Enrichment of nutrients and metals in seawater associated with anthropogenic activities can threaten aquatic ecosystems. Consequently, nutrient and metal concentrations are parameters used to define water quality. The European Union’s Water Framework Directive (WFD) goes further than a contaminant-based approach and utilises indices to assess the Ecological Status (ES) of transitional water bodies (e.g. estuaries and lagoons). One assessment is based upon the abundance of opportunistic Ulva species, as an indication of eutrophication. The objective of this study was to characterise Ireland’s Ulva blooms through the use of WFD assessment, metal concentrations and taxonomic identity. Furthermore, the study assessed whether the ecological assessment is related to the metal composition in the Ulva. WFD algal bloom assessment revealed that the largest surveyed blooms had an estimated biomass of 2164 metric tonnes (w/w). DNA sequences identified biomass from all locations as Ulva rigida, with the exception of New Quay, which was Ulva rotundata. Some blooms contained significant amounts of As, Cu, Cr, Pb and Sn. The results showed that all metal concentrations had a negative relationship (except Se) with the Ecological Quality Ratio (EQR). However, only in the case of Mn were these differences significant (p = 0.038). Overall, the metal composition and concentrations found in Ulva were site dependent, and not clearly related to the ES. Nevertheless, sites with a moderate or poor ES had a higher variability in the metals levels than in estuaries with a high ES.
Cystoseira is a common brown algal genus widely distributed
throughout the Atlantic and Mediterranean regions whose taxonomical assignment
of specimens is often hampered by intra- and interspecific morphological
variability. In this study, three mitochondrial regions, namely cytochrome
oxidase subunit 1 (COI), 23S rDNA (23S), and 23S-tRNAVal intergenic spacer
(mt-spacer) were used to analyse the phylogenetic relationships of 22
Cystoseira taxa (n = 93 samples). A total
of 135 sequences (48 from COI, 43 from 23S and 44 from mt-spacer) were newly
generated and analysed together with Cystoseira sequences (9
COI, 31 23S and 35 mt-spacer) from other authors. Phylogenetic analysis of these
three markers identified 3 well-resolved clades and also corroborated the
polyphyletic nature of the genus. The resolution of Cystoseira
taxa within the three clades improves significantly when the inclusion of
specimens of related genera was minimized. COI and mt-spacer markers resolved
the phylogeny of some of the Cystoseira taxa, such as the
C. baccata, C.
foeniculacea and C.
usneoides. Furthermore, trends between phylogeny, embryonic
development and available chemotaxonomic classifications were identified,
showing that phylogenetic, chemical and morphological data should be taken into
account to study the evolutionary relationships among the algae currently
classified as Cystoseira. The resolution of
Cystoseira macroalgae into three well supported clades
achieved here is relevant for a more accurate isolation and identification of
natural compounds and the implementation of conservation measures for target
species.
The evolutionary history of the genus Ruppia has been shaped by hybridization, polyploidisation and vicariance, that have resulted in a problematic taxonomy. Recent studies provided insight into species circumscription, organelle takeover by hybridization, and revealed the importance of verifying species identification to avoid distorting effects of mixing different species, when estimating population connectivity. In the present study, we use microsatellite markers to determine population diversity and connectivity patterns in Ruppia cirrhosa including two spatial scales: 1) from the Atlantic Iberian coastline in Portugal to the Siculo-Tunisian strait in Sicily, and 2) within the Iberian peninsula comprising the Atlantic-Mediterranean transition. The higher diversity in the Mediterranean Sea suggests that populations have had longer persistence there, suggesting a possible origin and/or refugial area for the species. The high genotypic diversities highlight the importance of sexual reproduction for survival and maintenance of populations.Results revealed a regional population structure matching a continent-island model, with strong genetic isolation and low gene flow between populations. This population structure could be maintained by waterbirds, acting as occasional dispersal vectors. This information elucidates ecological strategies of brackish plants species in coastal lagoons, suggesting mechanisms used by this species to colonize new isolated habitats and dominate brackish aquatic macrophyte systems, yet maintaining strong genetic structure suggestive of very low dispersal.
Climate-driven range-shifts create evolutionary opportunities for allopatric divergence and subsequent contact, leading to genetic structuration and hybrid zones. We investigate how these processes influenced the evolution of a complex of three closely related Cystoseira spp., which are a key component of the Mediterranean-Atlantic seaweed forests that are undergoing population declines. The C. tamariscifolia complex, composed of C. tamariscifolia s.s., C. amentacea and C. mediterranea, have indistinct boundaries and natural hybridization is suspected. Our aims are to (1) infer the genetic structure and diversity of these species throughout their distribution ranges using microsatellite markers to identify ancient versus recent geographical populations, contact zones and reproductive barriers, and (2) hindcast past distributions using niche models to investigate the influence of past range shifts on genetic divergence at multiple spatial scales. Results supported a single, morphologically plastic species the genetic structure of which was incongruent with a priori species assignments. The low diversity and low singularity in northern European populations suggest recent colonization after the LGM. The southern Iberian genetic hotspot most likely results from the role of this area as a climatic refugium or a secondary contact zone between differentiated populations or both. We hypothesize that life-history traits (selfing, low dispersal) and prior colonization effects, rather than reproductive barriers, might explain the observed genetic discontinuities.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.