Marine Ecology-An Evolutionary Perspective最新文献

The current study examines the population structure and reproductive traits of the porcelain crab Petrolisthes rufescens (Heller 1861) among the samples collected from the rocky intertidal region of Shivrajpur village, located on the Saurashtra coast of Gujarat. Understanding the population ecology of this species is crucial for its significant role in ecological processes, such as nutrient cycling, and its potential susceptibility to environmental stressors. Specimens were collected over 12 consecutive months (March 2019–February 2020) from a 500 m² area during low tide using the hand-picking method. A total of 1191 individuals were collected, comprising 552 males, 475 non-ovigerous females, and 164 ovigerous females. Adult male individuals were significantly larger than adult non-ovigerous females, with an average carapace length of 9.28 ± 1.32 mm compared to 8.56 ± 1.12 mm in females. The overall and monthly sex ratios were slightly female-biased (1:1.2). The size-frequency distribution in both males and females showed an apparent bimodal pattern. Ovigerous females were present year-round, suggesting that reproduction occurs on a continuous basis. However, a relatively higher proportion of ovigerous females were observed during March–May and August–October at the Shivrajpur coast over the study period. Reproductive biology was assessed by examining egg characteristics, including total number, size, weight, and alongside the carapace length of ovigerous females. A significant positive correlation was found between the size of ovigerous females and their reproductive output, including total egg count (197 ± 87.53), egg mass weight (10.78 ± 8.26 mg), and egg size (0.59 ± 0.09 mm). This study provides baseline data for future research on the species' response to environmental changes and the increasing anthropogenic pressures affecting coastal ecosystems.

Estuaries play a crucial role in maintaining marine biodiversity and providing key ecosystem services, but they are increasingly impacted by local anthropization and global climate change. Developing effective management strategies requires a deep understanding of the genetic structure and diversity of marine species, including how their populations are connected across their distributional range. Here, we used cytochrome oxidase 1 (COI) data to test the hypothesis of significant genetic structuring in the semiterrestrial crab Armases rubripes along its distribution, from the Caribbean to the Western South Atlantic coastline. Patterns of genetic diversity, population structure, and demographic history were assessed, and phylogenetic analysis was performed. Our results support this hypothesis, revealing a potential cryptic species complex, with species-level divergence between the Caribbean and Brazilian regions. These two regions exhibit exclusive haplotypes, with up to 16 mutational steps between them, and were recovered as well-supported clades in our phylogenetic reconstructions and high genetic distances that are consistent with interspecific differentiation. We also uncovered unexpected genetic structure within the Brazilian coast, revealing distinct South and North groups among our sampling sites. The analysis of historical demography suggests that Caribbean clade remained stable over time, while Brazilian South group showed signs of recent demographic expansion. Overall, our results suggest that A. rubripes is likely a species complex, with Caribbean and Brazil representing separate evolving lineages.

This study provides the first detailed assessment of the spatio-temporal distribution of benthic amphipods in Chilika Lagoon. Seasonal changes in species composition, diversity, and distribution were analyzed across four lagoon sectors, along with environmental factors influencing these patterns. Thirteen species belonging to seven genera and families were recorded, with Aoridae, Eriopisidae, and Maeridae being dominant. Permutational Multivariate Analysis of Variance (PERMANOVA) and Canonical Analysis of Principal Coordinates (CAP) analyses revealed clear separation between post-monsoon/winter assemblages and those from pre-monsoon/monsoon seasons. Amphipod communities differed markedly from earlier records, likely due to long-term ecological changes in the lagoon, though Quadrivisio bengalensis and Victoriopisa chilkensis persisted, indicating their resilience. Principal Component Analysis (PCA) and Distance-based Linear Models (DistLM) showed amphipod diversity significantly correlated positively with dissolved oxygen and pH, and negatively with depth and temperature. General Linear Model (GLM) identified dissolved oxygen as the primary driver that can model the amphipod distribution in the studied area. The results of Canonical Correspondence Analysis (CCA) demonstrated that amphipod species show varying degrees of specialization, with F. odishi exhibiting a strong environmental affinity, while most taxa display broader ecological tolerance. In contrast, Quadrivisio bengalensis, Quadrivisio chilikensis, and Ampelisca sp. were associated with higher temperature and higher total organic carbon (TOC). Overall, this study establishes a much-needed ecological baseline for benthic amphipods in Chilika Lagoon, demonstrating the species-specific responses to environmental conditions and offering a framework for detecting future ecological change.

Merluccius productus, commonly referred to as the Pacific Hake, is well known as a relevant species in the structure and functioning of its marine food web networks, acting as a foraging species. Additionally, it represents an important resource for the fishing industry. Nevertheless, little is known about its feeding habits. Therefore, this work describes the diet of the Pacific hake inhabiting the Gulf of California. Samples were obtained from six exploratory fishing research trips conducted between 2014 and 2017. The Prey-Specific Index of Relative Importance (%PSIRI) was used to quantify the dietary components of the Pacific hake. Additionally, to determine its feeding strategy, a similarity analysis was conducted and the Levin's Index and Morisita–Horn Index were calculated. The sampling included 1772 organisms with sizes ranging from 13.3 to 98.4 cm TL. The analysis of 39.2% of stomachs revealed the presence of different prey items, allowing the identification of 23 distinct prey types grouped into three categories: bony fish, crustaceans, and mollusks. The Prey-Specific Index of Relative Importance indicated that the diet is mainly composed of Solenocera mutator (25.2%), fish remains (24.9%), Nyctiphanes simplex (18.7%), and Benthosema panamense (8.3%), collectively accounting for 77.1% of the diet composition. The low Levin's index value (Bi = 0.19) classified the Pacific hake as a specialized predator, while the Morisita–Horn index indicated a moderate level of dietary overlap (Cλ = 0.42). The temporal similarity analysis revealed an overall similarity of 60%, allowing the identification of three distinct groups. Notably, Group B, composed of stomach contents from F-2014 and C-2014, exhibited a higher similarity of 76.1%. The highest contribution to the similarity of this group was represented by the euphausiids N. simplex (41.03%). Our results suggest that M. productus primarily feeds on highly abundant and available prey species in its environment, predominantly pelagic crustaceans, performing vertical migration to feed. The high frequency of crustaceans such as S. mutator and N. simplex, along with the fish B. panamense, further supports the classification of M. productus as a specialized predator.

Hydromedusae are diverse zooplankton that sometimes have great impacts on aquatic ecosystems. We investigated the seasonal occurrences and assemblage structure of hydromedusae in the offshore area of Sagami Bay, central Japan. Throughout the study, 33 holoplanktonic and 9 meroplanktonic hydromedusae species were collected. Unlike the nearshore hydromedusan assemblage, low species richness of meroplanktonic hydromedusae was a characteristic feature offshore. Total abundances drastically changed seasonally, with a spring peak. Muggiaea atlantica, Obelia sp., Solmundella bitentaculata, Rathkea octopunctata, Sugiura chengshanense, Liriope tetraphylla, and Aglaura hemistoma were abundant, with these seven species together comprising 58.7%–97.9% of the hydromedusan assemblage. Seasonal occurrence patterns differed among species. For example, M. atlantica was the most abundant and occurred throughout the year, with a spring peak that was probably affected by water temperature; Obelia sp. showed multiple abundance peaks, which might be driven by advections. A redundancy analysis (RDA) showed that seasonal occurrence of hydromedusae was closely related to both physical and biological factors. Our findings indicate that succession of the offshore hydromedusan assemblage was seasonal, but it was also influenced by short-term hydrographic processes such as the strong intrusion of oceanic water into the bay.

Marine biological invasions are accelerating under the influence of global trade and climate change, posing one of the most pressing threats to ocean biodiversity. This review critically examines the genetic consequences of invasive species in marine ecosystems, with a focus on mechanisms such as hybridization, introgression, genetic homogenization, and population bottlenecks. Invasive species not only disrupt native gene pools through processes such as hybridization and genetic introgression but can also shift evolutionary pathways, reduce adaptive potential, and destabilize ecological networks. Through key case studies including Pterois spp. in coral reefs and Carcinus maenas in estuarine systems, this review highlights the multifaceted genetic impacts across diverse marine environments. It further explores how emerging stressors, such as ocean warming and habitat degradation, intensify these effects. Despite progress in applying next-generation sequencing tools for detection and monitoring, substantial gaps remain in our understanding of invasion dynamics at both genetic and ecosystem levels. The review advocates for a more integrated framework that combines genomic data, policy action, and public engagement to improve invasive species management. Ultimately, this work underscores the urgent need for transdisciplinary strategies to preserve marine genetic diversity and ecosystem resilience in an era of escalating environmental change.

Marine fungi have a crucial but little-studied role in the dynamics of disease, holobiont stability and nutrient cycling in coral reef ecosystems. Despite having more than 1500 identified species, little is known about the ecological roles of marine fungi in comparison to bacteria and algae. Fungal populations live in the surrounding waters, sediments, bones, mucous and coral tissues. Ascomycota, Basidiomycota and Chytridiomycota are among the many phyla that they constitute. These fungi function as mutualists, pathogens, decomposers and bioindicators that influence coral health through food provisioning, antimicrobial activity and stress tolerance. However, when opportunistic species are subjected to environmental stress, they can exacerbate disease. Specifically, warming, acidification, eutrophication, pollution, hypoxia and sedimentation are environmental changes that impact fungal diversity and function. As a result, microbial networks become unstable and more pathogenic. Nutrient turnover and fungus-mediated decomposition impact reef carbon fluxes and ecosystem structure, causing bioerosion and biodiversity loss. Present research is limited by inadequate functional validation, taxonomic and regional biases and a lack of understanding of multi-stressor interactions, microbial networks and pathogen spreading pathways. This study highlights the critical roles that marine fungi play in disease dynamics, nutrient cycling and reef resilience by summarising the research on their interactions with coral. It identifies significant knowledge gaps in the context of global change and offers directions for integrative research that uses omics methods, experimental manipulation and predictive modelling to direct reef management and conservation.