Total Taxa Research Articles

Extant coccolithophores from the western equatorial Indian Ocean off Tanzania and coccolith distribution in surface sediments

Living coccolithophores and coccoliths from surface sediments were investigated in the western equatorial Indian Ocean off Tanzania, from the coast and Pemba Channel to the open ocean. In total, 49 plankton samples from 8 stations and 20 surface sediment samples collected in February 2008 were analysed. Coccolithophore standing stock ranged from barren up to almost 23,000 coccospheres/l in the upper water column and the living community comprised 47 different taxa in total. In addition, six more species were only found as detached coccoliths. Coccolithophore numbers were generally low and only Florisphaera profunda, Gephyrocapsa oceanica, and Emiliania huxleyi were numerically important (>5,000 coccospheres/l). Two distinct depth-related assemblages were identified. The upper photic zone (down to about 50m) in the Pemba Channel was dominated by G. oceanica and can be related to slightly increased nutrient conditions. In contrast, the upper photic zone community in the open ocean (down to about 70m) is characterised by high numbers of Umbellosphaera irregularis, typically indicating oligotrophic stratified waters, high sea-surface temperatures and strong water stratification. The lower photic-zone flora in the whole study area is generally dominated by F. profunda and accompanying species. A total of 40 species were identified in the surface sediments and total coccolith numbers vary drastically from <1000 to 18,200 x 106 coccoliths/g of sediment. The absolute numbers are much lower near-shore and strikingly enhanced further offshore mainly due to heavy dilution by fine-grained terrigenous sediments. Nevertheless, the occurrence of species in the plankton communities compares well to those of the surface sediment assemblages although plankton samples are from just one season. This points to an excellent preservation potential in this area, which can be explained by high supply of clay-rich sediments and a therefore rapid burial of the coccoliths in shelf and upper slope sediments.

The phylogenetic position of Neogosseidae (Gastrotricha: Chaetonotida) and the origin of planktonic Gastrotricha

Planktonic forms of Gastrotricha have been known since the 1850s, despite the fact that they are rather uncommon and difficult to collect. They are characterized by a round sack-shaped body, an absence of furcal adhesive tubes, and a different distribution of the locomotory ciliation compared to epibenthic and periphytic gastrotrichs. Today, planktonic gastrotrichs are classified into the three taxa—Dasydytidae, Neogosseidae, and Undula—but their origin and whether they share a recent common ancestor remain largely unknown. A long-held view is that planktonic taxa are derived from benthic ancestors related to Chaetonotus (Zonochaeta), but the hypothesis has never been properly tested. Here, in order to elucidate the phylogeny and origin of planktonic Gastrotricha, we provide the first molecular data on the very rare genera Kijanebalola and Neogossea, both members of the family Neogosseidae. We use Bayesian and maximum likelihood phylogenetics to analyze sequences of 18S rDNA, 28S rDNA, and COI mtDNA spanning 71 taxa in total. We find high support for a common origin of planktonic gastrotrichs, with monophyly of both Dasydytidae and Neogosseidae. Planktonic forms have evolved from epibenthic or periphytic ancestors, and the closest extant clade comprises members of Chaetonotus (Zonochaeta) + Chaetonotus heteracanthus Remane, 1927. These results further imply that the motile spines and underlying muscle patterns that control them in species of Dasydytidae are adaptations to the planktonic environment that evolved independently of those in other species of Gastrotricha.

Reach-scale stream restoration in agricultural streams of southern Minnesota alters structural and functional responses of macroinvertebrates

Recent studies suggest that stream restoration at the reach scale may not increase stream biodiversity, raising concerns about the utility of this conservation practice. We examined whether reach-scale restoration in disturbed agricultural streams was associated with changes in macroinvertebrate community structure (total macroinvertebrate taxon richness, total macroinvertebrate density, Ephemeroptera, Plecoptera, Trichoptera [EPT] taxon richness, % abundance of EPT taxa) or secondary production (macroinvertebrate biomass over time). We collected macroinvertebrate samples over the course of 1 y from restored and unrestored reaches of 3 streams in southern Minnesota and used generalized least-square (GLS) models to assess whether measures of community structure were related to reach type, stream site, or sampling month. After accounting for effects of stream site and time, we found no significant difference in total taxon richness or % abundance of EPT taxa between restored and unrestored reaches. However, the number of EPT taxa and macroinvertebrate density were significantly higher in restored than in unrestored reaches. We compared secondary production estimates among study reaches based on 95th-percentile confidence intervals generated via bootstrapping. In each study stream, secondary production was significantly (2–3×) higher in the restored than in the unrestored reach. Higher productivity in the restored reaches was largely a result of the disproportionate success of a few dominant, tolerant taxa. Our findings suggest that reach-scale restoration may have ecological effects that are not detected by measures of total taxon richness alone.

Microbial diversity in the deep-sea sediments of Iheya North and Iheya Ridge, Okinawa Trough

In this study, we analyzed the bacterial and archaeal diversities of the deep-sea sediments in Iheya North and Iheya Ridge, Okinawa Trough, using the high-throughput sequencing technology of Illumina MiSeq 2500 platform. Four samples (IN1, IN2, IR1 and IR2) were used in this study, of which IN1 and IN2 were located at regions close to and distant, respectively, from the active hydrothermal vents in Iheya North, while IR1 and IR2 were located at regions close to and distant, respectively, from the active hydrothermal vents in Iheya Ridge. The four samples were rich in different metal elements. Sequence analysis based on the V3–V4 regions of 16S rDNA gene obtained 170,363 taxon tags, including 122,920 bacterial tags and 47,433 archaeal tags, which cover 31 phyla, 50 classes, 59 orders, 87 families, and 138 genera. Overall, the microbial communities in all samples were dominated by bacteria, in which Proteobacteria was the largest phylum, followed by Chloroflexi, Firmicutes, Acidobacteria, Actinobacteria, Gemmatimonadetes, and Nitrospirae, which together accounted for 64.6% of the total taxon tags. In contrast to the high bacterial diversities, the archaeal diversity was low and dominated by Thaumarchaeota, which accounted for 22.9% of the total taxon tags. Comparative analysis showed that (i) IN2 and IR2 exhibited more microbial richness than IN1 and IR1, (ii) IR1 and IR2 exhibited higher microbial diversities than IN1 and IN2, (iii) samples from Iheya Ridge and Iheya North fell into two groups based on principle component analysis. Furthermore, microbes potentially involved in sulfur, nitrogen, and metal metabolism and cycling were detected in all samples. These results provide for the first time a comparative picture of the microbial diversities in the sediments of Iheya North and Iheya Ridge and indicate that geological features and distance from active hydrothermal vents likely play important roles in the shaping of microbial community structure.

Meiofauna distribution on hard substrata in a submarine cave

For the first time the meiofauna of the rocky walls of a submarine cave was studied. The cave, known as il Ciolo (Strait of Otranto, south-east Italy) is a closed tunnel about 125 m long, with a maximum depth of 6 m below sea level. The meiofauna was collected from artificial panels and natural rocky walls. This double approach enabled: (1) the description of the community's initial organization (on artificial substrata), and (2), especially for Harpacticoida, its mature composition (on rocky walls), which also helped to establish spatial differences. The collected samples yielded 70 taxa in total. Harpacticoida represented the most important group of organisms in terms of both abundance and identified taxa. The meiofauna assemblage appeared not to be affected by community age, with the exception of the very early stage. The meiofauna of the cave showed assemblage differences from the entrance to the innermost positions, but not as evident as in the case of the macrobenthos. The similarity of community composition at different ages (6, 12 and 24 months) and at different positions along the cave could be the consequence of the specimens’ vagility.

Biogeographic analysis of the woody plants of the Southern Appalachians: Implications for the origins of a regional flora.

We investigated the origins of 252 Southern Appalachian woody species representing 158 clades to analyze larger patterns of biogeographic connectivity around the northern hemisphere. We tested biogeographic hypotheses regarding the timing of species disjunctions to eastern Asia and among areas of North America. We delimited species into biogeographically informative clades, compiled sister-area data, and generated graphic representations of area connections across clades. We calculated taxon diversity within clades and plotted divergence times. Of the total taxon diversity, 45% were distributed among 25 North American endemic clades. Sister taxa within eastern North America and eastern Asia were proportionally equal in frequency, accounting for over 50% of the sister-area connections. At increasing phylogenetic depth, connections to the Old World dominated. Divergence times for 65 clades with intercontinental disjunctions were continuous, whereas 11 intracontinental disjunctions to western North America and nine to eastern Mexico were temporally congruent. Over one third of the clades have likely undergone speciation within the region of eastern North America. The biogeographic pattern for the region is asymmetric, consisting of mostly mixed-aged, low-diversity clades connecting to the Old World, and a minority of New World clades. Divergence time data suggest that climate change in the Late Miocene to Early Pliocene generated disjunct patterns within North America. Continuous splitting times during the last 45 million years support the hypothesis that widespread distributions formed repeatedly during favorable periods, with serial cooling trends producing pseudocongruent area disjunctions between eastern North America and eastern Asia.

Diversity and composition of macroinvertebrate assemblages in high-altitude Tibetan streams

Knowledge on the ecology of streams at extreme altitudes is relatively sparse. We conducted a preliminary survey of the macroinvertebrate fauna of Tibetan streams in June 2009 and August 2011 and compared streams with different water sources. We collected quantitative samples of macroinvertebrates and measured physicochemical variables at 16 sites (8 each sampling year) at altitudes ranging from 4315 to 5065 m a.s.l. and grouped the sites into 3 types according to origin: glacier-fed, rain-fed, and lake-outlets. We identified 38 taxa, with a mean of 8.9 taxa per site. Overall the benthic fauna was dominated by insects (71%), mainly Diptera (especially Chironomidae). Ephemeroptera, Plecoptera, and Trichoptera were found at nearly all sites but mostly in low numbers; however, the fauna was significantly different in the 2 sampling years, especially due to the proportions of Chironomidae (68% in June 2009 and 10% in August 2011) and Baetidae (6% vs. 35%, respectively). The 3 stream types had significantly different faunas. Rain-fed streams had the highest total taxon richness (γ-diversity), but glacier-fed streams had a slightly higher taxon turnover rate (β-diversity). Percent glacial cover in the catchment and water turbidity explained most of the variability in taxon richness. Although not particularly taxon rich compared to other high-altitude streams, the Tibetan stream fauna showed considerable spatial variability. The fast retreat of the glaciers and permanent snow fields in Tibet makes further studies on distribution patterns and driving forces for aquatic biodiversity urgent.

Effect of the invader Boccardia proboscidea (Polychaeta: Spionidae) on richness, diversity and structure of SW Atlantic epilithic intertidal community

In Mar del Plata (Argentine, SW Atlantic), a large seaside resort, the sewage discharges impact the littoral ecosystem. The invader polychaete Boccardia proboscidea has developed reefs since spring of 2008. The effect of this species on the richness, diversity and structure of epilithic intertidal community was assessed through an MBACI design in both sewage-impacted and reference sites, and Before/After the invasion. The presence of reefs of B. proboscidea since spring 2008 has caused a significant reduction of total individuals, total taxa and diversity in sewage-impacted sites regarding the reference ones. The species analyzed showed a high variable response because patterns were dominated by small-scale variability. Occasional peaks in abundance were observed on a single sampling site and time and a large variation among replicates. The associated fauna, formerly rich and diverse in impacted sites, shows a tendency to disappear as the ecosystem engineer Brachidontes rodriguezii is replaced by monocultures of B. proboscidea.

Effects of fine sediment addition and removal on stream invertebrates and fish: a reach‐scale experiment

Summary Land use change due to intensifying agricultural practices has profound effects on streams and rivers worldwide, and has been identified as an important source of fine sediment inputs to streams affecting both habitats and biota. Although the effects of sedimentation on stream organisms have been widely studied, manipulative field experiments involving fish and conducted at the reach scale are lacking. Further, it is unknown whether experimentally removing fine sediment from streams can reverse the negative impacts of sedimentation. Two farmland streams were manipulated for 2 months, by adding or removing fine sediment (using a powerful water blaster) in 50‐m reaches twice (initially and 1 month later). Each stream contained one sediment addition, one removal and one control reach separated by buffer zones. Streams were sampled on five occasions, and water physicochemistry, invertebrate community variables and fish densities (native species and introduced brown trout), diet and condition were determined. Multivariate benthic invertebrate community composition changed in response to the sediment manipulations. Total taxon richness, density of the caddis fly larva Aoteapsyche spp. and brown trout density responded negatively to sediment addition and positively to its removal. A similar trend, although not statistically significant, was observed for native fish density. Trout condition was also poorer in sediment addition reaches than in removal or control reaches. Our study provides experimental evidence from real streams that increased levels of deposited fine sediment can not only affect stream habitats and invertebrate communities, but also fish communities including trout density and condition. Further, sediment removal can reverse these negative effects, at least temporarily. These findings should help decision makers develop mitigation plans for current farming practices and improved best management systems for the future.

Marine benthic ecological functioning over decreasing taxonomic richness

Alterations to ecosystem function due to reductions in species richness are predicted to increase as humans continue to affect the marine environment, especially in coastal areas, which serve as the interface between land and sea. The potential functional consequences due to reductions in species diversity have attracted considerable attention recently but little is known about the consequence of such loss in natural communities. We examined how the potential for function is affected by natural reductions in taxon richness using empirical (non-simulated) coastal marine benthic macrofaunal data from the Skagerrak-Baltic Sea region (N. Europe), where taxon richness decreases 25-fold, from 151 to 6 taxa. To estimate functional changes we defined multiple traits (10 traits and 51 categories) on which trait category richness, functional diversity (FD) and number of taxa per trait category were calculated. Our results show that decrease in taxon richness leads to an overall reduction in function but functional richness remains comparatively high even at the lowest level of taxon richness. Although the taxonomic reduction was sharp, up to 96% of total taxon richness, we identified both potential thresholds in functioning and subtler changes where function was maintained along the gradient. The functional changes were not only caused by reductions in taxa per trait category, some categories were maintained or even increased. Primarily, the reduction in species richness altered trait categories related to feeding, living and movement and thus potentially could have an effect on various ecosystem processes. This highlights the importance of recognising ecosystem multifunctionality, especially at low taxonomic richness. We also found that in this system rare species (singletons) did not stand for the functional complexities and changes. Our findings were consistent with theoretical and experimental predictions and suggest that a large proportion of the information about alterations of function is found in measures such as functional diversity and number of taxa per trait category.

The study of distribution characteristics of vascular and naturalized plants in Dokdo, South Korea

This study was performed to investigate the distribution of vascular plants and the characteristics of naturalized plants in Dokdo Island, South Korea. The survey was conducted a total of 5 times from June 2012 to September 2013. The number of plants confirmed in this study was 60 taxa in total: 29 families, 49 genera, 55 species, 2 subspecies and 3 varieties. To classify them by regional groups, 53 taxa were confirmed in the Dongdo and 38 taxa were confirmed in the Seodo. Among them, the distribution of Stellaria neglecta Weihe and Puccinellia nipponica Ohwi was first discovered in this study. The naturalized plants distributed in Dokdo was 7 taxa: Chenopodium album L., Sonchus asper (L.) Hill, Sonchus oleraceus L., Ipomoea purpurea Roth, Brassica juncea (L.) Czern., etc. Overall, concerns over the naturalized plants in Dokdo are high regardless of the scale of their distribution and the appearance frequency.

Distribution characteristics of plants in the Ungseokbong Mountain, Gyeongsangnam-do, Korea

This study was conducted 13 surveys from 2007 through 2012. The surveys on the entire plants distribution in the Ungseokbong Mountain found 491 taxa in total: 99 families, 290 genera, 419 species, 3 subspecies, 61 varieties, and 8 forms. 1,211 specimens were secured as evidence. In particular, 11 taxa of the rare plants which were designated by the Korea Forest Service were confirmed, and 12 taxa of the endemic plants were confirmed in this study. Those plants above Class III of the specific plants designated by the Ministry of Environment were confirmed 19 taxa. Among them, in particular, it was confirmed that Kirengeshoma koreana Nakai has a new habitat in the Unseokbong. Naturalized plants included 34 taxa accounting for 6.9% were representatively confirmed.

The distribution of vascular plants in Banronsan (Mt.) at Jeongseon Gangwon-do, Korea

To study the distribution of vascular plants in Banronsan (Mt.) located in Jeongseon-gun, Gangwon-do, Korea. The vascular flora in Banronsan (Mt.) were surveyed a total of four times-three times from May 2010 to October 2010, and once in August 2012. This result revealed 447 taxa in total: 89 families, 278 genera, 390 species, four subspecies, 47 varieties, and six form. In the flora of this area, 15 taxa were Korean endemic plants including Aconitum pseudolaeve Nakai, Lysimachia coreana Nakai, and Saussurea macrolepis (Nakai) Kitam., and 17 taxa were rare and endangered plants of Korea including Astragalus koraiensis Y.N. Lee, Pseudostellaria japonica Pax, and Paeonia japonica (Makino) Miyabe and Takeda. Three taxa were found as a special forest conservation species designated by the Korea Forest Service including Delphinium maackianum Regel and Daphne pseudomezereum var. koreana (Nakai) Hamaya. Besides, 76 taxa were found to be specific floristic plants designated by the Ministry of Environment, whereas naturalized plants in this area were 32 taxa. Resource plants were categorized by usage into eight groups: 189 edible, four fiber, 127 medical, 48 ornamental, 150 pasturing, three industrial, 10 dyeing, and eight timber plants.

Bioassessment of Benthic Macroinvertebrates of the Middle Penns Creek, Pennsylvania Watershed

ABSTRACT During October and November 2011, an assessment of the benthic macroinvertebrate assemblage was conducted in the middle Penns Creek (PA) watershed. The survey consisted of 10 tributary sites within a 40km portion of the watershed. The goals were to establish baseline conditions for headwater streams in this section of the watershed, determine their current biotic health, and suggest possible designated use upgrades. All sample sites were low-order (1–3) streams typically of higher gradient. We calculated the Pennsylvania Benthic Macroinvertebrate Index of Biotic Integrity at each site based on the following biotic indices: Beck's Index, Total Taxa Richness, EPT (Ephemeroptera + Plecoptera + Trichoptera) Taxa Richness (Pollution Tolerance Values 0–4), Shannon Diversity Index, Hilsenhoff Biotic Index, and Percent Sensitive Individuals (Pollution Tolerance Values 0–3) . All study streams are currently designated by Pennsylvania Department of Environmental Protection (PA DEP) as Cold Water Fish (1), High Quality (6), or Exceptional Value (3) streams. We found six streams to be of highest biotic quality (IBI score >80). Benthic macroinvertebrate IBI scores for Little Poe Creek (93.2) exceeded the current designated use of High Quality by PA DEP, and should be considered for a re-designated increase to Exceptional Value. In total, 10 pollution sensitive genera (Epeorus, Leuctra, Sweltsa, Tallaperla, Acroneuria, Pteronarcys, Agapetus, Dolophilodes, Wormaldia, and Diplectrona) were present across all study streams. Panther Run (51.9) received the lowest benthic macroinvertebrate IBI score, possibly due to low total organisms which may suggest it could be experiencing ecological stressors. Our overall results indicate these Penns Creek streams to currently be of good biotic health, however long-term monitoring may be necessary to further assess anthropogenic impacts within the watershed.

The use of the axiophyte species concept to describe the ecological network of the Birmingham and Black Country of the UK West Midlands

Abstract The UK conurbation of Birmingham and the Black Country has recently been surveyed for a new Flora, on the basis of a 1 km square grid. The present paper uses the data to describe the ecological network of the conurbation. The total number of taxa per 1 km squares is shown to be moderately but significantly correlated, and the number of native taxa more strongly correlated, with the area of the previously-established network of protected sites. Nevertheless coincidence maps of total numbers or numbers of native species per 1 km square give only poor representations of the ecological network compared with maps of protected sites. Axiophytes are defined as plant species 90% restricted to conservation habitats and recorded in fewer than 25% of 2km × 2km squares in a county. Applying the concept to 1 km squares in Birmingham and the Black Country creates a list of 256 axiophytes. Numbers of axiophytes are shown to be more strongly correlated with areas of protected sites than total taxa or native taxa and a coincidence map of the axiophytes is found to provide a useful quantitative assessment of the ecological network. Maps of axiophytes are used to divide the network into core and linking areas and their use in consolidating and improving the botanical ecological network is explored.

Influence of hydropower dams on the state of macroinvertebrates assemblages in the Virvyte river, Lithuania

AbstractMacroinvertebrate organization along the Virvytė River was examined to relate biological response in environmental changes. Benthic macroinvertebrates and a range of environmental variables were sampled from three study sections: control, HPP dams and below HPP dams. Total macroinvertebrate taxon number (NT = 28), EPT taxon number (NT = 13) and Shannon-Wiener diversity index (H′ = 3.85) were the highest in control sites of the river and the smallest in HPP dams (17, 5, 2.75, respectively). Taxon number and total abundance of macroinvertebrates declined significantly both in HPP dams and below them in comparison with the control sites. Total macroinvertebrate abundance in the control sites (698±41 ind.m−2) was significantly higher than in HPP dams and below them (430±21 ind.m−2 and 425±22 ind.m−2, respectively). The obtained data show that the investigated sections differed in terms of composition and relative abundance of different taxa of macroinvertebrates. Compared to reference conditions (cont...

Effects of anthropogenic impacts on benthic macroinvertebrates assemblages in subtropical mountain streams

The nature of the riparian and surrounding landscape has been modified by anthropogenic activities, which may subsequently alter the composition and functional structure of macroinvertebrate assemblages. The effect of these changes on function of benthic fauna is difficult to assess due to the scarce knowledge on functional structures in tropical streams. In this study we evaluate whether sites impacted and unimpacted by anthropogenic alterations differed in assemblage composition and density, richness and diversity of each functional feeding group. The selection of the sites was related to their distinct riparian characteristics, following the QBRy riparian quality index. Collector-gatherer was the dominant functional feeding group, comprising 91% of total density, whereas the proportion of shredders was very low, representing less of 0.5% of total density. Asemblage composition of macroinvertebrates differed between impacted and unimpacted sites. Predators were dominant in taxa number, representing about 60% of total taxa richness. In addition, the diversity and richness of collector-gatherers differed significantly between degraded and unimpacted sites, reflecting the sensitivity of this group to environmental changes and the utility to be used in the assessment of anthropogenic modifications. The results of this study reinforce the idea that riparian corridor management is critical for the distribution of macroinvertebrate assemblages as well as functional organization of lotic streams.

Prescribed‐Fire Effects on an Aquatic Community of a Southwest Montane Grassland System

AbstractThe use of prescription fire has long been recognized as a reliable management tool to suppress vegetative succession processes and to reduce fuel loading to prevent catastrophic wildfires, but very little attention has been paid to the effects on aquatic systems. A late‐fall prescribed burn was implemented to characterize effects on an aquatic community within a montane grassland system in north‐central New Mexico. The fire treatment was consistent with protocols of a managed burn except that the fire was allowed to burn through the riparian area to the treatment stream to replicate natural fire behavior. In addition to summer and fall preburn assessment of the treatment and reference stream, we characterized immediate postfire effects (within a week for macroinvertebrates and within 6 months for fish) and seasonal effects over a 2‐year period. Responses within the treatment stream were compared with an unburned reference stream adjacent to the prescription burn. During the burn, the diel range in air temperature increased by 5°C while diel range in water temperature did not change. Carbon–nitrogen ratios did not differ between treatment and reference streams, indicating the contribution of ash from the surrounding grassland was negligible. Although total taxa and species richness of aquatic macroinvertebrates were not altered, qualitative indices revealed departure from preburn condition due to loss of sensitive taxa (mayflies [order Ephemeroptera] and stoneflies [order Plecoptera]) and an increase in tolerant taxa (midges [order Chironomidae]) following the burn. Within 1 year of the burn, these attributes returned to preburn conditions. The density and recruitment of adult Brown Trout Salmo trutta did not differ between pre‐ and postburn collections, nor did fish condition differ. Fire is rarely truly replicated within a given study. Although our study represents one replication, the results will inform managers about the importance in timing (seasonality) of prescription burn and anticipated effects on aquatic communities.Received January 9, 2013; accepted June 27, 2013

Towards a protocol for stream macroinvertebrate sampling in China

Standard protocols are critical for maximizing data comparability and aggregation in national monitoring programs, and taxa richness is a common indicator of site condition and biological diversity. There are two general approaches for sampling stream macroinvertebrate assemblages: targeted richest habitat and site wide. At seven sites, we compared three methods: Ontario Benthic Biomonitoring Network (OBBN), Environmental Monitoring and Assessment Program (EMAP), and Rapid Bioassessment Protocol (RBP). The OBBN method produced a biased sample at a site with a single small riffle, the RBP method produced the most total taxa, and the EMAP method produced the most taxa at four sites and the most individuals at six sites. The RBP method produced asymptotes for percent tolerant individuals, percent chironomid individuals, and Hilsenhoff Biotic Index score after five to ten stations. The EMAP method produced asymptotes for those metrics after 10 to 20 stations per site. The EMAP method typically required half the number of stations as the RBP method to obtain 70-90% of true taxa richness as estimated by the Jaccard coefficient. We conclude that the EMAP method is preferable because of its greater precision in taxa richness estimates.

Sandy beach macrofaunal assemblages as indicators of anthropogenic impacts on coastal dunes

Ocean sandy beaches are iconic recreational assets to society and have undergone rapid degradation caused by both natural and anthropogenic pressures. A major effect of urbanisation on biota stems from artificial structures placed in aquatic systems. While the installation of these structures has been widespread, our understanding of how they impact shoreline habitats and fauna is relatively limited. On the sandy Leirosa Beach, on the European Atlantic coast (Portugal), a decade of cumulative impacts was recorded, with disruption of the frontal dune, dune nourishment and the incorporation of geotextiles to reconstruct the dune and maintain it as an artificial structure. Two years after the dune rehabilitation process at Leirosa Beach, seasonal sampling campaigns (from spring 2010 to winter 2011) were carried out to assess the effects of the artificial dune (and the first signs of its eventual disruption) on macrofauna compared to a natural dune on the same beach. During the study period, the rehabilitated foredune maintained the average slope, with similar sediment characteristics (finer sediments) when compared with the natural dune system, with no physical significant differences being appreciated between the two sites. The macrofaunal assemblages were represented especially by crustaceans (amphipods and isopods), with similar mean total density, taxon richness and diversity between sites. Special attention was given to the supralittoral species, and the results revealed that the natural zone harboured a significantly higher density of sandhopper Talitrus saltator with respect to the artificial zone. PERMANOVA results detailed the significant difference that occurred, particularly during the warmer seasons (spring and summer 2010), the recruitment period described for this species along this coast. In fact, SIMPER analysis revealed that T. saltator accounted for 46% of the dissimilarities between the natural and artificial dune sites. The presence of geotextiles extending across the supralittoral zone appeared, on the one hand, to allow for the presence of talitrids, but the application of textiles around the area prevented them from burrowing, thus causing them to avoid the rehabilitated area. The results highlighted the potentially negative effects of this artificial dune system if textile disruption continues, and the usefulness of T. saltator as an effective and reliable ecological indicator for these ecosystems. Thus, evaluating the risks and magnitude of human interventions is a major challenge for sandy beach ecologists, and baseline information is required if we are to better understand how resident macrofaunal species deal with future impact scenarios.