Aquatic Ecology最新文献

Calanoid copepods have gained significant interest due to their rapid response to changes in environment. This study examined the seasonal variation in the size of calanoid copepods and their relationships to various environmental parameters in a tropical coast of India. Zooplankton samples were collected at Marina Beach, India, from January to December 2021. Ten calanoid species were selected based on their distribution to study the seasonal variation in the size, and the results showed a clear seasonal pattern, with smaller size of calanoid observed during summer months with high temperatures and larger sizes during the monsoon season associated with increased rainfall and nutrient availability. Negative correlations were observed between copepod size variation and temperature, while positive correlations were observed with dissolved oxygen, pH, salinity, and chlorophyll-a concentration. Acrocalanus gibber, Acrocalanus gracilis and Canthocalanus pauper showed changes that are more pronounced in body size (0.89–0.99, 1.12–1.23 mm and 1.41–1.52 mm, respectively) indicating species-specific responses to environmental fluctuations. These findings highlight the influence of environmental parameters in determining the size of calanoid copepods in tropical oceans. Moreover, this study contributes to our understanding of the ecological processes and global warming that determine copepod size variation in coastal ecosystems.

Despite jellyfish’s ecological and socioeconomic impacts, they are still an understudied component of marine ecosystems. Even with its conspicuous size, reaching ~ 1 m in bell diameter, Drymonema gorgo has been rarely observed, with only a few occurrences in the literature, suggesting that it is not a common species. Here, we gathered historical records from literature, personal communication, and novel data from the World Wide Web (WWW) to obtain observations of D. gorgo along the Brazilian coast. A total of 63 observations from 1857 to 2022 were compiled, of which 57 were extracted from the web. Observations on this jellyfish concentrated between 22° S and 27° S, especially in the Cabo Frio region in Rio de Janeiro. They were reported throughout the year, except in August and October, with the highest concentrations in March (late summer). Based on the notable complement on information about its occurrence in the last ten years, we hypothesize that D. gorgo is probably not as rare as suggested by the near absence of previous literature records. In addition, biological associations of D. gorgo with other species were also discovered such as (1) predation on the jellyfish Aurelia sp. and Chrysaora lactea; (2) food item for the green turtle Chelonia mydas; and (3) association with fishes. This study provides evidence of the potential use of the WWW to obtain ecological data about conspicuous marine species occurrence, such as D. gorgo, helping to fill knowledge gaps and overcome difficulties in its detection using traditional methodologies.

An analysis of ectoparasite infestations in Champsocephalus gunnari at South Orkney Islands, Antarctica, was performed, which revealed the prevalence, mean abundance, and mean intensity of the two species of parasites collected. The parasites’ preference for parts of the infested host fish was also investigated. The host–parasite trophic relationship was further examined using stable carbon and nitrogen isotopic analysis. The results showed that Eubrachiella antarctica was more inclined to parasitize the fins of C. gunnari. The carbon isotope ratio (δ¹³C) of the host was negatively correlated with the values for carbon isotopic discrimination (Δδ¹³C) between host and E. antarctica. The relationship between E. antarctica and C. gunnar is considered “parasitic” because E. antarctica has a higher trophic level than that of host C. gunnari, while Trulliobdella capitis may be a carrier parasite of C. gunnari or show a “symbiotic” relationship with it. The ecological niche spaces of the three species do not overlap, indicating the existence of specific trophic niches in the marine food web.

Cyanobacterial harmful algal blooms (cyanoHABs) are extremely detrimental to the environment and cause sizable economic losses. Microcystis aeruginosa is reported to be inhibited by Eurasian watermilfoil (Myriophyllum spicatum), and onset of the inhibitory effects of M. spicatum varied depending on the seasons. This study aimed to investigate the seasonal allelopathy effects in the metabolomes of M. spicatum using gas chromatography–mass spectrometry and predict the most effective season for its allelopathic inhibitory effects on the growth of M. aeruginosa. A machine learning approach using multi-layer perceptron was used to predict the season with maximum anti-cyanobacterial potential. The prediction model suggested that M. spicatum collected in August would have higher growth-inhibiting effects than other months with 93.6 (± 2.9) likelihood. These results were consistent with coexistence experiments where M. spicatum collected in August showed the earliest onset of inhibition. The study concluded that the inhibitory potential of M. spicatum on cyanobacterial growth was strong in the summer, especially in August. This suggests that neural network machine learning can be applied to a variety of topics using accumulated data, making clearer and more useful predictions possible even in multivariate and complex environmental data.

Gelatinous zooplankton are essential components of healthy ecosystems. Given their characteristic life cycle, ecological aspects and adaptability to a variety of oceanic conditions, these organisms are considered indicators of climate change, having particular advantages relative to other taxa. Citizen science initiatives are becoming increasingly frequent, providing data that are otherwise difficult to collect and interesting results for different taxa worldwide, allowing for example the detection of new occurrences. The ongoing citizen science program GelAvista, running since 2016, gathers data reported by observers on jellyfish occurrences in Portuguese waters, in the north-eastern Atlantic. The program has enhanced the knowledge of these organisms, providing data on biodiversity, and the dynamics of their distribution and abundance. Particular sightings of hydromedusae were received through GelAvista for mainland Portugal, close to the Tagus River, in the Lisbon Bay region. The species was morphologically and molecularly identified as Odessia maeotica, comprising its first reported occurrence in the Lisbon Bay. The details on the occurrence of the species are provided and discussed given the current knowledge of the species.

Citizen science online platforms are increasingly making important sources of biological information available at the click of a button, allowing the interaction of volunteers and scientists to report and identify the world’s diversity. In this work, we combined the data available in citizen science platforms (iNaturalist and GelAvista) and the effort and collaboration of a diverse team of scuba-divers, scientists, and underwater photographers to report for the first time the presence of the stauromedusa Lipkea (Cnidaria: Staurozoa) in Portugal. Based on DNA (COI and 16S), we identified the species as Lipkea ruspoliana. However, the marginal lappets of some Portuguese specimens are similar to those of Lipkea sturdzii, a species described based on a single specimen in 1893 and never reported again. These results suggest that L. sturdzii is a synonym of L. ruspoliana, although further taxon and habitat sampling for genetic studies and investigations of intraspecific morphological variation are necessary. In addition, we provided data on species ecology, reviewed the records of Staurozoa from Portugal, and mapped the world geographic distribution of Lipkea. Staurozoa is a cryptic group of cnidarians, and Lipkea seems to be a particularly rare genus. Citizen science has proved to be a valuable contribution to studies on the group, enabling biological discussions that otherwise would be more challenging.

Invasive species are continuously introduced in several ecosystems from human activities. Aquaculture activities are noteworthy among the many different species introduction vectors currently in place, generating a pattern of constant, frequent or massive release of propagules into aquatic ecosystems, increasing species establishment success rates. Reported cases in marine or brackish ecosystems, however, are still scarce. As aquaculture constantly generate propagules with the ability to employ these facilities as corridors to further spread to interconnected brackish and freshwater ecosystems, colonising high salinity systems, this study aimed to compile evidence of Tilapiines detected in Brazilian coastal marine and brackish ecosystems. Nineteen records were obtained, with the presence of this invader suggested as higher following rainfall seasons. The widespread distribution of Tilapiines is relatively well-known in Brazilian freshwater ecosystems but, up to now, its potential to use brackish and marine ecosystems as ecological corridors has been described only experimentally. Our findings highlight the potential for a typically freshwater invader to spread through marine ecosystems, raising concerns regarding the licensing of aquaculture projects within rivers and estuaries, as tilapia may significantly affect native Brazilian biota.

Data collection by citizen scientists is emerging as an important practice for biodiversity detection, mapping, and compilation of big data in open online platforms such as iNaturalist, acting as a source of biodiversity discovery. However, the validation of species identification is a central issue for the scientific use of these data. Here we compared the list of marine species in the Western Atlantic Ocean obtained in iNaturalist with that generated from scientific collections to understand whether there are taxonomic bias favoring some types of organisms, and to understand the amount of trustful information at the species level in iNaturalist. We also present the first bioblitz results of marine biodiversity in Brazil, an iNaturalist Citizen Science campaign advertised by social media, as a case study. We found that marine taxa with higher richness were well represented in iNaturalist (Arthropoda, Mollusca and Chordata), nonetheless Annelida, Bryozoa, Nematoda, Nemertea, Platyhelminthes, Porifera, Chlorophyta, and Rhodophyta were under-represented. Taxa with small, cryptic, parasitic and/or sessile organisms were poorly represented. According to the methods applied in this study, we showed that 72% of the records are probably well identified, except for Bryozoa and Platyhelminthes. Brazilian marine records in iNaturalist add up to only 1/30 of the total West Atlantic records analyzed but there was a steep increase from 2021 to 2022, as a possible contribution of our bioblitz campaign especially for Arthropoda, Echinodermata, and Annelida. We conclude that the record of marine biodiversity by citizen scientists is a valuable tool, but the engagement of taxonomists is strongly recommended to increase the correct identification of species.

Chinook salmon (Oncorhynchus tshawytscha) is invading South America. Both the high plasticity and genetic diversity of introduced propagules have been hypothesized to be responsible for the success of this species’ invasion. Yet, the influence of environmental variability on the expressed phenology of the adult spawning migration has been overlooked in this region. Here, we examined the consistency in timing, duration, and relative abundance of adult salmon migrants and their associations with environmental river conditions and surrounding ocean in a regulated river system in Patagonia. We conducted monthly long-term snorkeling fish surveys (2010–2019) and collected associated environmental information from the river and ocean. We observed a recent increase in duration of the spawning migration and a decline in the relative abundance of adult migrants. A warming phase of the Southern Pacific Ocean (during the two previous years) was associated to an extended migration season, whereas a colder river in fall was associated to a lower number of adult migrants. Collectively, our findings suggest that rapid phenological shifts could occur in a recently established salmon population (circa 1980). This process could be explained by novel selective pressures and expression of life history traits in response to novel environmental regimes. Further long-term surveys of introduced salmon can aid in parsing the relationships between environmental regimes and the biology and persistence of these self-sustained populations.