Marine Ecology-An Evolutionary Perspective最新文献

Green turtles, Chelonia mydas, migrate to the Ogasawara Islands for breeding once every few years. However, the foraging grounds of these turtles prior to their visit to the Ogasawara Islands remain uncertain. In this study, we examined the genetic similarity between macroalgal specimens collected from various coastal regions and macroalgal fragments in the gut contents of green turtles visiting the Ogasawara Islands in order to estimate their foraging grounds. A total of 4 green, 13 brown, and 3 red algal species were identified from the gut contents of 62 adult green turtles. Macroalgal species composition differed by year of green turtle harvest, but not by sex of green turtle. Grateloupia angusta and Besa paradoxa were the most abundant temperate species obtained from the intestines, but they are rarely distributed around the Ogasawara Islands. Therefore, the cox1 gene and/or cox2-cox3 spacer region, which are useful to detect intraspecific genetic diversity, were analyzed for the two algal species obtained from the intestines and collected from various sea coasts. Four haplotypes of G. angusta recovered from the intestines were identical to specimens from some Japanese Pacific coasts and Korean islands. In contrast, a single haplotype of B. paradoxa retrieved from the intestines was identical to that of specimens from Enoshima, which is close to Tokyo. These data suggest that green turtles may have come to the Ogasawara Islands from different foraging grounds depending on the year. Determining the origin of green turtle diets is important to better understand the migratory connectivity between grazing and breeding grounds.

The mother-of-pearl oyster Pinctada mazatlanica (Hanley, 1856) obtained full protection from the Mexican government after the fishery collapse in 1939. P. mazatlanica was listed in 1994 as a threatened species in the “Special Protection” category. However, no quantitative assessment of the state of the population has been done so far. Our study is the most comprehensive summer interannual monitoring program conducted so far in the Eastern Pacific using SCUBA diving censuses conducted in 314 sampling sites located along the Mexican Pacific between 1998 and 2021. We propose the hypothesis that although P. mazatlanica had full protection with the NOM-059, global warming reported in northwest Mexico has caused a decrease in the population abundance along the Pacific coast, which may render the protection effort useless. However, we demonstrate that P. mazatlanica was the numerically dominant macro–mollusk and occupied the 18th ranked abundance place compared with the entire epibenthic macroinvertebrate fauna that included 241 species at rocky reefs of the Mexican Pacific, particularly abundant along the peninsular coast of the Gulf of California. Population frequency size distribution of P. mazatlanica dorsoventral length showed positive population growth and latitudinally similar dorsoventral length range (2–30 cm, mode 14 cm when protandry takes place) along the peninsular coast of the Gulf of California, indicating a stable population in time and space. We observed high abundances in the central Gulf of California (Baja Peninsula), mainly from Loreto to La Paz. We conclude that P. mazatlanica is a stable and healthy population along the rocky reefs of the peninsular coast of the Gulf of California even during prolonged anomalous warm events in 2013–2016. Therefore, the present protection status should be modified accordingly.

Seaweed and mangrove ecosystems, as integral components of the blue carbon habitat, play pivotal roles in global carbon sequestration and coastal protection. This study explores the bacterial communities and their functional profiles from the coastal habitats of Goa, emphasising their critical roles in the blue carbon ecosystems. The bacterial diversity based on the metabarcoding analysis of the V3–V4 region of the 16S rRNA gene was assessed from the seaweed habitats at Dona Paula and the mangrove ecosystem at Chorao, Goa. Proteobacteria, Cyanobacteria and Actinobacteria dominated the seaweed ecosystems. In contrast, mangrove ecosystems had a more complex microbiota, including Firmicutes and Planctomycetes, which thrive in anaerobic conditions. A comparative reanalysis of taxonomic and functional profiles from the study locations and seven additional locations from different seaweed and mangrove ecosystems of Goa reported in previous studies was also carried out to understand the temporal changes from 2017 to 2024. The results showed a significant presence of Firmicutes at selected locations, with an increased abundance of pathogenic taxa such as Bacillus, Clostridium and Shewanella. These locations, Anjuna, Hawaii and Bogmolo in the seaweed and Ribandar, Panaji and Campal in the mangrove habitats of Goa, were situated near urban regions and influenced by anthropogenic activities, including tourism and urban runoff. Analysis of the bacterial functional profiles also showed an increased representation of the genes associated with xenobiotic biodegradation pathways in these locations. These findings emphasise the urgent need for effective conservation strategies to protect these vital ecosystems against the rising threats of anthropogenic pressures, pollution and climate change.

Multi-species fish foraging associations occur when individuals from two or more aquatic species forage with one another. Associations involving octopuses have been documented in the Pacific, Atlantic and Indian Oceans and the Red Sea. To determine which fishes interact with an octopus species in temperate coastal waters off eastern Australia, we video-recorded foraging common Sydney octopus, Octopus tetricus, at Fly Point in the Port Stephens-Great Lakes Marine Park, New South Wales. This study provides evidence that crimsonband wrasse and Günther's wrasse from family Labridae and yellowfin bream from family Sparidae attend common Sydney octopus. The octopuses and attendants did not behave aggressively towards each other. However, aggression between different attendants and agonistic interactions between wrasses were observed. Octopuses produce visual cues, such as appearance changes and substrate disturbances, which may have attracted attendants. Following an octopus is a novel feeding behaviour that appears to be learned by only some individuals in each attendant species. These findings will improve our understanding of interspecies interactions and trophic relationships in temperate coastal marine ecosystems.

Beach seine is a popular fishing gear along the coast of West Africa. The low selectivity of this gear, coupled with its mode of operation, results in the bycatch of juveniles of commercially important fish species and other non-target organisms, which are consequently discarded. This study investigates the macrofaunal constituents of beach seine bycatch discarded along the coast of Ghana and the potential implications for the country's fisheries. Discards from two beach seine nets were collected and examined monthly from Dzelukofe, Bortianor, and Cape Coast over a period of six months, from August to October 2022 for the wet season and December 2022 to February 2023 for the dry season. In total, 71 species (15,708 individuals) were recorded at Dzelukofe, 65 species (5158 individuals) at Duakor, and 62 species (8030 individuals) at Bortianor. Eighty (80) species made up of 20,545 individuals were recorded during the dry season, while 75 species comprising 8,351 individuals were recorded during the wet season. Bivalves accounted for 41.1% of the macrofauna encountered, followed by cephalopods (35.7%) and malacostracans (21.9%). The remaining macrofauna together accounted for < 3%. Cuttlefish eggs dominated (43.07%) the discards in the dry season, while being completely absent in the wet season. The cuttlefish eggs were most prominent in Dzelukofe, accounting for > 50% of the sample. Pinctada radiata dominated (41.4%) at Duakor, while Gari fervensis (46.6%) was dominant in Bortianor. Juveniles and early life stages of commercially important species made up almost 85% of the discards. Potentially, about 8,600,000 cuttlefish eggs were discarded through beach seining activities, which could have produced at least 100,000 adult cuttlefish. This trend could be true for other commercially important fish species found in the beach seine discards. For a country whose fisheries sector generates over 1 billion USD in revenue each year and contributes to at least 4.5% of GDP, further studies on the implications of beach seine fisheries on the economy are recommended for better management strategies.

The blood cockle, Tegillarca granosa, holds significant importance within the Asian shellfish ecosystem, both in terms of economic viability and ecological significance. The investigation focused on examining the genetic diversity, historical biogeography, and population structure of the species in order to enhance our comprehension of its evolutionary history. We selected a total of five sites across the Indonesian Archipelago for sample collection. Sequence variation in a segment of mitochondrial DNA control region was characterized in a sample of 200 individuals. Genetic diversity (h = 0.88–0.96) and nucleotide diversity (π = 0.51–0.98) were found to be high compared to the estimates reported for many other similar shellfish taxa. Nonetheless, analysis of molecular variance revealed significant genetic differentiation, F_ST = 0.5530 (p < 0.0001 after Bonferroni corrections). Furthermore, the pairwise fixation index values exhibited significance across all population locations, indicating a constraint on dispersion potential and gene flow. This pattern presumably indicates restricted dispersion ability, facilitating local adaptation to specific locales, hence enhancing the biological, oceanographic, and geographic influences on genetic structure. The findings presented herein establish a basis for formulating improved conservation strategies for the target species.