Ex-situ mariculture can support the restoration of the endangered seagrass Zostera capensis

Large‐scale losses of seagrass areas have been associated with eutrophication events, which have led to an overproduction of photosynthetic organisms including epiphytes. Grazers that feed on epiphytes can exert a significant top–down control in the system, but the effects of physical factors on grazing activity and feeding behaviour have been rarely examined. We addressed the combination of hydrodynamic regime and seagrass shoot density can alter the feeding and foraging behaviours of mesograzers. A full factorial experiment, with flow velocity (high, medium and low) and shoot density (high versus low) as main factors, was conducted in a racetrack flume using artificial seagrass plots. The results showed that when high flow velocity conditions were combined with low shoot density, consumption of epiphytes by mesograzers was strongly reduced. In contrast, when flow velocity was low or shoot density was high, mesograzers exhibited high feeding rates and vigorous swimming behaviour. These results clearly indicate that hydrodynamic stress reduces the time that mesograzers can spend feeding, since it inhibits their swimming behaviour, and thus indirectly affecting to the density of epiphytes. Therefore, the triggering of trophic cascade effects in seagrass communities under these experimental conditions depended on the interrelationship and feedbacks among shoot density, abiotic (flow velocity) and biotic (epiphytes and mesograzers) compartments, with flow velocity exerting a top–down control on seagrass ecosystems.

We obtained and analyzed a baseline dataset of Zostera marina (eelgrass) dynamics in three adjacent bays in Nova Scotia, Canada. The field sites were Kejimkujik National Park Seaside (Keji), Port l’Hebert (PH), and Port Joli (PJ). Measures of Z. marina growth and production, including shoot density, aboveground and belowground biomass, and shoot productivity, were sampled monthly for 1 year. Physical parameters, including water temperature, suspended solids, nutrients, ice cover, and algal presence, were also measured. Seasonal cycles in shoot density, leaf length, and aboveground biomass of Z. marina were evident at all sites. Shoots persisted throughout the winter; however, shoot density was lowest at PH and Keji due to ice cover. Belowground biomass at all sites did not show seasonal signals. Greatest differences in measured Z. marina parameters were observed at Keji compared with PH and PJ. Restricted water exchange at Keji caused high water temperatures, low flushing rates, and prolific algal growth, probably resulting in lower shoot densities and biomass than in PH and PJ. Our study provides some of the first data on Z. marina dynamics in the Atlantic Canadian region, and will provide a critical baseline for future comparisons of plant condition and estimates of variability in potential monitoring parameters.

Effects of seagrass habitat fragmentation on juvenile blue crab survival and abundance

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 183:87-94 (1999) - doi:10.3354/meps183087 Effects of changes in seagrass shoot density and leaf height on abundances and distribution patterns of juveniles of three gobiid fishes in a Zostera marina bed Masahiro Horinouchi*, Mitsuhiko Sano Department of Global Agricultural Sciences, Graduate School of Agricultural and Life Sciences, University of Tokyo, Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan *E-mail: adiver@hongo.ecc.u-tokyo.ac.jp ABSTRACT: The effects of changes in the structural complexity of a seagrass Zostera marina habitat on the densities of juveniles of 3 gobiid fishes, Pterogobius zonoleucus, Chaenogobius heptacanthus and Chasmichthys gulosus, were investigated by field experimentation at Moroiso and Aburatsubo Bays, Miura Peninsula, Japan. Following seagrass manipulation, involving reduction of leaf heights and shoot densities as well as complete removal of seagrass, juvenile densities of all 3 gobiids were found to be higher in those quadrats with sparser or shorter seagrass, the abundance in the seagrass-cleared quadrat always being greater than that in the control. In the quadrat with the lowest shoot density, juveniles resided among the shoots, and were evenly distributed over a horizontal plane. In the quadrat with the shortest seagrass, juveniles appeared above the canopy, and were positioned as in the seagrass-cleared quadrat, i.e. near the surrounding walls of untreated seagrass. By contrast, in the experimental patches lacking surrounding walls of unmanipulated seagrass, no juveniles appeared. The results indicated that water column-distributed juveniles of the 3 gobiid species prefer sparser seagrass and open areas close to the wall of untreated seagrass. KEY WORDS: Habitat complexity · Seagrass bed · Gobiid juveniles Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 183. Publication date: July 06, 1999 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 1999 Inter-Research.

Seasonality in vegetation biometrics and its effects on sediment characteristics and meiofauna in Baltic seagrass meadows

Seagrass meadows underpin a variety of ecosystem services and are recognized as globally important habitats and a conservation priority. However, seagrass populations are currently impacted by a range of biotic and abiotic stressors, and many are in decline globally. As such, improved understanding of seagrass populations and their associated faunal assemblages is needed to better detect and predict changes in the structure and functioning of these key habitats. Here, we analyzed a large dataset—collected by recreational scuba divers volunteering on a citizen science project—to examine spatiotemporal patterns in ecological structure and to provide a robust and reliable baseline against which to detect future change. Seagrass (Zostera marina) shoot density and the abundance of associated faunal groups were quantified across 2 years at 19 sites nested within three locations in southwest UK, by collecting in situ quadrat samples (2,518 in total) during 328 dives. Seagrass shoot density and meadow fragmentation was comparable across locations but was highly variable among sites. Faunal abundance and assemblage structure varied between areas with or without seagrass shoots; this pattern was largely consistent between locations and years. Overall, increased seagrass density was related to increased faunal abundance and explained shifts in faunal assemblage structure, although individual faunal groups were affected differently. More broadly, our study shows that well‐funded and orchestrated citizen science projects can, to some extent, gather fundamental information needed to benchmark ecological structure in poorly studied nearshore marine habitats.

Core/shell structured sSiO2/mSiO2 composite particles: The effect of the core size on oxide chemical mechanical polishing

Total biomass, shoot density, leaf length and leaf width of the dominant seagrass Thalassia testudinum were compared between two coastal environments in the northeastern part of the Yucatan peninsula (Mexico). The coastal environments were (a) an exposed sublittoral zone (<1 km from the shoreline) and (b) a sheltered coastal lagoon. Plant morphology was monitored at monthly intervals from June 2001 to May 2002. There was a clear morphological variation between coastal environments throughout the period of study. In the exposed sublittoral zone, total biomass and shoot density were lower and leaves were longer and wider. In contrast, in the sheltered lagoon, total biomass and shoot density were higher and the leaves shorter and narrower. Overall, high values of total biomass, shoot density and leaf width were observed during the warm weather seasons (rainy and dry) whereas the low values were observed during the cold fronts weather season (nortes); leaf length followed a reverse trend. Results presented here stress the need to take into account the natural pattern of morphological variation in the design of sampling and monitoring programs.

The effects of sea urchin grazing and drift algal blooms on a subtropical seagrass bed community.

Solubility enhancement of Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) using polypolypropylene oxide core PAMAM dendrimers

Effect of core size on the magnetoelectric properties of Cu0.8Co0.2Fe2O4@Ba0.8Sr0.2TiO3 ceramics

IntroductionIn vivo distribution of polyethylene glycol (PEG)ylated functional nanoparticles is vital for determining their imaging function and therapeutic efficacy in nanomedicine. However, contradictory results have been reported regarding the effect of core size and PEG surface of the nanoparticles on biodistribution.MethodsTo clarify this ambiguous understanding, using iron oxide nanoparticles (IONPs) as a model system, we investigated the effect of core size and PEG molecule weights on in vivo distribution in mice. Three PEGylated IONPs, including 14 nm IONP@PEG2,000, 14 nm IONP@PEG5,000, and 22 nm IONP@PEG5,000, were prepared with a hydrodynamic size of 26, 34, and 81 nm, respectively. The blood pharmacokinetics and tissue distribution were investigated in detail.ResultsThe results indicated that the PEG layer, rather than core size, played a dominant role in determining the half-life time of IONPs. Specifically, increased molecular weight of the PEG layer led to a longer half-life time. These PEGylated IONPs were mainly excreted by liver clearance. While the PEG molecular layer constituted the key factor to determine the clearance ratio, core size affected the clearance rate.ConclusionComplete blood count analysis and histopathology suggested excellent biocompatibility of PEGylated IONPs for future clinical trials.

Application of nitrogen (N) in early spring is often recommended for low shoot density winter wheat in northern temperate areas such as Sweden. Regional N-strategy field trials in such areas generally show no relationship between early N and grain yield but the effects on shoot numbers and other yield components are seldom investigated. This study quantified the effect of three N fertilization strategies on the number of tillers at GS30-31 and the grain yield of winter wheat with low shoot density in early spring, in order to evaluate the importance of early N application. The investigations were carried out from 1999–2002 in four annual field experiments on a clay soil in south-west Sweden using winter wheat (cvs. Kosack and Tarso) with shoot densities in early spring ranging from 360–850 shoots m−2. A positive relationship between time of first N application as number of days before GS30 and increase in number of shoots from GS20-21 to GS30-31 was observed. The relationship was strongest in experiments with the lowest shoot density in early spring (360–560 shoots m−2) and the additional increase with each day of earlier availability of N before GS30 was 11 shoots m−2. In wheat with this low shoot density in early spring, N was needed before GS30 to avoid yield reductions. Whether N was applied and available 24 or 13 days before GS30 did not affect yield, despite significantly more shoots being present at GS30-31 with earlier N application.

An investigation of how the presence of seagrass and seagrass patch size in high- and low-energy environments affected growth of an infaunal bivalve (hard clam, Mercenaria mercenaria) was carried out. Two general size classes of clams were used, mean length ca. 40.0 mm (41.9 mm) and mean length ca. 20.0 mm (22.3 mm and 19.0 mm), to see if growth responses were the same for large- and small-sized clams. Seagrass density, length and species composition as well as sediment characteristics were measured at high- and low-energy sites to determine if changes in seagrass and/or sediment dynamics could explain observed growth patterns. The incidence of siphon cropping was also evaluated as a potential influence on clam growth. Large clams grew faster inside than outside vegetation at both high- and low-energy sites. Within the vegetation, growth of large clams was faster in medium-sized patches of seagrass (2-3 m across) than in small patches (1 m across) and was intermediate in large patches (> 4-5 m across). There was no apparent correlation between seagrass shoot density, blade length, or species composition and growth of clams in patches of different size. Growth of small clams (22.3 mm) within seagrass was independent of the two seagrass patch sizes tested (large vs. small), but did vary among sites. Growth of clams was not correlated with differences in shoot density, blade length or species composition among sites. Growth of small clams (19.0 mm) also varied with energy regime and with presence/absence of vegetation. Small clams grew significantly more within seagrass under both high- and low-energy conditions, but the effect was more pronounced at high-energy sites than at low. Seagrass shoot density, blade length, and species composition did not vary between high and low energy regimes, but did vary among sites from the beginning to the end of the experiment. Long-term averages of sediment stability based on grain size characteristics suggest that the baffling effect of seagrass varies greatly with energy regime. Vegetated sediments at high-energy sites contained significantly more fine material than the unvegetated sediments while there was no difference in the fine fraction between vegetated and unvegetated sediments at low-energy sites. The difference in sediment stability between seagrass cover under high- and low-energy conditions may contribute to the magnitude of the difference in the growth response of small clams to the presence of vegetation at exposed and protected sites. Other factors also contributed to the increased growth of clams in seagrass beds at the protected sites where grain size analysis suggests similar sedimentary dynamics both within and outside of the vegetation. Mean adjusted siphon weights, however, for both large and small clams were independent of seagrass cover and energy regime implying that siphon nipping differences did not influence growth patterns of clams. Based on this study, and previous investigations, the effect of seagrass cover on growth of clams appears to be the result of a complex interaction among food supply, predation disturbance, and sediment stability with the relative importance of these processes varying with size of the clam, hydrographic regime, and local site differences.

We studied the relationships between functional traits of Halophila beccarii (shoot density, seed bank density, number of blades, above-ground biomass, below-ground biomass, leaf length, leaf width, and petiole length) and environmental factors (pH, salinity, temperature, physical disturbance by humans, and algal coverage) in seven populations along the coast of China. There were statistically significant differences in the functional traits of H. beccarii between tropical and subtropical regions. Traits such as shoot density, seed bank density, and biomass were notably higher in tropical populations, whereas leaf dimensions showed greater variability across regions. Further analysis using a linear mixed-effects model revealed that water temperature and salinity positively influenced shoot density, seed bank density, and biomass. Conversely, salinity negatively impacted traits such as leaf length, leaf width, and petiole length. Additionally, physical disturbance by humans and algal coverage demonstrated statistically significant negative correlations with shoot density and biomass. These findings provide insights into the environmental adaptability and conservation needs of this vulnerable seagrass species.