Marine Ecology-An Evolutionary Perspective最新文献

In Japan, fishery grounds for Ruditapes philippinarum are located in estuarine and tidal flat habitats and occur over an extensive geographic range. In these habitats, due to increasing risks from environmental stressors, there is a need to develop rapid and reliable methods for inferring compositions of macrobenthic assemblages and their respective relationships with environmental and biological factors. This study examines spatial variations of macrobenthic assemblages on the fishery grounds and evaluates size-fractioned nematode data as a predictor of the macrobenthic assemblages. Multivariate analyses were carried out on the macrobenthic assemblage at 34 sites in Japan, using nematode density of three size fractions and sediment environmental variables as explanatory parameters. Four groups of assemblages were recognized by cluster analysis. Ruditapes philippinarum was the indicator taxonomic unit of one of the assemblages (Group 2) which occurred mainly in northeastern Japan, reflecting the recent decreasing trend of the population in southwestern Japan. Comparisons of seven models by distance-based redundancy analysis (dbRDA) revealed that the model with the density of medium and large-sized nematode (≥ 0.125 mm), in addition to sediment environmental variables, best explained the variation in the composition of the macrobenthic assemblages. The dbRDA result indicated that the increase in nematode density of these size fractions related to the occurrence of the Group 2 assemblage. Therefore, density data of medium and large nematode (≥ 0.125 mm) contain useful information for modeling macrobenthic assemblages on Ruditapes fishery grounds.

The evolution of body size and its association with sexual size dimorphism (SSD) in species is a subject of significant debate in evolutionary ecology. Rensch's rule predicts that SSD tends to decrease with body size in species where females are the larger sex. However, to comprehend the underlying causes of SSD emergence, it is necessary to understand how ecological and evolutionary processes differentially influence males and females. In this study, we quantified the effects of geographic, biotic, and abiotic factors on body size and evaluated Rensch's rule in penaeid shrimps by examining how ecological and evolutionary processes—such as sexual selection and resource competition—affect males and females differently. We reconstructed the phylogenetic relationships within the group and analyzed the evolution of male and female body sizes in 65 species of the family Penaeidae using phylogenetic comparative models. Our findings revealed that the sexual dimorphism detected in the family follows Rensch's rule. Male size is primarily influenced by female size, with males becoming larger as females increase in size, suggesting a role for sexual selection. Our results demonstrate how multiple ecological and evolutionary forces act differentially on males and females, shaping the emergence and evolution of SSD. These findings offer new insights into the ecological and evolutionary dynamics shaping sexual size dimorphism in marine organisms, with broader implications for understanding patterns of body size evolution.

The marine ecology of precious coral reefs is being saved with great effort. This extensive analysis provides in-depth information on the complex environment of biofilm development on coral reefs, along with insights into virulence dynamics and preventive conservation mechanisms in the face of environmental stress. With the mounting concerns that human activities and climate change pose to coral reefs, this investigation closely examines the disturbances brought about by microorganisms associated with biofilms. While addressing the complex equilibrium found in biofilm microenvironments, the narrative illustrates the positive ecological impacts of biofilm dynamics and their interactions with host corals are dealt with. The analysis reveals the need to comprehend these factors in order to create well-informed conservation approaches, and it also highlights knowledge gaps about how virulence variables affect coral health. It emphasizes the ecological implications of biofilm dynamics, showing how they impact pathogen defense, nutrient cycling, and the overall health of coral ecosystems. This review emphasizes the critical issue of the interplay between biofilm formation, environmental stress, and virulence dynamics, and the need for specialized conservation techniques. The assessment provides information on preventive measures that are crucial to maintaining the resilience and vibrancy of these important marine ecosystems, and prioritizes ecological effects in order to concentrate conservation efforts.

This study investigates the diversity of endophytic fungi associated with mangrove roots along the Sri Vijaya Puram coast, South Andaman. Root samples were collected from five stations between July 2014 and July 2016. A total of 256 fungal isolates were obtained from 637 root segments, with the highest diversity (H′ = 2.276) recorded in the stilt roots of Rhizophora apiculata . Fungal identification was performed using morphological characteristics and ITS region-based molecular methods, with sequences compared to entries in the NCBI GenBank database using BLAST, revealing that most isolates belonged to the phylum Ascomycota. The detailed findings emphasize the ecological significance of mycobiota associated with mangrove roots, suggesting their potential role in nutrient cycling and contribution to ecosystem stability in the coastal waters of South Andaman.

Harmful algal blooms (HABs) are a growing environmental concern that require better understanding, prediction, and study. Even though photosynthesizing algae produce 70% of atmospheric oxygen, their unexpected outbreaks can harm the environment. A delicate interplay of various environmental factors drives the intricate dynamics of algal blooms. Artificial neural network (ANN) models provide profound insights into the nonlinear and unpredictable behavior of algal blooms. Neural networks can also improve prediction accuracy, pattern recognition, species identification, and correlation analysis. The ANN's ability to comprehend and process diverse datasets, along with its adaptability, makes it suitable for real-time monitoring systems, allowing for early warnings and proactive mitigation in HAB management. This review paper summarizes recent findings and demonstrates how ANNs contribute to HAB research. Based on this review, we discuss the challenges of using ANNs in this context and offer recommendations for future research directions to explore emerging trends in the field.

Alison Reef is an oceanic atoll located in the southern part of the Spratly Islands in the South China Sea. A total of 46 genera of scleractinians, the octocorals Heliopora spp. and Tubipora sp., and two hydrocoral species, Millepora platyphylla and M. cf. dichotoma, were recorded during the coral survey conducted in July 2022 in this atoll. Moreover, a diverse and abundant coral community (mean cover 51.4 ± SD 14.3%) dominated by acroporids was revealed in the deep zone of the lagoon (20–25 m depth). In contrast, the shallow zone of the lagoon (2–5 m) revealed two times lower coral cover, whereas the mean proportion of coral rubble was five times greater than in the deep zone, demonstrating the general coral reef decline in the shallow zone. Of the 34 coral genera observed in the deep zone of the lagoon, 14 species from 6 genera were found to be most abundant in this coral community. Ten of these species belonged to Acroporidae (Acropora, Montipora, Isopora and Anacropora). The dominance of acroporids distinguished this community from that in the same depth zone on the forereef. A thriving coral community dominated mostly by thermally susceptible coral taxa in the deep zone of the lagoon seemed to have been maintained for at least the last three decades. This phenomenon suggests the deep lagoons of open-type atolls with pronounced water renewal and negligible anthropogenic impact may serve as environmental refugia for a number of reef-building corals in light of global climate change.