Age and growth of the mutton hamlet Alphestes afer, with a review of the size and age of sex change among epinephelids.

This paper presents results on the age, growth and population structure of a small grouper, the mutton hamlet Alphestes afer, and discusses the observed size and age structure patterns in relation to reproductive strategies among the epinephelids. Ages were determined by examination of sectioned otoliths, which showed a distinct pattern of alternating translucent and opaque zones that formed annually, as validated with tetracycline labelling. The von Bertalanffy growth function was adjusted to the length-at-age data of the males and females, but no significant differences were observed between the resulting parameters. The females, however, were older at given sizes and attained larger sizes and ages, with a maximum observed longevity of 13 years and a total length (LT ) of 26 cm, while the males attained maximum longevities of only 10 years and a 22 cm maximum LT . The LT and age range for the sex change was 16-25 cm and 3-11 years. The total mortality rate (Z) was estimated to be 0·55 for females and 0·82 for males. With the males younger and smaller than the females, this species differed from the pattern commonly observed for protogynous epinephelids. Males had slower growth after maturation, probably due to energy allocation to sperm production during sexual development. This study shows that demography is an important tool to understand the pathways for reproductive strategies in grouper populations.

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.

Effects of life phase and schooling patterns on the foraging behaviour of coral-reef fishes from the genus Haemulon.

During this study (December 2009 to December 2010), underwater visual surveys using the focal animal method were performed in the coastal reefs of Tamandaré, north-eastern Brazil. The aim was to analyse the effects of the life phase (juvenile and adult) and schooling patterns (school and solitary) on the feeding behaviour (foraging rates and substratum preferences) of four species of the genus Haemulon (Haemulon aurolineatum, Haemulon parra, Haemulon plumieri and Haemulon squamipinna). PERMANOVA analysis (P < 0·05) indicated that ontogenetic changes and schooling patterns directly influence foraging behaviour. Schooling individuals had low foraging rates (mean ± s.d. = 2·3 ± 2·1 bites 10 min(-1)) and mobility, usually remaining near the bottom; however, solitary fishes had high foraging rates (mean ± s.d. = 12·5 ± 4·6 bites 10 min(-1)). Juveniles preferred feeding in the water column (75% of the total number of bites), whereas adults foraged mainly in sand (80%) and bare rock (20%). All four Haemulon species displayed similar patterns of feeding behaviour as well as preferences for foraging sites and display competition for food resources. In contrast, little is known about their habitat use and foraging behaviour over the diel cycle, particularly the newly settled and early juvenile stages.

Zooplankton exposure to microplastic contamination in a estuarine plume-influenced region, in Northeast Brazil.

This work describes the spatio-temporal distribution of suspected plastic and microplastic (MP) particles in estuarine plumes and analyzes the microplastic/zooplankton ratio. Subsurface hauls with a conical-cylindrical net were deployed in the coastal area of Tamandare (Pernambuco, Brazil), covering the plume of two rivers and a bay adjacent to coral reefs. A total of 2079 suspected plastic particles were detected, mostly fibers and fragments (>60%). Organic matter digestion was made using a 30% hydrogen peroxide solution, of which approximately 50% of suspected particles were validated as MPs. The average MP abundance was significantly higher during the high rainfall season (53.8 ± 89.6 and 18.8 ± 32.3 particles/m³, respectively), with higher values registered in the plume area (108.9 ± 158.5 and 44.6 ± 55.5 particles/m³). Polymer identification using FT-IR confirmed that suspected particles were mainly polypropylene, polyamide, and polyurethane. These results confirm the hypothesis of a temporal transport variation of MPs from the river to the coastal environments, particularly since the plume influences debris input. Eleven animal phyla were identified, and the subclass Copepoda was predominant (90%), particularly the nauplius stage (70%). Over 70% of verified MPs range between 20 and 2000 µm, equivalent to the most common size of zooplanktonic organisms. Results support that coastal areas near estuarine plumes are exposed to microplastic contamination, affecting species dependent on zooplankton in marine coastal food webs.

Assessment of basal and gonadotropin-releasing hormone-stimulated gonadotropins by immunochemiluminometric and immunofluorometric assays in normal children.

CONTEXT: Recently, new methodologies have been applied to commercial immunofluorometric (IFMA) and immunochemiluminometric (ICMA) LH and FSH assays. OBJECTIVE: The objective of the study was to use ICMA to establish basal and GnRH-stimulated LH and FSH reference values in normal subjects of different ages and sexual development, compared with IFMA. DESIGN AND METHODS: We established basal and GnRH-stimulated LH and FSH levels of 315 prepubertal and pubertal children (170 males and 145 females) divided into five groups according to Tanner stage. Of these, 106 subjects (59 males and 47 females) were submitted to GnRH test. The prepubertal upper limit of normal for basal LH, determined by the 95th percentiles of the prepubertal population, were 0.2 IU/liter (ICMA) and 0.6 IU/liter (IFMA) in both genders. RESULTS: No overlap of basal LH levels determined by ICMA was observed between prepubertal and pubertal males, but basal LH determined by IFMA overlapped in 11.8% of subjects. In girls, both methods yielded overlapping values (10.4%, ICMA; and 84.6%, IFMA). The LH peak after GnRH stimulation that defined puberty was 4.1 IU/liter (ICMA) and 3.3 IU/liter (IFMA) in boys and 3.3 IU/liter (ICMA) and 4.2 IU/liter (IFMA) in girls. After GnRH stimulation, values determined by the two methods overlapped in both genders. CONCLUSIONS: We conclude that ICMA is more sensitive and precise than IFMA, permitting differentiation of pubertal and prepubertal stage in boys under basal conditions. However, in girls the overlap of basal values was marked, indicating the need for the GnRH test to establish maturity of the hypothalamus-pituitary-gonadal axis.