Neonatal salt wasting syndrome: Aldosterone synthase deficiency caused by a new splicing variant in CYP11B2.

Aldosterone synthase deficiency (ASD) is a rare autosomal recessive disorder involving isolated aldosterone deficiency without any compromise of other adrenal hormones. This condition manifests mainly in the neonatal period and in infants as a salt wasting syndrome with vomiting and failure to thrive. Due to its potentially life-threatening effects, ASD requires a careful and early diagnosis based on appropriate hormonal investigations in order to initiate adequate management: rehydration as well as salt and fludrocortisone supplementation. Genetic analysis of the CYP11B2 gene will confirm ASD in most cases. We report the case of a newborn with a typical clinical presentation associated with some uncommon phenotypic features (hyperhidrosis, liver injury). Furthermore, our patient carries a new CYP11B2 splicing variant to be added to the approximately 60 pathogenic or likely pathogenic variants already reported.

Case Report: Longitudinal follow-up and testicular sperm extraction in a patient with a pathogenic NR5A1 (SF-1) frameshift variant: p.(Phe70Serfs*5).

Background: Steroidogenic factor 1 (SF-1), encoded by the nuclear receptor subfamily 5 group A member 1 (NR5A1) gene, is a transcriptional factor crucial for adrenal and gonadal organogenesis. Pathogenic variants of NR5A1 are responsible for a wide spectrum of phenotypes with autosomal dominant inheritance including disorders of sex development and oligospermia-azoospermia in 46,XY adults. Preservation of fertility remains challenging in these patients. Objective: The aim was to offer fertility preservation at the end of puberty in an NR5A1 mutated patient. Case report: The patient was born of non-consanguineous parents, with a disorder of sex development, a small genital bud, perineal hypospadias, and gonads in the left labioscrotal fold and the right inguinal region. Neither uterus nor vagina was detected. The karyotype was 46,XY. Anti-Müllerian hormone (AMH) and testosterone levels were low, indicating testicular dysgenesis. The child was raised as a boy. At 9 years old, he presented with precocious puberty treated by triptorelin. At puberty, follicle-stimulating hormone (FSH), luteinising hormone (LH), and testosterone levels increased, whereas AMH, inhibin B, and testicular volume were low, suggesting an impaired Sertoli cell function and a partially preserved Leydig cell function. A genetic study performed at almost 15 years old identified the new frameshift variant NM_004959.5: c.207del p.(Phe70Serfs*5) at a heterozygous state. He was thus addressed for fertility preservation. No sperm cells could be retrieved from three semen collections between the ages of 16 years 4 months and 16 years 10 months. A conventional bilateral testicular biopsy and testicular sperm extraction were performed at 17 years 10 months of age, but no sperm cells were found. Histological analysis revealed an aspect of mosaicism with seminiferous tubules that were either atrophic, with Sertoli cells only, or presenting an arrest of spermatogenesis at the spermatocyte stage. Conclusion: We report a case with a new NR5A1 variant. The fertility preservation protocol proposed at the end of puberty did not allow any sperm retrieval for future parenthood.

Changes in the clinical management of 5α-reductase type 2 and 17ß-hydroxysteroid dehydrogenase type 3 deficiencies in France.

Objectives: To examine the changes in diagnostic practices and clinical management of patients with 5α-reductase type 2 (SRD5A2) or 17ß-hydroxysteroid dehydrogenase type 3 (HSD17B3) deficiency since molecular diagnoses became available. Methods: Clinical, laboratory, and therapeutic data were retrieved from the medical records of 52 patients with a molecular diagnosis of SRD5A2 (n = 31) or HSD17B3 (n = 21) deficiency. Temporal trends regarding age at assessment and initial sex assignment over 1994-2020 were qualitatively analyzed. Age at molecular diagnosis was compared between two subgroups of patients according to their year of birth. Results: Fifty-eight percent (n = 30) patients were diagnosed during the perinatal period, 33% (n = 17) during infancy, and 9% (n = 5) during adolescence or adulthood. Over the studied period, the patients' age at initial assessment and diagnosis frankly decreased. The median (range) age at diagnostic confirmation was 10.5 (0-53.2) years for patients born before 2007 and 0.4 (0-9.3) years for those born in 2007 or later (P = 0.029). Genetic testing identified 27 different variants for the SRD5A2 gene (30% novel, n = 8) and 18 for the HSD17B3 gene (44% novel, n = 8). Before 2002, most patients were initially assigned as females (95%, n = 19), but this proportion dropped for those born later (44%, n = 14; P < 0.001). The influence of initial genital appearance on these decisions seemingly decreased in the most recent years. Therapeutic interventions differed according to the sex of rearing. Ten percent (n = 2) patients requested female-to-male reassignment during adulthood. Conclusion: This study showed, over the past two decades, a clear trend toward earlier diagnosis and assignment of affected newborns as males.

Loss of LGR4/GPR48 causes severe neonatal salt wasting due to disrupted WNT signaling altering adrenal zonation.

Disorders of isolated mineralocorticoid deficiency, which cause potentially life-threatening salt-wasting crisis early in life, have been associated with gene variants of aldosterone biosynthesis or resistance; however, in some patients no such variants are found. WNT/ß-catenin signaling is crucial for differentiation and maintenance of the aldosterone-producing adrenal zona glomerulosa (zG). Herein, we describe a highly consanguineous family with multiple perinatal deaths and infants presenting at birth with failure to thrive, severe salt-wasting crises associated with isolated hypoaldosteronism, nail anomalies, short stature, and deafness. Whole exome sequencing revealed a homozygous splice variant in the R-SPONDIN receptor LGR4 gene (c.618-1G>C) regulating WNT signaling. The resulting transcripts affected protein function and stability and resulted in loss of Wnt/ß-catenin signaling in vitro. The impact of LGR4 inactivation was analyzed by adrenal cortex-specific ablation of Lgr4, using Lgr4fl/fl mice mated with Sf1:Cre mice. Inactivation of Lgr4 within the adrenal cortex in the mouse model caused decreased WNT signaling, aberrant zonation with deficient zG, and reduced aldosterone production. Thus, human LGR4 mutations establish a direct link between LGR4 inactivation and decreased canonical WNT signaling, which results in abnormal zG differentiation and endocrine function. Therefore, variants in WNT signaling and its regulators should systematically be considered in familial hyperreninemic hypoaldosteronism.

Steroid Profiling in the Amniotic Fluid: Reference Range for 12 Steroids and Interest in 21-Hydroxylase Deficiency.

CONTEXT: Determination of steroid levels in the amniotic fluid gives some insight on fetal adrenal and gonadal functions. OBJECTIVE: Our objectives were to establish reference ranges of 12 steroid levels throughout pregnancy and to compare them with steroid levels from pregnancies with fetuses presenting with 21-hydroxylase deficiency (21OHD). METHODS: Liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) was applied to 145 "control" amniotic fluid samples from gynecology activity (12 + 6 to 32 + 4 gestational weeks, GW). The following steroids were analyzed according to gestational age and compared to 23 amniotic fluid samples from fetuses with classic 21OHD confirmed by molecular studies: delta-4-androstenedione (D4), dehydroepiandrosterone (DHEA), 17-hydroxyprogesterone (17OHP), 11-deoxycortisol (11OH), 21-deoxycortisol (21OH), corticosterone, deoxycorticosterone (DOC), testosterone, pregnenolone, 17-hydroxypregnenolone (17Pregn), cortisol, and cortisone. Chromosomal sex was determined by karyotype and gestational age by biometric measurements. RESULTS: Analysis of control samples showed a statistically significant difference for D4 and testosterone levels according to fetal sex. Cortisol, corticosterone, and DOC had lower concentrations before 20 GW than after 20 GW, whereas 17Pregn and pregnenolone had higher concentrations before 20 GW. This allowed us to establish age- and sex-dependent reference values. We observed higher 21OH, 17Pregn, D4, and testosterone levels in females with 21OHD than female controls. The ratios 17OHP/17Pregn, D4/DHEA, and 11OH/17OHP appeared discriminant for the diagnosis of 21OHD. CONCLUSION: Our study provides information on fetal steroidogenesis and suggests reference values for 12 steroids during pregnancy. This allows a prenatal diagnosis of 21OHD within 24 hours and might be useful in the diagnosis of other variations of sex development.

Epileptic encephalopathy as a new feature of the sudden infant death with dysgenesis of the testes syndrome caused by TSPYL1 variants.

Sudden infant death with dysgenesis of the testes syndrome (SIDDT) is a rare autosomal recessive disorder associating developmental sex disorder (DSD) in patients with 46,XY karyotype and visceroautonomic dysfunction responsible for sudden infant death. First described in 2004, very few patients have since been reported. We describe here a new patient with SIDDT and epileptic encephalopathy (EE). We provide the phenotypic description and genetic results of a boy carrying biallelic TSPYL1 deleterious variants. We also reviewed the data of the 26 previously described patients with SIDDT. Our patient presented gonadal dysgenesis, cardio-respiratory dysfunction, and repeated seizures, leading in 1 month to severe intractable EE. He died at age 10 months of cardiorespiratory arrest. Four other reported patients from two families presented with progressive epilepsy, including one with severe EE. No similar phenotype was described in the 22 other patients and the recurrent variant p.Val242Glufs*52 appears to be more frequently associated with seizures. To note, our patient is the first case with compound heterozygous TSPYL1 variants. These findings expand the phenotypic spectrum of SIDDT by reporting progressive epilepsy and severe EE as a possible outcome. This information may help in managing patients with SIDDT.

Genotype, Mortality, Morbidity, and Outcomes of 3ß-Hydroxysteroid Dehydrogenase Deficiency in Algeria.

Background: 3ß-hydroxysteroid dehydrogenase 2 (3ßHSD2) deficiency is a rare form of congenital adrenal hyperplasia (CAH), with fewer than 200 cases reported in the world literature and few data on outcomes. Patients and Methods: We report a mixed longitudinal and cross-sectional study from a single Algerian center between 2007 and 2021. Virilization and under-masculinization were assessed using Prader staging and the external masculinization score (EMS), pubertal development staged according to the system of Tanner. Adrenal steroids were measured using mass spectrophotometry (LC-MS/MS). A genetic analysis of HSD3B2 was performed using Sanger sequencing. Results: A 3ßHSD2 defect was confirmed in 6 males and 8 females from 10 families (8 consanguineous), with p.Pro222Gln mutation in all but two siblings with a novel deletion: c.453_464del or p.(Thr152_Pro155del). Probable 3ßHSD2 deficiency was diagnosed retrospectively in a further 6 siblings who died, and in two patients from two other centers. In the genetically confirmed patients, the median (range) age at presentation was 20 (0-390) days, with salt-wasting (n = 14) and genital anomaly (n = 10). The Prader stage for female patients was 2 (1-2) with no posterior fusion of the labia. The EMS for males was 6 (3-9). Median (range) values at diagnosis for 17-hydroxyprogesterone (17-OHP), dehydroepiandrosterone sulfate (DHEA-S), and 17-hydroxypregnenolone (17OHPreg) were elevated: 73.7 (0.37-164.3) nmol/L; 501.2(9.4-5441.3) nmol/L, and 139.7 (10.9-1500) nmol/l (NB >90 nmol/L diagnostic of 3ßHSD2 defect). Premature pubarche was observed in four patients (3F:1M). Six patients (5F:1M) entered puberty spontaneously, aged 11 (5-13) years in 5 girls and 11.5 years in one boy. Testicular adrenal rest tumors were found in three boys. Four girls reached menarche at 14.3 (11-14.5) years, with three developing adrenal masses (surgically excised in two) and polycystic ovary syndrome (PCOS), with radiological evidence of ovarian adrenal rest tumor in one. The median IQ was 90 (43-105), >100 in only two patients and <70 in three. Conclusions: The prevalence of 3ßHSD2 deficiency in Algeria appears high, with p.Pro222Gln being the most frequent mutation. Mortality is also high, with significant morbidity from adrenal tumors and PCOS in adolescence and an increased risk of learning disability. The finding of adrenal tumors in older patients with 3ßHSD2 indicates under-replacement, requiring effective hydrocortisone and fludrocortisone treatment rather than surgical removal.

Effect of Recombinant Gonadotropin on Testicular Function and Testicular Sperm Extraction in Five Cases of NR0B1 (DAX1) Pathogenic Variants.

Background: NR0B1 pathogenic variants can cause congenital adrenal hypoplasia or primary adrenal insufficiency in early childhood usually associated with hypogonadotropic hypogonadism. NR0B1 is necessary for organogenesis of the adrenal cortex and to maintain normal spermatogenesis. In humans, restoration of fertility in patients carrying NR0B1 pathogenic variants is challenging. Objective: The aim of the study was to investigate the clinical, hormonal, histological, spermiological, and molecular genetic characteristics of a cohort of patients with NR0B1 pathogenic variants, monitored for fertility preservation. Patients: We included five patients, including four teenagers, with NR0B1 pathogenic or likely pathogenic variants. They all had primary adrenal insufficiency and were receiving replacement therapy with glucocorticoids and mineralocorticoids. Patients received recombinant follicle-stimulating hormone and recombinant human chorionic gonadotropin in order to induce spermatogenesis. Combined gonadotropin treatment was initiated between 13 years and 15 years and 6 months for the four teenagers and at 31 years and 2 months for the only adult. Physical and hormonal assessments were performed just before starting gonadotropin treatment. After 12 months of gonadotropin treatment, physical examination and hormonal assessments were repeated, and semen analyses were performed. If no sperm cells were observed in at least 2 semen collections at 3-month interval, testicular biopsy for testicular sperm extraction was proposed. Results: Bilateral testicular volume increased from 8 ml (interquartile range, 6-9) to 12 ml (10-16) after gonadotropin treatment. Inhibin B levels were relatively stable: 110 ng/L (46-139) before and 91 ng/L (20-120) at the end of gonadotropin treatment. Azoospermia was observed in all semen analyses for all cases during gonadotropin treatment. Three patients agreed to testicular biopsy; no mature sperm cells could be retrieved in any. Conclusion: We characterized a cohort of patients with NR0B1 pathogenic or likely pathogenic variants for fertility preservation by recombinant gonadotropin treatment, which began either at puberty or in adulthood. No sperm cells could be retrieved in semen samples or testicular biopsy even after gonadotropin treatment, indicating that gonadotropin treatment, even when started at puberty, is ineffective for restoring fertility.

In cases of familial primary ovarian insufficiency and disorders of gonadal development, consider NR5A1/SF-1 sequence variants.

RESEARCH QUESTION: Primary ovarian insufficiency (POI) is defined as the early exhaustion of ovarian function, before the age of 40 years. Its origin is genetic in 20-25% of cases. In rare cases, sequence variants of the NR5A1/SF-1 gene may result in POI, or in various disorders of gonadal development (DGD) or adrenal insufficiency. DESIGN: This study describes the cases of two families in which the association of DGD and POI enabled a diagnosis of NR5A1 deleterious variations. Their clinical, hormonal, ultrasound and genetic characteristics are reported. RESULTS: The mothers of the affected children were 21 and 29 years when POI was diagnosed. Each nonetheless had two spontaneous pregnancies. The children have different phenotypes and different forms of DGD. None of the affected family members had adrenal insufficiency. A new sequence variant of the NR5A1 gene was identified in one family: p.Cys283Phe (c.848G>T), and the NR5A1 sequence variant c.86G>C was found in the other family. CONCLUSION: Sequence variation of the NR5A1 gene is a possibility that must be considered when a woman with POI or a diminished ovarian reserve has a family member or child with DGD. If a variant is identified, genetic counselling is essential for the patient and his/her family.

Reversion SAMD9 Mutations Modifying Phenotypic Expression of MIRAGE Syndrome and Allowing Inheritance in a Usually de novo Disorder.

Context: MIRAGE (Myelodysplasia, Infection, Restriction of growth, Adrenal hypoplasia, Genital phenotypes, Enteropathy) syndrome is a severe multisystem disorder with high mortality. It is caused by a heterozygous gain of function mutation in the growth repressor gene SAMD9. The increasing number of reported cases displays a spectrum of phenotypes that may be explained by an adaptation mechanism, with appearance of a somatic second hit mutation with revertant effects. Objective: To determine the genetic basis of the MIRAGE syndrome rapidly corrected in a living and healthy 46,XY patient. Subjects and Methods: A 46,XY patient born with growth restriction and disorders of sex development had thrombocytopenia and necrotizing enterocolitis during the neonatal period suggestive of the syndrome. Faced with the rapid improvement of the patient's phenotype, an adaptation mechanism was sought by repeating genetic analysis at different ages; her parents also underwent genetic analysis. Results: The previously described p.(Thr778Ile) mutation was identified and surprisingly transmitted by the asymptomatic mother in this usually de novo syndrome. To explain the rapid improvement of the patient's phenotype and absence of symptoms in the mother, an adaptation mechanism was sought. For the mother, a non-sense mutation was found (p.(Arg221*)) in cis, and most likely appeared in utero. It was not transmitted to her child. The child harbored a different non-sense mutation (p.(Arg285*)) that most likely appeared near day 20. Conclusions: We show that pathogenic variants can be inherited from a healthy parent as the adaptation mechanism may arise early in life and mask symptoms. Presence of revertant mosaicism mutations could explain "incomplete penetrance" in other disease. For a better management and outcomes in patients, appearance of this natural gene therapy should be sought by repeating genetic analysis.

Optimized nested PCR enhances biological diagnosis and phylogenetic analysis of human parvovirus B19 infections.

Diagnosis and epidemiological analysis of human parvovirus B19 (hB19V) infections are essential for disease management in severely ill patients. This study aimed to evaluate the performance of an optimized NS1-VP1u nested PCR for detection and sequencing of viruses in clinical samples using 224 clinical and five reference samples. PCR sensitivity, specificity, and positive and negative predictive values were perfect (100%). While phylogenetic analysis of a 615 bp-long fragment demonstrated that the viruses in all of the samples belonged to genotype 1, this study confirmed that this optimized PCR could detect all known hB19V with high performance.

Aberrant Splicing Is the Pathogenicity Mechanism of the p.Glu314Lys Variant in CYP11A1 Gene.

Context: The cholesterol side chain cleavage enzyme (CYP11A1) catalyzes the conversion of cholesterol to pregnenolone, the first rate-limiting step of steroidogenesis. CYP11A1 mutations are associated with primary adrenal insufficiency (PAI) as well as disorders of sex development (DSD) in 46,XY patients. Objective: To define the pathogenicity mechanism for the p.Glu314Lys variant, previously reported, and found in four additional patients with CYP11A1 deficiency. Subjects and Methods: DNA of four patients presenting with delayed PAI and/or 46,XY DSD were studied by Sanger or Massively Parallel sequencing. Three CYP11A1 mutations were characterized in vitro and in silico, and one by mRNA analysis on testicular tissue. Results: All patients were compound heterozygous for the previously described p.Glu314Lys variant. In silico studies predicted this mutation as benign with no effect on splicing but mRNA analysis found that it led to incomplete exon 5 skipping. This mechanism was confirmed by minigene experiment. The protein carrying this mutation without exon skipping should conserve almost normal activity, according to in vitro studies. Two other mutations found in trans, the p.Arg120Gln and p.Arg465Trp, had similar activity compared to negative control, consistent with the in silico studies. Conclusions: We provide biological proof that the p. Glu314Lys variant is pathogenic due to its impact on splicing and seems responsible for the moderate phenotype of the four patients reported herein. The present study highlights the importance of considering the potential effect of a missense variant on splicing when it is not predicted to be disease causing.

P450 Oxidoreductase Deficiency: Loss of Activity Caused by Protein Instability From a Novel L374H Mutation.

CONTEXT: P450 oxidoreductase (POR) is required for the activities of steroid-metabolizing cytochrome P450 enzymes in the endoplasmic reticulum. POR deficiency (PORD) is a form of congenital adrenal hyperplasia. Objective and Aim: Enzymatic and structural analysis of a novel L374H POR mutation from a patient with 46,XX disorder of sexual development. Design, Setting, Patient, and Intervention: The patient was a 46,XX girl with nonconsanguineous Turkish parents. She had virilized external genitalia at birth, a uterus and ovaries, and no sign of Antley-Bixler syndrome. The initial diagnosis was CYP21A2 deficiency with no mutations in CYP21A2, but POR mutations were found. Functional testing was done after producing recombinant POR proteins for analyzing enzymatic and structural properties. MAIN OUTCOME: Novel mutations were causing severe loss of POR activities for metabolism of steroids and small molecules. RESULTS: The L374H mutation reduced activities by 80% in cytochrome c, 97% in thiazolyl blue tetrazolium bromide, and 86% in ferricyanide reduction assays. The catalytic efficiency of the 17 α-hydroxylation of progesterone and the 17,20-lyase reaction of 17-OH pregnenolone was decreased by 87 and 90%, respectively; 21-hydroxylation of progesterone was decreased by 96%, and androstenedione aromatization was decreased by 90%. Analysis of the mutant structure by molecular dynamics simulations revealed structural instability. Flavin release and fast proteolysis assays showed that the L374H mutant is less stable than wild-type POR, confirming the bioinformatics prediction. CONCLUSIONS: This is the first report of a mutation causing PORD by affecting protein stability that causes severe reduction in POR activities. Detailed characterization of individual mutations in POR is required for understanding novel molecular mechanisms causing PORD.

Evolution of steroids during pregnancy: Maternal, placental and fetal synthesis.

Progesterone, estrogens, androgens and glucocorticoids are involved in pregnancy from implantation to parturition. Their biosynthesis and their metabolism result from complex pathways involving the fetus, the placenta and the mother. The absence of expression of some steroïdogenic enzymes as CYP17 in placenta and in adrenal fetal zone and the better determination of the onset and variation of others especially HSD3B2 during the pregnancy explain the production of the steroid hormones. Moreover the consequences of some disorders of steroidogenesis (especially aromatase, POR, CYP11A1 and 21-hydroxylase deficiencies) in fetus and mother during the pregnancy have permit to elucidate these complex pathways. This better knowledge of steroid hormones production associated with their dosages in maternal plasma/urine or amniotic fluid using new specific assays as LC-MS MS could facilitate the follow-up of normal and pathological pregnancies. Moreover, these advances should be a basis to evaluate the impact of multiple pathologies of the pregnancy and pharmacologic and xenobiotic consequences on their metabolism.

A late 17α-hydroxylase deficiency diagnosis that leads to the discovery of a new CYP17 gene mutation.

17α-Hydroxylase deficiency is a rare form of congenital adrenal hyperplasia. It leads to a reduced production of cortisol and sex steroids and thus an increase in adrenocorticotrophic hormone and gonadotrophins levels. High adrenocorticotrophic hormone levels result in an accumulation of 17-deoxysteroids, such as deoxycorticosterone and corticosterone. Deoxycorticosterone and corticosterone have an important mineralocorticoid activity. We report the case of a 66-year-old woman who presented with hypertension and symptomatic hypokalaemia. Primary hyperaldosteronism was suspected and a right adrenal mass was removed. After surgery, the patient was referred to the endocrinology department for persistant hypokalaemia. Actually, she presented some signs of hypogonadism (impuberism, primary amenorrhea, infertility). Cortisol and 17OH-progesterone serum levels were low. Deoxycorticosterone and corticosterone were markedly elevated. The hypothesis of 17α-hydroxylase deficiency was considered and confirmed by genetic exploration. A non-sense mutation c.938G>A (p.Trp313X) in exon 5 of the CYP17 gene was found that had never been reported so far to our knowledge. Moreover, the patient's karyotype found a mosaic Turner syndrome. This case is particularly interesting because of the delay of diagnosis. The 17α-hydroxylase deficiency diagnosis is to be considered when hypertension is associated with hypokalaemia and hypogonadism, even in adult patients.

Genetic of gonadal determination.

Fetal sexual differentiation results from complex subsequent intracellular signaling and hormonal events that interact together in a definite timing. This process contributes to the setting of gonad determination, internal and external genitalia resulting in a female or male phenotype. Here, we review our current knowledge of gonadal determination drawing on insights from knock-out and transgenic mouse models and analysis of patients with disorders of sex development (DSD).

Complementarity of rotating video and underwater visual census for assessing species richness, frequency and density of reef fish on coral reef slopes.

Estimating diversity and abundance of fish species is fundamental for understanding community structure and dynamics of coral reefs. When designing a sampling protocol, one crucial step is the choice of the most suitable sampling technique which is a compromise between the questions addressed, the available means and the precision required. The objective of this study is to compare the ability to sample reef fish communities at the same locations using two techniques based on the same stationary point count method: one using Underwater Visual Census (UVC) and the other rotating video (STAVIRO). UVC and STAVIRO observations were carried out on the exact same 26 points on the reef slope of an intermediate reef and the associated inner barrier reefs. STAVIRO systems were always deployed 30 min to 1 hour after UVC and set exactly at the same place. Our study shows that; (i) fish community observations by UVC and STAVIRO differed significantly; (ii) species richness and density of large species were not significantly different between techniques; (iii) species richness and density of small species were higher for UVC; (iv) density of fished species was higher for STAVIRO and (v) only UVC detected significant differences in fish assemblage structure across reef type at the spatial scale studied. We recommend that the two techniques should be used in a complementary way to survey a large area within a short period of time. UVC may census reef fish within complex habitats or in very shallow areas such as reef flat whereas STAVIRO would enable carrying out a large number of stations focused on large and diver-averse species, particularly in the areas not covered by UVC due to time and depth constraints. This methodology would considerably increase the spatial coverage and replication level of fish monitoring surveys.

Remote high-definition rotating video enables fast spatial survey of marine underwater macrofauna and habitats.

Observing spatial and temporal variations of marine biodiversity from non-destructive techniques is central for understanding ecosystem resilience, and for monitoring and assessing conservation strategies, e.g. Marine Protected Areas. Observations are generally obtained through Underwater Visual Censuses (UVC) conducted by divers. The problems inherent to the presence of divers have been discussed in several papers. Video techniques are increasingly used for observing underwater macrofauna and habitat. Most video techniques that do not need the presence of a diver use baited remote systems. In this paper, we present an original video technique which relies on a remote unbaited rotating remote system including a high definition camera. The system is set on the sea floor to record images. These are then analysed at the office to quantify biotic and abiotic sea bottom cover, and to identify and count fish species and other species like marine turtles. The technique was extensively tested in a highly diversified coral reef ecosystem in the South Lagoon of New Caledonia, based on a protocol covering both protected and unprotected areas in major lagoon habitats. The technique enabled to detect and identify a large number of species, and in particular fished species, which were not disturbed by the system. Habitat could easily be investigated through the images. A large number of observations could be carried out per day at sea. This study showed the strong potential of this non obtrusive technique for observing both macrofauna and habitat. It offers a unique spatial coverage and can be implemented at sea at a reasonable cost by non-expert staff. As such, this technique is particularly interesting for investigating and monitoring coastal biodiversity in the light of current conservation challenges and increasing monitoring needs.