Aquatic Ecology最新文献

An investigation aimed at recording NIS settlement by the employment of a bare artificial substratum constituted by caged lightweight expanded clay (EC) has been carried out in a confined marine basin. Packaged substratum, submitted to different organic treatments and a control was positioned in spring both in the water column and into the bottom sediment. Two months experiment provided 17 non-indigenous (NIS) versus 154 indigenous species (IS). Eleven “slow” colonizing NIS occurred at mean density of 0.2 ± 0.08 ind. L⁻¹, whereas six species of “fast” colonizing NIS reached a mean density of 34.5 ± 13.0 ind. L⁻¹ (individual organisms) and a coverage of 37.1 ± 31.6 cm² L⁻¹ (modular organisms). PCoA plots ordered assemblages according to time (from 48% up to 75% total variation) and to organic treatment (about 22%) both for individual and modular organisms. In general, organic contamination exerted negative effect both on NIS and IS, and the reference condition was preferred. Among individual NIS, the best colonizer in terms of density and biomass was primarily the sphaeromatid Paracerceis sculpta for both sediment-buried (64.78 ind-cm² L⁻¹ and 217.43 mg L⁻¹) and suspended artificial substratum (143.94 ind-cm² L⁻¹ and 483.14 mg L⁻¹). The amphinomid Linopherus canariensis prevailed in the buried artificial substratum (52.27 ind-cm² L⁻¹ and 92.81 mg L⁻¹ respectively). Sessile and modular NIS appeared more susceptible to the initial organic contamination and the artificial substratum suspended into the water column was more suitable for these colonizers. Celleporaria brunnea (79.74 ind-cm² L⁻¹), Paraleucilla magna (66.69 ind-cm² L⁻¹), Hydroides elegans (12.49 ind-cm² L⁻¹) prevailed in the mean surface coverage among other NIS and IS species. The organic enrichment reduced to four up to five times the colonization rate of the first two species.

Experimental data showed the great competitive capacity of NIS in the early stages of fouling, both under control and organically-enriched conditions, although this type of disturbance affected the whole fouling assemblage.

Zooplankton are essential components of the aquatic food chain. Their density and composition are influenced by abundant of particular nutrients which promotes planktonic bloom. Domestic sewage is mostly anoxic to hypoxia in nature that favours largely pollution resistant species of zooplankton. The present study deals with the density, biochemical composition and gut microbes of Cladoceran (Moina macrocopa) from domestic sewage water monthly and seasonally. Hydrological parameters and zooplankton density in sewage water showed much variation in different seasons. The monthly variations of M. macrocopa density showed minimum (766.67 ± 152 Ind./L) during December 2019 and maximum (11,600.00 ± 360 Ind./L) during March 2020. Further, seasonal mean density was minimum during monsoon (1444.44 ± 185 Ind./L) and maximum during post-monsoon (9744.44 ± 725 Ind./L) showed distinct seasonal variations. Untreated sewage water in canal boost up solitary zooplankton M. macrocopa abundantly even in anoxic condition with optimum nutrients during the post-monsoon season. Total proteins and carbohydrates of M. macrocopa were maximum during post-monsoon and minimum during monsoon whereas total lipids were maximum during pre-monsoon and minimum during monsoon season. Present finding reveal that, M. macrocopa was found in untreated domestic sewage waste water solitarily in high density in different seasons. Physico-chemical parameters and availability of rich nutrients were the key factors which favouring high density and biochemical profiles of M. macrocopa. Further, abundant anaerobic coli form bacterial strains viz. Klebsiella pneumonia, Exiguobacterium profundum, Escherichia coli JSG and Escherichia coli JSG2 in gut of M. macrocopa indicates its preferred food in anoxic condition and reflect well adaptation in polluted environment.

Despite some research on coral reproduction from the southern Persian Gulf and Gulf of Oman, no known studies have been published investigating coral reproduction in the northern Persian Gulf. This study examined the spawning time for a scleractinian branching coral “Acropora downingi” in Kish Island, the northern Persian Gulf. All investigated A. downingi colonies (100% of colonies) contained premature oocytes with cream in color at 11th March 2022 to mature oocytes with orange in color at 9th, 15th, and 16th April 2022. On April 17, 2022, there were no traces of eggs in the sections of the branches, indicating that the spawning occurred on 16th April 2022. The moon reached its full phase at 23:25 on 16th April 2022. These are the first records of spawning by Acropora corals in northern reefs in the Persian Gulf.

Reproduction is a fundamental biological aspect of the recruitment of individuals and to maintenance of stable populations. Thus, an important question is understating the impact of human disturbances, such as fire, on reproduction success. In this study, we evaluated the effect of fire and environmental temperature on the reproductive recruitment of two Neotropical species of freshwater turtles (Podocnemis expansa, and Podocnemis unifilis). Our hypotheses are as follows: (i) nesting areas exposed to fire exhibit lower reproductive recruitment of turtles, and (ii) years with higher environmental temperatures are associated with increasing reproductive recruitment of turtles. To test these hypotheses, we used data collected from long-term monitoring of nesting sites (2006–2021) of freshwater turtles in Rio das Mortes, Central Brazil. The number of fire outbreaks and environmental temperature were our independent variables; while the number of live hatchlings per reproductive season, the number of unviable eggs, and the total number of eggs were our response variables. The findings indicated that fire harmed the reproductive recruitment of turtle species, and the total number of eggs was negatively influenced by fire and environmental temperature. Long-term monitoring and experimental studies are essential for the understanding of the relationship between human and natural effects on the Neotropical freshwater turtle population. In turn, it contributes to the implementation of effective conservation measures for freshwater turtles.

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.