Hydrobiology, Volume 1, Issue 4 (December 2022) – 7 articles

The Current River is a cold-water, thermally constant Missouri Ozark stream and is one of the few remaining free-flowing rivers in the U.S. The Current River’s baseflow is largely fed by hundreds of springs, which include five first-magnitude springs. Little attention has been given to the influence of spring inflows on river temperature and spring influence on biodiversity. The objectives of this study were to demonstrate how large springs affect river macroinvertebrate communities, and to explore the relationships among macroinvertebrate diversity and habitat variables to estimate spring influences on community structure and diversity. Aquatic macroinvertebrates were collected from 42 riffle/run habitats of the Current River main-stem, tributaries, and springs during the winter season. Samples at each site were collected using a Slack-Surber sampler for macroinvertebrates with additional habitat variables collected: substrate size, embeddedness, periphyton, filamentous green algae, vegetation, depth, current velocity, temperature, dissolved oxygen, specific conductance, and pH. Beta diversity analysis was performed on consecutive pairs of site taxa richness values using the Wilson–Shmida calculation to determine the impact of main-stem confluences with either tributaries or springs, and invertebrate community relationships were explored using nonmetric multidimensional scaling (NMDS). Water temperature and taxa richness exhibited similar patterns, with higher temperatures being associated with lower taxa richness. Downstream of each large-magnitude spring, taxa richness sharply decreased, while taxa richness increased downstream of tributaries. Beta diversity usually declined downstream of the confluences with springs, but increased downstream of the tributaries. Data from large springs were closely grouped in NMDS, while tributaries and main-stem sites were more widely scattered. These data indicate spring inputs produce more homogenous conditions in the main-stem river compared to more heterogenous conditions produced by tributary inputs. Macroinvertebrate diversity along the Current River also does not follow predictions from the river continuum concept, but rather diversity peaks are downstream of springs. Our data clearly demonstrate the strong influence of large springs on macroinvertebrate communities in the Current River. Full article

Climate change is enhancing the frequency of cyanobacterial blooms not only during summer but also in spring and autumn, leading to increased ecological impacts. The bacterioplankton community composition (BCC), in particular, is deeply affected by these blooms, although at the same time BCC can also play important roles in blooms’ dynamics. However, more information is still needed regarding BCC during species-specific cyanobacterial blooms. The goal of this study was to assess BCC succession in a hypereutrophic shallow lake (Vela Lake, Portugal) during a warm spring using a metagenomic approach to provide a glimpse of the changes these communities experience during the dominance of Aphanizomenon-like bloom-forming species. BCC shifts were studied using 16S rRNA gene metabarcoding and multivariate analyses. A total of 875 operational taxonomic units (OTUs) were retrieved from samples. In early spring, the dominant taxa belonged to Proteobacteria (mainly Alphaproteobacteria—Rickettsiales) and Bacteroidetes (Saprospirales, Flavobacteriales and Sphingobacteriales). However, at the end of May, a bloom co-dominated by cyanobacterial populations of Aphanizomenon gracile, Sphaerospermopsis aphanizomenoides and Synechococcus sp. developed and persisted until the end of spring. This led to a major BCC shift favouring the prevalence of Alphaproteobacteria (Rickettsiales and also Rhizobiales, Caulobacteriales and Rhodospirillales) and Bacteroidetes (Saprospirales, followed by Flavobacteriales and Sphingobacteriales). These results contribute to the knowledge of BCC dynamics during species-specific cyanobacterial blooms, showing that BCC is strongly affected (directly or indirectly) by Aphanizomenon-Sphaerospermopsis blooms. Full article

Understanding of the trait-based ecology of the periphytic algal community has increased in the last decade. However, the relationship between their functional diversity and ecosystem functions, such as primary production, has been speculated on, but yet not proven. Human impacts promote changes in biotic communities leading to a risk of extinction, with consequences for the functioning of aquatic ecosystems. In this study, we unraveled the associations between the taxonomic and functional components of periphytic algal diversity, stream eutrophication, and productivity patterns. Furthermore, we simulated future patterns of species extinction to predict how productivity may change when facing extinction. Primary production and taxonomic and functional diversity of the periphytic algal communities were estimated in five streams across a trophic gradient in the Ave River basin (northwest Portugal). Our results demonstrated that eutrophication led to a unimodal pattern of taxonomic diversity, while functional diversity tended to increase with increasing eutrophication. We found that only functional diversity had a positive association with primary production. The extinction estimations indicated that almost all species found in our study were at high extinction risk. When we spatially scaled our extinction simulations, we found poor-productive streams after the extirpation of a few species. However, at the regional scale, the ecosystem supports the extinction of at least 40% of species before turning into a poor-productive system. Intermediate levels of disturbance are probably beneficial for the diversity of periphytic algal communities, to a certain extent. Moreover, functionally diverse communities were more productive, and the alleged future extinction of species is likely to lead to poor-productive streams if regionally focused conservation initiatives are not implemented. We recommend that, using simulations of functional extinction, it is possible to infer how the loss of these microorganisms could alter ecosystem functioning, to better predict human impacts on aquatic ecosystems. Full article

The use of seaweed as a source of bioactive extracts has received increased attention from the market in recent years—particularly for nutraceutical applications. In this context, this study evaluated the nutraceutical application of seaweed biomass and extracts from three seaweeds from Portugal: Ulva sp., Laminaria ochroleuca, and Chondrus crispus. For each of the said seaweeds, four different extracts were obtained using GRAS solvents—acetone (A), ethanol (E), ethanol–water (1:1) (EW), and one polysaccharide-rich extract (P) using water and further precipitation with ethanol. The bioactive potential of the extracts was assessed in terms of antioxidant capacity (ABTS^•+, DPPH^•, ^•NO, O₂^•− scavenging, and ORAC-FL assay) and anti-inflammatory capacity (COX inhibition and human red blood cell membrane stabilisation). Furthermore, the biochemical profile was determined for the raw biomass and extracts to better comprehend their possible applications as nutraceuticals. The results show that all extracts have antioxidant potential. Five extracts (L. ochroleuca E, EW, and P and Ulva sp. E and P) showed anti-inflammatory capacity. Overall, L. ochroleuca EW extract exhibited the most promising potential as both an antioxidant and anti-inflammatory and is an interesting candidate nutraceutical ingredient. Full article

Phaeodactylum tricornutum is a marine diatom rich in omega-3 fatty acids, a nutraceutical-relevant product. Long chain-polyunsaturated fatty acids (LC-PUFAs) are crucial dietary components for human development and growth. With the availability of genome information and genetic engineering tools, the productivities of OMEGAs have improved, but the functional and organizational relationship of such protein-encoding genes associated with LC-PUFAs biosynthesis is still not clear. Henceforth, our study highlights the conservation pattern, functionality and interaction of LC-PUFAs protein-encoding genes via in silico analysis. The transcriptome and quantitative PCR analysis demonstrates downregulation of ACS4, ELO6b, PTD5a, and MYB106 genes associated with LC-PUFAs synthesis and upregulation of ECoAH and ACAT1 genes associated with β-oxidation in nitrogen-depleted conditions in P. tricornutum. Phylogenomics studies of LC-PUFAs protein-encoding genes show a highly conserved evolutionary pattern in various microalgal lineages. Further, for elucidating the interaction of LC-PUFA metabolic genes, subcellular networks were predicted and pathway enrichment analysis was performed, providing new insights on the crosstalk between LC-PUFA protein-encoding genes (ELO6, PTD5, ACS, and ACL1), regulatory elements (LEC2, MYB, WIN) and transporters (ABCD1). In conclusion, such extensive functional enrichment analysis will undoubtedly aid in the development of genetically engineered algal strains with enhanced production of biomolecules i.e., LC-PUFAs. Full article

With a current global estimation of 600–700 individuals, Monachus monachus is considered among the most threatened seal species globally and is ranked as “Endangered” by the IUCN Red List of Threatened Species. The Mediterranean distribution of the species is fragmented, and the largest known sub-population inhabits its easternmost areas. The present study analyses the occurrence of M. monachus on Samos Island, in the north-eastern Aegean Sea, Greece. From May 2017 to November 2019, data were collected through a combination of monitoring approaches, including visual monitoring from a land position, opportunistic sightings collected by citizen science, and data of stranded individuals. Results indicate the constant occurrence of monk seals in the waters and coastal areas of Samos Island, confirming the importance of this area for conservation purposes. Furthermore, the results show that an integrated methodological approach can contribute to enhancing and increasing data collection, representing an effective method for conservation studies. This approach could be applied in other locations, allowing the scientific community to identify regions of interest, where to expand targeted monitoring and apply conservation measures. Full article

The odonates of Algeria have been studied for more than a century and a half, but the Northwestern part of the country has historically received little attention. A recent study in central North Algeria reported a species new to the country, suggesting that new investigations in unexplored areas are necessary to fully understand the local odonatofauna. We studied assemblages of odonates in 23 sites in Sidi Bel Abbes (Northwest Algeria) by bimonthly recording adults across a 200 m-transect from May to August of 2019–2022. Our sampling yielded 29 species (13 damselflies and 16 dragonflies) belonging to 19 genera and seven families. We recorded a new locality for the regionally endangered Coenagrion mercuriale, expanding the western range limit of the species in Algeria. We documented the occurrence of Selysiothemis nigra, a species that has recently become more frequent in North Africa. Ischnura pumilio and Onychogomphus forcipatus unguiculatus, which are relatively rare in the region, were also recorded. The arid-dwelling Trithemis kirbyi and the Mediterranean endemic Orthetrum nitidinerve were quite common in the study area. This study fills an important gap of knowledge in our understanding of odonate geographic distribution in North Africa. Full article