Marine Ecology-An Evolutionary Perspective最新文献

Nutrient availability limits phytoplankton growth throughout much of the global ocean, and this has led scientists to consider fertilizing the ocean with phytoplankton growth-limiting nutrients. We studied the response of phytoplankton to the addition of natural materials such as rice husk and bamboo leaves through field mesocosm experiments. Rice husk released only SiO₄⁴⁻ while the bamboo leaves released SiO₄⁴⁻ and also NH₄⁺, which led to a phytoplankton community shift from picophytoplankton to microphytoplankton. The bamboo addition led to a diatom bloom with an increase in diatom abundance, and the supply of nutrients particularly benefited Nitzschia spp., along with Navicula spp., Chaetoceros spp., Leptocylindrus spp., and Pseudo-nitzschia spp. Such a proliferation of diatoms triggered by bamboo addition lowered the partial pressure of carbon dioxide (pCO₂) by upto 60 μatm in 8 days. Our findings reveal that bamboo has high potential in ocean fertilization experiments, as it gave better pCO₂ reduction when compared to most global ocean fertilization experiments. Furthermore, the ecological success of bamboo in drawing down pCO₂ over other SiO₄⁴⁻ sources indicates that diatom proliferation is mainly regulated by nitrogen limitation in the Arabian Sea. This study has implications for CO₂ sequestration, the aquaculture industry, and broader environmental health.

As environmental change accelerates, marine invertebrate growth rates may change in response to a variable environment. Some colonial invertebrates manifest annual growth checks in their skeletons, as somatic growth slows or stops in winter. Here we describe a morphometric measurement methodology to quantify growth rates using annual growth checks visible on X-rays and SEM images. We tested our method on three rigid erect perennial cheilostome bryozoan colonies belonging to the marine species Cellarinella nutti, Melicerita chathamensis, and M. obliqua. They were collected from 150 to 500 m water depth and from 48° S to 78° S latitude. The growth checks in all three species were identified visually in X-ray images. We trialed the use of morphometric data from composite SEM images, including measures of branch width, number of autozooids across branch, autozooid length, and autozooid width, but they did not significantly correlate with growth checks from the X-ray images in all species. In the two polar species, the winter growth checks were associated with slightly longer autozooids. Assuming that growth checks were annual, growth rates were calculated to be from 2.81 to 3.54 mm/year, decreasing over time. Our hypothesis is that a combination of X-ray imaging and morphometric data collection on composite SEM images shows promise for application to other bryozoan species and marine invertebrates from temperate/polar regions.

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.