Climate change,glacier retreat and a new ice‐free island offer new insights on Antarctic benthic responses

The Antarctic Peninsula is among the places on Earth that registered major warming in the last 60 yr. Massive ice losses, represented by glacier retreat, ice‐shelf collapses and sea‐ice reduction are among the main impacts of this regional warming. The loss of sea‐bed ice coverage, on the one hand has been affecting benthic assemblages, but on the other it is opening up new areas for benthic colonisation. Potter Cove (South Shetland Islands) offered the opportunity of assessing both processes. We recently reported a sudden shift of benthic assemblages related to increased sedimentation rates caused by glacier retreat. This glacier retreat also uncovered a new island that presents a natural experiment to study Antarctic benthic colonisation and succession. We sampled the new island by photo‐transects taken up to 30 m depth. Here, we report an unexpected benthic assemblage characterised by high species richness, diversity and structural complexity with a well‐developed three‐dimensional structure and epibiotic relationships. Filter feeders comprised the largest trophic group at all depths, mainly ascidians, sponges and bryozoans. Densities were also surprising, recording only six ascidian species with a mean of ～310 ind. m^–2. These values are at least an order of magnitude higher than previous Antarctic reports on early colonisation. This finding challenges the extended idea of a slow and continuous recruitment in Antarctica. However, it also opens the question of whether these complex assemblages could have been present under the glacier in ice‐free refuges that are now exposed to open sea conditions. Under the current scenario of climate change, these results acquire high relevance as they suggest a two‐fold effect of the Antarctic Peninsula warming: the environmental shifts that threaten coastal ecosystems, and also the opening up of new areas for colonisation that may occur at a previously unimagined speed.     

Use of tolerance values to diagnose water-quality stressors to aquatic biota in New England streams

Identification of stressors related to biological impairment is critical to biological assessments. We applied nationally derived tolerance indicator values for four water-quality variables to fish and benthic macroinvertebrate assemblages at 29 sites along an urban gradient in New England. Tolerance indicator values (TIVs), as biologically based predictors of water-quality variables, were determined for dissolved oxygen, nitrite plus nitrate (nitrate), total phosphorus, and water temperature for each site based on observed biological assemblages (TIV_O), and for expected assemblages (TIV_E). The quotient method, based on a ratio of the TIVs for observed and expected assemblages (tolerance units), was used to diagnose potential water-quality stressors. In addition, the ratio of measured water-quality values to water-quality criteria (water-quality units) was calculated for each water-quality variable to assess measured water-quality stressors. Results from a RIVPACS predictive model for benthic macroinvertebrates and Bray-Curtis dissimilarity for fish were used to classify sites into categories of good or impaired ecological condition. Significant differences were detected between good and impaired sites for all biological tolerance units (fish and benthic macroinvertebrate assemblages averaged) except for nitrate (P = 0.480), and for all water-quality units except for nitrate (P = 0.183). Diagnosis of water-quality stressors at selected sites was, in general, consistent with State-reported causes of impairment. Tolerance units for benthic macroinvertebrate and fish assemblages were significantly correlated for water temperature (P = 0.001, r = 0.63), dissolved oxygen (P = 0.001, r = 0.61), and total phosphorus (P = 0.001, r = 0.61), but not for nitrate (P = 0.059, r = −0.35). Differences between the two assemblages in site-specific diagnosis of water-quality stressors may be the result of differences in nitrate tolerance.     

Taxonomic and functional diversity of stream invertebrates along an environmental stress gradient

Anthropogenic stress has been identified as main driver of freshwater biodiversity loss. Adverse effects on the biodiversity of freshwater organisms, such as macroinvertebrates, may propagate to associated ecosystem functions, such as organic matter breakdown (OMB). In this context, the functional diversity (FD) of communities has been suggested to be a more suitable predictor of changes in ecosystem functions than taxonomic diversity (TD). We investigated the response of TD and FD of invertebrate communities to an environmental stress gradient and the relation of both metrics to the rate of organic matter breakdown. For this, we sampled macroinvertebrates and determined OMB using leaf bags along an environmental stress gradient (i.e. changes in physicochemical and hydromorphological conditions) in 29 low-order streams. Taxonomic richness decreased with increasing environmental stress (r = −0.55) but was not related to OMB. Conversely, the Simpson diversity of communities was not associated with the gradient but correlated moderately (r = 0.41) with OMB. Of three functional diversity indices (functional richness, evenness and divergence), only functional richness correlated moderately with the stress gradient (r = −0.41) and any of the indices correlated with OMB. Nevertheless, functional metrics such as specific trait modalities and the total abundance of the dominant shredders correlated higher (r = 0.46 and 0.48) with OMB than the TD indices. Given a relatively small species pool in our study and methodical constraints such as the limited resolution of autecological information, the FD might perform better in other contexts and if focusing on response and effect traits for the stressor and ecosystem function under scrutiny, respectively.     

Late Eocene sea retreat from the Tarim Basin (west China) and concomitant Asian paleoenvironmental change

The Paleogene sediments of the southwest Tarim Basin along the West Kunlun Shan in western China include the remnants of the easternmost extent of a large epicontinental sea. This shallow sea once extended across the Eurasian continent before it retreated westward and eventually separated as the Paratethys Sea. Climate modeling results suggest that this sea retreat is an equally important forcing mechanism as the Tibetan plateau uplift in the aridification of the Asian continental interior and the intensification of the Asian monsoon system. The age and paleogeography of the retreat are poorly constrained, hindering the understanding of its cause and paleoenvironmental impacts. This study reports litho- and biostratigraphic results from two sections recording the last major regression out of the Tarim Basin that is expressed by a regional transition from marine clastics and limestones to continental red-beds. Rich micro- and macrofossil assemblages, including benthic foraminifera, ostracods, bivalves, calcareous nannofossils and organic walled dinoflagellate cysts (dinocysts), indicate a shallow, proximal and marine environment. Strong similarity to assemblages known from Central Asia and Europe confirms that surface–ocean connections extended across Eurasia from the Tarim Basin to the western Tethys during the latest Eocene. Moreover, the recovered fossil associations date the last marine sediments as earliest Priabonian in age (~ 37 Ma; overlap between dinoflagellate Mps Interval Zone and calcareous nannofossil Zone CP 14). The retreat of the sea from the Tarim Basin is time-equivalent with the sea level lowstand at the Bartonian–Priabonian boundary but pre-dates both the Oligocene–Miocene regional uplift of the Pamir mountains and Kunlun Shan and the major eustatic sea-level falls of the Eocene–Oligocene Transition (~ 34 Ma) and mid-Oligocene (~ 30 Ma), which are usually held responsible for the sea retreat. Furthermore, a concomitant and significant aridification step occurs at ~ 36.6 Ma (top of chron C17n.1n) as recorded by regional sedimentary records of the Xining Basin along the northeastern Tibetan Plateau, suggesting that the Tarim Sea served as a significant moisture contributor for the Asian interior.     

Mapping biodiversity in three-dimensions challenges marine conservation strategies: The example of coralligenous assemblages in North-Western Mediterranean Sea

Multi-facet diversity indices have been increasingly widely used in conservation ecology but congruence analyses both on horizontal and vertical axes have not yet been explored. We investigated the vertical and horizontal distributions of α and β taxonomic (TD), functional (FD) and phylogenetic diversity (PD) in a three-dimensional structured ecosystem. We focused on the Mediterranean coralligenous assemblages which form complex structures both vertically and horizontally, and are considered as the most diverse and threatened communities of the Mediterranean Sea. Although comparable to tropical reef assemblages in terms of richness, biomass and production, coralligenous assemblages are less known and more rarely studied, in particular because of their location in deep waters. Our study covers the entire range of distribution of coralligenous habitats along the French Mediterranean coasts, representing the most complete database so far developed for this important ecosystem. To our knowledge, this is the first analysis of spatial diversity patterns of marine biodiversity on both horizontal and vertical scales.Our study revealed that taxonomic diversity differed from functional and phylogenetic diversity patterns at the station level, the latter two being strongly structured by depth, with shallower stations generally richer than deeper ones. Considering all stations, phylogenetic diversity was less congruent to taxonomic diversity (Pearson's correlation of r = 0.48) but more congruent to functional diversity (r = 0.69) than randomly expected. Similar congruence patterns were revealed for stations deeper than 50 m (r = 0.44 and r = 0.84, respectively) but no significantly different congruence level than randomly expected was revealed among diversity facets for more shallow stations. Mean functional α- and β-diversity were lower than phylogenetic diversity and even lower than taxonomic α- and β-diversity for both vertical and horizontal scales. Low FD and PD values at both α- and β-diversity indicated functional and phylogenetic clustering. Community dissimilarities (β-diversity) increased over depth especially in central and eastern part of the French Mediterranean littoral and in northern Corsica, indicating coralligenous vertical structure within these regions. Overall horizontal β-diversity was higher within the 50–70 m depth belts.We conclude that taxonomic diversity alone is inadequate as a basis for setting conservation goals for this ecosystem and additional information, at least on phylogenetic diversity, is needed to preserve the ecosystem functioning and coralligenous evolutionary history. Our results highlight the necessity of considering different depth belts as a basis for regional scale conservation efforts. Current conservation approaches, such as the existing marine protected areas, are insufficient in preserving coralligenous habitats. The use of multi-facet indices should be considered, focusing on preserving local diversity patterns and compositional dissimilarities, both vertically and horizontally.     

Environmental determinants of chironomid communities in remote northern lakes across the treeline – Implications for climate change assessments

Chironomids (Diptera: Chironomidae) in northern lakes are especially sensitive to climate change impacts. In addition, environmental factors other than direct temperature increase might play an important role in functioning of these keystone aquatic communities. We examined 31 lakes at the treeline ecotone in subarctic Finnish Lapland for their surface sediment chironomid fauna to assess the influence of different environmental factors on the communities. We aim to improve understanding of the climate-driven catchment and limnological factors, for the assessment of climate change impacts. Our results indicated that organic content of the sediment, total nitrogen, water depth and pH that are all likely to change under global warming had statistically significant influence on the chironomid assemblages and associated indicator taxa were assigned for these variables. In addition, a dissolved organic carbon (DOC) threshold (4 mg l⁻¹) was observed that divided the study sites based on their chironomid composition. Sites with high DOC concentrations and benthic microbial mats had distinctive chironomid fauna from low-DOC sites without microbial mats indicating the significance of benthic versus planktonic productivity in the structure and functioning of polar lakes. The results provide important knowledge on chironomid-environmental relationships in climate-sensitive subarctic lakes and create basis for chironomid-based environmental change assessments in remote northern areas.     

Lake macroinvertebrate assemblages and relationship with natural environment and tourism stress in Jiuzhaigou Natural Reserve,China

With increasing human population and urbanization, tourism in natural reserves and other protected lands is growing. It is critical to monitor and assess the impacts of tourism on ecosystem health. However, there is a general lack of information on biological communities in natural reserves of developing countries and of tools for assessing human impacts. In the present study, we investigated macroinvertebrate assemblages in nine lakes in Jiuzhaigou Natural Reserve of China. Both benthic (20 dips of D-net) and light-trap samples (2 h) were collected at each lake and all benthic specimens and adults of Ephemeroptera, Plecoptera, and Trichoptera (EPT) were identified and counted. Water temperature and water quality variables were measured on site or in the Lab. Seventy taxa were recorded and dominated by dipterans and caddisflies. Light traps contributed 47% of taxa richness and 66% of EPT richness at the lakes. Detrended Correspondence Analysis showed that water temperature and tourism index were strongly associated with the changes of assemblage composition. Taxa richness and EPT richness calculated for the composite samples (benthic + light trap) were well fit with Poisson generalized linear model (adjusted R² = 0.83 and 0.85, respectively), generally decreasing with increasing elevation, tourism index, and total-N. Tourism index was ranked as the top predictor for EPT richness based on multiple model weights, and elevation for taxa richness. In comparison, when based on benthic samples, neither of the metrics could be fitted with the seven environmental variables selected. These findings highlight the benefit of combined use of the sampling methods for lake monitoring and offered an analytical guide to developing biological indicators of lake ecosystem health in protected areas.     

Foraminiferal assemblage indices: A comparison of sediment and reef rubble samples from Conch Reef,Florida, USA

Benthic foraminiferal assemblages are increasingly utilized as indicators of water and sediment quality in coastal-marine environments. Most reef-dwelling foraminifers live on firm substrata such as reef or phytal surfaces, while most assessments have examined assemblages from sediments. This case study compared relative abundances of total foraminiferal-shell assemblages between sediment and phytal/rubble samples collected from one reef within one week. A total of 117 species within 72 genera were identified, with the same taxa in both sample sets in different proportions. Larger benthic foraminifers and some agglutinated taxa were concentrated about 1.5–3 fold in sediment samples, while nearly two-thirds of small, fragile shells were lost. Several common indices were compared, including Taxonomic Richness (number of genera), Shannon (H), Simpson's (D) and Fisher (α) diversity indices, Evenness (E), and the FORAM Index (FI). Highly significant differences (p < 0.001) between shell assemblages from 13 sets of phytal/rubble substrata and sediments were found in mean number (± standard deviation) of genera (49 ± 4 vs. 34 ± 10) and mean FI (5.6 ± 0.8 vs. 3.6 ± 0.4); both reflecting greater relative abundances of smaller foraminifers in the rubble samples. Fisher diversity was marginally significant (p = 0.05); other indices showed no significant differences between sample types. Although assessment of total assemblages is substantially less costly than distinguishing between specimens that were live or dead when collected, many researchers report those distinctions. The results of our study provide insight that can assist interpretations of studies that use live assemblages to calculate the FI, rather than total assemblages for which it was originally developed.     

Microbial–meiofaunal interrelationships in coastal sediments of the Red Sea

Population density and biomass of bacteria and meiofauna were investigated seasonally in the sediments of the north-western bank of Red Sea. Samples of sediments were collected seasonally from three different stations to determine microphytobenthic biomass (chlorophyll a), protein, lipid, carbohydrate, and total organic matter concentrations. These investigations revealed that microbial components tended to increase their dominancy, whereas sensitive meiofauna were extremely reduced during the entire study period. Thus a very low density of the total meiofauna (with an annual average of 109 ± 26 ind./10 cm²) was recorded whilst the benthic microbial population densities exhibited higher values (ranging from 0.31 ± 0.02 × 10⁸ to 43.67 ± 18.62 × 10⁸/g dry sediment). These changes in the relative importance analysis of benthic microbial components versus meiofaunal ones seem to be based on the impact of organic matter accumulation on the function and structure of these benthic communities. Proteins, lipids and carbohydrates showed very low concentration values, and the organic matter mostly consisted of carbohydrates, reflecting lower nutritional values for benthic fauna in general and meiofauna in particular. The distribution of microbial and meiofaunal communities seems to be dependent on the quality of the organic matter rather than on its quantity. Total organic matter concentrations varied between 5.8 and 7.6 mg/g, with organic carbon accounting for only 32% of the total organic matter. Chlorophyll a attained very low values, fluctuating between 0.11 and 0.56 μg/g, indicating the oligotrophy of the studied area. The very low concentration of chlorophyll a in the Red Sea sediment suggests that the sedimentary organic matter, heterotrophic bacteria and/or protozoa constitute an alternative resource that is consumed by meiofauna when algae are less abundant. Protozoa, therefore, represent the “missing link in bacteria–meiofauna interaction in the Red Sea marine sediment ecosystem.     

Recurrent vernal presence of the toxic Alexandrium tamarense/Alexandrium fundyense (Dinoflagellata) species complex in Narragansett Bay,USA

The vernal occurrence of toxic dinoflagellates in the Alexandrium tamarense/Alexandrium fundyense species complex in an enclosed embayment of Narragansett Bay (Wickford Cove, Rhode Island) was documented during 2005 and 2009–2012. This is the first report of regular appearance of the Alexandrium fundyense/Alexandrium tamarense species complex in Narragansett Bay. Thecal plate analysis of clonal isolates using SEM revealed cells morphologically consistent with both Alexandrium tamarense Lebour (Balech) and Alexandrium fundyense Balech. Additionally, molecular analyses confirmed that the partial sequences for 18S through the D1–D2 region of 28S were consistent with the identity of the two Alexandrium species. Toxin analyses revealed the presence of a suite of toxins (C1/2, B1 (GTX-5), STX, GTX-2/3. Neo, and GTX-1/4) in both Alexandrium tamarense (6.31 fmol cell⁻¹ STX equiv.) and Alexandrium fundyense (9.56 fmol cell⁻¹ STX equiv.) isolated from Wickford Cove; the toxicity of a Narragansett Bay Alexandrium peruvianum isolate (1.79 fmol cell⁻¹ STX equiv.) was also determined. Combined Alexandrium tamarense/Alexandrium fundyense abundance in Wickford Cove reached a peak abundance of 1280 cells L⁻¹ (May of 2010), with the combined abundance routinely exceeding levels leading to shellfishing closures in other systems. The toxic Alexandrium tamarense/Alexandrium fundyense species complex appears to be a regular component of the lower Narragansett Bay phytoplankton community, either newly emergent or previously overlooked by extant monitoring programs.     

Influences of short-term pre-slaughter dietary manipulation in sheep and goats on pH and microbial loads of gastrointestinal tract

Sheep (BW = 39.9 kg, n = 16) and goats (BW = 32.8 kg, n = 16) were used in a completely randomized design to determine the effect of short-term pre-slaughter diet and feed deprivation (FD) time on pH and microbial loads in the gastrointestinal tract (GIT) contents. In a 2 × 2 × 2 factorial treatment arrangement, the main effects of species, diet, and FD time prior to slaughter and their interactions were studied. Animals were fed either a hay or concentrate diet for 4 d and then feed deprived for either 12 or 24-h prior to slaughter. The pH of rumen and colon contents as well as weight of GIT was measured. The contents of rumen and rectum were also sampled for microbial analysis. The GIT of sheep (1.82 kg) was heavier (P < 0.05) than that of goats (1.46 kg). The 12-h FD group (1.74 kg) had a higher (P < 0.05) GIT weight than the 24-h FD group (1.53 kg). Hay-fed animals had higher (P < 0.05) rumen (7.08 vs. 6.43) and colon pH values (7.02 vs. 6.56) than those of the concentrate-fed animals. The 24-h FD group (3.39 ± 0.272 log₁₀CFU/g) contained more (P < 0.05) Escherichia coli in the rumen than did the 12-h FD (2.17 ± 0.272 log₁₀CFU/g) group. The concentrate-fed animals (3.49 ± 0.289 log₁₀CFU/g) had higher (P < 0.05) coliform counts in the rumen than the hay-fed animals (2.43 ± 0.289 log₁₀CFU/g). The 24-h FD group (3.42 ± 0.289 log₁₀CFU/g) had a higher (P < 0.05) concentration of coliform than did the 12-h FD group (2.50 ± 0.289 log₁₀CFU/g). The 24-h FD group (3.31 ± 0.259 log₁₀CFU/g) also had higher (P < 0.05) Enterobacteriaceae counts in the rumen than did in the 12-h FD group (2.47 ± 0.259 log₁₀CFU/g). Goats (5.71 ± 0.158 log₁₀CFU/g) had lower (P < 0.05) total plate counts in the rumen compared to sheep (6.27 ± 0.158 log₁₀CFU/g). The concentrate-fed animals had higher (P < 0.05) E. coli (6.44 vs. 4.01 ± 0.468 log₁₀CFU/g), total coliform (6.74 vs. 4.16 ± 0.469 log₁₀CFU/g), Enterobacteriaceae (6.93 vs. 3.83 ± 0.651 log₁₀CFU/g), and total plate counts (7.79 vs. 7.28 ± 0.170 log₁₀CFU/g) in the rectum than the hay-fed animals. The results indicate that microbial loads in the GIT of small ruminants may be reduced by either feeding hay for 4 d or depriving feed for 12-h prior to slaughter.     

History dependence of the electromyogram: Implications for isometric steady-state EMG parameters following a lengthening or shortening contraction

Residual force enhancement (RFE) and force depression (FD) refer to an increased or decreased force following an active lengthening or shortening contraction, respectively, relative to the isometric force produced at the same activation level and muscle length. Our intent was to determine if EMG characteristics differed in the RFE or FD states compared with a purely isometric reference contraction for maximal and submaximal voluntary activation of the adductor pollicis muscle. Quantifying these alterations to EMG in history-dependent states allows for more accurate modeling approaches for movement control in the future. For maximal voluntary contractions (MVC), RFE was 6–15% (P < 0.001) and FD was 12–19% (P < 0.001). The median frequency of the EMG was not different between RFE, FD and isometric reference contractions for the 100% and 40% MVC intensities (P > 0.05). However, root mean square EMG (EMG_RMS) amplitude for the submaximal contractions was higher in the FD and lower in the RFE state, respectively (P < 0.05). For maximal contractions, EMG_RMS was lower for the FD state but was the same for the RFE state compared to the isometric reference contractions (P > 0.05). Neuromuscular efficiency (NME; force/EMG) was lower in the force depressed state and higher in the force enhanced state (P < 0.05) compared to the isometric reference contractions. EMG spectral properties were not altered between the force-enhanced and depressed states relative to the isometric reference contractions, while EMG amplitude measures were.     

Folate deprivation induces cell cycle arrest at G0/G1 phase and apoptosis in hippocampal neuron cells through down-regulation of IGF-1 signaling pathway

Folate deficiency contributes to impaired adult hippocampal neurogenesis, yet the mechanisms remain unclear. Here we use HT-22 hippocampal neuron cells as model to investigate the effect of folate deprivation (FD) on cell proliferation and apoptosis, and to elucidate the underlying mechanism. FD caused cell cycle arrest at G0/G1 phase and increased the rate of apoptosis, which was associated with disrupted expression of folate transport and methyl transfer genes. FOLR1 and SLC46A1 were (P < 0.01) down-regulated, while SLC19A1 was up-regulated (P < 0.01) in FD group. FD cells exhibited significantly (P < 0.05) higher protein content of BHMT, MAT2b and DNMT3a, as well as increased SAM/SAH concentrations and global DNA hypermethylation. The expression of the total and all the 3 classes of IGF-1 mRNA variants was significantly (P < 0.01) down-regulated and IGF-1 concentration was decreased (P < 0.05) in the culture media. IGF-1 signaling pathway was also compromised with diminished activation (P < 0.05) of STAT3, AKT and mTOR. CpG hypermethylation was detected in the promoter regions of IGF-1 and FOLR1 genes, while higher SLC19A1 mRNA corresponded to hypomethylation of its promoter. IGF-1 supplementation in FD media significantly abolished FD-induced decrease in cell viability. However, IGF-1 had limited effect in rescuing the cell phenotype when added 24 h after FD. Taken together, down-regulation of IGF-1 expression and signaling is involved in FD-induced cell cycle arrest and apoptosis in HT-22 hippocampal neuron cells, which is associated with an abnormal activation of methyl transfer pathway and hypermethylation of IGF-1 gene promoter.     

Comparison of Zostera marina and maerl community metabolism

The photosynthetic and repiratory metabolism of Zostera marina and maerl communities was compared, in the same area of the Bay of Brest in March–April, using benthic chambers. P–E curves for both oxygen and carbon were established for bottom irradiances between 0 and 525 μmol m⁻² s⁻¹. An exponential function was fitted to calculate daily production. Community metabolic quotients did not differ for maerl and seagrass beds. Community photosynthetic quotients were significantly higher (1.19) whereas community respiratory quotients were lower (0.70) than 1. Maerl and seagrass bed P–E curves mainly differed by the minimum saturating irradiance (E_k). Net community production was estimated to 26.8 mmol C m⁻² d⁻¹ for Z. marina meadows and 8.6 mmol C m⁻² d⁻¹ for maerl beds. The two communities can, therefore, be considered as autotrophic during the March–April period. Community respiration did not differ between Z. marina meadows and maerl beds, with an average value of 53.8 mmol C m⁻² d⁻¹ during a day. In similar environmental conditions, the production of maerl beds corresponds to approximately one third that of seagrass meadows. The maerl communities, therefore, form productive ecosystems, relevant to temperate coastal ecosystems functioning.     

Benthic Trophic Interactions in an Antarctic Shallow Water Ecosystem Affected by Recent Glacier Retreat

The western Antarctic Peninsula is experiencing strong environmental changes as a consequence of ongoing regional warming. Glaciers in the area are retreating rapidly and increased sediment-laden meltwater runoff threatens the benthic biodiversity at shallow depths. We identified three sites with a distinct glacier-retreat related history and different levels of glacial influence in the inner part of Potter Cove (King George Island, South Shetland Islands), a fjord-like embayment impacted since the 1950s by a tidewater glacier retreat. We compared the soft sediment meio- and macrofauna isotopic niche widths (δ¹³C and δ¹⁵N stable isotope analysis) at the three sites to investigate possible glacier retreat-related influences on benthic trophic interactions. The isotopic niches were locally shaped by the different degrees of glacier retreat-related disturbance within the Cove. Wider isotopic niche widths were found at the site that has become ice-free most recently, and narrower niches at the older ice-free sites. At an intermediate state of glacier retreat-related disturbance (e.g. via ice-growler scouring) species with different strategies could settle. The site at the earliest stage of post-retreat development was characterized by an assemblage with lower trophic redundancy. Generally, the isotopic niche widths increased with increasing size spectra of organisms within the community, excepting the youngest assemblage, where the pioneer colonizer meiofauna size class displayed the highest isotopic niche width. Meiofauna at all sites generally occupied positions in the isotopic space that suggested a detrital-pool food source and/or the presence of predatory taxa. In general ice scour and glacial impact appeared to play a two-fold role within the Cove: i) either stimulating trophic diversity by allowing continuous re-colonization of meiofaunal species or, ii) over time driving the benthic assemblages into a more compact trophic structure with increased connectedness and resource recycling.     

Evaluation of stream ecosystem health and species association based on multi-taxa (benthic macroinvertebrates,algae, and microorganisms) patterning with different levels of pollution

Benthic communities of macroinvertebrates, algae, and microorganisms were concurrently collected using a Surber sampler (30 × 30 m²; 300 μm mesh), brush (5 × 5 cm²), and syringe (100 mL; Denaturing Gradient Gel Electrophoresis), respectively, to determine the ecological integrity of streams with different levels of pollution. Macroinvertebrates provided a clearer representation of the gradient of pollution, while a broader scope of species distribution was observed for algae and microorganisms, including sites severely polluted with heavy metals. Species associations among different taxa were presented on the Self-Organizing Map (SOM) and Nonmetric Multidimensional Scaling (NMDS) based on environmental factors. After screening, indicator species visualized on the SOM represented a wider range of environmental impacts and were more illustrative with benthic macroinvertebrates in least polluted sites. In contrast NMDS presented species more closely associated with overall variance of communities with severe pollution, mainly in microorganisms and algae. Multi-taxa community analysis using SOM and NMDS in combination would provide a comprehensive assessment for addressing ecological integrity in streams.     

Changes in masticatory muscle activity in children with cerebral palsy

The objective of the study was to determine whether children with cerebral palsy (CP) have abnormal bilateral masseter and temporal muscle activation during mastication. The muscular activity of 32 children aged between 7 and 13 years was assessed during the task of non-habitual mastication by means of surface electromyograms. During non-habitual mastication, the amplitude of all assessed muscles in the inactive period and the amplitude of the Right Masseter and Left Temporal muscles in the active period of children with CP was greater (p < 0.05) in relation to the group of children with Typical Development (TD). Considering each muscle individually, only the duration of the active period of Right Masseter and Right Temporal muscles in children with CP was lower (p < 0.05) than in the TD children. Considering the four analyzed muscles, the duration of time of general active period, when at least one muscle should be activated, was higher in children with CP (p < 0.05) than in children with TD showing greater time variation in inactivation (p < 0.05). The higher muscle activity during the phases of the masticatory cycle, with longer duration of the active period and with greater variability between the muscles to inhibit this activity show greater difficulty in coordinating the muscles of mastication in children with CP compared to children with TD.     

Development of Halomonas TD01 as a host for open production of chemicals

Genetic engineering of Halomonas spp. was seldom reported due to the difficulty of genetic manipulation and lack of molecular biology tools. Halomonas TD01 can grow in a continuous and unsterile process without other microbial contaminations. It can be therefore exploited for economic production of chemicals. Here, Halomonas TD01 was metabolically engineered using the gene knockout procedure based on markerless gene replacement stimulated by double-strand breaks in the chromosome. When gene encoding 2-methylcitrate synthase in Halomonas TD01 was deleted, the conversion efficiency of propionic acid to 3-hydroxyvalerate (3HV) monomer fraction in random PHBV copolymers of 3-hydroxybutyrate (3HB) and 3HV was increased from around 10% to almost 100%, as a result, cells were grown to accumulate 70% PHBV in dry weight (CDW) consisting of 12 mol% 3HV from 0.5 g/L propionic acid in glucose mineral medium. Furthermore, successful deletions on three PHA depolymerases eliminate the possible influence of PHA depolymerases on PHA degradation in the complicated industrial fermentation process even though significant enhanced PHA content was not observed. In two 500 L pilot-scale fermentor studies lasting 70 h, the above engineered Halomonas TD01 grew to 112 g/L CDW containing 70 wt% P3HB, and to 80 g/L CDW with 70 wt% P(3HB-co-8 mol% 3HV) in the presence of propionic acid. The cells grown in shake flasks even accumulated close to 92% PHB in CDW with a significant increase of glucose to PHB conversion efficiency from around 30% to 42% after 48 h cultivation when pyridine nucleotide transhydrogenase was overexpressed. Halomonas TD01 was also engineered for producing a PHA regulatory protein PhaR which is a robust biosurfactant.     

Review of salinity effects on abundance,growth, and survival of nearshore life stages of pink shrimp (Farfantepenaeus duorarum)

The pink shrimp (Farfantepenaeus duorarum) has been selected as an ecological indicator to assess ecological effects on estuaries of implementation of the Comprehensive Everglades Restoration Plan that seeks to restore historical freshwater flows and nearshore salinity regimes in southern Florida. Concern over altered freshwater delivery impacts on pink shrimp productivity was expressed as early as the 1960s. The present review assessed pink shrimp scientific literature of the past 75+ years (>500 publications) to glean information relevant to understanding potential influence of freshwater management on pink shrimp productivity. The review was organized around “Essential Fish Habitat” metrics concerning abundance, growth, survival, distribution, productivity, and behavior. It summarizes previous pink shrimp field, laboratory, and modeling studies. Where possible, statistical analyses and meta-analyses of previously published data were performed to investigate consistency among independent findings. Pink shrimp occur in a wide range of salinities (0.5–67 ppt). A majority of studies (53.3%) reported maximal abundance between ∼20 to 35 ppt salinities. One laboratory study reported maximal growth at 30 ppt. Meta-analysis of reported growth rates did not yield results due to non-convergence of regression models. Reported survival was maximal at ∼30 ppt and remained high (>80% survival) across salinities of ∼15 to 40 ppt. A regression model that combined survival data across studies confirmed a previously reported parabolic relationship between salinity and survival; in this regression, 35 ppt maximized survival. Productivity, conditional upon survival and growth, was maximized at polyhaline (18–30 ppt) conditions. Inshore hypersalinity (>40 ppt) may elicit young pink shrimp behavioral cues counterproductive to settlement in nearshore areas. Virtually no information exists regarding postlarval pink shrimp movement or preference relative to salinity gradients. Realization and preservation of nearshore polyhaline conditions and elimination of hypersalinity should maximize growth, survival, and density, thus improving pink shrimp productivity. New and updated statistical models predicting pink shrimp distribution, abundance, growth, survival, and productivity relative to salinity conditions are needed to better guide freshwater management decisions.