This paper provides one of the most comprehensive studies of metal distributions in three main macroalgae species. In this novel study, levels of total, intracellular and surface bound Pb, Zn, As, Cd, Co, Cr, Cu, Mn and Ni associated with Polysiphonia lanosa (L) Tandy, Ascophyllum nodosum (L) Le Jolis, Fucus vesiculosus (L) and Ulva sp. were determined. Additionally, water and sediment metal levels were analysed to gain an insight into the relative uptake efficiencies of different macroalgal species. Samples were collected from a clean site in Fethard-on-Sea, Wexford, Ireland (52°11′53.68′N, 6°49′34.64′W), in May 2008. Results demonstrated that total, intracellular and surface bound metal levels varied according to metal and seaweed species, with the highest proportion of metals found to be intracellular. Inhibition of Mn uptake by Zn was indicated for P. lanosa. Furthermore, P. lanosa had enhanced bioaccumulation ability, with the highest Concentration Factor reported of any seaweed to date.

A fine-scale survey of δ15N, δ13C, tissue-N in seaweeds was conducted using samples from 17 sampling points at two sites (Grandcamp-Maisy (GM), Courseulles/Mer (COU)) along the French coast of the English Channel in 2012 and 2013. Partial triadic analysis was performed on the parameter data sets and revealed the functioning of three areas: one estuary (EstA) and two rocky areas (GM∗, COU∗). In contrast to oceanic and anthropogenic reference points similar temporal dynamics characterized δ15N signatures and N contents at GM∗ and COU∗. Nutrient dynamics were similar: the N-concentrations in seawater originated from the River Seine and local coastal rivers while P-concentrations mainly from these local rivers. δ15N at GM∗ were linked to turbidity suggesting inputs of autochthonous organic matter from large-scale summer seaweed beachings made up of a mixture of Rhodophyta, Phaeophyta and Chlorophyta species. This study highlights the coupling between seaweed beachings and nitrogen sources of intertidal macroalgae.

One of the objectives of the BALMAS project was to conduct Port Baseline Biological Surveys of native and non-indigenous benthic flora in 12 Adriatic ports. Samples of macroalgae growing on vertical artificial substrates were collected in spring and autumn 2014 and/or 2015. A total number of 248 taxa, 152 Rhodophyta, 62 Chlorophyta, and 34 Ochrophyta, were identified. Of these, 13 were non-indigenous seaweeds, mainly filamentous macroalgae, that were probably introduced through hull fouling. Some of these taxa had already been described in the study areas, others were recorded for the first time, a few were no longer detected at sites where they had previously been recorded (e.g. Sargassum muticum). Some other NISS reported for the Adriatic Sea, were not collected at any sampling site (i.e. Caulerpa cylindracea, Codium fragile). Possible reasons for the absence of these species are discussed.

Eutrophication causes the major impact in the coastal waters of the state of Yucatan. In general, loss of water quality and biological communities and massive development of toxic microorganisms are some of the consequences of this phenomenon. To reveal changes in species composition and cell abundance of the taxocoenosis of epibenthic dinoflagellates before and after a harmful algal bloom event in the water column that lasted about 150days (August–December 2011) in the Dzilam – San Crisanto area (northern Yucatan Peninsula, southeastern Gulf of Mexico) were the main objectives of the present study. In August 2011 and September 2012, sampling along 20 transects perpendicular to the coastline along the entire northern Yucatan coast, starting from 20 sampling sites from El Cuyo in the east to Celestún in the west, at a distance of 50, 150 and 250m from the coast, was carried out. Physicochemical characteristics measured before and after the bloom were within the ranges previously reported in the study area. Salinity was the most stable characteristic, with mean values of 36.25 and 36.42 in 2011 and 2012, respectively. Phosphates were the only parameter that showed a wide range with higher values before the bloom (0.03–0.54μM/l). A total of 168 macrophyte (seaweeds and seagrasses), sponge and sediment samples (105 in 2011 and 63 in 2012) that included associated microphytobenthos were taken by snorkeling from 0.7 to 5m depth. Six substrate types were distinguished: Chlorophyta, Phaeophyceae, Rhodophyta, Angiospermae (seagrasses), Demospongiae (sponges) and sediment. Chlorophytes dominated the collected samples: 38 samples in 2011 and 23 in 2012. Avrainvillea longicaulis f. laxa predominated before the bloom and Udotea flabellum after it. In total, 25 epibenthic dinoflagellate species from 11 genera were found. The genus Prorocentrum was the most representative in terms of the number of species. The highest total dinoflagellate cell abundances were observed in the sites with different types of macrophytes (up to 2441cells/g substrate wet weight in 2011 and up to 1068cells/g in 2012). The lowest cell densities were observed in the areas with scarce or no macrophytes on sandy seafloor. Before the bloom, Prorocentrum rhathymum (up to 4995cells/g) and P. cf. sipadanensis (up to 5275cells/g) were the most abundant, and after the bloom the latter was dominant (up to 3559cells/g); in 2012, both variety of substrates and dinoflagellate cell abundance diminished. A canonical correspondence analysis revealed significant relationships between the physicochemical variables and epiphytic/benthic dinoflagellate species either before or after the bloom. The pelagic bloom resulted in the loss of substrate for epiphytic dinoflagellates, which caused replacement of the dominant species and a decrease in cell abundance of the whole taxocoenosis.

Little information is known about biofilm formation in the thermally stressed coral reef systems north of the Arabian Gulf. The current study investigates the abundance and diversity of marine microbes involved in biofilm formation and their succession over a period of 14weeks (May–August 2007) at temperatures exceeding 32°C. The results showed variations in microbial numbers and the development of more stable biofilm communities as the biofilms aged. The culture-dependent technique and microscopic examination of the developed biofilms showed the dominance of key species known for their role in precipitating CaCO3 such as Vibrio and in facilitating coral larvae settlement and metamorphosis such as Pseudoalteromonas, Bacillariophyceae and Rhodophyceae. The results revealed biofilm formations with microbial diversities that have the potential to support the larval settlement and metamorphism of marine organisms and to consolidate and stabilize biofilms via the process of calcification in the thermally stressed coral reef system considered herein.

Marine coastal ecosystems are affected by a vast array of human-induced disturbances and stresses, which are often capable of overwhelming the effects of natural changes. Despite the conceptual and practical difficulty in differentiating between disturbance and stress, which are often used interchangeably, the two terms bear different ecological meanings. Both are external agents, but the former causes mortality or physical damage (subtraction of biomass), whereas the latter causes physiological alteration (reduction in productivity). Sensitivity of marine organisms may thus have a dual connotation, being influenced in different ways by disturbance and by stress following major environmental change. Coralligenous assemblages, which shape unique biogenic formations in the Mediterranean Sea, are considered highly sensitive to change. In this paper, we propose a method to differentiate between disturbance and stress to assess the ecological status of the coralligenous assemblages. Disturbance sensitivity level (DSL) and stress sensitivity level (SSL) of the sessile organisms thriving in the coralligenous assemblages were combined into the integrated sensitivity level of coralligenous assemblages (ISLA) index. Changes in the coralligenous status were assessed in space, along a gradient of stress (human-induced pressures) at several sites of the western Mediterranean, and in time, from a long-term series (1961–2008) at Mesco Reef (Ligurian Sea) that encompasses a mass mortality event in the 1990s. The quality of the coralligenous assemblages was lower in highly urbanised sites than that in sites in both marine protected areas and areas with low levels of urbanisation; moreover, the quality of the assemblages at Mesco Reef decreased during the last 50years. Reduction in quality was mainly due to the increase in stress-tolerant and/or opportunist species (e.g. algal turfs, hydroids and encrusting sponges), the disappearance of the most sensitive macroalgae (e.g. Udoteaceae and erect Rhodophyta) and macro-invertebrates (e.g. Savalia savaglia, Alcyonium coralloides and Smittina cervicornis), and the appearance of invasive alien algal species. Although the specific indices of SSL or DSL well illustrated the changes in the spatial or temporal datasets, respectively, their integration in the ISLA index was more effective in measuring the change experienced by the coralligenous assemblages in both space and time.

To show the influence of coastal habitat degradation on the availability of food for green turtles (Chelonia mydas), we assessed the dietary preferences and macroalgae community at a feeding area in a highly urbanized region. The area showed low species richness and was classified as degraded. We examined stomach contents of 15 dead stranded turtles (CCL=44.0cm (SD 6.7cm)). The diet was composed primarily of green algae Ulva spp. (83.6%). In contrast, the macroalgae community was dominated by the green alga Caulerpa mexicana. We found a selection for red algae, seagrass and Ulva spp., and avoidance for C. mexicana and brown alga Dictyopteris delicatula. The low diversity of available food items, possibly a result of environmental degradation, likely contributed to the low dietary diversity. The nutritional implications of this restricted diet are unclear.

Given the authoritative and well-documented publication records that crenic habitats support the substantial aquatic biodiversity, understanding of algal dynamics in response to anthropogenic and natural stressors in these crenic systems seems paramount. We sampled and monitored twelve freshwater springs for a period of 2 years from 2014 to 2015 to observe algal dynamics and the factors govern the distribution and dynamics. We used ANOVA, nMDS, PCA, ANOSIM, SIMPER, and BIOENV to reveal the key physicochemical variables influencing the distributional pattern and dynamics of algae. The analysis of variance (ANOVA, Tukey’s post hoc test) revealed significant difference among the springs with dominance of Bacillariophyceae (62%) followed by Chlorophyceae (18%) whereas nMDS ordination of abundance data in two-dimensional space resulted in a significant separation between spring sites (stress value of 0.13). One-way nested ANOSIM produced a significant distinction between periphytic algal communities in springs (global test R = 0.928, p = 0.001). The results of SIMPER revealed the highest average dissimilarity (60.95%) between springs S4 and S5, with the top five contributing families including Cyanophyceae (30.25%), Bacillariophyceae (25.98%), Rhodophyceae (16.74%), Chlorophyceae (13.64%), and Chrysophyceae (13.39%). BIOENV analysis of the periphytic algal data suggested that the assemblage pattern in all crenic habitats were controlled by discharge, conductivity, dissolved oxygen, total alkalinity, and total phosphorus. Since, springs are groundwater-dependent ecosystems acting as ecohydrologic refugia, any small change in groundwater discharge could strongly influence the ambient conditions (including water quality and temperature), which in turn influences the biological assemblage patterns and ecosystem services. Therefore, changes in discharge may provide information on possible future ecological change in the springs in relation to rising aridification.

Six seaweed species of the Rhodophyta family were sampled for atwo-year period from June 1996 to August 1998 along the Atlanticcoast of Ghana (part of the Atlantic Ocean). The species wereanalysed to determine the levels of eleven chemicalelements namely: Al, As, Br, Cd, Fe, La, Mn, Ni, Hg, V and Zn byInstrumental Neutron Activation Analysis (INAA). Al, Br, Ni, andZn were measured in all the seaweed species studied. The elementAl generally showed the highest concentrations in most of thespecies analysed while Hg levels were the lowest. Precision andaccuracy of the method have been evaluated and the detectionlimits also calculated. The results showed high variability inand between species, among sampling sites and times ofcollection. The high values of metal concentrations in themacroalgae suggest that these marine organisms can be used asbiological indicators for studing marine pollution.