With the rapid development of global aquaculture, the frequent occurrence of fish diseases has had a serious impact on the efficiency of aquaculture and the ecological environment. Antimicrobial peptides, as a kind of natural immune active substance existing in organisms, participate in innate immunity and adaptive immunity. Due to their extensive antibacterial properties and low toxicity, they have gradually become a hot topic in scientific research. This article reviews the classification, tissue distribution, mechanism of action, extraction, and synthesis techniques of antimicrobial peptides (AMPs) derived from fish, as well as their applications in disease prevention in aquaculture, product preservation, and antibiotic substitution. Although antimicrobial peptides are expected to become alternatives to antibiotics, challenges such as environmental stability, production costs, and regulatory frameworks remain to be addressed. This article holds that antimicrobial peptides derived from fish are a feasible strategy for sustainable aquaculture. The future development direction lies in biotechnology-driven optimization, carrier innovation, and combined application with traditional antibiotics.
Blooms of phototrophic protists play a crucial role in marine biogeochemical cycles, significantly impacting carbon fluxes and overall ecosystem productivity. Eukaryotes of the nano- and microplankton are responsible for the large spring and summer blooms visible from space in the highly dynamic southwestern Atlantic Ocean. Here, we investigated the composition and abundance of protistan plankton during late spring 2021 across three contrasting oceanographic regions of the southwestern Atlantic Ocean: the Patagonian continental shelf, the core of the Malvinas Current (MC), and the adjacent energetic open ocean in the Argentine basin. Using a combination of in situ sampling and satellite-derived chlorophyll-a, particulate inorganic carbon, sea surface temperature, and geostrophic currents, we identified marked differences in water masses and plankton communities. High chlorophyll-a concentration over the outer continental shelf was related to blooms of phototrophic and mixotrophic dinoflagellates and large diatoms. This plankton accumulation over the shelf was associated with the permanent thermohaline front that develops along the shelf-break, with upwelling as the main driver of high productivity. However, in waters of the MC and the open ocean protists exhibited lower biomass and diversity, with prevalence of nanoflagellates and coccolithophores. The results suggest that the water column stability and the N:Si and N:P nutrient ratios shape the distinct bloom-forming functional types. This study contributes with data on taxonomic diversity identified by microscopy which, along with remote sensing approaches, provide insights into how protists respond to environmental changes at different spatial and temporal scales.
Harlequin frogs, genus Atelopus, are a species-rich group of bufonid anurans from the Neotropics with more than 100 species. For nearly four decades now, this group has suffered from massive population declines. Almost all species are threatened with extinction, and many populations and several species are considered extinct or possibly extinct. This results in a limited sampling available for studies on harlequin frog systematics, especially in terms of molecular genetic information. However, efficient conservation of harlequin frogs requires an improved taxonomy. This is further complicated through the circumstance that many Atelopus species are relatively poor in external morphological characters combined with a high level of intra-specific character variation (e.g. coloration and body size). At the same time, cryptic diversity exists with well differentiated species (supported by osteology and molecular genetics) almost indistinguishable by external morphology. We compiled the largest dataset to date for mitochondrial (12S, 16S, cyt b) and nuclear (POMC, RAG1) markers and present a phylogeny (likelihood and Bayesian inference methods) including 152 samples from 104 populations scattered over the entire geographic range of the genus. Four allo- or parapatric main clades are distinguished: I. Sierra Nevada; II. Venezuelan-Andean; III. Andean-Chocó-Central American (with the ignescens and the varius-longirostris clades); and IV Amazonian (containing the tricolor and the flavescens-spumarius clades). The phylogenetic relationships within these clades remain to be resolved. Taxonomic implications included both splitting and lumping, but taxonomic action is here only taken for populations related to A. spumarius from western Amazonia. Besides redescriptions of A. spumarius sensu stricto and A. colomai, we describe two new species based on morphology, skull osteology and bioacoustics. Additional yet understudied populations from Amazonia may be allocated to these species or may represent additional undescribed taxa.
Understanding the population dynamics of marine mammals is essential for assessing their resilience to historical harvesting pressures and current anthropogenic threats. The South American sea lion (SASL, Otaria byronia), widely distributed along the South American coasts, represents the largest biomass of northern and central Patagonia. This species faces threats such as incidental fishing captures, aquaculture, and tourism, with well-documented impacts on its population. However, the effects of Highly Pathogenic Avian Influenza (HPAI) H5N1 on its population dynamics are poorly understood. This study provides new insights into the impact of the 2023 avian influenza outbreak on the SASL in northern Patagonia. Population trends and age-sex class composition of colonies were updated, incorporating the HPAI outbreak in the R & iacute;o Negro rookeries to compare trends before and after the epizootic event. A positive trend in SASL abundance was observed from 2007 to 2022 across most age and sex classes. However, in the 2024 census, 7175 +/- 145 individuals were counted across three colonies, with the largest, Punta Bermeja, recording a 27.6% decline. During the 2023 outbreak, 1476 deaths were reported, affecting all age and sex classes. These findings suggest the HPAI H5N1 outbreak significantly impacted the previously positive population trend.
Anurans are the most threatened group of tetrapods. Although the number of Data Deficient species has been drastically reduced during the latest global assessment, there remain crucial gaps in knowledge about their biology. For more than half of all species, their larval stages are entirely unknown, posing a major obstacle to effective conservation. This is especially important for species with a biphasic life cycle, in which drivers of extinction can impact tadpoles and adults differently. To address this, we integrated global data on anuran tadpoles with ancestral state reconstructions and Geographic Information System based analyses to identify key areas for discovering free-living tadpoles. Our results show that strategically focusing research on 0.25% of Earth’s terrestrial surface could reveal more than half of the undescribed tadpoles, and covering 1% could account for all of them. These priority areas are concentrated mainly in biodiversity hotspots and include the Tropical Andes, Eastern Brazil, Tropical Africa, India, Southeast Asia and New Guinea. Each region exhibits unique ecological and evolutionary traits in anuran larval diversity, highlighting their importance for targeted research. Given the alarming rate of habitat loss and the high biodiversity within these regions, this study underscores the need for urgent conservation efforts to protect both known diversity and diversity yet to be discovered.
