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The Mediterranean Sea represents the lower latitudinal limit of the European sprat range, where it is considered a sentinel species favoring temperate-cold temperatures. Sprattus sprattus is a plankton feeder that plays an important ecological role in contributing to the transfer of energy from lower to higher trophic levels, but climate-driven increases in sea temperatures may reduce the suitability of the pelagic habitat and threaten the tropho-dynamic role of sprat in areas such as the Adriatic Sea. The latter is an enclosed basin characterized by shallow waters and high annual temperature variations. Here, to investigate present and future habitat suitability areas for sprat, we applied four species distribution models (SDMs) using fishery-independent data collected from 2004 to 2021, along with remotely sensed and modeled environmental variables. A set of nine environmental predictors was tested, and the resulting best model was averaged in an ensemble model approach. The best ensemble models revealed good to high accuracy (sensitivity and specificity ≥ 0.8). The sea surface temperature and chlorophyll concentration emerged as the main explanatory variables in predicting the potential habitat of sprats, followed by bathymetry. The resulting probability of occurrence maps revealed that the species is bounded in the northern Adriatic Sea, where a longitudinal shift of high-suitability habitats from inshore to deeper and colder waters was detected between early and late summer. Future projections under IPCC representative concentration pathway (RCP) scenarios 4.5 (intermediate emission) and 8.5 (high emission-warm) underline small changes along with a gain of new areas in late summer in the short-term period up to 2050. Conversely, the temperature increase projected for the end of the century is predicted to cause a loss of suitable habitat area for sprats of up to 88% under a high emission-warm scenario relative to current habitat occupancy throughout the basin. [ABSTRACT FROM AUTHOR]

The European sprat is a small plankton-feeding clupeid present in the northeastern Atlantic Ocean, in the Mediterranean Sea, and in the brackish Baltic Sea and Black Sea. This species is the target of a major fishery and, therefore, an accurate characterization of its genetic population structure is crucial to delineate proper stock assessments that aid ensuring the fishery's sustainability. Here, we present (i) a draft genome assembly, (ii) pooled whole genome sequencing of 19 population samples covering most of the species' distribution range, and (iii) the design and test of a single nucleotide polymorphism (SNP)-chip resource and use this to validate the population structure inferred from pooled sequencing. These approaches revealed, using the populations sampled here, three major groups of European sprat: Oceanic, Coastal, and Brackish with limited differentiation within groups even over wide geographical stretches. Genetic structure is largely driven by six large putative inversions that differentiate Oceanic and Brackish sprats, while Coastal populations display intermediate frequencies of haplotypes at each locus. Interestingly, populations from the Baltic and the Black Seas share similar frequencies of haplotypes at these putative inversions despite their distant geographic location. The closely related clupeids European sprat and Atlantic herring both show genetic adaptation to the brackish Baltic Sea, providing an opportunity to explore the extent of genetic parallelism. This analysis revealed limited parallelism because out of 125 independent loci detected in the Atlantic herring, three showed sharp signals of selection that overlapped between the two species and contained single genes such as PRLRA , which encodes the receptor for prolactin, a freshwater-adapting hormone in euryhaline species, and THRB , a receptor for thyroid hormones, important both for metabolic regulation and the development of red cone photoreceptors. [ABSTRACT FROM AUTHOR]

The Mediterranean Sea represents the lower latitudinal limit of the European sprat range, where it is considered a sentinel species favoring temperate–cold temperatures. Sprattus sprattus is a plankton feeder that plays an important ecological role in contributing to the transfer of energy from lower to higher trophic levels, but climate-driven increases in sea temperatures may reduce the suitability of the pelagic habitat and threaten the tropho-dynamic role of sprat in areas such as the Adriatic Sea. The latter is an enclosed basin characterized by shallow waters and high annual temperature variations. Here, to investigate present and future habitat suitability areas for sprat, we applied four species distribution models (SDMs) using fishery-independent data collected from 2004 to 2021, along with remotely sensed and modeled environmental variables. A set of nine environmental predictors was tested, and the resulting best model was averaged in an ensemble model approach. The best ensemble models revealed good to high accuracy (sensitivity and specificity ≥ 0.8). The sea surface temperature and chlorophyll concentration emerged as the main explanatory variables in predicting the potential habitat of sprats, followed by bathymetry. The resulting probability of occurrence maps revealed that the species is bounded in the northern Adriatic Sea, where a longitudinal shift of high-suitability habitats from inshore to deeper and colder waters was detected between early and late summer. Future projections under IPCC representative concentration pathway (RCP) scenarios 4.5 (intermediate emission) and 8.5 (high emission-warm) underline small changes along with a gain of new areas in late summer in the short-term period up to 2050. Conversely, the temperature increase projected for the end of the century is predicted to cause a loss of suitable habitat area for sprats of up to 88% under a high emission-warm scenario relative to current habitat occupancy throughout the basin.

This study aims to identify the spring diet composition and feeding strategy of the European sprat, Sprattus sprattus. Diet composition of European sprat was investigated for the first time in the central Black Sea coast of Turkey. Examined of the 115 specimens (6 - 9.1 cm total length) of stomach, 12 (10.4%) had emty. Diet analysis was described based on gravimetric percentages (W%), frequency of abundance (N%), frequency of occurrence (%F) and relative importance index (IRI%). Feeding strategy was analyzed and graphically (Costello) represented, considering the frequency of abundance (N%) and frequency of occurrence (%F) indexes and grouping prey into higher taxonomic categories. Twenty species were identified, belonging to four prey groups: Polychaeta, Crustacea, Mollusca and Chaetognatha. Finally copepods proved to be the most important food item considering the above-cited indexes. All other prey taxa were identified as accidental preys. At least seven copepod species were identified, where Calanus euxinus appeared all round with %IRI≥50. Also results of feeding strategy analyses revealed a trophic specialization toward a single prey.

Sprat Sprattus sprattus is a common fish across the European seas. It is of great importance for fishing industry, also in the southern Baltic Sea. Although parasitic fauna of the species has already been a subject of interest, it is still not very well explored in the southern Baltic Sea. In 2009 and 2011, 187 specimens of the European sprat from the Gulf of Gdańsk (26 ICES subdivision) were examined for the presence of parasites. The parasites found represented Digenea: Lecithaster gibbosus (Rudolphi, 1802) and Nematoda: Hysterothylacium aduncum (Rudolphi, 1802) and Contracaecum spp. The overall prevalence was 3.2% with the mean intensity of 1.0 and abundance of 0.005. The parasite fauna of the European sprat from the southern Baltic Sea is poorly diversified and infection rates are low in comparison to other European seas. A checklist of parasites in European sprat world-wide is also provided. [ABSTRACT FROM AUTHOR]

The article presents a study which examines the neutral population structure of the marine fish European sprat Sprattus sprattus L. It states that the study employs 931 sprat specimens from various locations in Baltic Sea, North Sea, and Adriatic Sea areas to find out their genetic division and salinity gradient. It notes that the study reveals that the population structure of the sprat resembles other marine fishes and suggests that spatially explicit differences observed in species likely reflect life histories of fishes. It concludes that the structures must be considered in complex ecosystem functions such as in multispecies management.