Otoliths are important structures for balance and hearing of fish and constitute a useful tool in fisheries science. This study provides, for the first time in the Mediterranean, information on the otolith morphometrics of Dentex maroccanus, collected from the South Aegean Sea, and enriches the existing information on its age and growth by sex. The otolith shape variables examined showed a more circular to square otolith shape, related to the body size. Significant differences between sexes were detected for the otolith Area, Diameter, Perimeter, and Radius. Exponential regressions were used to examine the relationship of the otolith variables with total body length, from which five showed a strong correlation (Diameter, Width, Radius, Area, and Perimeter). The eviscerated weight–length relationship exhibited an isometric growth for both sexes, whereas when total weight was applied, a positive allometric growth was found for females. Sagittal otolith readings revealed four age groups for females and five for males. A Bhattacharya method was used for age validation. Von Bertalanffy growth parameters were as follows: L∞ = 23.08, k = 0.27, t₀ = −1.93 for females and L∞ = 24.07, k = 0.24, t₀ = −2.26 for males. This research offers valuable biological information for Dentex maroccanus useful in fisheries science.

Otoliths, the functional earstones of teleost fishes, record growth in the form of microscopic increments, making them key archives of individual life histories. While increment analysis is commonly applied to modern otoliths, studies of fossil (Holocene) otoliths remain limited. Traditional methods such as light microscopy (LM) and secondary electron (SE) imaging often fail to resolve microincrements, leading to underestimation and inconsistent findings. We used backscattered electron (BSE) imaging to examine modern and radiocarbon‐dated Holocene otoliths of the black goby ( Gobius niger Linnaeus, 1758) from the northern Adriatic Sea. Our aim was to assess whether BSE imaging improves microincrement visibility. Standard BSE imaging outperformed LM, detecting 22.6% more increments than in thin‐sectioned and 55.7% more increments than in surface‐polished Holocene otoliths. High‐resolution BSE imaging with extended scan times and optimized settings revealed over 250% more increments than a standard BSE workflow. These results show that imaging quality and scan strategy significantly influence microincrement detection, and that optimized BSE workflows greatly improve the resolution of growth records. Notably, microincrement visibility in the Holocene otoliths was unaffected by post‐mortem alteration or radiocarbon age, indicating robust internal preservation. In contrast, LM imaging of thin‐sectioned modern otoliths yielded higher increment counts than the BSE method due to their natural translucency and intact internal structures, confirming that traditional methods are effective for recent material. Our study demonstrates that an optimized BSE workflow improves the analysis of fossil otoliths and enables more complete reconstructions of fish growth over long timescales.

Otoliths, the calcified biominerals in the inner ear of teleost fishes, provide a unique opportunity to investigate changes in growth parameters in historical fish populations as they are preserved in large numbers in marine sediments. They exhibit species-specific morphology and serve as life history archives, as they grow continuously in a concentric fashion by the accretion of alternating mineral- and protein-rich layers around a core, making them valuable for ecological and palaeontological studies. We employ sclerochronological analyses on otoliths from fish sampled alive as well as on radiocarbon-dated fossil otoliths derived from a sediment core off the coast of Piran, Slovenia. We want to verify the accuracy of historical growth patterns, which is fundamental to reconstructing reliable long-term chronologies and drawing meaningful conclusions about past fish growth dynamics. We focus here on the non-commercial but very common demersal species, the black goby (Gobius niger Linnaeus, 1758) which inhabits the Adriatic shelf regions in large numbers today and in the Holocene. We aim to test the hypothesis that growth rates and subsequently body sizes of these non-commercial fishes have undergone changes during the late Holocene and Anthropocene in the northern Adriatic Sea due to climate-induced environmental perturbations.Before applying growth modeling to the fossil otoliths, it is crucial to ensure the preservation and reliability of the incremental record. Accordingly, we employ a comprehensive approach by comparing modern and Holocene gobiid otoliths using visual, structural and microchemical techniques. Our coupled approach includes light microscopy (LM), backscatter electron (BSE) imaging, electron backscatter diffraction (EBSD), and electron probe microanalysis (EPMA). We analyse macro- and micro-optical features, crystallographic structures, and chemical variations within the otolith incremental record. We use a novel technique to determine the geological ages of the fossil specimens in which we cut the otoliths in half, allowing sclerochronological analysis and radiocarbon dating on the same specimen.Our visual and microchemical analyses revealed that key microincremental features are well preserved in the Holocene otoliths, enabling a direct comparison with modern counterparts. Despite occasional diagenetic alterations that potentially hinder incremental analysis in some of the Holocene specimens, bipartite incremental features, which are essential for growth analysis, are well preserved in both sets of otoliths. Additionally, visual and microchemical patterns indicate that modern otoliths exhibit partially vateritic structures.Our study bridges the temporal gaps by directly comparing modern and fossil otoliths from the same species and study area. This approach reveals the hidden details in their microstructures and helps to establish a potential growth baseline for fish living in pre-industrial times. By examining historical fish size and growth patterns in populations living before significant human-induced environmental changes, we are providing insights into the effects of climate change on fish populations, which is important for fisheries management and conservation.

Climate warming is expected to lead to a reduction in the body size of marine organisms, a trend already observed in commercial fishes, but the effects of temperature rise on size distribution in exploited populations are difficult to separate from the impact of overfishing and other anthropogenic stressors. We aim to test the hypothesis that fish body sizes, as well as growth rates changed during the late Holocene and Anthropocene in the northern Adriatic Sea due to environmental perturbations caused by climate warming. We perform sclerochronological analysis on modern otoliths from fish sampled alive, as well as radiocarbon-dated fossil otoliths of non-commercial, demersal gobies (Gobius niger Linnaeus, 1758) sampled from a sediment core taken off Piran (Slovenia) to quantify changes in body size and growth parameters throughout the Holocene. Otoliths are the aragonitic structures of the fish’ inner ear with species-specific morphology, and thanks to their incremental growth, they serve as unique environmental and life-history archive. Moreover, otolith size correlates with fish size. We use otoliths cut in half to perform both sclerochronology and radiocarbon dating, obtaining a high-resolution time series of changes in fish body size, growth dynamics and life history parameters. We employ backscatter electron (BSE) imaging and electron probe microanalysis (EPMA) to identify body sizes and growth dynamics, as well as to correlate their growth increments with climatic and other environmental parameters. The reconstructed changes in body size and growth rates of very common, non-commercial fish species over the last 7.000 years, can serve as an ecological baseline for evaluating the magnitude of ongoing temperature rise and future shifts in fish populations in response to global warming.

Mesopelagic ecosystems are vital to the ocean’s health yet face unprecedented threats due to accelerating climate change. Lanternfish (family Myctophidae) are key sentinels of midwater ecosystem health because they dominate mesopelagic fish biomass and mediate energy, nutrient, and carbon transfer across ocean layers. Despite their ecological importance, very little is known about their potential response to climate change stressors due to logistical challenges when studying mesopelagic ecosystems. We use thousands of fossil fish otoliths (calcium carbonate ear stones) recovered from marine surface sediments to reconstruct lanternfish growth, body size and energetic investment across contrasting oceanographic regimes. We compare assemblages from the highly productive, but oxygen-poor Tropical Eastern Pacific (TEP) and the oligotrophic, well-ventilated Caribbean, to test how oxygen availability and food supply shape mesopelagic fish energetics across the Isthmus of Panama. Otoliths from marine sediments serve as a cost-efficient, powerful archive to overcome methodological barriers and allow us to reconstruct long-term changes in lanternfish dynamics. We quantify energetic changes in lanternfish assemblages by reconstructing lanternfish body size estimates and mean per-capita biomass from otolith measurements and growth trajectories derived from increment biochronologies. Our results reveal anomalously small lanternfish in the TEP today, despite the region’s tendency to host larger fishes relative to the Caribbean, providing the first indication that mesopelagic fish size is potentially related to oxygen limitation. We then extend this approach to fossil otoliths to explore changes before the closure of the Isthmus of Panama using the Late Miocene/Pliocene as an analog system for warmer than modern conditions to test how mesopelagic ecosystems might respond to future climate change. We find that lanternfish dominated Panama’s ancient fish assemblages in the Caribbean but declined in relative abundance toward the Isthmus closure, while their mean per-capita biomass remained stable over the past 8 Ma. These results imply higher lanternfish biomass during periods of prolonged warming and lower biomass under less productive, better-oxygenated Caribbean conditions created by the Isthmus uplift. Yet in contrast to Panama’s geological past, our results suggest that oxygen availability exerts a dominant control on lanternfish energetics and production in the modern TEP. By integrating otolith archives from deep time to the recent past, we mapped shifts in lanternfish energetics in response to major environmental changes, revealing their sensitivity to oxygen availability and indicating that projected ocean deoxygenation might constrain the energetic capacity of the mesopelagic zone in a future ocean.

Marine fishes are increasingly affected by climate warming and anthropogenic stressors, particularly since the beginning of the Industrial Revolution. The widely accepted Temperature-Size Rule (TSR) predicts that aquatic ectotherms grow faster, mature earlier, but attain smaller adult sizes under warmer conditions. However, its universal applicability remains controversial, and growth responses vary among species, ontogenetic ages and ecosystems. Fossil fish remains offer a unique opportunity to understand long-term growth and body size variability, providing historical baseline data, predating significant human impacts. Otoliths, incrementally grown CaCO3 structures in the inner ear of teleost fishes, are well-preserved in the fossil record and exhibit species-specific morphologies. These biominerals preserve detailed records of growth, age, life history, and environmental conditions in the form of daily, seasonal, and annual growth bands that can be analyzed through sclerochronological analyses. Our study focuses on the black goby (Gobius niger Linnaeus, 1758), a non-commercial, resident demersal species that is highly abundant in temperate shelf regions of the Atlantic and Mediterranean Sea, today and in the geological past. We use fossil otoliths from Holocene sediment cores off the coast of Piran (Slovenia) in the northern Adriatic Sea and modern otoliths from living populations caught in the same area to test whether anthropogenic climate warming has altered the growth patterns of this species, as predicted by the TSR. To assess growth patterns over the past millennia, sclerochronological analyses, including light microscopy and backscatter electron imaging of incremental records, are combined with radiocarbon dating on the same specimens. Our first results reveal no significant differences in overall growth patterns between fossil and modern populations. However, modern otoliths exhibit greater structural complexity and stress-related features, such as vaterite formations, alongside more variable growth patterns. Our study highlights the importance of integrating fossil and modern data to examine long-term growth trends and to expand our knowledge beyond commercially important and charismatic species to inform conservation and management strategies today.