Marine Ecology-An Evolutionary Perspective最新文献

The dominance of any organism in a given habitat depends on its competitive ability. Competition among coral genera is an important factor determining the assemblage structure within reefs and other coral-dominated habitats. Here, we assessed the competition between scleractinian corals growing on natural and recruiting on artificial reefs. We evaluated different forms of direct-contact competition and investigated the variation among genera in their competitive abilities. We documented a total of 4151 interactions between 28 coral genera, with two-thirds of the interactions being between corals of the same genus. We found that the competitive ability of each genus was not necessarily related to the genus abundance. The genera Coelastrea, Dipsastraea, and Leptastrea were recorded as more competitive despite their sparser natural occurrence on the reef. Meanwhile, Lithophyllon and other Fungiidae corals were the most competitive genera. While Oulastrea was a competitive genus on the artificial reefs, it was the opposite on natural reefs. The greater competitive capacity of genera with relatively smaller colony sizes, like Oulastrea and Coelastrea, supports the hypothesis of a trade-off between aggression and growth. These findings are further discussed with regard to the possible influence of competition among recruits on the development of mature reef communities.

Estuarine lagoons provide nursery habitats for marine fishes; however, small lagoons (< 1 km²) have been overlooked. To evaluate the nursery function of small estuarine lagoons (SELs) for temperate marine fish, this study used seining on the coast of the northwestern Pacific (Kyushu, temperate Japan) during the juvenile seasons (winter and spring) to perform juvenile sampling at two scales and an abundance/size comparison of blackfin seabass (Lateolabrax latus). As a preliminary survey, habitat-scale (inside vs. outside lagoon habitats) sampling was attempted in two SELs during February and April. Subsequently, seascape-scale sampling was undertaken during the juvenile season (January–May). The seascape consisted of two types of estuaries (lagoons and rivers) and sandy beaches (embayed and exposed). A preliminary survey showed no clear difference in abundance among the habitats, but significantly larger juveniles were observed inside than outside the two SELs. In the seascape survey, peak juvenile abundance during the first half of the study period was concentrated in habitats other than the lagoon estuary, whereas no peak was recorded during the second half. Moreover, the lagoon estuary was significantly larger than the marine habitats, and the monthly occurrence of juveniles was continuous in the lagoon estuary but intermittent in the riverine estuary. These results imply that seabass juveniles utilize the SEL habitat as they grow, highlighting the potential nursery function of estuarine lagoons for marine fish, even at a small scale.

Shipwrecks and artificial reefs play a critical role in restoring marine biodiversity in degraded ecosystems. This study assesses the ecological impacts of the 2023 ENSO event and chronic anthropogenic pressures on the San Luciano Shipwreck Reef (central Mexican Pacific), based on comparative monitoring during 2017–2018 and 2023. Using standardized indicators from the Global Coral Reef Monitoring Network and the biological condition gradient (BCG), we evaluated benthic communities, structural features, and physiological stress markers. Biodiversity was highest at the wreck's ends, where structural complexity increased due to metal degradation. In 2023, over 90% of coral colonies showed bleaching and mortality, accompanied by bioeroder proliferation and invasive species such as Carijoa riisei. Coral cover declined by over 85%, and biomarkers such as the Chl a/PC ratio and zooxanthellae density confirmed elevated stress levels. These changes placed the reef at level V of the BCG. The deterioration observed is strongly linked to the combined influence of ENSO-related anomalies and persistent port-related impacts, such as nutrient loading, turbidity, and invasive species transport. Findings underscore the vulnerability of artificial reefs to cumulative stressors and support the inclusion of shipwrecks as valuable sentinel sites in reef monitoring and conservation planning.

The influence of the drought event on the structure and distribution of the copepod community was investigated in the Caeté Estuary, northeast of Pará, Brazil, through field surveys performed in three sectors of the estuary from June/2013 to June/2014. The occurrence of a dry event in June/2013 was marked by low rainfall and consequently by lower river runoff, increased seasonal average salinity (19.71 ± 5.64), dissolved nutrient concentrations, and high phytoplankton biomass (chlorophyll-a). These conditions allowed a substantial increase in copepod density, particularly toward the mouth of the estuary, which was dominated by estuarine and coastal species such as Pseudodiaptomus richardi, Oithona hebes, Acartia lilljeborgii, Acartia tonsa, and Paracalanus quasimodo, which presented higher densities in Jun/2013 than those obtained during the normal precipitation period (June/2014). Marine species allowed a slight increase in diversity and richness, possibly caused by the increased recruitment rate from adjacent coastal waters. Results highlight that salinity, driven by precipitation, regulates copepod distribution and composition, with droughts affecting estuarine trophic dynamics in the Caeté Estuary. Future studies focused on conservation efforts must consider connectivity between resident and transitory species while addressing trophic interactions like predation and food availability. Adaptive management strategies that integrate these factors can help sustain estuarine ecosystems against climate anomalies and anthropogenic pressures in tropical estuarine systems with similar characteristics in the Amazon region and worldwide.

The study of the burrowing and boring pattern is an important bioturbatory behavioral display that provides information about interactions of animals with their surrounding factors and habitat selection preferences. Previous studies have explored the boring activities of sphaeromatid isopods in a variety of substrates, including wood, polystyrene, and rock, across different regions worldwide. However, no previous reports have been documented on the boring pattern of isopods in hard mud substratum. Present studies were carried out on the silt-clay rich hard substratum of coastal mudflats at Kamboi, the northern innermost region of the Gulf of Khambhat, Gujarat. This habitat is selectively preferred by the isopod Sphaeroma annandalei Stebbing 1911, which is indicated by its abundance. To decipher the boring patterns, we examined the sediment blocks during low tides, took multidirectional sections of the exposed regions, and photographed the boring patterns. It showed that there were incidences of the bores of different sizes crossing each other. We primarily interpreted it as the borings of younger and older isopods. However, to further confirm, resin casting was done, which gave us a complex network of interconnected borings. It clearly exposed, for the first time, the continuous interconnected burrows of different sizes of individuals (0.56 mm to 4.75 mm) of S. annandalei in hard mudflat habitat. The study has recorded the presence of two species, S. annandalei and Cirolana willeyi Stebbing 1904, for the first time from Gujarat.

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.