Nutrient additions to seagrass seed planting improve seedling emergence and growth

To maximize the opportunities of seagrass as a nature-based solution requires restoration to occur on a large scale. New methods and knowledge are required that can solve ecological bottlenecks, improving its reliability and effectiveness. Although there is increasing interest in the use of seeds for seagrass restoration there exists a limited understanding of how best to plant them with the most knowledge on germination and seedling emergence coming from laboratory studies. Here we present the results of a novel field study on the emergence success of seeds of the seagrass Zostera marina when subjected to varied planting treatments. Seeds were planted into hessian bags according to a factorial design of three treatments (sediment type, detritus addition, and nutrient addition). By adding nutrients to natural sediment, the present study provides some evidence of seagrass shoot emergence and maximum shoot length doubling. The present study provides evidence that even in heavily nutrient-rich environments, seagrass sediments may require additional nutrients to improve seedling emergence and growth. It also highlights the highly variable nature of planting seagrass seeds in shallow coastal environments. Critically this study provides increasing levels of evidence that small subtleties in the method can have large consequences for seagrass restoration and that for restoration to scale to levels that are relevant for nature-based solutions there remain many unknowns that require consideration.

Spatial variation of plastic debris on important turtle nesting beaches of the remote Chagos Archipelago, Indian Ocean

We report Anthropogenic Marine Debris (AMD) in Chagos Archipelago in the Indian Ocean, globally amongst the most isolated island groups. AMD on 14 island beaches in five atolls were surveyed in 2019 using two techniques: Marine Debris Tracker (MDT) along littoral vegetation and photoquadrats in open beach. Over 60 % of AMD in both beach zones was composed of plastics, especially bottles and fragments (mean = 44.9 %, 27.2 %, range = 16.5-73.2 %, 4.8-55.9 % respectively in vegetation; mean = 28.7 %, 31.5 %, range = 17.7-40.7 %, 11.6-60.0 % respectively in open beach). The density of plastic debris in littoral vegetation (MDT data: 1995 bottles, 3328 fragments per 100 m²) was 10-fold greater than in open beach (photoquadrat data: 184 bottles, 106 fragments per 100 m²). Significant latitudinal variation in vegetation AMD occurred (8-fold greater in southern atolls, p = 0.006). AMD varied within island zones: most debris observed on oceanside beaches (oceanside vs lagoon, W = 365, p < 0.001; ocean vs island tip, W = 107, p = 0.034). Standardisation of surveys using the open-source MDT App is recommended. Debris accumulation hotspots overlapped with sea turtle nesting habitat, guiding future beach clean-up prioritisation.

The discovery of deep-water seagrass meadows in a pristine Indian Ocean wilderness revealed by tracking green turtles

Our understanding of global seagrass ecosystems comes largely from regions characterized by human impacts with limited data from habitats defined as notionally pristine. Seagrass assessments also largely focus on shallow-water coastal habitats with comparatively few studies on offshore deep-water seagrasses. We satellite tracked green turtles (Chelonia mydas), which are known to forage on seagrasses, to a remote, pristine deep-water environment in the Western Indian Ocean, the Great Chagos Bank, which lies in the heart of one of the world's largest marine protected areas (MPAs). Subsequently we used in-situ SCUBA and baited video surveys to survey the day-time sites occupied by turtles and discovered extensive monospecific seagrass meadows of Thalassodendron ciliatum. At three sites that extended over 128 km, mean seagrass cover was 74% (mean range 67-88% across the 3 sites at depths to 29 m. The mean species richness of fish in seagrass meadows was 11 species per site (mean range 8-14 across the 3 sites). High fish abundance (e.g. Siganus sutor: mean MaxN.site^-1 = 38.0, SD = 53.7, n = 5) and large predatory shark (Carcharhinus amblyrhynchos) (mean MaxN.site^-1 = 1.5, SD = 0.4, n = 5) were recorded at all sites. Such observations of seagrass meadows with large top predators, are limited in the literature. Given that the Great Chagos Bank extends over approximately 12,500 km² and many other large deep submerged banks exist across the world's oceans, our results suggest that deep-water seagrass may be far more abundant than previously suspected.

The basal subcellular distribution of beta-adrenergic receptor kinase is independent of G-protein beta gamma subunits

beta-Adrenergic receptor kinase (beta ARK-1 or GRK2) is a key regulatory protein involved in the regulation of G-protein-coupled receptors which associates with microsomal and plasma membranes. beta gamma Subunits of G-proteins have been suggested to mediate agonist-dependent membrane translocation of beta ARK, but their possible role in maintaining the complex subcellular distribution of the kinase is not known. In this study we show that lovastatin-mediated inhibition of G gamma subunits isoprenylation in HEK-293 cells stably transfected with beta ARK1 leads to a significant release of G beta subunits to the cytosol without causing changes in total particulate beta ARK or in the association of this kinase to plasma or microsomal membrane fractions. In addition, transient overexpression of mutant forms of G gamma unable to become isoprenylated resulted in a marked sequestration of G beta to the soluble compartment, but caused no rearrangement in the distribution of cotransfected beta ARK. These results indicate that anchoring of beta ARK to cellular membranes under basal conditions is independent of the availability of heterotrimeric G-protein subunits.

A rapid and sensitive method of identification of HTLV-II subtypes

There are 2 subtypes of human T-cell lymphoma/leukemia virus type II (HTLV-II), A and B. HTLV-II is increasingly associated with rare forms of lymphocytic neoplasia and a neurodegenerative disorder, characterized by hyperspasticity and ataxia. We have used PCR to amplify, clone and sequence 140 bp of the pol gene from many isolates of HTLV-IIA and HTLV-IIB from around the world. Analysis of these and other published sequence established that all HTLV-IIA sequences contained a unique Hinf I site and all HTLV-IIB sequences a unique Mse I site. A rapid and specific oligomer restriction (OR) assay was developed utilizing the primer pair SK110/SK111 and subsequent digestion with these enzymes. Concordance between sequenced and OR-based subtyping of DNA amplified by PCR was absolute among 22 HTLV-II isolates tested. Further OR or sequence analyses on an additional 30 other isolates indicated that the majority of North American non-indian HTLV-II isolates were subtype A, while all Paleo-Amerindian samples, including those from the Seminole of Florida; the Guaymi from Panama; and the Toba, Chorote, Wichi, and Chulupe of Argentina, belonged to subtype B. The SK110/SK111 PCR-OR format should facilitate molecular epidemiology studies of HTLV-II infection and allow for subtype stratification in assessing the sensitivity and specificity of HTLV detection formats and HTLV-II disease association.

Thermospray HPLC/MS: a new mass spectrometric technique for the profiling of steroids

The analysis of various steroid classes by thermospray HPLC-MS using solvent systems containing 0.1 M ammonium acetate has been described. For simple unconjugated 3-oxo-4-ene steroids the positive ion spectra are dominated by a parent ion M + H+ and with increasing numbers of hydroxyl group intense ions formed by sequential losses of water (M + H- n18)+ become important. Steroids with dihydroxyacetone side-chains readily lose these side-chains and the resulting (M + H-60)+ fragment is the base peak in their spectra. The (M + H-60)+ ion is not important for most steroids with glycerol-type side-chains. Although competition between thermal degradation and vaporization was observed at lower concentrations, the effect was minimized after optimizing conditions and the protonated molecular ion was easily detected when as little as 1-10 pmol of material were injected on-column. Steroid glucuronides when analyzed in the negative ion mode give simple spectra with base peak and parent ion (M-H)-. Lack of fragmentation permits facile and sensitive measurement of individual glucoronides by selected-ion-monitoring. Extensive fragmentation is seen in the positive ion mode with sequential losses of H2O from the molecular ions (M + NH4)+ and from the aglycone fragment ion. For simple unconjugated steroids the sensitivity of HPLC-MS in selected-ion-monitoring mode can be excellent. When the protonated molecular ion of testosterone was monitored the signal/noise ratio for 30 pg testosterone was about 10.