Aquatic Ecology最新文献

The acidification of the ocean caused by the diffusion of anthropogenic carbon dioxide (CO₂) into seawater has been believed to threaten the stability of the marine ecosystem. As one of the major contributors to the primary production in oligotrophic oceans, the response of Trichodesmium to the acidification of the ocean has attracted a lot of attention. Therefore, in this study, we applied physiological and biochemical methods to identify the influences of high pCO₂ and low pH conditions on the growth of T. erythraeum. Our results showed that the low pH during the acidification of the ocean was the main factor inhibiting the growth of T. erythraeum. In addition, low pH caused oxidative stress to T. erythraeum, as evidenced by the increase of the reactive oxygen species and antioxidant enzyme’s activities. The activity of carbonic anhydrase (CA) enzyme is dually regulated by pCO₂ and pH, and T. erythraeum can adapt to different levels of pCO₂ and pH in seawater by flexibly adjusting CA enzyme activity. We also discovered that the stimulatory effect of high pCO₂ on the exopolysaccharide (EPS) content of T. erythraeum outweighed the inhibitory effect of low pH during the process of ocean acidification. In conclusion, this study systematically revealed the effects of high pCO₂ and low pH caused by the acidification of the ocean on the growth and EPS of T. erythraeum. These results provide new insights into the response mechanisms of T. erythraeum in the acidified ocean under future climate conditions.

This research was designed to investigate the acute toxic effect of cadmium chloride on freshwater turtle Mauremys reevesii. Mauremys reevesiis were exposed to a wide range of cadmium chloride by intraperitoneal injection for 7 days and the survival numbers of the animals were noted to determine the dose of cadmium chloride for 0% mortality rate (Dn) and the dose of cadmium chloride for 100% mortality rate (Dm). Karber’s method was used to test the LD₅₀ of cadmium chloride in Mauremys reevesii. The results showed that cadmium has acute toxic effect on freshwater turtle Mauremys reevesii. Dm and Dn were 500 and 20 mg·kg⁻¹ separately. The LD₅₀ value was 89.8 mg·kg⁻¹ for cadmium chloride, with the 95% confidence limit of 85.2–98.5 mg·kg⁻¹. The results indicated that cadmium had acute toxicity on turtle Mauremys reevesii.

Research conducted in intermittent rivers located in semiarid regions has revealed that the hydroperiod significantly affects the composition and dynamics of limnic communities. In our study, we examined the impact of key factors associated with abiotic heterogeneity resulting from irregular hydroperiods and the conservation status of two intermittent rivers in the semiarid region of Brazil on the structure and dynamics of limnic mollusk communities. For this, we collected material monthly throughout two years on the Itaim and Guaribas rivers, in Piauí semiarid region. We employed Two-Way Analysis of Variance (ANOVA) and PERMANOVA to assess variations in community structure based on mollusk species richness and abundance across the different rivers and seasons. Additionally, we employed Redundancy Analysis (RDA) to examine the influence of explanatory variables on community structure. Our findings demonstrate that in intermittent rivers within the Brazilian semiarid region, multiple factors contribute to the shaping of limnic communities, with anthropogenic disturbances playing a predominant role, challenging previous studies that have primarily emphasized the influence of hydroperiod on such communities.

An appraisal of the snail (Mollusca: Gastropoda) assemblage of the Sundarbans mangrove region, West Bengal, India, was made through consistent monitoring of three selected sites. In a span of 3 years, 18 species of snails under 11 families, and 9 orders were collected in 304 samples with the Shanon-Weiner diversity index (H’) ranging between 0.8445 and 1.6909. In terms of numerical abundance, Stenothyra deltae (34.07 ± 5.71SE) and Cerithidia cingulata (26.01 ± 1.33SE) were dominant, while Nassarius stolatus (0.01 ± 0.01 SE) qualified as a rare species in the three sites. Significant differences (p < 0.05) in abundance in the sites were observed for Cerithidia cingulata, C. alata, Gangetica miliacea, and Stenothyra deltae. A canonical correspondence analysis reflected that the abundance of G. miliacea is shaped by the conductivity, C. cingulata is linked with temperature and the phosphate concentration is a better predictor of the abundance of S. deltae. The pattern of the diversity of the snails may probably reflect the variations in the environmental quality including the food resources. Thus, the snail assemblage pattern may be used as a basis for the biological monitoring of the Sundarbans mangroves and other similar sites.

The European beaver, the largest rodent in Europe, has enormous skills in transforming and adapting its habitat. It chooses a place for its habitat that provides it with food and a high degree of security. He builds dams to regulate water levels. It is assumed that beaver dams can survive for several dozen years, depending on the continuity of use. When a damaged dam is reused, beavers are able to quickly restore the structure to a suitable condition. By monitoring one of the dams for several years, we managed to record this interesting process. In this case, it was determined that the time needed to rebuild the dam and restore the water level was approximately 8 h. This, of course, depends on local conditions, but the data obtained allows for a better understanding of this process.

Invasive fish species can play an important role in aquatic ecosystems and have a significant impact on ecosystem dynamics, which influences primary production, planktonic communities, and aquatic macrophytes. The presence and density of invasive fish can disrupt nutrient ratios and ecological processes, leading to potential ecological consequences for invaded habitats. This experimental investigation focused on the invasive armored catfish species P. ambrosettii (Loricariidae) and postulated that high densities of armored catfish in invaded environments may affect nutrient cycling due to high N: P excretion rates. Furthermore, we sought to identify how these changes in nutrient concentration impact phytoplankton, protozooplankton, and the biomass of two invasive macrophytes. We carried out a 30-day experimental study at the Nupélia Applied Ecology Laboratory at the State University of Maringá with 20 fiber cement mesocosms with a volume of 135 L. These mesocosms had continuous water circulation and were used to simulate the natural conditions of lakes invaded by P. ambrosettii. We simulated five treatments that represented density at different levels of invasion: control (no fish), low-density (one fish), medium–low (two fish), medium–high (three fish) and high-density (four fish). The treatments affected abiotic variables such as pH, dissolved oxygen, and electrical conductivity, and nitrogen and phosphorus concentrations increased with increasing fish density, as expected. In turn, nutrient concentrations had effects on chlorophyll-a and macrophyte biomass. The chlorophyll-a and Eichhornia crassipes biomass were positively related to the increase in phosphorus, while Hydrilla verticillata showed a positive relationship with both nutrients nitrogen and phosphorous. The zooplankton community showed different density behaviors in relation to treatments. Its composition was influenced by the different treatments, and it underwent significant variations along the nutrient gradient. As predicted, the different densities of P. ambrosettii led to changes in the structure of the ecosystem. In treatments with higher fish densities, the environment was characterized by low oxygenation, high conductivity, and high concentrations of nitrogen and phosphorus. These conditions favored the dominance of phytoplankton and aquatic macrophytes, while the density and species composition of zooplankton was low. The effects observed in this experimental study contribute to insights into the field of invasion biology and its relationships with nutrient dynamics. The effects that may arise from the invasion and high population density of the armored catfish Pterygoplichthys in invaded locations reinforce the importance of understanding these processes in the functioning of the ecosystem and how this directly or indirectly impacts the dynamics of coexisting communities in natural environments.

Energy acquisition and allocation between the somatic compartments are essential for the ecological success of an organism. The seasonal pattern of energy allocation among the different organs was evaluated in the snail Zidona dufresnei. The somatic indexes, energy density and energy content of the gonads, digestive gland, foot, and secondary sexual glands of Z. dusfresnei. The lowest foot index (FI), energy density and energy content were found in winter. The high digestive gland index (DI) and energy content (EC_DIG) observed in spring likely coincide with the peak of productivity. The male’s gonads did not show seasonal energetic variation, although the gonadosomatic index (GI) of males was lower in summer than in other months. The mass and energy content of the albumen and capsule glands exhibited a decreasing pattern from spring to winter. The foot is suggested as the main energy reservoir in Z. dufresnei, the digestive gland as an energy reservoir that contributes to the gonadal maturation, whereas the energy of the capsule and the albumen glands contributes to the spawning. This study highlights seasonal variations in the energy content of the foot (edible compartment) and the significance of secondary sexual glands in understanding the bioenergetics of Z. dusfresnei and offspring fitness. These findings should be taken into consideration in fisheries management decisions for this ecologically and commercially important species.

Fresh water fishes carry heavy infection of helminth parasites. Infection of these parasites may result poor growth, postpone sexual maturity and mortality of fishes, and cause human and animal diseases. This study recorded seasonal variations in gastrointestinal parasites found in fishes collected from the Mundeswari River, Hooghly, West Bengal, India. Total 1368 fishes were examined in four different seasons, namely Winter (December, January, February), Summer (March, April, May), Monsoon (June, July, August), Post monsoon (September, October, November) during December 2017–November 2021. Season wise abundance of four types of endo-helminthes namely Acanthocephala, Nematode, Trematode and Cestode, were recorded. The results indicated that climatic conditions are directly or indirectly influenced the intensity of parasitic infection and among the seasons the intestines or body cavity of fishes were recorded high parasitic infection during the winter season as compared to summer, monsoon and post monsoon.

This investigation presents pioneering discoveries concerning the endemic seaweed Ulva ovata across multiple sites in the Gulf of Khambhat, India, going beyond its type locality, Gopnath. The primary objective of this research was to examine the substrate type and various environmental factors affecting seaweed diversity at five sites where endemic U. ovata was found. Identifying 11 seaweed species under Chlorophyta and Rhodophyta phyla, the study highlights rocky sites exhibiting higher Simpson (D) and Shannon (H′) diversity indices, species richness, and percentage cover during cold months. k-dominance analysis indicates more species at Pingaleshwar, Unchakotda, and Gopnath. Bray Curtis similarity shows similarity in seaweed composition between Unchakotda-Pingaleshwar, and Kuda-Khadsaliya, whereas Gopnath forms a different cluster mode. Key species U. rigida and U. ovata, identified by SIMPER analysis, act as bio-indicators for future studies. Five sites demonstrate distinct seawater temperature, dissolved oxygen, light intensity, salinity, total dissolved solids (TDS), electrical conductivity (EC), wind velocity, UV index, nitrate (NO₃⁻), and nitrite (NO₂⁻) significantly impacting seaweed diversity. This study enhances understanding of seaweed distribution and environmental influences in the Gulf of Khambhat, offering insights into ecological dynamics and implications for marine conservation and management strategies.

Commercial success of a pet species predicts its invasiveness, making the most traded species more likely to become introduced. Turtles are among the most traded species, making it critical to monitor their introduction, and in Portugal several invasive turtle species have been detected in nature. This study reports the first official record of Mauremys sinensis and lists its unofficial records in Portugal. This is a critically endangered species in its native range but invasive out of its native range. Two M. sinensis individuals (one adult male and a juvenile) were found in a lake near Évora, alongside native Mauremys leprosa. Additionally, iNaturalist database analysis revealed 14 citizen science records of this species in 10 municipalities in Portugal since 2021 These records were located from North to South of continental Portugal but also in the Madeira Island. The presence of invasive turtles can impact native species through competition, predation, disease transmission, and hybridization. Pet trade is the primary source of these species, and legislation has been ineffective in preventing their introduction. This study also highlights the need for comprehensive strategies, including whitelists and blacklist, to address the invasive pet trade, protect native ecosystems, and prevent further introductions of species like M. sinensis.