Beach wrack: Discussing ecological roles, risks, and sustainable bioenergy and agricultural applications

The equilibrium of the marine ecosystem is currently threatened by several constraints, among which climate change and anthropogenic activities stand out. Indeed, these factors favour the growth of macroalgae, which sometimes end up stranded on the beaches at the end of their life cycle, forming what is known as beach wrack. Despite its undeniable important ecological role on beaches, as it is an important source of organic matter (OM), and provides food and habitat for several invertebrates, reptiles, small mammals, and shorebirds, the overaccumulation of beach wrack is often associated with the release of greenhouse gases, negatively impacting tourist activities, and generating economic expenses for its removal. Although currently beach wrack is mainly treated as a waste, it can be used for numerous potential applications in distinct areas. This review aimed at providing a solid point of view regarding the process of wrack formation, its spatiotemporal location, as well as its importance and risks. It also contains the current advances of the research regarding sustainable alternatives to valorise this organic biomass, that range from bioenergy production to the incorporation of wrack in agricultural soils, considering a circular economy concept. Although there are some concerns regarding wrack utilisation, from its variable availability to a possible soil contamination with salts and other contaminants, this review comprises the overall beneficial effects of the incorporation of this residue particularly in the organic agricultural model, strengthening the conversion of this wasted biomass into a valuable resource.

A new species of Batillipes (Arthrotardigrada: Batillipedidae) from the mid littoral zone of the southeast coast of India

Studies of marine tardigrades from Indian waters is very limited and relatively obscure. A new species of marine tardigrade is described from the southeast coast of India as part of an effort to better understand the marine tardigrade biodiversity of the Indian subcontinent. Batillipes kalami sp. nov. described from the sandy sediments of the mid littoral zone can be differentiated from all its congeners by the presence of unconstricted primary clavae, two pairs of lateral body projections between leg II and leg III, long and blunt ended lateral body projections between leg III and leg IV, shape of leg IV sensory organs and the presence of dorsal indentations in its head.

Short-term effects of trampling on intertidal Mytilus galloprovincialis beds

Human trampling represents one of the main anthropogenic pressures in the rocky intertidal. This habitat includes many ecosystem engineers such as mussels that provide biogenic habitat and multiple services. This research assessed potential impacts of human trampling on beds of the mussel, Mytilus galloprovincialis, on NW shores of Portugal. To test for direct effects of trampling on mussels and indirect effects on the associated assemblages, three treatments were applied: control (untouched beds), low and high intensity of trampling. Effects of trampling were dependent on the taxa. Thus, values of shell length of M. galloprovincialis were greater under the highest intensity of trampling while abundances of Arthropoda, Mollusca and Lasaea rubra showed the opposite pattern. Moreover, total number of taxa and abundances of Nematoda and Annelida showed higher values under low trampling intensity. The implications of these results to manage human use in areas with ecosystem engineers are discussed.

Effects of habitat homogenisation on assemblages associated with mussel clumps

Biodiversity loss is considered one of the main threats to marine ecosystems. In this framework of biodiversity decline, organisms that provide biogenic habitat play a relevant role by their capacity to structure assemblages and influence ecological processes. The Mediterranean mussel Mytilus galloprovincialis is considered an ecosystem engineer because it alters local environmental conditions maintaining habitat suitability for other organisms, and enhancing local biodiversity. Although it is widely recognized that mussel beds increase diversity, the drivers shaping these assemblages are poorly explored. We investigate whether mussel size homogenisation shapes the abundance, richness and structure of macrobenthic assemblages associated with mussel beds in two shores of the Galician coast (NW Spain). At each shore, two sites, 10 m apart, were selected and at each site, faunal assemblages were compared between mussel clumps showing shells of various sizes (control), and mussel clumps with closely similar-sized mussels, considered as homogenised. Homogenised clumps showed, in general, higher values in total number of individuals and species than control clumps. Regarding the effect of mussel size homogenisation on the multivariate structure of the assemblages, significant differences between control and homogenised clumps were found in three out of the four sites. Most relevant associated species usually reached higher abundances in homogenised clumps than control ones. Therefore, mussel size homogenisation influenced the structure of the macrofaunal assemblages associated with mussel beds but, its effect was context dependent (i.e., varied with sites). Information about the species contribution to dissimilarities among homogenised and control clumps was provided and the potential influence of sediment and algae on mussel clumps was discussed.

Public perception of ecosystem services provided by the Mediterranean mussel Mytilus galloprovincialis related to anthropogenic activities

Background

Mussels provide many ecosystem services as habitat, food, water filtration and recreational fishing. However, mussels are vulnerable to anthropogenic pressures such as harvesting or trampling, among others. In this frame, it would be paramount to engage society in marine conservation and improving its awareness about environmental policies. The first step lies in properly assessing what is the perception and concerns of society about marine ecosystems. Our study aims to fill this gap by examining public perception of services provided by Mytilus galloprovincialis, its state of conservation and the factors (including anthropogenic activities) shaping mussel beds.

Methods

This study is based on a face-to-face survey consisting of seven open-ended and seven multiple-choice questions of 404 people conducted in 2019 at different shores in the North Portuguese coast. The influence of respondent profile in terms of age, education, gender and place of residence was also assessed.

Results

Most of the participants in our survey (74%) considered that mussels contributed to human well-being and life quality; however, only 31% considered that mussels provide us with many benefits. Regarding the perceived state of mussel services, most of the respondents asserted that mussel services (purification of seawater, habitat, food for other species) worsened in the last 10 years. In contrast, the service as human food was perceived as in an identical state and scientific and traditional knowledge was the only service perceived in a better state. Concerning the state of mussel beds, most of the participants perceived it as good (45%) but a similar percentage (41%) asserted ignoring it. When considering the influence of different factors on mussel beds, only environmental management was considered as having a positive impact by a higher percentage of respondents. The majority of the participants considered that factors included in the questionnaire contributed to worsen mussel beds, ranging between 51% for coastal erosion and 90% for pollution. Education level and age were the main socio-economic factors driving public awareness about the importance of mussel services, its state of conservation and the factors shaping mussel beds.

Discussion

Results showed that perception about the importance of mussels for human well-being and the quantity of delivered benefits increased with the education level. Moreover, older people perceived human food as the most important service offered by mussels. Therefore, our results suggest that mussels are mainly known as food resource; however, most of the people ignore their relevant ecological role and the many other benefits that mussels provide. Thus, it is necessary to actively engage society about importance of mussel beds. As M. galloprovincialis is a relevant economic resource, our data could improve the diffusion of knowledge among citizens, stakeholders and scientists, contributing to its sustainability.

Fucoid Macroalgae Have Distinct Physiological Mechanisms to Face Emersion and Submersion Periods in Their Southern Limit of Distribution

During high tide, macroalgae are submersed, facing adequate environmental conditions, however, at low tide, these species can be exposed to high UV radiation and desiccation, leading to an overproduction of reactive oxygen species, causing oxidative stress. Since intertidal organisms present differential sensitivity to abiotic fluctuations, this study aimed to evaluate the physiological responses [photosynthetic pigments, hydrogen peroxide (H₂O₂), lipid peroxidation (LP), and thiols and proline] of three macroalgae, from different intertidal levels, towards tidal regimes. Samples of Pelvetia canaliculata, Ascophyllum nodosum, and Fucus serratus were collected from beaches located on the southern limit of distribution in periods of potential stress (Summer and Spring), under low and high tide. The photosynthetic pigments of P. canaliculata and F. serratus were generally higher during low tide, and the oxidative damage evidenced by H₂O₂ and LP increased in the Summer, while A. nodosum showed greater oxidative damage in the Spring. While thiol content did not change, proline levels were species- and tidal-specific among sampling dates. P. canaliculata presented higher resilience to unfavorable conditions, while F. serratus was the most sensitive species. The physiological responses analyzed were species-specific, pointing to the high susceptibility of low intertidal organisms to expected extreme climatic events.

Sediment Characteristics Determine the Flowering Effort of Zostera noltei Meadows Inhabiting a Human-Dominated Lagoon

Recent studies have shown increasing Zostera noltei meadows in areas modified by anthropogenic activities. However, it is not entirely clear whether this trend of expansion could be linked to a greater reproductive effort in the species. Anthropogenic stressors can induce the reproductive effort of seagrass meadows as a response to stress, but other variables, such as seagrass biometrics or environmental factors, can also influence their sexual reproduction. To increase the knowledge regarding this issue, we monitored the flowering effort, seagrass biometrics and abiotic parameters of three Z. noltei meadows in an area that has been highly modified by anthropogenic activities during the past decades. Results showed that silt and clay content in the sediment (strongly correlated with organic matter) and seagrass vertical shoot density explained 54% of the variability in the flowering effort of the meadows. This study suggests that stress-induced flowering of Z. noltei may occur under determinate environmental conditions, such as silty environments with organic enrichment.

Spatial-temporal variability of Mytilus galloprovincialis Lamarck 1819 populations and their accumulated sediment in northern Portugal

Mytilus galloprovincialis is an ecosystem engineer that provides habitat and generates environmental heterogeneity, increasing local biodiversity. Moreover, it is an economically important species representing 14% of the global production of marine bivalves. Natural drivers and the increase of anthropogenic pressures, such as sediment stress, influence its populations on rocky shores. The objective of this study was to explore the spatial-temporal patterns of different M. galloprovincialis attributes along the north of Portugal. For that purpose, six rocky shores were selected and sampled six times along the year 2019. The percentage of cover, density, spat density, condition index, clump thickness, size classes and clump sediment content were considered. Results showed the lack of seasonality in M. galloprovincialis along the north coast of Portugal. However, density, spat stage, clump thickness, condition index and size classes showed some variability among dates and shores. The percentage cover and sediment content only significantly differed among shores. Our results indicated an absence of seasonality for all the studied variables, probably because temperature was always within the optimum range for this species and the abundance of food supply in the study area independently of the season. The accumulated sediment on mussel clumps did not show any temporal variability with only significant differences among shores. The accumulated sediment was composed mainly by medium and coarse sand and it was correlated with mussel average size, condition index, but especially with the mussel clump thickness.

The role of urbanisation in affecting Mytilus galloprovincialis

Urbanisation is considered as one of the most critical and widespread threats to coastal marine ecosystems. The aim of this study was to compare the density, percentage cover, thickness of clumps, condition index and size-frequency distribution of Mytilus galloprovincialis between urban and non-urban shores, at nested spatial scales, in the Northern Portuguese coast. M. galloprovincialis was selected as model because it is economically and ecologically relevant. Moreover, the relationship between mussel size and the other variables (i.e. density, percentage cover, thickness and condition index) were investigated. Mussels on urban shores showed a smaller density and a greater frequency of larger individuals. A significant negative correlation between mussel length with density and with thickness of clumps was also found. Our results seem to indicate that recruitment has declined on urban shores and, as a result, intraspecific competition is also smaller, leading to more resources being available for a fewer individuals which can reach larger sizes. As mussel beds support a great biodiversity of invertebrates and provide many ecosystem services, urbanisation may have indirect effects on communities associated with mussels. Understanding the vulnerability of mussel beds to urbanisation could inform management.

Batillipes pennaki Marcus, 1946 (Arthrotardigrada: Batillipedidae): deciphering a species complex

Batillipes pennaki has been considered a common and a cosmopolitan marine tardigrade species. However, the original diagnosis of this species is very incomplete, and consequently there is a high probability of incorrect records. Therefore, a comparative analysis of quantitative and qualitative morphological characters among eight different populations from the Atlantic basin was done in this study to investigate if B. pennaki is a complex of similar species, each with a restricted distribution range. The result of discriminant analyses showed clear morphometric differences between populations that were arranged into three main groups, distinguishing Western Atlantic populations, Eastern Atlantic populations and a Mediterranean population. Furthermore, the result of analyses of morphological structures revealed peculiarities of some traits with taxonomic relevance, such as leg IV sensory organs and primary clavae, consistent with the clusters revealed by quantitative data, allowing us to distinguish three different pseudocryptic species and supporting the hypothesis that B. pennaki is a species complex.

Mollusc diversity associated with the non-indigenous macroalga Asparagopsis armata Harvey, 1855 along the Atlantic coast of the Iberian Peninsula

The aims of this study were to explore mollusc assemblages associated with the non-indigenous macroalga Asparagopsis armata, to compare them with those on other macroalgae at the study region and to explore potential differences on mollusc assemblages between two regions in the Atlantic coast of the Iberian Peninsula, where A. armata is present. To achieve this, at each region, four intertidal shores were sampled. Twenty-nine mollusc species were reported and thus, A. armata harboured similar or higher diversity than other annual macroalgae in this area. When compared with perennial macroalgae, results depend on the species and studied area. Moreover, significant differences in structure of mollusc assemblages between the two studied regions were found. However, these were due to differences in the relative abundance of species rather than the presence of exclusive species at each region.

Relationship between structure of macrobenthic assemblages and environmental variables in shallow sublittoral soft bottoms

We establish baseline knowledge of abundance, diversity and multivariate structure of macrobenthos from shallow sublitoral soft bottoms in the North Portuguese coast and elucidate main environmental factors that shape their spatial patterns. In this area distribution of soft bottoms is patchy, surrounded by boulders and rocky substrates. This particular landscape and the lack of significant anthropogenic disturbances are values for the conservation of this habitat. Sediment and physicochemical properties of the water column were studied to provide models for each studied macrobenthic variable. Our models highlighted that most of variation (59%-72%) in macrobenthic spatial patterns was explained by the studied environmental variables. Sedimentary variables were more relevant that those of the water column. Therefore, disturbances affecting sedimentary environment could cause dramatic changes in macrobenthic assemblages because of the limited availability of soft bottoms in the area. In this way, results are useful to adopt right management and conservation strategies.

Two new species of Tardigrada (Eutardigrada: Ramazzottiidae, Macrobiotidae) from the supralittoral zone of the Atlantic Iberian Peninsula rocky shores

Two new species of Eutardigrada were found in supralittoral lichens, growing on rocky shores at two localities of the Western Atlantic coast of the Iberian Peninsula. Ramazzottius littoreus sp. nov., found in San Cibrao (North of Spain), has the dorsal cuticle sculptured with small tubercles and claws with accessory points similar to R. oberhaeuseri. It can be distinguished from all the other known Ramazzottius species with the same type of cuticular sculpture by the dotted egg shell and the peculiar reticulation visible at the bulbous base of egg processes. Macrobiotus halophilus sp. nov., found in Cascais (Centre of Portugal), belongs to the Macrobiotus hufelandi group. The slightly wrinkled egg shell and egg processes in the shape of inverted chalice with dentate distal disc, identifies it as a member of the Macrobiotus persimilis subgroup. The new dioecious species differs from the six other species of the M. persimilis subgroup by a unique combination of some characters (small and very sparse circular cuticular pores, granulation on legs I-III and dentate lunules on legs IV), by measurements of some structures (claws and buccal apparatus), and by the number, dimension and shape of egg processes.

Consistent patterns of variation in macrobenthic assemblages and environmental variables over multiple spatial scales using taxonomic and functional approaches

Spatial variability of environmental factors and macrobenthos, using species and functional groups, was examined over the same scales (100s of cm to >100 km) in intertidal sediments of two transitional water systems. The objectives were to test if functional groups were a good species surrogate and explore the relationship between environmental variables and macrobenthos. Environmental variables, diversity and the multivariate assemblage structure showed the highest variability at the scale of 10s of km. However, abundance was more variable at 10s of m. Consistent patterns were achieved using species and functional groups therefore, these may be a good species surrogate. Total carbon, salinity and silt/clay were the strongest correlated with macrobenthic assemblages. Results are valuable for design and interpretation of future monitoring programs including detection of anthropogenic disturbances in transitional systems and propose improvements in environmental variable sampling to refine the assessment of their relationship with biological data across spatial scales.

A new species of heterochelous tanaidacean Tanaissus (Paratanaoidea: Tanaissuidae) from the north-west Iberian Peninsula

A new species of tanaidomorph, Tanaissus bamberi, is described from the north-western region of the Iberian Peninsula. Its most remarkable character is the presence of morphologically different right and left chelae in the males. The species occurs sympatrically with T. lilljeborgi, mainly in intertidal and subtidal sediments of medium to muddy sands typical of fully marine and estuarine salinities.

Structural complexity of macroalgae influences epifaunal assemblages associated with native and invasive species

Habitat structure is a primary factor determining the organism distribution. Here, two native and one invasive macroalgal species, apparently different in morphology, were sampled to examine the effects of habitat complexity on the abundance (N), taxon richness (S) and structure of their associated epifaunal assemblages by means of univariate and multivariate techniques. Dry weight and fractal measures were used as proxies of habitat quantity and habitat architecture respectively. Results revealed significant differences in the complexity and in N, S and the structure of epifaunal assemblages among macroalgae and significant correlations between complexity and epifauna. Results suggested that, beside the effect of habitat quantity, the habitat architecture also seems to play a significant role in shaping epifaunal assemblages. Complexity of the studied invasive macroalga significantly differed from that of native species and hosted also different assemblages. Therefore, our findings suggest that invasive macroalgae, if structurally different from native species, induce changes in the associated epifauna.

Fucus spiralis as monitoring tool of metal contamination in the northwest coast of Portugal under the European Water Framework Directives

Metals (Cd, Cr, Cu, Fe, Mn and Zn) in coastal seawaters and soft tissues of macroalga Fucus spiralis from the northwest coast of Portugal were determined to assess spatial variations of metal bioavailabilities and bioaccumulation factors to compare different ecological quality classifications. Both coastal seawaters and soft tissues of F. spiralis showed significant spatial variations in their metal concentrations along the coast. The macroalgae F. spiralis accumulated more efficiently Cd, Mn and Zn and showed low bioaccumulation factors to Cr, Cu and Fe. Regarding the metal guidelines of the Norwegian Pollution Control Authority, the entire northwest (NW) coast of Portugal in April 2013 should be classified as 'class I--unpolluted' for all metals, except in Ave for Cu ('class II--moderately polluted') and Cavado for Cd and Cu ('class II-moderately polluted'), revealing the low metal bioavailabilities of these seawaters. As there were always significant positive correlations between all metals in seawaters and F. spiralis, this macroalga species was considered a suitable monitoring tool of metal contamination in the NW coast of Portugal and a useful aquatic organism to be included in the European Environmental Specimen Banks in order to establish a real-time environmental monitoring network under the European Water Framework Directives.

Effects of subtle pollution at different levels of biological organisation on species-rich assemblages

We investigated effects of subtle nutrient enrichment and metal pollution on different levels of biological organization (i.e. whole assemblage, population and individual) of species-rich assemblages. We used rockpools as model system, applying a multi-factorial sampling design to test hypotheses on differences between disturbed and reference locations. Results indicated that disturbed and reference locations supported similar assemblages, as well as individual fitness-related life-traits were ineffective to discriminate between the two conditions. In contrast, assemblages responded to pollution through a reduction of the abundance of sensitive species and a proliferation of tolerant species, although these alterations were detectable only once the influence of dominant taxa was down-weighed by data transformation. Present findings suggest that, contrarily to individual level variables, assemblage structure after data transformation and patterns of distribution and abundance of differently sensitive taxa would be a powerful tool to detect effects of subtle pollution on species-rich assemblages.

The invasive kelp Undaria pinnatifida (Laminariales, Ochrophyta) along the north coast of Portugal: distribution model versus field observations

After the first report of Undaria pinnatifida in north Portugal (between 1999 and 2007), a rapid spread of this species could be expected due to the presence of a stable population and the favourable environmental conditions proposed by distribution models. However, field surveys showed that U. pinnatifida was not present in most of the rocky shores in north Portugal. It seems that U. pinnatifida cannot outcompete native species outside of marinas in north Portugal. The only population in natural rocky shores was found in Buarcos, where this species was frequent. This study provides density data of U. pinnatifida that will be useful in the future to monitor changes on its abundance and distribution in the centre and south of Portugal.

Shifts from native to non-indigenous mussels: enhanced habitat complexity and its effects on faunal assemblages

Ecosystem engineers such as mussels may affect strongly both the structure of benthic assemblages and the ecosystem functioning. The black-pygmy mussel Limnoperna securis is an invasive species that is spreading along the Galician coast (NW Spain). Its current distribution overlaps with the distribution of the commercial native mussel species Mytilus galloprovincialis, but only in the inner part of two southern Galician rias. Here, we analysed the assemblages associated with clumps of the two mussel species and evaluated if the invasive species increased complexity of habitat. To measure complexity of clumps we used a new method modified from the "chain and tape" method. Results showed that the identity of the mussel influenced macrofaunal assemblages, but not meiofauna. L. securis increased the complexity of clumps, and such complexity explained a high percentage of variability of macrofauna. The shift in dominance from M. galloprovincialis to L. securis may alter habitat structure and complexity, affecting the macrofaunal assemblages with unpredictable consequences on trophic web relations.

Invasion of Sargassum muticum in intertidal rockpools: patterns along the Atlantic Iberian Peninsula

Spatial patterns of non-indigenous species show scale-dependent properties. Sargassum muticum is an invasive macroalga widely distributed along the Atlantic Iberian Peninsula. Despite being quite abundant from Norway to South Portugal, there is little information about its patterns of distribution, particularly at a large spatial scale (i.e. thousands of kilometres). Here, we examined the spatial variation in the invasion success of S. muticum from rockpools at multiple spatial scales using a hierarchical design. In addition, we analysed how the richness of native assemblages was related to its invasion success and how this relationship changed over different scales. Most of the variation in the invasion success was found at the smallest scales of pool and plot. Furthermore, the invasibility of native macroalgal assemblages was related to the native species richness, but causes that determined invasion success could not be separated from the effects provoked by the invader. Results suggest that small-scale (centimetres to metres) processes contribute considerably to the heterogeneity of S. muticum invasion success.

Physical factors driving intertidal macroalgae distribution: physiological stress of a dominant fucoid at its southern limit

Climate change is driving species range shifts worldwide. However, physiological responses related to distributional changes are not fully understood. Oceanographers have reported an increase in ocean temperature in the northwest Iberian Peninsula that is potentially related to the decline in some cold-temperate intertidal macroalgae in the Cantabrian Sea, namely Fucus serratus. Low tide stress could also play a role in this decline. We performed one mensurative (in situ) and two manipulative (in culture) experiments designed to evaluate the interactive effects of some physical factors. The first experiment analysed field response to low tide stress in marginal (mid-Cantabrian Sea and northern Portugal) versus central (Galicia) populations of F. serratus. Then a second experiment was performed that utilized either harsh or mild summer conditions of atmospheric temperature, irradiance, humidity, and wind velocity to compare the responses of individuals from one marginal and one central population to low tide stress. Finally, the combined effect of sea temperature and the other factors was evaluated to detect interactive effects. Changes in frond growth, maximal photosynthetic quantum yield (F(v)/F(m)), temperature, and desiccation were found. Three additive factors (solar irradiation, ocean and air temperatures) were found to drive F. serratus distribution, except under mildly humid conditions that ameliorated atmospheric thermal stress (two additive factors). Mid-Cantabrian Sea temperatures have recently increased, reaching the inhibitory levels suggested in this study of F. serratus. We also expect an additive secondary contribution of low tide stress to this species decline. On the northern Portugal coast, ocean warming plus low tide stress has not reached this species' inhibition threshold. No significant differential responses attributed to the population of origin were found. Mechanistic approaches that are designed to analyse the interactive effects of physical stressors may improve the levels of confidence in predicted range shifts of species.

Two strategies to live in low chronic pollution estuaries: the potential role of lifestyle

Although physiological and genetic adaptation to toxic stress has been the focus of recent research, the role of lifestyle in pollution tolerance has received less attention. In this study, copper tolerance of benthic and epi-benthic species of harpacticoid copepods was investigated. Concentration-response curves were generated for populations of both species but collected at contaminated and uncontaminated estuaries. The population of the benthic species from the contaminated site showed higher tolerance than its population from the uncontaminated site. The epi-benthic species showed no inter-specific differences in tolerance. The comparison of tolerance between field collected animals of the benthic species and animals from the same population but reared in the laboratory for two generations suggested the existence of a genetic inherited tolerance. Results revealed the importance that lifestyle may have on the generation of tolerance to toxic substances and highlight a potential unforeseen role of it in maintenance of biodiversity on contaminated habitats.

Individual, population and community level effects of subtle anthropogenic contamination in estuarine meiobenthos

The study presented here searched for the level of taxonomic resolution required to detect the effects of low-level chronic pollution on estuarine meiobenthic communities. Meiofauna from two sites, with special attention to harpacticoid copepods, was analysed at different taxonomic levels of aggregation using uni- and multivariate methods. Adaptation processes that could buffer biodiversity disruptions were also considered through the analysis of fitness-related and tolerance traits in the harpacticoid copepod Paronychocamptus nanus. Results showed that uni- and multivariate analyses could be inadequate when assessing subtle anthropogenic contamination. Instead, the assessment of inter-population differences in tolerance to the main source of stress rises as a required procedure if potential effects of this type of contamination are being investigated. Specifically, a 96 h acute toxicity test performed with populations from the affected site appears as a faster and reliable general tool to assess impacts of low-level chronic pollution in estuaries.

Shallow sublittoral meiofauna communities and sediment polycyclic aromatic hydrocarbons (PAHs) content on the Galician coast (NW Spain), six months after the Prestige oil spill

The aim of this work was to detect the impact of Prestige oil spill on meiobenthic community structure at higher levels of taxonomic aggregation. In addition, the relationship between sediment individual polycyclic aromatic hydrocarbon (PAH) concentration and meiofauna community structure was investigated. Six months after the Prestige oil spill, meiobenthos community and sediment PAHs content from seven shallow subtidal localities along the Galician coast were studied. Two sites presented differences in community structure, characterized by high densities of nematodes, gastrotrichs and turbellarians, and low densities of copepods. Chrysene and triphenylene were only found at these two disturbed sites and could be responsible for differences of meiobenthos community structure. However, differences in community structure of sites could be linked with sedimentary parameters, and discrimination between the effect of PAHs and sedimentary parameters was impossible due to the lack of baseline studies on meiobenthos and PAHs contents in this area.