Marine Ecology-An Evolutionary Perspective最新文献

Populations at a species' distribution edges often present reduced gene flow, increased impact of genetic drift, and impoverished genetic variation, globally compromising their ability to adapt to environmental changes. This study assessed the genetic diversity, structure, and connectivity of the Mediterranean endemic seagrass Posidonia oceanica at its easternmost distribution limit, from diverse thermal regimes around Cyprus, contextualised within a set of 16 Turkish populations in the Levantine and Aegean Seas (eastern Mediterranean). The genetic assessments were based on sets of 13 to 16 microsatellite loci, depending on the analysis. Our findings revealed lower genotypic and allelic richness in the Cypriot populations, which also presented lower connectivity and higher differentiation among them in comparison to the Turkish ones. Additionally, the genetic and genotypic diversity and the connectivity of Cypriot populations were highly variable, with populations presenting high diversity and connectivity, while others exhibited extremely low diversity and high isolation. The discrepancies among the Cypriot populations were potentially due to differences in the sexual reproductive output related to the different thermal regimes around the island and the presence of barriers to gene flow along the island's southern coastline. This study advances our understanding of the genetic connectivity and genetic diversity of range-edge P. oceanica populations in the Eastern Mediterranean. This knowledge can guide the management of conservation and ecosystem restoration initiatives for this habitat-forming seagrass species.

Porpita porpita (Linnaeus, 1758), commonly known as the blue button jellyfish, is a pleustonic hydrozoan distributed in tropical and subtropical oceans and occasionally observed in mass strandings. On April 10, 2024, the first mainland beach stranding of this species in southeastern Bangladesh was recorded at Mundar-Deil beach along the Teknaf coast, during a national heatwave. This represents only the second confirmed occurrence of P. porpita in Bangladesh, ~23 km north of the first sighting at St. Martin's Island in 2014. Environmental parameters, including salinity, wind, currents and sea surface temperature were recorded on-site. Morphological and morphometric analyses of 65 collected specimens revealed that the total diameter was significantly correlated (p < 0.05) with the disc diameter (r = 0.981), mantle length (r = 0.895), and the average tentacle length (r = 0.751). Additionally, disc coloration and float structure aided in species verification and ecological interpretation. The occurrence during peak pre-monsoon heat and elevated salinity highlights the species' possible northward latitudinal range shift in response to climate change. This event may be driven by synergistic effects of global warming, monsoonal currents, strong pre-monsoon onshore winds, and declining predation pressure particularly from sea turtles, whose nesting has decreased by over 80% due to entanglement, habitat loss, and predation by feral species. These findings underscore the ecological indicator potential of P. porpita and the need for continued surveillance of gelatinous zooplankton to understand ecosystem responses under warming scenarios in the Bay of Bengal. The presence of P. porpita signals a potential ecological imbalance and suggests that this hydrozoan may serve as an emerging bioindicator of environmental shifts in the Bay of Bengal region.

Understanding how non-native scyphozoan jellyfish interact with native communities provides insights into the ecological processes structuring their populations. Aurelia coerulea is a problematic invasive species, with no known predators of the polyp stage outside its native range. Austraeolis ornata is a potential predator of A. coerulea polyps, but little is known about its biology and ecology. Both species inhabit shallow coastal waters across southern Australia, suggesting that interactions between them are likely and could influence population dynamics. Here, we tested the hypothesis that A. ornata recognizes A. coerulea as prey and exhibits high predation potential on introduced polyp populations. We conducted four experiments to: (1) determine whether nudibranchs can detect and locate jellyfish polyps as prey, (2) test whether nudibranchs show any preference between non-native jellyfish polyps and a confirmed native prey, (3) assess the relationship between nudibranch size and the number of jellyfish polyps consumed, and (4) evaluate whether nudibranchs can survive and grow on an exclusive diet of jellyfish polyps. Nudibranchs located their prey and began feeding within 14 ± 6 min, showing clear predatory behavior, and consumed up to 197 jellyfish polyps predator⁻¹ day⁻¹, with feeding rate strongly correlated with body size. Furthermore, nudibranchs grew an average of 9.8 ± 5.2 mm in length and 334.7 ± 184.8 mg in weight over 3 weeks, confirming their ability to survive and sustain growth on an exclusive diet of jellyfish polyps. These findings suggest that A. ornata recognizes A. coerulea polyps as prey and could likely play an important ecological role in regulating introduced A. coerulea polyp populations in southern Australia.

Habitat partitioning reduces competition among ecologically similar species and promotes their coexistence within the same environment. In this study, we evaluated the abundance, microhabitat use, reef occupancy, spatial overlap, and agonistic interactions of the sympatric territorial damselfishes Stegastes acapulcoensis and Stegastes flavilatus at La Entrega reef, Oaxaca, Mexico. Using visual censuses, habitat characterizations, in situ observations, and non-invasive video recordings, we found that S. acapulcoensis exhibited higher abundance than S. flavilatus across all reef zones. Both species exhibited clear habitat partitioning along the reef zones, with S. acapulcoensis occupying sites with high percentages of live coral and algae, as well as large shelters, while S. flavilatus used sites characterized by high rugosity and the presence of rock, sand, and rubble. Although S. flavilatus defended larger territories than S. acapulcoensis (6.6 ± 4.9 m² vs. 4.5 ± 1.5 m², respectively), S. acapulcoensis occupied a greater proportion of the reef area (58% vs. 18%). Spatial overlap between species was limited (10%–25%) but increased up to 40% among individuals of size class III in the deep zone, where the availability of preferred microhabitats for both species was substantially lower. Both species displayed a higher frequency of agonistic interactions toward conspecifics; however, interspecific interactions increased in the deep zone. Our results suggest that the spatial partitioning of S. acapulcoensis and S. flavilatus is driven by differences in microhabitat selection, resulting in relatively low spatial overlap and predominantly intraspecific aggression. Our findings show that the fine-scale selection of species-specific microhabitats and interspecific agonistic interactions drive spatial segregation and maintain ecological differentiation between S. acapulcoensis and S. flavilatus, thereby promoting their coexistence even in overlapping reef zones within structurally complex systems.

Decapods play vital ecological and economic roles, yet their diversity and distribution in the coastal waters of Matang remain poorly understood. Increasing anthropogenic pressures have further impacted their habitats, underscoring the need for improved biodiversity assessments. Conventional monitoring methods are often limited by inconsistencies, invasiveness, low taxonomic resolution, and inefficiency in complex habitats. This study evaluated the effectiveness of environmental DNA (eDNA) metabarcoding to assess decapod diversity in Matang waters. A total of 136 seawater samples were collected from predefined zones between October 2021 and October 2022. DNA was extracted using the CTAB method, and a partial mitochondrial cytochrome c oxidase subunit 1 (COI) gene region was amplified. The amplicons were sequenced using the Illumina MiSeq platform. This approach identified 12 decapod species from six families: Penaeidae (3 species), Lucideridae (1 species), Sergestidae (3 species), Dotillidae (1 species), Pilumnidae (1 species), and Diogenidae (3 species). Dominant species included Acetes japonicus (46%), Acetes indicus (27%), and Diogenes fasciatus (10.9%). Notably, eight species matched records from previous conventional surveys, while four additional taxa: 2 Diogenes spp. (Diogenes fasciatus, Diogenes rectimanus), a Dotillidae crab (Ilyoplax serrata), and a Pilumnidae crab (Aniptumnus sp.) were newly detected in the area. These findings indicate that decapod richness in Matang is likely underestimated. In summary, eDNA metabarcoding offers a promising, non-invasive alternative for biodiversity monitoring in dynamic environments and complements traditional methods. This study establishes a foundation for long-term decapod monitoring and supports conservation efforts in the Matang region.

Intertidal mudflats are highly productive ecosystems and contribute significantly to the coastal dynamics in the northwestern Indian Ocean. The endemic to the northwestern Indian Ocean crab, Leptochryseus kuwaitense, is the predominant species in this ecosystem and is responsible for most bioturbation through burrow construction. The present study aims to investigate the phylogeography of L. kuwaitense by collecting samples from five localities along the Persian Gulf and the Gulf of Oman, using COX1 sequences and geometric-morphometric analyses. Phylogeographic analyses revealed some degrees of genetic differentiation among the five localities, but did not detect any obvious geographic pattern, and no isolation was recovered between the Persian Gulf and the Gulf of Oman. Morphometric analysis also revealed no notable differences in shape between the two gulfs. This pattern of population structure is likely due to the disconnection between the sheltered mudflats, the typical habitat of L. kuwaitense, along the studied localities. The lack of geographic pattern in the genetic structure is probably imposed by the complex surface currents in this area. Demographic results indicate a recent population expansion for L. kuwaitense along the northwestern Indian Ocean. The Bayesian Skyline Plot revealed that the increase in effective population size happened during the last glacial maximum, through which a large proportion of mudflats in the northwestern Indian Ocean were unsuitable for this crab.