Aquatic Ecology最新文献

This study aimed to analyse the microbial biodiversity in ceriantharian tubes through shotgun metagenomics, to enhance the understanding of ecological dynamics in these microhabitats. We sampled two tubes of Ceriantheomorphe brasiliensis in Florianópolis (SC), and two tubes of Ceriantheopsis lineata in Alcatrazes archipelago (AK), South and Southeast Brazil, respectively. The environmental DNA from the tubes was extracted, amplified, and submitted to shotgun metagenomics sequencing on the Illumina HiSeq platform, and the biodiversity analysis was run using the Kraken2 software. Our results indicate that Ceriantharia-associated microbiomes likely harbour novel microbial diversity, as roughly only 8% of metagenomic reads were classified. Microbial composition was highly similar in both locations, with the Bacteria domain predominating, particularly the phyla Pseudomonadota and Actinomycetota. Nitrososphaerota was consistently the most common archaeal phylum in all samples. The bacterial classes Betaproteobacteria and Planctomycetia, and the archaeal class Nitrososphaeria were present in all four tubes, as were the bacterial family Pseudomonodaceae and the archaeal family Nitrosopumilaceae. Roseobactereaceae dominated alphaproteobacterial families from AK tubes, while Streptomycetaceae prevailed among actinobacterial families from SC tubes. The α-diversity indicates similar values between AK and SC samples, with slight distinctions favouring SC. β-diversity results show higher similarity within the same locations (AK or SC) than between different locations, highlighting spatial influence on microbial composition. To the best of our knowledge, this study is the first to address microbial composition found in ceriantharian tubes, using shotgun metagenomics, and our findings set up the scenario for a wider comprehension of these cnidarians as key holobionts in marine ecosystems.

The relationship between biodiversity and ecosystem functioning (BEF) is one of the central themes of ecological research. Phytoplankton play important ecological functions in aquatic ecosystems. Although the BEF in phytoplankton communities was found in various types of natural aquatic ecosystems, it has not been examined in artificial ecosystems at small scale. Artificial reef, a submerged device built by human, can pump nutrient-rich bottom water to the surface, mimicking natural upwelling to feed phytoplankton. Here we quarterly investigated the phytoplankton communities in the artificial reef zone and its adjacent water in a subtropical bay. Our results showed positive linear relationship of phytoplankton richness to productivity in the artificial reef zone. The slope of richness-productivity relationship increased with water temperature and was relatively higher in the summer. Phytoplankton resource use efficiency (RUE) was positively correlated with richness but negatively correlated with evenness in the artificial reef zone. Compared to the adjacent natural zone, the artificial reef zone had more diverse phytoplankton communities and higher productivity during the growing season. The phytoplankton BEF pattern we found provides evidence for the role of artificial reef in the functioning of subtropical bay ecosystem.

A case of massive fish mortality is reported in an aquatic body in the municipality of Izamal in Yucatan, Mexico. The fish analyzed exhibited signs of hemorrhage and suffocation. Analysis of the phytoplankton samples revealed the presence of a flagellated microalga with characteristics consistent with Prymnesium parvum, particularly due to the presence of the haptonema. The average densities of the microalgae were approximately 16 × 10⁶ cells L⁻¹. The documentation of this species in the Yucatán Peninsula and the observed effects represent an emerging risk for the aquatic ecosystems of the region. This risk is linked to the extensive connectivity between aquatic systems in the region, combined with the significant dispersion capability of the species, which is magnified by the increasing eutrophication conditions in these bodies of water.

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.