Ca y Zn:Ca de ER y GSM. Los resultados de este trabajo sugieren la presencia de al menos dos stocks de P. brasiliensis en el aérea de estudio.

Use of otolith strontium: calcium and zinc:calcium ratios as an indicator of the habitat of Percophis brasiliensis Quoy & Gaimard, 1825 in the southwestern Atlantic Ocean

We evaluate the simultaneous use of Sr: Ca and Zn: Ca ratios of the sagitta otolith as a potential indicator of the habitat of Percophis brasiliensis along a latitudinal gradient in the southwestern Atlantic Ocean (34-42ºS and 51-67ºW), in order to reliably identify fish stocks. Fish were collected in three sampling sites: Argentine-Uruguayan Common Fishing Zone (AUCFZ), El Rincón (ER) and San Matías Gulf (SMG). The otolith Sr:Ca and Zn:Ca ratios were determined by ICP-OES and EDTA volumetric method. The otolith Sr:Ca ratio was similar in the three sampling sites, while the Zn:Ca ratio was significantly higher in AUCFZ than in ER and SMG for all age groups. The discriminant analysis showed an association between the otolith Sr:Ca and Zn:Ca ratios from ER and SMG. Present results suggest the potential occurrence of two fish stocks of P. brasiliensis in the study area.(AU)

Evaluamos el uso simultáneo de las relaciones Sr:Ca y Zn:Ca de los otolitos sagittae como un potencial indicador de hábitat de Percophis brasiliensis a lo largo de un gradiente longitudinal el Atlántico sudoccidental (34-42ºS - 51-67ºW) con el fin de contribuir a la identificación de los stocks pesqueros. Los peces fueron capturados en tres sitios de muestreo: Zona Común de Pesca Argentina-Uruguaya (ZCPAU), El Rincón (ER) y el Golfo San Matías (GSM). Las relaciones Sr:Ca y Zn:Ca se determinaron por ICP-OES y por titulación con EDTA. La relación Sr:Ca fue similar en los tres sitios de muestreo. La relación Zn:Ca fue mayor en la ZCPAU que en las demás areas (ER y GSM) para todos los rangos de edad. El análisis discriminante mostró una asociación entre las relaciones Sr:Ca y Zn:Ca de ER y GSM. Los resultados de este trabajo sugieren la presencia de al menos dos stocks de P. brasiliensis en el aérea de estudio.(AU)