Life goes on: Spatial heterogeneity promotes biodiversity in an urbanized coastal marine ecosystem

Both human populations and marine biodiversity are concentrated along coastlines, with growing conservation interest in how these ecosystems can survive intense anthropogenic impacts. Tropical urban centres provide valuable research opportunities because these megacities are often adjacent to mega-diverse coral reef systems. The Pearl River Delta is a prime exemplar, as it encompasses one of the most densely populated and impacted regions in the world and is located just northwest of the Coral Triangle. However, the spatial and taxonomic complexity of this biodiversity, most of which is small, cryptic in habitat and poorly known, make comparative analyses challenging. We deployed standardized settlement structures at seven sites differing in the intensity of human impacts and used COI metabarcoding to characterize benthic biodiversity, with a focus on metazoans. We found a total of 7184 OTUs, with an average of 665 OTUs per sampling unit; these numbers exceed those observed in many previous studies using comparable methods, despite the location of our study in an urbanized environment. Beta diversity was also high, with 52% of the OTUs found at just one site. As expected, we found that the sites close to point sources of pollution had substantially lower diversity (44% less) relative to sites bathed in less polluted oceanic waters. However, the polluted sites contributed substantially to the total animal diversity of the region, with 25% of all OTUs occurring only within polluted sites. Further analysis of Arthropoda, Annelida and Mollusca showed that phylogenetic clustering within a site was common, suggesting that environmental filtering reduced biodiversity to a subset of lineages present within the region, a pattern that was most pronounced in polluted sites and for the Arthropoda. The water quality gradients surrounding the PRD highlight the unique role of in situ studies for understanding the impacts of complex urbanization pressures on biodiversity.

Heterotrophy in marine animal forests in an era of climate change

Marine animal forests (MAFs) are benthic ecosystems characterised by biogenic three-dimensional structures formed by suspension feeders such as corals, gorgonians, sponges and bivalves. They comprise highly diversified communities among the most productive in the world's oceans. However, MAFs are in decline due to global and local stressors that threaten the survival and growth of their foundational species and associated biodiversity. Innovative and scalable interventions are needed to address the degradation of MAFs and increase their resilience under global change. Surprisingly, few studies have considered trophic interactions and heterotrophic feeding of MAF suspension feeders as an integral component of MAF conservation. Yet, trophic interactions are important for nutrient cycling, energy flow within the food web, biodiversity, carbon sequestration, and MAF stability. This comprehensive review describes trophic interactions at all levels of ecological organisation in tropical, temperate, and cold-water MAFs. It examines the strengths and weaknesses of available tools for estimating the heterotrophic capacities of the foundational species in MAFs. It then discusses the threats that climate change poses to heterotrophic processes. Finally, it presents strategies for improving trophic interactions and heterotrophy, which can help to maintain the health and resilience of MAFs.

Coral carbonate-bound isotopes reveal monsoonal influence on nitrogen sources in Southeastern China's Greater Bay Area from the mid-Holocene until the Anthropocene

Most anthropogenic nitrogen (N) reaches coastal waters via rivers carrying increasing loads of sewage, fertilizer, and sediments. To understand anthropogenic N impacts, we need to understand historical N-dynamics before human influence. Stable isotope ratios of N preserved in carbonates are one way to create temporal N records. However, records that span periods of human occupation are scarce, limiting our ability to contextualize modern N dynamics. Here, we produce a fossil-bound N-record using coral subfossils, spanning 6700 years in China's Greater Bay Area (GBA). We found that during the mid-to-late Holocene, the GBA's coastal N was dominated by fluvial sources. The weakening of the Asia monsoon throughout the late-Holocene decreased river outflow, leading to a relative increase of marine nitrate. This source shift from riverine-to-ocean dominance was overprinted by anthropogenic N. During the late 1980s to early 1990s, human development and associated effluent inundated the coastal system, contributing to the decline of coral communities.

Protocol to track the biosynthesis of cholesterol in cultured HCC cells using 13C compound-specific stable isotopic tracers

Cholesterol biosynthesis supports proliferation and drives resistance to tyrosine kinase inhibitor (TKI) therapy in hepatocellular carcinoma (HCC). Here, we present a protocol for using stable isotopic tracers to track the biosynthesis of cholesterol in cultured HCC cells. We describe steps for cell preparation, incubation, separation, and homogenization. We then detail lipid extraction and compound-specific isotope analysis for comparing and quantifying cholesterol synthesis between TKI-resistant HCC cells and their mock counterparts. This protocol can be expanded for use with other shorter-chained lipids.

A survey of patient informational preferences when choosing between medical and surgical therapy for ulcerative colitis: a sub-study from the DISCUSS project

AIM

People living with ulcerative colitis (UC) have two broad treatment avenues, namely medical or surgical therapy. The choice between these can depend on patient preference as well as the receipt of relevant information. The aim of this study was to define the informational needs of patients with UC.

METHOD

A postal survey was designed to capture respondent demographics, treatment experienced within the previous 12 months and informational preferences by rating a long list of items. It was delivered through two hospitals that provide tertiary inflammatory bowel disease services. Descriptive analyses were performed to describe demographics and experiences. Principal component analysis was carried out using a varimax rotation to investigate informational needs.

RESULTS

A total of 101 responses were returned (20.1% response rate). The median age of respondents was 45 years and the median time since diagnosis was 10 years. Control preferences skewed towards shared (42.6%) or patient-led but clinician-informed (35.6%). Decision regret was low for the population (median 12.5/100, range 0-100). Key informational needs related to medical therapy were benefits and risks of long-term therapy, burden of hospital attendance, reproductive health, need for steroid treatment and impact on personal life. For surgery, these were stoma information, effect on daily life, effect on sexual and reproductive health, risks and benefits and disruption of life due to surgery.

CONCLUSION

This study has identified key areas for discussion when counselling patients about treatment decisions around medical therapy and surgery for UC.

Improving stable isotope assessments of inter- and intra-species variation in coral reef fish trophic strategies

Fish have one of the highest occurrences of individual specialization in trophic strategies among Eukaryotes. Yet, few studies characterize this variation during trophic niche analysis, limiting our understanding of aquatic food web dynamics. Stable isotope analysis (SIA) with advanced Bayesian statistics is one way to incorporate this individual trophic variation when quantifying niche size. However, studies using SIA to investigate trophodynamics have mostly focused on species‐ or guild‐level (i.e., assumed similar trophic strategy) analyses in settings where source isotopes are well‐resolved. These parameters are uncommon in an ecological context. Here, we use Stable Isotope Bayesian Ellipses in R (SIBER) to investigate cross‐guild trophodynamics of 11 reef fish species within an oceanic atoll. We compared two‐ (δ¹⁵N and δ¹³C) versus three‐dimensional (δ¹⁵N, δ¹³C, and δ³⁴S) reconstructions of isotopic niche space for interpreting guild‐, species‐, and individual‐level trophic strategies. Reef fish isotope compositions varied significantly among, but also within, guilds. Individuals of the same species did not cluster together based on their isotope values, suggesting within‐species specializations. Furthermore, while two‐dimensional isotopic niches helped differentiate reef fish resource use, niche overlap among species was exceptionally high. The addition of δ³⁴S and the generation of three‐dimensional isotopic niches were needed to further characterize their isotopic niches and better evaluate potential trophic strategies. These data suggest that δ³⁴S may reveal fluctuations in resource availability, which are not detectable using only δ¹⁵N and δ¹³C. We recommend that researchers include δ³⁴S in future aquatic food web studies.

Elucidating sources of atmospheric NOX pollution in a heavily urbanized environment using multiple stable isotopes

Atmospheric deposition of nitrogen (N) from rain and aerosols can be a significant non-point source - particularly in urbanized coastal areas and contribute to coastal eutrophication and hypoxia. Here, we present geochemical and isotopic data from surface waters coupled with an 18-month time series of geochemical and isotopic data measured on wet and dry deposition over Hong Kong from June 2018. Dual stable isotopes of nitrate (δ¹⁵N-NO₃^- and δ¹⁸O-NO₃^-) of rain and total suspended particulates (TSP) were analyzed to trace the sources and understand seasonal pattern of atmospheric nitrate. The δ¹⁵N of TSP, δ¹⁵N-NO₃ in rain and TSP ranged from +0.94 to +17.6‰, -4.1 to +3.0‰ and -1.3 to +9.0‰ respectively. δ¹⁵N varied seasonally with higher values in winter and lower values in summer. This variation can be explained by a change in the sources of atmospheric NO_x driven by the East Asian Monsoon. It was found that most NO_x comes from coal burning in winter and a mix of vehicle emissions, fossil fuel combustion and lightning in summer. Moreover, the estimated dry and wet deposition of nitrate and ammonium in Hong Kong is around 18 kg N ha^-1 annually, which is of the same order of magnitude as N released by sewage effluents and groundwater. This implies that atmospheric N deposition over the N-limited waters of the eastern side of Hong Kong could contribute significantly to the N budget. Therefore, atmospheric N deposition may alter the local N marine cycling, thus monitoring its impact is crucial for water quality in Southern China.

O058 Characteristics and prognosis of cerebrovascular fibromuscular dysplasia (FMD) - a retrospective cohort study

Introduction

Fibromuscular dysplasia (FMD) is a rare, non-atherosclerotic, non-inflammatory vascular disorder that primarily affects renal and cerebrovascular vessels. Limited data are available on the clinical characteristics of cerebrovascular FMD, particularly from the UK/Europe.

Methods

We performed a retrospective cohort analysis of all cases of carotid/cerebrovascular FMD presenting to our regional vascular service, by case-note review, and searching all relevant clinical databases.

Results

Eighty-six patients were identified between 1998–2020. Stroke or TIA was the most common mode of presentation. The most frequent vascular pattern was bilateral extracranial internal carotid artery FMD. Concomitant cerebrovascular complications - dissection, aneurysm or occlusive disease of the carotid, vertebral and cerebral vessels was common (41%) and included two cases of carotid cavernous fistula. FMD was also observed in the renal/visceral vessels and aorta in 13(15%) of the cohort (60% of those who had extracranial imaging), with 5% having aneurysm or dissection of other vessels. 19(22%) of patients required carotid/cerebrovascular intervention (mainly for intracranial aneurysm), with 10% requiring intervention for other vascular complications. Recurrent cerebrovascular events (stroke/TIAs and aneurysmal disease requiring intervention) was seen in 23% of cases. Overall mortality was 7% over a median follow-up period of 47 months.

Conclusion

The co-existence of intracranial aneurysm and other cerebrovascular complications in patients with carotid FMD is high and requires careful surveillance. Vascular complications in other vascular beds are also frequent and probably under-estimated. We would recommend a low threshold for routine imaging of all vascular beds in patients presenting with carotid/cerebrovascular FMD.

Take-home message

Fibromuscular dysplasia is rare but when presenting as a stroke, other vascular beds may be involved,

Caspase-3-induced activation of SREBP2 drives drug resistance via promotion of cholesterol biosynthesis in hepatocellular carcinoma

Accumulating evidence has demonstrated that drug resistance can be acquired in cancer through the repopulation of tumors by cancer stem cell (CSC) expansion. Here, we investigated mechanisms driving resistance and CSC repopulation in hepatocellular carcinoma (HCC) as a cancer model using two drug-resistant, patient-derived tumor xenografts that mimicked the development of acquired resistance to sorafenib or lenvatinib treatment observed in HCC patients. RNA sequencing analysis revealed that cholesterol biosynthesis was most commonly enriched in the drug-resistant xenografts. Comparison of the genetic profiles of CD133+ stem cells and CD133- bulk cells from liver regeneration and HCC mouse models showed that the cholesterol pathway was preferentially upregulated in liver CSCs compared to normal liver stem cells. Consistently, SREBP2-mediated cholesterol biosynthesis was crucial for the augmentation of liver CSCs, and loss of SREBP2 conferred sensitivity to tyrosine kinase inhibitors, suggesting a role in regulation of acquired drug resistance in HCC. Similarly, exogenous cholesterol-treated HCC cells showed enhanced cancer stemness abilities and drug resistance. Mechanistically, caspase-3 (CASP3)-mediated cleavage of SREBP2 from the endoplasmic reticulum to promote cholesterol biosynthesis, which consequently caused resistance to sorafenib/lenvatinib treatment by driving activation of the sonic hedgehog signaling pathway. Simvastatin, an FDA-approved cholesterol-lowering drug, not only suppressed HCC tumor growth but also sensitized HCC cells to sorafenib. These findings demonstrate that CSC populations in HCC expand via CASP3-dependent, SREBP2-mediated cholesterol biosynthesis in response to tyrosine kinase inhibitor therapy and that targeting cholesterol biosynthesis can overcome acquired drug resistance.

Coral-associated nitrogen fixation rates and diazotrophic diversity on a nutrient-replete equatorial reef

The role of diazotrophs in coral physiology and reef biogeochemistry remains poorly understood, in part because N2 fixation rates and diazotrophic community composition have only been jointly analyzed in the tissue of one tropical coral species. We performed field-based 15N2 tracer incubations during nutrient-replete conditions to measure diazotroph-derived nitrogen (DDN) assimilation into three species of scleractinian coral (Pocillopora acuta, Goniopora columna, Platygyra sinensis). Using multi-marker metabarcoding (16S rRNA, nifH, 18S rRNA), we analyzed DNA- and RNA-based communities in coral tissue and skeleton. Despite low N2 fixation rates, DDN assimilation supplied up to 6% of the holobiont's N demand. Active coral-associated diazotrophs were chiefly Cluster I (aerobes or facultative anaerobes), suggesting that oxygen may control coral-associated diazotrophy. Highest N2 fixation rates were observed in the endolithic community (0.20 µg N cm-2 per day). While the diazotrophic community was similar between the tissue and skeleton, RNA:DNA ratios indicate potential differences in relative diazotrophic activity between these compartments. In Pocillopora, DDN was found in endolithic, host, and symbiont compartments, while diazotrophic nifH sequences were only observed in the endolithic layer, suggesting a possible DDN exchange between the endolithic community and the overlying coral tissue. Our findings demonstrate that coral-associated diazotrophy is significant, even in nutrient-rich waters, and suggest that endolithic microbes are major contributors to coral nitrogen cycling on reefs.

Investigating the link between Pearl River-induced eutrophication and hypoxia in Hong Kong shallow coastal waters

We present geochemical analysis of 75 surface water samples collected in 2016 in Hong Kong coastal waters. We found that nitrogen distribution around Hong Kong can be characterized by two regimes driven by the influence of the Pearl River: 1) a regime where nitrate is the dominant species of nitrogen, associated with lower salinity and more faecal coliform and 2) a regime where dissolved organic nitrogen is dominant, associated with higher salinity and fewer faecal coliform. While the impact of the Pearl River on Hong Kong coastal waters is well characterized, we used the sharp contrast between the nitrogen regimes to produce new evidence about the role of the Pearl River on the generation of local hypoxia in Hong Kong. The impact of nitrate originating from the Pearl River on the generation of hypoxia in Hong Kong might be less important than previously thought, as no sign of eutrophication was found within the zones dominated by dissolved organic nitrogen and an historical decoupling of surface processes and bottom water oxygenation was observed. Moreover, we measured elevated ammonium levels and rapid cycling of ammonium and dissolved organic nitrogen in Victoria Harbour suggesting local sources, such as wastewater, might be rapidly oxidized and thus play an important role in the consumption of oxygen locally. A first-order calculation highlighted the potential for wastewater to drive the observed seasonal decline in oxygen. Taken together, these evidences suggest that eutrophication might not be the primary driver in the generation of seasonal hypoxia and that oxidation of ammonium released locally might play a bigger role than initially thought.

Holobiont nitrogen control and its potential for eutrophication resistance in an obligate photosymbiotic jellyfish

BACKGROUND

Marine holobionts depend on microbial members for health and nutrient cycling. This is particularly evident in cnidarian-algae symbioses that facilitate energy and nutrient acquisition. However, this partnership is highly sensitive to environmental change-including eutrophication-that causes dysbiosis and contributes to global coral reef decline. Yet, some holobionts exhibit resistance to dysbiosis in eutrophic environments, including the obligate photosymbiotic scyphomedusa Cassiopea xamachana.

METHODS

Our aim was to assess the mechanisms in C. xamachana that stabilize symbiotic relationships. We combined labelled bicarbonate (13C) and nitrate (15N) with metabarcoding approaches to evaluate nutrient cycling and microbial community composition in symbiotic and aposymbiotic medusae.

RESULTS

C-fixation and cycling by algal Symbiodiniaceae was essential for C. xamachana as even at high heterotrophic feeding rates aposymbiotic medusae continuously lost weight. Heterotrophically acquired C and N were readily shared among host and algae. This was in sharp contrast to nitrate assimilation by Symbiodiniaceae, which appeared to be strongly restricted. Instead, the bacterial microbiome seemed to play a major role in the holobiont's DIN assimilation as uptake rates showed a significant positive relationship with phylogenetic diversity of medusa-associated bacteria. This is corroborated by inferred functional capacity that links the dominant bacterial taxa (~90 %) to nitrogen cycling. Observed bacterial community structure differed between apo- and symbiotic C. xamachana putatively highlighting enrichment of ammonium oxidizers and nitrite reducers and depletion of nitrogen-fixers in symbiotic medusae.

CONCLUSION

Host, algal symbionts, and bacterial associates contribute to regulated nutrient assimilation and cycling in C. xamachana. We found that the bacterial microbiome of symbiotic medusae was seemingly structured to increase DIN removal and enforce algal N-limitation-a mechanism that would help to stabilize the host-algae relationship even under eutrophic conditions. Video abstract.

Response to Comment on Trophic strategy and bleaching resistance in reef-building corals

Recently, we published a novel method used to assess the trophic niches of different coral species and demonstrated that their nutrition varied considerably, with some species highly dependent on their photosynthetic algal symbionts and others able to feed on plankton to meet energetic requirements. Adjustments to the use of this tool are necessary when it is applied to other scientific questions and symbiotic organisms. We respond to a comment highlighting a risk of bias in the methods, discuss suggested adjustments, and propose further refinements to improve method robustness.

Modification of fatty acid profile and biosynthetic pathway in symbiotic corals under eutrophication

Symbiotic corals receive energy not only by ingesting food (e.g. plankton, inorganic/organic matter, i.e. heterotrophy), but also by endosymbiosis, which supplies photosynthates (dissolved inorganic carbon, i.e. autotrophy). These two sources of energy have distinct fatty acid (FA) profiles, which can be used to differentiate corals by their primary feeding mode. FA profiles have been applied as biomarkers to evaluate the quality of nutrition in the midst of environmental change. However, species-specific responses of coral FA profiles and biosynthetic pathway under cultural eutrophication are still unknown. We collected two coral species (Acropora samoensis, Platygyra carnosa) from sites with different levels of eutrophication to test for variations in FA profiles. Gas Chromatography-Mass Spectrometry (GC-MS) was performed to identify FA profiles and quantify their concentration. Our main findings are threefold: 1) chronic eutrophication inhibits corals' ability to synthesize essential FA; 2) PUFA:SFA ratio and certain FA biomarkers or their pathway can be successfully utilized to determine the relative degree of autotrophy and heterotrophy in corals; 3) under eutrophication, different FA profiles of coral host tissue are attributed to different feeding strategies. Thus, our research provides significant new insights into the roles of FA as a risk assessment tool in coral reef ecosystems under the pressure of eutrophication.

In Vitro Permeability, Irritability, and Release Evaluation of Commonly Used Topical Diclofenac Gel Preparations (1%, 5%, and 10%)

Recently, there has been an increase in the use of compounded topical pain preparations, raising concerns that clinicians and patients may not be aware of the potential safety risks. Topical diclofenac is one of the most widely used pain medications, often used for joint ailments such as osteoarthritis and other musculoskeletal pain. Systemic exposure to diclofenac has a dose-related risk for gastrointestinal, cardiovascular, and renal adverse events, particularly in elderly patients. Topical diclofenac preparations are frequently compounded in pharmacies at the concentrations of 1% to 10% (or higher) with or without other active ingredients such as camphor. Considering the significantly higher strengths of the compounded preparations as compared to the commercially available products (1% to 3%) and the frequency of application (sometimes up to six times a day), concerns arise as to the levels of absorption with these formulations and their potential toxicity. The objective of this initial study was formulated in an attempt to shed light on safety concerns of topical diclofenac preparations. A study was designed to evaluate the in vitro release, irritability, and permeability of three different concentrations of compounded diclofenac gels (1%, 5%, and 10%) in PLO GEL MEDIFLO and VersaPro Gel bases. Using MatTek's EpiDerm system, skin irritability and the in vitro permeation of compounded diclofenac gels were evaluated. Additionally, the in vitro release profile, drug content, content uniformity, and physical properties of the compounded gels (pH, homogeneity) were assessed. In all cases, the drug content, content uniformity, physical properties, and preparation stability during the recommended beyond-use dating (90 days) were acceptable. The release profiles of all tested preparations followed the Higuchi model. The in vitro skin irritation evaluation of the tested formulations indicated no irritant preparation. The permeability assessment of the formulated gels revealed that there is a correlation between drug release and percutaneous absorption. VersaPro Gelbased preparations, which showed a lower percentage of drug release over the experiment time, showed a significantly lower average flux at steady-state and the average percentage of absorbed dose after 24 hours. The percentage absorption (%abs) from different formulations ranged from 11.18% to 19.6% depending on the gel base. The permeability coefficient, kp, (cm/hr) ranged from 0.019 to 0.037, and the average flux (µg/cm2/hr) ranged from 8.7 to 103 depending on the gel base and the diclofenac concentration. Based on our findings and previously reported data, the possibility exists that higher diclofenac concentrations in compounded topical preparations may lead to significantly higher blood concentrations as compared to commercially available products, which in turn may also lead to serious side effects. Accordingly, there is a need for clinical studies to evaluate the safety of compounded diclofenac preparations with higher diclofenac contents than United States Food and Drug Administrationapproved formulations.

A systematic review and meta-analysis of outcomes after elective surgery for ulcerative colitis

AIM

Approximately 20%-30% of patients with ulcerative colitis (UC) will undergo surgery during their disease course, the vast majority being elective due to chronic refractory disease. The risks of elective surgery are reported variably. The aim of this systematic review and meta-analysis is to summarize the outcomes after elective surgery for UC.

METHODS

A systematic review was conducted that analysed studies reporting outcomes for elective surgery in the modern era (>2002). It was prospectively registered on the PROSPERO database (ref: CRD42018115513). Searches were performed of Embase and MEDLINE on 15 January 2019. Outcomes were split by operation performed. Primary outcome was quality of life; secondary outcomes were early, late and functional outcomes after surgery. Outcomes reported in five or more studies underwent a meta-analysis of incidence using random effects. Heterogeneity is reported with I² , and publication bias was assessed using Doi plots and the Luis Furuya-Kanamori index.

RESULTS

A total of 34 studies were included (11 774 patients). Quality of life was reported in 12 studies, with variable and contrasting results. Thirteen outcomes (eight early surgical complications, five functional outcomes) were included in the formal meta-analysis, all of which were outcomes for ileal pouch-anal anastomosis (IPAA). A further 71 outcomes were reported (50 IPAA, 21 end ileostomy). Only 14 of 84 outcomes received formal definitions, with high inter-study variation of definitions.

CONCLUSION

Outcomes after elective surgery for UC are variably defined. This systematic review and meta-analysis highlights the range of reported incidences and provides practical information that facilitates shared decision making in clinical practice.

A systematic review and meta-analysis of outcomes after elective surgery for ulcerative colitis

AIM

Approximately 20%-30% of patients with ulcerative colitis (UC) will undergo surgery during their disease course, the vast majority being elective due to chronic refractory disease. The risks of elective surgery are reported variably. The aim of this systematic review and meta-analysis is to summarize the outcomes after elective surgery for UC.

METHODS

A systematic review was conducted that analysed studies reporting outcomes for elective surgery in the modern era (>2002). It was prospectively registered on the PROSPERO database (ref: CRD42018115513). Searches were performed of Embase and MEDLINE on 15 January 2019. Outcomes were split by operation performed. Primary outcome was quality of life; secondary outcomes were early, late and functional outcomes after surgery. Outcomes reported in five or more studies underwent a meta-analysis of incidence using random effects. Heterogeneity is reported with I² , and publication bias was assessed using Doi plots and the Luis Furuya-Kanamori index.

RESULTS

A total of 34 studies were included (11 774 patients). Quality of life was reported in 12 studies, with variable and contrasting results. Thirteen outcomes (eight early surgical complications, five functional outcomes) were included in the formal meta-analysis, all of which were outcomes for ileal pouch-anal anastomosis (IPAA). A further 71 outcomes were reported (50 IPAA, 21 end ileostomy). Only 14 of 84 outcomes received formal definitions, with high inter-study variation of definitions.

CONCLUSION

Outcomes after elective surgery for UC are variably defined. This systematic review and meta-analysis highlights the range of reported incidences and provides practical information that facilitates shared decision making in clinical practice.

The effect of temperature on physiology, toxicity and toxin content of the benthic dinoflagellate Coolia malayensis from a seasonal tropical region

Coolia malayensis is one of the commonly found benthic dinoflagellates in Hong Kong which can produce biotoxins and threaten the early life stages of marine invertebrates. Seawater temperature has been recognized as one of the primary environmental factors that affect the formation of harmful algal blooms. The present study evaluated the responses of C. malayensis, including growth, toxicity and toxin content (putative analogues of okadaic acid and azaspiracids), after exposure to a range of seven different temperatures (i.e., 16°C, 18°C, 20°C, 22°C, 24°C, 26°C, and 28°C). The highest algal density and specific growth rate were recorded at 24°C. Significantly higher F_v/F_m (maximum quantum yield of PSII) and total phaeo-pigment values were observed in the exponential growth phase at 28°C. The toxicity of the algal extract, which was assessed by the lethality rate of Artemia larvae, increased with temperature. The highest toxin content was detected at the second highest temperature treatment, i.e., 26°C. Overall, temperature had significant effects on the physiological activities and toxicity of C. malayensis. This study has raised attention to the potentially increasing risks posed by toxic benthic dinoflagellates during heat waves in coastal waters.

Coral reef diversity losses in China's Greater Bay Area were driven by regional stressors

Observations of coral reef losses to climate change far exceed our understanding of historical degradation before anthropogenic warming. This is a critical gap to fill as conservation efforts simultaneously work to reverse climate change while restoring coral reef diversity and function. Here, we focused on southern China's Greater Bay Area, where coral communities persist despite centuries of coral mining, fishing, dredging, development, and pollution. We compared subfossil assemblages with modern-day communities and revealed a 40% decrease in generic diversity, concomitant to a shift from competitive to stress-tolerant species dominance since the mid-Holocene. Regions with characteristically poor water quality-high chl-a, dissolved inorganic nitrogen, and turbidity-had lower contemporary diversity and the greatest community composition shift observed in the past, driven by the near extirpation of Acropora These observations highlight the urgent need to mitigate local stressors from development in concert with curbing greenhouse gas emissions.

Competitive traits of coral symbionts may alter the structure and function of the microbiome

In the face of global warming and unprecedented coral bleaching, a new avenue of research is focused on relatively rare algal symbionts and their ability to confer thermal tolerance to their host by association. Yet, thermal tolerance is just one of many physiological attributes inherent to the diversity of symbiodinians, a result of millions of years of competition and niche partitioning. Here, we revealed that competition among cocultured symbiodinians alters nutrient assimilation and compound production with species-specific responses. For Cladocopium goreaui, a species ubiquitous within stable coral associations, temperature stress increased sensitivity to competition eliciting a shift toward investment in cell replication, i.e., putative niche exploitation. Meanwhile, competition led Durusdinium trenchii, a thermally tolerant “background” symbiodinian, to divert resources from immediate growth to storage. As such, competition may be driving the dominance of C. goreaui outside of temperature stress, the destabilization of symbioses under thermal stress, the repopulation of coral tissues by D. trenchii following bleaching, and ultimately undermine the efficacy of symbiont turnover as an adaptive mechanism.

Microbial symbionts and ecological divergence of Caribbean sponges: A new perspective on an ancient association

Marine sponges host diverse communities of microbial symbionts that expand the metabolic capabilities of their host, but the abundance and structure of these communities is highly variable across sponge species. Specificity in these interactions may fuel host niche partitioning on crowded coral reefs by allowing individual sponge species to exploit unique sources of carbon and nitrogen, but this hypothesis is yet to be tested. Given the presence of high sponge biomass and the coexistence of diverse sponge species, the Caribbean Sea provides a unique system in which to investigate this hypothesis. To test for ecological divergence among sympatric Caribbean sponges and investigate whether these trends are mediated by microbial symbionts, we measured stable isotope (δ13C and δ15N) ratios and characterized the microbial community structure of sponge species at sites within four regions spanning a 1700 km latitudinal gradient. There was a low (median of 8.2 %) overlap in the isotopic niches of sympatric species; in addition, host identity accounted for over 75% of the dissimilarity in both δ13C and δ15N values and microbiome community structure among individual samples within a site. There was also a strong phylogenetic signal in both δ15N values and microbial community diversity across host phylogeny, as well as a correlation between microbial community structure and variation in δ13C and δ15N values across samples. Together, this evidence supports a hypothesis of strong evolutionary selection for ecological divergence across sponge lineages and suggests that this divergence is at least partially mediated by associations with microbial symbionts.

Quantifying the Impact of Anthropogenic Atmospheric Nitrogen Deposition on the Generation of Hypoxia under Future Emission Scenarios in Chinese Coastal Waters

Atmospheric deposition is an important source of nitrogen to coastal waters. In nitrogen-limited waters, the atmosphere can contribute significantly to eutrophication and hypoxia. This is especially true in China, where nitrogen emissions have increased dramatically and are projected to further increase in the future. Here, we modeled the potential future impact of change in atmospheric nitrogen deposition on hypoxia in Chinese coastal seas. We used changes in nitrogen deposition under two IPCC scenarios that included emission regulation and climate change (representative concentration pathway (RCP) 4.5 and 8.5) to evaluate the impacts of such deposition on hypoxia in the 2030s and 2100s. We found that by 2030 the extent of hypoxic areas would increase up to 5% in China seas under RCP 8.5 due to the projected increase in nitrogen deposition. However, the hypoxia extent was projected to decrease by up to 9% by 2100 once emission regulations included in RCP 4.5 and 8.5 are implemented. The South China Sea was found to be the most sensitive region to changes in nitrogen loads, which indicates that more effort in emissions control is needed to avoid expansion of the hypoxic zones in that specific region.

Trophic strategy and bleaching resistance in reef-building corals

Ocean warming increases the incidence of coral bleaching, which reduces or eliminates the nutrition corals receive from their algal symbionts, often resulting in widespread mortality. In contrast to extensive knowledge on the thermal tolerance of coral-associated symbionts, the role of the coral host in bleaching patterns across species is poorly understood. Here, we applied a Bayesian analysis of carbon and nitrogen stable isotope data to determine the trophic niche overlap between corals and their symbionts and propose benchmark values that define autotrophy, heterotrophy, and mixotrophy. The amount of overlap between coral and symbiont niche was negatively correlated with polyp size and bleaching resistance. Our results indicated that as oceans warm, autotrophic corals lose their competitive advantage and thus are the first to disappear from coral reefs.

Megacity development and the demise of coastal coral communities: Evidence from coral skeleton δ15 N records in the Pearl River estuary

Historical coral skeleton (CS) δ¹⁸ O and δ¹⁵ N records were produced from samples recovered from sedimentary deposits, held in natural history museum collections, and cored into modern coral heads. These records were used to assess the influence of global warming and regional eutrophication, respectively, on the decline of coastal coral communities following the development of the Pearl River Delta (PRD) megacity, China. We find that, until 2007, ocean warming was not a major threat to coral communities in the Pearl River estuary; instead, nitrogen (N) inputs dominated impacts. The high but stable CS-δ¹⁵ N values (9‰-12‰ vs. air) observed from the mid-Holocene until 1980 indicate that soil and stream denitrification reduced and modulated the hydrologic inputs of N, blunting the rise in coastal N sources during the early phase of the Pearl River estuary urbanization. However, an unprecedented CS-δ¹⁵ N peak was observed from 1987 to 1993 (>13‰ vs. air), concomitant to an increase of NH₄⁺ concentration, consistent with the rapid Pearl River estuary urbanization as the main cause for this eutrophication event. We suggest that widespread discharge of domestic sewage entered directly into the estuary, preventing removal by natural denitrification hotspots. We argue that this event caused the dramatic decline of the Pearl River estuary coral communities reported from 1980 to 2000. Subsequently, the coral record shows that the implementation of improved wastewater management policies succeeded in bringing down both CS-δ¹⁵ N and NH₄⁺ concentrations in the early 2000s. This study points to the potential importance of eutrophication over ocean warming in coral decline along urbanized coastlines and in particular in the vicinity of megacities.

Effects of tourism-derived sewage on coral reefs: Isotopic assessments identify effective bioindicators

Pulau Redang and Pulau Tioman have experienced huge tourism growth over the last two decades, but minimal sewage treatment may threaten the resilience of their coral reefs. This study uses stable isotope techniques to identify suitable bioindicators of sewage nutrients (δ¹⁵N) at these islands by measuring macroalgae (Lobophora spp.), gastropods (Drupella spp.), scleractinian coral (Acropora spp.), and leather coral (Sinularia spp.). At tourist hubs using seepage septic tank systems, enrichment of Acropora δ¹⁵N (Redang, +0.7‰) and Sinularia δ¹⁵N (Tioman, +0.4‰) compared to pristine background levels indicate enhanced sewage nutrient discharge. Carbon isotopes and survey data suggest that sedimentation did not confound these δ¹⁵N trends. Potential damaging effects of sewage discharge on the coral reef communities at both islands are highlighted by strong correlations between Acropora δ¹⁵N and regional variation in coral reef community structure, and exclusive occurrence of degraded reefs at regions of high sewage influence.

Subtropical thermal variation supports persistence of corals but limits productivity of coral reefs

Concomitant to the decline of tropical corals caused by increasing global sea temperatures is the potential removal of barriers to species range expansions into subtropical and temperate habitats. In these habitats, species must tolerate lower annual mean temperature, wider annual temperature ranges and lower minimum temperatures. To understand ecophysiological traits that will impact geographical range boundaries, we monitored populations of five coral species within a marginal habitat and used a year of in situ measures to model thermal performance of vital host, symbiont and holobiont physiology. Metabolic responses to temperature revealed two acclimatization strategies: peak productivity occurring at annual midpoint temperatures (4-6°C lower than tropical counterparts), or at annual maxima. Modelled relationships between temperature and P:R were compared to a year of daily subtropical sea temperatures and revealed that the relatively short time spent at any one temperature, limited optimal performance of all strategies to approximately half the days of the year. Thus, while subtropical corals can adjust their physiology to persist through seasonal lows, seasonal variation seems to be the key factor limiting coral productivity. This constraint on rapid reef accretion within subtropical environments provides insight into the global distribution of future coral reefs and their ecosystem services.

A pollution gradient contributes to the taxonomic, functional, and resistome diversity of microbial communities in marine sediments

BACKGROUND

Coastal marine environments are one of the most productive ecosystems on Earth. However, anthropogenic impacts exert significant pressure on coastal marine biodiversity, contributing to functional shifts in microbial communities and human health risk factors. However, relatively little is known about the impact of eutrophication-human-derived nutrient pollution-on the marine microbial biosphere.

RESULTS

Here, we tested the hypothesis that benthic microbial diversity and function varies along a pollution gradient, with a focus on human pathogens and antibiotic resistance genes. Comprehensive metagenomic analysis including taxonomic investigation, functional detection, and ARG annotation revealed that zinc, lead, total volatile solids, and ammonia nitrogen were correlated with microbial diversity and function. We propose several microbes, including Planctomycetes and sulfate-reducing microbes as candidates to reflect pollution concentration. Annotation of antibiotic resistance genes showed that the highest abundance of efflux pumps was found at the most polluted site, corroborating the relationship between pollution and human health risk factors. This result suggests that sediments at polluted sites harbor microbes with a higher capacity to reduce intracellular levels of antibiotics, heavy metals, or other environmental contaminants.

CONCLUSIONS

Our findings suggest a correlation between pollution and the marine sediment microbiome and provide insight into the role of high-turnover microbial communities as well as potential pathogenic organisms as real-time indicators of water quality, with implications for human health and demonstrate the inner functional shifts contributed by the microcommunities.

Teaching History of Pharmacy in U.S. Pharmacy Schools

Objective. To determine how the standards for teaching pharmacy history were met by U.S. pharmacy schools, whether schools wanted to expand their commitment to pharmacy history, what pedagogical assistance, if any, was desired, and whether elective courses were offered. Methods. There were 133 school deans who were asked to identify the responsible faculty for teaching pharmacy history. A 10-question online survey instrument was designed and emailed to these faculty or the dean if no faculty were identified. Follow-up emails were sent at 2-week intervals. If they were non-responsive after three attempts, then telephone solicitation was attempted. Results. There were 100 schools (75%) that responded. Fifty-three percent were public and 47% were private; with 50% having class sizes of 100 or less, 41% with 101-250, and 9% having over 250. Eighty-six percent of respondents meet the ACPE requirement within a required course. Seventy-two percent devote only one to five hours of instruction to meet the requirement. Sixty-eight percent use no supporting literature, and among those who do, there was no common textbook. Interestingly, 21% wanted more teaching time, and 91% desired pedagogical assistance, varying from a packaged course (26%) to a syllabus with assignments and assessment banks (23%). Conclusion. Since no time or material guidelines were established to fulfill the ACPE pharmacy history educational requirements, these results provide a starting point to judge what is adequate and/or preferred. With the development of teaching guidelines and adoptable teaching materials, the pedagogical solution to this ACPE standard may become more complete and consistent.

Whale Shark Tourism: Impacts on Coral Reefs in the Philippines

Reef-based tourism has been developing rapidly in recent decades yet its impacts on reef ecosystems are often overlooked. In Tan-awan, Oslob, Philippines, whale sharks are attracted to the shallow reefs where they are provisioned up to 50 tons y^-1 of feed and this phenomenon in turn attracts >300,000 y^-1 visitors. Given the intensive provisioning and concentrating tourism activities, we hypothesized that the whale shark tourism-impacted site (IS) will have greater impacts on reef degradation and higher anthropogenic nitrogen pollution level compared to its reference site (RS). Ecological surveys revealed that relative to the RS, the IS had 36% higher relative abundance of Pocillopora and Porites coral over other genera, >2.5-fold lower coral density, and 20% higher macroalgal cover, which we concluded are signs of reef degradation. Also, we conducted stable nitrogen isotope analysis on gorgonian skeletons to trace nitrogen sources at both sites through time. Although an average 1‰ isotope enrichment found in the IS relative to the RS could indicate anthropogenic nitrogen inputs in the IS, this enrichment was consistent over time and existed before the tourism developed. Despite that, we cautioned against the imminent threat of local eutrophication caused by the continued inputs of nitrogen derived from provisioning and tourism activities. In summary, this study provided the first documentation of the impacts of provisioned whale shark tourism on the local reefs in Tan-awan and established an ecological baseline for future comparisons. Such assessments can offer important information on reef health, coastal development, and tourism management.

Nitrogen sources and cycling revealed by dual isotopes of nitrate in a complex urbanized environment

Elevated nutrient inputs have led to increased eutrophication in coastal marine ecosystems worldwide. An understanding of the relative contribution of different nutrient sources is imperative for effective water quality management. Stable isotope values of nitrate (δ¹⁵N_NO3-, δ¹⁸O_NO3-) can complement conventional water quality monitoring programs to help differentiate natural sources of NO₃^- from anthropogenic inputs and estimate the processes involved in N cycling within an ecosystem. We measured nutrient concentrations, δ¹⁵N_NO3-, and δ¹⁸O_NO3- in 76 locations along a salinity gradient from the lower end of the Pearl River Estuary, one of China's largest rivers discharging into the South China Sea, towards the open ocean. NO₃^- concentrations decreased with increasing salinity, indicative of conservative mixing of eutrophic freshwater and oligotrophic seawater. However, our data did not follow conservative mixing patterns. At salinities <20 psu, samples exhibited decreasing NO₃^-concentrations with almost unchanged NO₃^- isotope values, indicating simple dilution. At salinities >20 psu, NO₃^- concentrations decreased, while dual NO₃^- isotopes increased, suggesting mixing and/or other transformation processes. Our analysis yielded mean estimates for isotope enrichment factors (¹⁵ε = -2.02‰ and ¹⁸ε = -3.37‰), Δ(15,18) = -5.5‰ and δ¹⁵N_NO3- - δ¹⁵N_NO2- = 12.3‰. After consideration of potential alternative sources (sewage, atmospheric deposition and groundwater) we concluded that there are three plausible interpretations for deviations from conservative mixing behaviour (1) NO₃^- uptake by assimilation (2) in situ NO₃^- production (from fixation-derived nitrogen and nitrification of sewage-derived effluents) and (3) input of groundwater nitrate carrying a denitrification signal. Through this study, we propose a simple workflow that incorporates a synthesis of numerous isotope-based studies to constrain sources and behaviour of NO₃^- in urbanized marine environments.

Short-term tissue decomposition alters stable isotope values and C:N ratio, but does not change relationships between lipid content, C:N ratio, and Δδ13C in marine animals

Measures (e.g. δ15N, δ13C, %C, %N and C:N) derived from animal tissues are commonly used to estimate diets and trophic interactions. Since tissue samples are often exposed to air or kept chilled in ice over a short-term during sample preparation, they may degrade. Herein, we hypothesize that tissue decomposition will cause changes in these measures. In this study, we kept marine fish, crustacean and mollusc tissues in air or ice over 120 h (5 days). We found that tissue decomposition in air enriched δ15N (range 0.6‰ to 1.3‰) and δ13C (0.2‰ to 0.4‰), decreased %N (0.47 to 3.43 percentage points from staring values of ~13%) and %C (4.53 to 8.29 percentage points from starting values of ~43%), and subsequently increased C:N ratio (0.14 to 0.75). In air, while such changes to δ13C were relatively minor and therefore likely tolerable, changes in δ15N, %N, %C and C:N ratio should be interpreted with caution. Ice effectively reduced the extent to which decomposition enriched δ15N (≤ 0.4‰) and δ13C (≤ 0.2‰), and eliminated decomposition in C:N ratio, %N and %C. In our second experiment, for fish tissues in either air or ice over 120 h, we observed no effects of decomposition on relationships between lipid content, C:N ratio, and Δδ13C (change in δ13C after lipid removal), which are employed to correct δ13C for samples containing lipid. We also confirmed that lipid in tissues caused large errors when estimating δ13C (mean ± standard error = -1.8‰ ± 0.1‰, range -0.6‰ to -3.8‰), and showed both lipid extraction and mathematical correction performed equally well to correct for lipids when estimating δ13C. We, therefore, recommend that specimens of marine animals should be kept in ice during sample preparation for a short-term, as it is an effective means for minimizing changes of the stable isotope measures in their tissue.

The assessment of online health videos for surgery in Crohn's disease

AIM

YouTube™ is an open-access, nonpeer-reviewed video-hosting site and is used as a source of publicly available healthcare information. This study aimed to assess the thematic content of the most viewed videos relating to surgery and Crohn's disease and to explore the viewer interactions with these videos.

METHOD

A search of YouTube™ was carried out using one search string. The 50 most viewed videos were identified and categorized by source and content themes and assessed for viewer interactions. Video comments were used to describe the usefulness of the video content to viewers.

RESULTS

The majority of videos were uploaded by patients (n = 21).The remainder were uploaded by individual healthcare professionals (n = 9), hospital/speciality associations (n = 18) and industry (n = 2). The median number of likes for patient videos was significantly higher than for hospital/speciality association videos (P < 0.001). Patient videos received more comments praising the video content (n = 27) and more comments asking for further information (n = 14). The median number of likes for 'experience of surgery' (P < 0.001) and 'experience of disease' (P = 0.0015) themed videos were significantly higher than for 'disease management' themed videos.

CONCLUSION

Crohn's disease patients use YouTube™ as a surgical information source. The content of patient-sourced videos focused on surgical and disease experience, suggesting that these themes are important to patients. Current patient developed videos provide limited information, as reflected by viewers requesting further information. Storytelling patient-centred videos combined with clinical evidence may be a good model for future videos.

Development of valid and reliable tools for student evaluation of teaching

INTRODUCTION

The objective of this project was to develop valid and reliable course and instructor student evaluation tools (SETs) of teaching for utilization by a college of pharmacy.

METHODS

A collection of 119 course and instructor evaluation items was compiled from a review of the primary literature and grouped into six different themes (subscales): organization, communication, motivation, rapport, fairness, and learning. Input was sought from the college of pharmacy faculty to reduce the list of items to a more manageable pilot tool (27 for course evaluations; 29 for instructor evaluations) for developing pilot SETs. The results were analyzed for internal consistency and reliability using Cronbach's alpha, and whether factor structures aligned with the content structure using Confirmatory Factor Analysis (CFA).

RESULTS

The Cronbach's alpha for all six subscales in the designed instructor evaluation and for three of the six subscales in the designed course evaluation were above 0.9, indicating high internal consistency and reliability. The CFA results indicated a moderate model fit with factor loadings for all items above 0.6. The correlation coefficients between each dimension were about 0.8, indicating high correlations among dimensions. Those data items found to be valid were then used to construct new course and instructor evaluation instruments, both consisting of three validated items in each of the six themes (subscales).

CONCLUSION

This report describes the process that one college of pharmacy employed to develop a valid and reliable SET. The methodology can inform other colleges and schools of pharmacy who wish to design, revise, or develop their own SETs.

A systematic review of online resources to support patient decision-making for full-thickness rectal prolapse surgery

Background

The internet is becoming an increasingly popular resource to support patient decision-making outside of the clinical encounter. The quality of online health information is variable and largely unregulated. The aim of this study was to assess the quality of online resources to support patient decision-making for full-thickness rectal prolapse surgery.

Methods

This systematic review was registered on the PROSPERO database (CRD42017058319). Searches were performed on Google and specialist decision aid repositories using a pre-defined search strategy. Sources were analysed according to three measures: (1) their readability using the Flesch–Kincaid Reading Ease score, (2) DISCERN score and (3) International Patient Decision Aids Standards (IPDAS) minimum standards criteria score (IPDASi, v4.0).

Results

Overall, 95 sources were from Google and the specialist decision aid repositories. There were 53 duplicates removed, and 18 sources did not meet the pre-defined eligibility criteria, leaving 24 sources included in the full-text analysis. The mean Flesch–Kincaid Reading Ease score was higher than recommended for patient education materials (48.8 ± 15.6, range 25.2–85.3). Overall quality of sources supporting patient decision-making for full-thickness rectal prolapse surgery was poor (median DISCERN score 1/5 ± 1.18, range 1–5). No sources met minimum decision-making standards (median IPDASi score 5/12 ± 2.01, range 1–8).

Conclusions

Currently, easily accessible online health information to support patient decision-making for rectal surgery is of poor quality, difficult to read and does not support shared decision-making. It is recommended that professional bodies and medical professionals seek to develop decision aids to support decision-making for full-thickness rectal prolapse surgery.

Life and death of a sewage treatment plant recorded in a coral skeleton δ15N record

We investigated the potential of coral skeleton δ¹⁵N (CS-δ¹⁵N) records for tracking anthropogenic-N sources in coral reef ecosystems. We produced a 56yr-long CS-δ¹⁵N record (1958-2014) from a reef flat in Guam that has been exposed to varying 1) levels of sewage treatment 2) population density, and 3) land use. Increasing population density (from <30 to 300ind·km^-2) and land use changes in the watershed resulted in a ~1‰ enrichment of the CS-δ¹⁵N record until a sewage treatment plant (STP) started operation in 1975. Then, CS-δ¹⁵N stabilized, despite continued population density and land use changes. Based on population and other considerations, a continued increase in the sewage footprint might have been expected over this time. The stability of CS-δ¹⁵N, either contradicts this expectation, or indicates that the impacts on the outer reef at the coring site were buffered by the mixing of reef water with the open ocean.

Creation of an active learning healthcare communications course using simulations relevant to pharmacy practice

BACKGROUND AND PURPOSE

The purpose of this project was to design and develop a health care communications course built around practice-like simulations and active learning in the first year of a professional pharmacy program.

EDUCATIONAL ACTIVITY AND SETTING

A three-credit health care communications course was divided into one didactic (two hours per week) and three simulation components (one hour per week). The simulation components consisted of one written patient education pamphlet, three group presentations, and three one-on-one patient counseling sessions. This was accomplished by breaking the class of approximately 75 students into eight separate sections, each consisting of 8-10 students and one instructor. Each week four sections were devoted to counseling role-plays: half in the role of pharmacists and half as patients. The other four sections were devoted to hour-long professional group presentations-half in the presenting group and half as audience. The students' performance in the simulated counseling sessions and group presentations has been tracked and analyzed to determine if the simulated exercises had a positive impact on the students' active communications skills.

FINDINGS

Consistently, over the first four years of the implementation of the course, students' communications skills, as measured by faculty assessments, in both professional group presentations and one-on-one counseling sessions significantly improved.

DISCUSSION AND SUMMARY

Incorporation of active-learning simulation exercises into a healthcare communications course has a positive impact on the development of students' communications skills. This creates a foundation upon which students can build over the remainder of the professional program and into their future careers.

New Insights on the Nitrogen Footprint of a Coastal Megalopolis from Coral-Hosted Symbiodinium δ15N

The development of megalopolises in coastal areas is often linked with severe eutrophication, requiring mitigation of anthropogenic dissolved inorganic nitrogen (DIN) pollution. Yet, identifying the DIN-sources responsible for eutrophication is challenging, hampering mitigation efforts. Here, we utilize the stable nitrogen isotope ratio of endosymbiotic dinoflagellate Symbiodinium spp. (δ¹⁵N_sym) associated with the hard coral Porites to trace DIN sources in one of the most urbanized areas of the planet: the Pearl River Delta (PRD). The mean δ¹⁵N_sym value found in the coastal waters of Hong Kong (HK), located on the eastern edge of the PRD, (7.4‰ ± 1.2‰) was +2.7‰ higher than at Dongsha Atoll, a reference site unaffected by anthropogenic-DIN (4.7‰ ± 0.4‰). The isotopic enrichment suggested a consistent dominance of DIN deriving from local and regional sewage discharges on the eastern edge of HK. Furthermore, the strong depletion of the summer δ¹⁵N_sym value (-1.6‰) observed in southern HK revealed that the Pearl River plume strongly modulates the coastal DIN pool. Our results revealed the value of benthic marine organisms' δ¹⁵N for deciphering the complex dynamics of coastal eutrophication and highlighted the pivotal role of transboundary coordination in DIN-pollution mitigation.

Investigating Bermuda's pollution history through stable isotope analyses of modern and museum-held gorgonian corals

For centuries, Bermuda has been challenged with wastewater management for the protection of human and environmental health. By quantifying the δ¹⁵N of the common sea fan Gorgonia ventalina sampled from 30 sites throughout Bermuda we show that sewage-derived nitrogen is detectable on nearshore coral reefs and declines across the lagoon to the outer rim. We also sampled gorgonians from two museum collections representing a 50y time-series (1958-2008). These samples revealed an increase in δ¹⁵N of >4.0‰ until the mid-1970s, after which δ¹⁵N values slowly declined by ~2.0‰. A δ¹⁵N chronology from a gorgonian skeleton exhibited a similar decline over the last 30-40years of approximately 0.6‰. We conclude that policies have been effective in reducing sewage impacts to Bermudian reefs. However, significant sources of sewage pollution persist and are likely have a strong impact on harbor and nearshore coral communities and human health.

Reefs of tomorrow: eutrophication reduces coral biodiversity in an urbanized seascape

Although the impacts of nutrient pollution on coral reefs are well known, surprisingly, no statistical relationships have ever been established between water quality parameters, coral biodiversity and coral cover. Hong Kong provides a unique opportunity to assess this relationship. Here, coastal waters have been monitored monthly since 1986, at 76 stations, providing a highly spatially resolved water quality dataset including 68 903 data points. Moreover, a robust coral species richness (S) dataset is available from more than 100 surveyed locations, composed of 3453 individual colonies' observations, as well as a coral cover (CC) dataset including 85 sites. This wealth of data provides a unique opportunity to test the hypothesis that water quality, and in particular nutrients, drives coral biodiversity. The influence of water quality on S and CC was analyzed using GIS and multiple regression modeling. Eutrophication (as chlorophyll-a concentration; CHLA) was negatively correlated with S and CC, whereas physicochemical parameters (DO and salinity) had no significant effect. The modeling further illustrated that particulate suspended matter, dissolved inorganic nitrogen (DIN) and dissolved inorganic phosphorus (DIP) had a negative effect on S and on CC; however, the effect of nutrients was 1.5-fold to twofold greater. The highest S and CC occurred where CHLA <2 μg L^-1 , DIN < 2 μm and DIP < 0.1 μm. Where these values were exceeded, S and CC were significantly lower and no live corals were observed where CHLA > 15 μg L^-1 , DIN > 9 μm and DIP > 0.33 μm. This study demonstrates the importance of nutrients over other water quality parameters in coral biodiversity loss and highlights the key role of eutrophication in shaping coastal coral reef ecosystems. This work also provides ecological thresholds that may be useful for water quality guidelines and nutrient mitigation policies.

Variations in nitrate isotope composition of wastewater effluents by treatment type in Hong Kong

Stable isotopes (δ(15)N, δ(18)O) can serve as tracers for sources of nitrogen in the receiving environment. Hong Kong discharges ~3×10(6)m(3)d(-1) of treated wastewater into the ocean from 68 facilities implementing preliminary to tertiary treatment. We sampled treated sewage from 18 plants across 5 treatment types and examined receiving seawater from northeast Hong Kong. We analyzed nitrate and nitrite (NO3(-)+NO2(-), hereafter NOx) ammonium (NH4(+)), phosphate (PO4(+)) concentrations and δ(15)NNOx, δ(18)ONOx. Sewage effluents contained high mean nutrient concentrations (NO3(-)=260μmolL(-1), NH4(+)=1400μmolL(-1), PO4(+)=50μmolL(-1)) with some indication of nitrogen removal in advanced treatment types. Mean δ(15)NNOx of sewage effluents from all plants and treatment types (12‰) was higher than natural sources and varied spatially and seasonally. There was no overall effect of sewage treatment type on δ(15)NNOx. A mass balance model indicated that sewage (>68%) remains a dominant source of nitrate pollution in seawater in Tolo Harbor.

To swim or not to swim? A disagreement between microbial indicators on beach water quality assessment in Hong Kong

The USEPA and the WHO now advocate the use of enterococci as indicators for marine water quality. This study investigated the outcomes for Hong Kong beach water quality assessment by comparing enterococcus measures with data from the HKEPD's monitoring programme. Six beaches were tested once every 2-3 months from November 2013 to June 2014 in order to identify the most contaminated sites, followed by intensive water sampling in sites found to have the highest enterococci densities (Clear Water Bay Second and Golden) every five to six days for six sampling events over a 30-day period in 2014. The geometric means of enterococci were found to be 124 and 41 cfu/100 mL at Clear Water Bay Second and Golden respectively, indicating that there may be higher risks of illness associated with swimming at both beaches than previously known. Moreover, beach sediments contained higher concentrations of enterococci than water, and warrant further study.