Exploring the Role of Determinants Affecting Responsible Underwater Behaviour of Marine-Based Tourists

This study utilised divers' demographic characteristics, diving experience, and attitudes to analyse the association between these factors and divers' responsible underwater behaviour among Chinese scuba divers in Hong Kong. More innovatively, the measurement construct of diving attitude was further employed as a mediator to investigate its influence on the relationship between divers' diving experience and responsible underwater behaviours based on the conceptual framework of previous works in the literature. The questionnaire data for this study were collected at four of the most popular dive sites among the marine protected areas in Hong Kong, with 398 valid samples after eliminating incomplete questionnaires. Regression results demonstrated that divers' demographic characteristics could significantly predict their responsible underwater behaviour, with age (b = 0.10, p < 0.05) and education (b = 0.15, p < 0.05) being found to be positively associated with their diving behaviour. In addition, path analysis demonstrated that divers' diving experience and attitude could explain 13.6% and 22.6% of the variance in predicting their responsible diving behaviour, respectively. However, no mediation effect was found on the relationship between diving experience and responsible underwater behaviour relative to diving attitude, given the absence of statistical effects regarding the positive impact of divers' diving experience on their attitude (β = 0.024, se = 0.022, t = 1.085, p = 0.279). Based on the research findings, theoretical and practical implications were discussed correspondingly, which are believed to be beneficial in promoting marine conservation and the sustainable development of marine-based nature tourism in Hong Kong.

Recreational specialization and the marine-based conservation behaviour intention of recreational divers in Hong Kong

This study examined divers' recreational specialization, pro-environmental attitudes, and marine-based conservation behaviour intentions. A questionnaire-based data collection approach was used to survey 398 divers who visited popular diving sites in Hong Kong by employing structural equation modelling to determine the potential relationships among the proposed variables. The results showed a statistically positive relationship between divers' recreational specialization and their pro-environmental attitudes, along with a statistically valid relationship between divers' recreational specialization and their marine-based conservation behaviour intentions. However, divers' pro-environmental attitudes were not statistically significant with their marine-based conservation behaviour intentions; thus, the discrepancy regarding different research findings between the current and previous studies was further discussed. In particular, our findings confirmed that recreational specialization could be a reliable predictor of divers' pro-environmental attitudes and marine-based conservation behaviour intentions to fill the research gaps regarding scuba diving-based nature tourism in Hong Kong. Consequently, management implications and recommendations were presented in accordance with the development of marine environmental conservation and sustainable scuba diving tourism in Hong Kong.

Microplastic contamination in edible clams from popular recreational clam-digging sites in Hong Kong and implications for human health

The ubiquitous presence of microplastics in edible bivalves and the human health risks associated with bivalve consumption have raised public concerns. Farmed and market-sold bivalves have received the most attention, while wild bivalves have received much less scrutiny. In the present study, 249 individuals were examined across six wild clam species from two popular recreational clam-digging sites in Hong Kong. Of the clams, 56.6 % contained microplastics, with an average abundance of 1.04 items/g (wet weight) and 0.98 items/individual. This resulted in an estimated annual dietary exposure of 14,307 items per Hong Kong resident. Moreover, the potential microplastic risks for humans associated with wild clam consumption were assessed using the polymer hazard index, and the results indicated a medium degree of risk, indicating that exposure to microplastics through wild clam consumption is inevitable and poses a potential health threat to humans. Further research is needed to facilitate a better understanding of the widespread occurrence of microplastics in wild bivalves, and further refinements of the risk assessment framework can hopefully allow a more accurate and holistic health risk assessment for microplastics.

Microplastic contamination in marine-cultured fish from the Pearl River Estuary, South China

Microplastics are ubiquitous in the aquatic environment. However, the occurrence of microplastics in farmed fish is under-researched. Herein, microplastic abundance in the stomach and intestine of marine-cultured hybrid groupers (Epinephelus fuscoguttatus × Epinephelus lanceolatus) in the Pearl River Estuary (PRE) was examined. Microplastics were detected in all fish samples, with an average abundance of 35.36 n/individual or 0.62 n/g. The fish intestine contained more microplastics (23.91 n/individual, i.e., 1.10 n/g) than the stomach (12.80 n/individual, i.e., 0.37 n/g). In addition, the ingested microplastics were predominantly fibre-shaped (70.1%), and nearly 70% were smaller than 1 mm in diameter. Potential factors affecting the ingestion of microplastics by farmed hybrid groupers include fish diet and the availability of microplastics in their feeding habitat.

The influences of emotional factors on householders' decarbonizing cooling behaviour in a subtropical Metropolitan City: An application of the extended theory of planned behaviour

Air-conditioning accounts for a vast amount of electricity consumption in Hong Kong, and household decarbonization of cooling is considered a vital means of reducing electricity use. However, little information is available on the determinants of household decarbonizing cooling behaviour, and emotional factors are often ignored in the pro-environmental behaviour literature. Thus, this study attempts to address this gap by applying an emotional extension of the theory of planned behaviour (TPB). A total of 295 valid responses were obtained using a questionnaire survey and tested via structural equation modeling (SEM). The incorporation of additional variables improves the explanatory power of the household decarbonizing cooling behaviour model, and the results reveal that subjective norms is the most influential factor, followed by affective connection to nature and negative anticipated emotions. Meanwhile, attitude towards the behaviour and perceived behavioural control are found to have a nonsignificant effect on behavioural intention. These findings not only highlight the importance of emotions in predicting electricity-saving behaviour, but also provide useful insights to formulate effective approaches for motivating citizens to engage in decarbonizing cooling behaviour at home.

Protected areas as a space for pandemic disease adaptation: A case of COVID-19 in Hong Kong

As COVID-19 has swept across the world, governments have been prompted to order social distancing measures, from the closure of schools, restaurants and public facilities to quarantines and lockdowns. Access to and contact with nature have been suggested to help combat impacts associated with isolation measures, and a coincidental surge in the number of visitors to country parks in Hong Kong has recently been observed. The current study sought to explore the visitation of country parks as an adaptation to COVID-19 by employing the socio-psychological model of precautionary adaptation (SPMPA). Questionnaire surveys were administered in 12 country parks in Hong Kong, and a total of 600 samples were collected. A conceptual model based on the SPMPA was proposed and tested through multiple regression analysis. Significant associations between perceived severity, threat experience and adaptative behaviour were found, suggesting the possible risks of visiting country parks. However, the relationships among perceived adaptation efficacy, adaptation cost and reliance on public adaptation implied that the adaptative benefits of visiting country parks may outweigh the risks when proper visitor management measures are implemented. The findings highlighted the importance of providing accessible protected areas or other types of nature-based spaces to facilitate the adaptation of people to disease outbreaks in both the short and long run.

Low level of microplastic contamination in wild fish from an urban estuary

Microplastic accumulation in estuarine environments is considered the dominant input of land-based plastics into the oceans. In this study, the level of microplastic contamination was evaluated in 26 species of wild fish from the Pearl River Estuary, South China. Results showed that microplastics abundance ranged from 0.17 items individual^-1 (Boleophthalmus pectinirostris & Acanthogobius flavimanus) to 1.33 items individual^-1 (Plectorhynchus cinctus) among different species. The distribution of microplastic abundance in the gills and gastrointestinal tracts was not significantly different. Microplastics in gills are strongly related to the filtration area of gills in 15 fish species. Fibers were the dominant shapes accounting for 93.45% of the total shapes. The majority of microplastics were <3 mm in size. The most common polymer composition was polyethylene terephthalate (38.2%) and the most common color was black (30.36%). The findings of this study provide baseline data for microplastic contamination in wild fish from an urban estuary.

Spatial variation of floatable plastic debris and microplastics in the Pearl River Estuary, South China

The estuaries of populated catchments have been documented as hotspots of plastic pollution. In this study, microplastics (0.355-5.0 mm) and large plastic debris (>5.0 mm) of surface water collected from the Inner Lingding Bay of the Pearl River Estuary (PRE) were quantified and categorized according to their size, shape, colour and composition. Both microplastics and large plastic debris were detected at all sampling sites with mean abundances of 2.376 ± 0.700 n/m³ and 0.110 ± 0.039 n/m³, respectively. Microplastics constitute 95.4% of the total abundance by number. The average microplastic concentration in the inner PRE was almost 3.5 times higher than that in the central PRE, indicating a positive correlation between plastic concentration and proximity to the river mouth. This result reveals the important role of rivers in transporting plastic debris from land to the oceans.

A meta-analysis of methodologies adopted by microplastic studies in China

China is the world's largest plastic producer and has been a focus of research on microplastic pollution. An increasing number of studies have documented plastics in the sediment, water and biota of China over the past decades. This systematic review compares different methodologies adopted by microplastic studies in China, including sampling equipment and methods; laboratory procedures in microplastic extraction and identification; and the characterisation and quantification of particles. In general, sediment samples were primarily collected with a grab sampler, while water samples were mostly taken from the surface using trawl nets. Different techniques, including density separation, chemical digestion, sieving and filtration, were applied to extract microplastics from the sample matrix. Visual sorting was an obligatory step that identifies microplastics by their morphological characteristics, such as size, shape and colour. Most studies in China reported the prevalence of irregular-shaped particles with sizes smaller than 1 mm. The chemical properties of microplastics were also assessed using infrared and Raman spectroscopy. Quantitative units commonly used for sediment, water and biota samples were "items per kg", "items per m³" and "items per individual", respectively. The inconsistencies in methods have marked the urgent warrant of a standardised methodology. It is believed that the findings of the present review can serve as an important waypoint contributing towards a more efficient and long-acting methodology for microplastic research, that can enable meaningful inter-study comparisons.

Contingent valuation of dolphin watching activities in South China: The difference between local and non-local participants

Ecotourism has seen both demand and attention increase globally and locally. Dolphin watching tours, as a type of nature-based activity, have become popular in Tai O of Hong Kong. However, little attention has been paid to the quality and pricing of the tour operators in relation to the expectations of visitors. This study seeks to understand the willingness to pay (WTP) of local and non-local visitors and the relationship between WTP and environmentally responsible behavioural intentions (ERBI) and satisfaction. The key findings include a positive correlation between WTP and ERBI for local visitors and a positive correlation between WTP and satisfaction for non-local visitors. These differences between local and non-local visitors are the result of the affective connection of local visitors to the environment, as such connection is not found among non-local visitors. These findings provide important clues to help improve pricing strategies and service quality towards achieving a sustainable ecotourism industry in Hong Kong, and they offer implications for ecotourism elsewhere.

Occurrence and distribution of microplastics in an urban river: A case study in the Pearl River along Guangzhou City, China

Microplastics, as emerging contaminants in the global environment, have become a cause for concern for both academics and the public. The present understanding of microplastic pollution is primarily focused on marine environments, and less attention has been given to freshwater environments, in particular, to urban rivers. In this study, microplastics were sampled from surface water and sediments in 14 sites located in the lower course of the Pearl River. These sampling sites are located along Guangzhou of South China, with built-up areas being the dominant land use. The abundances of microplastics in surface water and sediments ranged from 379 to 7924 items·m^-3 and 80 to 9597 items·kg^-1, respectively. Polyethylene and polypropylene were the common types of microplastics, together accounting for 64.3% and 73.8% of surface water and sediment samples, respectively. Fibers were the dominant microplastic shapes in both water and sediment samples. The abundances of microplastics varied in surface water and sediments with each site, which might be affected by multiple factors. Our results indicated that wastewater treatment plants (WWTP) could reduce microplastics from municipal sewage which was finally discharged into the Pearl River along Guangzhou.

Occurrence and Composition of Microplastics in the Seabed Sediments of the Coral Communities in Proximity of a Metropolitan Area

In marine environments, microplastics have become a focus in scientific research in the last decade due to the global threat this pollutant poses to the marine environment. Corals in Hong Kong are under threat due to the degradation of the marine environment caused by human activities. This study investigated the occurrence, abundance and composition of microplastic debris (0.3⁻5 mm) in seabed sediments adjacent to coral communities in Hong Kong. Twenty-four benthic sediment samples were collected from four study sites located along the northeastern and eastern shores of Hong Kong. Microplastic concentrations ranged from 169 ± 48 to 221 ± 45 items/kg, and the mean concentration of microplastics in the seabed sediments was 189 ± 50 items/kg, which was comparable to similar studies in other regions. Microplastics accounted for 95.4% of particles extracted from benthic sediment samples using 40× light microscopy. ATR-FTIR spectroscopy analysis showed that polyethylene (PE) and polyethylene terephthalate (PET) comprised the majority of polymer types, contributing 45.3% and 29.3%, respectively. The proportion of microplastics made from PE and PET in seabed sediments was significantly higher than that observed in local beach sediments. The proportion of microplastics made from PE and low-density polyethylene (LDPE) and polypropylene (PP) together in the seabed sediments was much higher than that of PET and polyvinyl chloride (PVC). The results have provided information with reference to environmental concentrations of microplastics for fringe reef habitat close to urban areas, which can be applied in studies concerning ecotoxicity of microplastics.

Spatio-temporal comparison of neustonic microplastic density in Hong Kong waters under the influence of the Pearl River Estuary

Rivers are recognised as an important source of plastic debris in the open sea. The Pearl River in China is estimated to transport 0.1milliontonnes of plastic waste to the open sea annually. However, no empirical study has been conducted to assess the plastic contamination levels in the Pearl River Estuary. Hong Kong is situated in the east of the Pearl River Estuary; its western waters are strongly influenced by river discharge, whereas the eastern waters are unaffected by the freshwater plume. In this study, we quantified the neustonic plastic debris density in the western and eastern waters of Hong Kong. The mean microplastic (0.355-4.749mm) and large plastic debris (≥4.75mm) densities in the western side were 3.627 and 0.758n/m³, respectively. Seasonal comparisons indicated that both size classes of plastic debris were significantly more abundant by number in the rainy season than the dry season (p<0.001). However, the influence of rivers on plastic density at the sea surface may be highly restricted to the estuarine delta, as no significant spatial difference was found between the western and eastern waters.

Microplastic Contamination of Wild and Captive Flathead Grey Mullet (Mugil cephalus)

A total of 60 flathead grey mullets were examined for microplastic ingestion. Thirty wild mullets were captured from the eastern coast of Hong Kong and 30 captive mullets were obtained from fish farms. Microplastic ingestion was detected in 60% of the wild mullets, with an average of 4.3 plastic items per mullet, while only 16.7% of captive mullets were found to have ingested microplastics, with an average of 0.2 items per mullet. The results suggested that wild mullets have a higher risk of microplastic ingestion than their captive counterparts. The most common plastic items were fibres that were green in colour and small in size (<2 mm). Polypropylene was the most common polymer (42%), followed by polyethylene (25%). In addition, the abundance of microplastics was positively correlated with larger body size among the mullets.

Characterisation of plastic microbeads in facial scrubs and their estimated emissions in Mainland China

Plastic microbeads are often added to personal care and cosmetic products (PCCPs) as an abrasive agent in exfoliants. These beads have been reported to contaminate the aquatic environment and are sufficiently small to be readily ingested by aquatic organisms. Plastic microbeads can be directly released into the aquatic environment with domestic sewage if no sewage treatment is provided, and they can also escape from wastewater treatment plants (WWTPs) because of incomplete removal. However, the emissions of microbeads from these two sources have never been estimated for China, and no regulation has been imposed on the use of plastic microbeads in PCCPs. Therefore, in this study, we aimed to estimate the annual microbead emissions in Mainland China from both direct emissions and WWTP emissions. Nine facial scrubs were purchased, and the microbeads in the scrubs were extracted and enumerated. The microbead density in those products ranged from 5219 to 50,391 particles/g, with an average of 20,860 particles/g. Direct emissions arising from the use of facial scrubs were estimated using this average density number, population data, facial scrub usage rate, sewage treatment rate, and a few conservative assumptions. WWTP emissions were calculated by multiplying the annual treated sewage volume and estimated microbead density in treated sewage. We estimated that, on average, 209.7 trillion microbeads (306.9 tonnes) are emitted into the aquatic environment in Mainland China every year. More than 80% of the emissions originate from incomplete removal in WWTPs, and the remaining 20% are derived from direct emissions. Although the weight of the emitted microbeads only accounts for approximately 0.03% of the plastic waste input into the ocean from China, the number of microbeads emitted far exceeds the previous estimate of plastic debris (>330 μm) on the world's sea surface. Immediate actions are required to prevent plastic microbeads from entering the aquatic environment.

Size distribution of stranded small plastic debris on the coast of Guangdong, South China

Beach environments are known to be conducive to fragmentation of plastic debris, and highly fragmented plastic particles can interact with smaller organisms. Even through stranded plastic debris may not interact directly with marine organisms, backwash processes may transport this debris back to coastal waters, where it may affect a wide range of marine life at different trophic levels. This study analysed the size distribution of stranded plastic debris (<10 mm) collected from eight coastal beaches in Guangdong Province, China. Polystyrene (PS) foams and fragments smaller than 7 mm were increasingly abundant in the smaller size classes, whereas resin pellets remained in their production sizes (∼3 mm). Microplastics (<5 mm) accounted for over 98% of the total plastic debris by abundance and 71% by weight, indicating that the plastic debris on these coastal beaches was highly fragmented and the majority of the plastic masses belonged to the microplastic size range. The observed size distributions of PS foams and fragments are believed to result from continued fragmentation. Previous studies found that the residence time of beached debris was less than one year on average, and no sign of plastic accumulation with depth in beach sediment was observed. Therefore, coastal beaches may represent a reservoir of highly fragmented and degraded microplastics that may be mobilised and returned to the sea during storm events. Further research on the dynamics and longevity of microplastics on beaches will help reveal the mass balance of microplastics on the shoreline and determine whether shorelines are sinks or sources of microplastics.

Plastic waste in the marine environment: A review of sources, occurrence and effects

This review article summarises the sources, occurrence, fate and effects of plastic waste in the marine environment. Due to its resistance to degradation, most plastic debris will persist in the environment for centuries and may be transported far from its source, including great distances out to sea. Land- and ocean-based sources are the major sources of plastic entering the environment, with domestic, industrial and fishing activities being the most important contributors. Ocean gyres are particular hotspots of plastic waste accumulation. Both macroplastics and microplastics pose a risk to organisms in the natural environment, for example, through ingestion or entanglement in the plastic. Many studies have investigated the potential uptake of hydrophobic contaminants, which can then bioaccumulate in the food chain, from plastic waste by organisms. To address the issue of plastic pollution in the marine environment, governments should first play an active role in addressing the issue of plastic waste by introducing legislation to control the sources of plastic debris and the use of plastic additives. In addition, plastics industries should take responsibility for the end-of-life of their products by introducing plastic recycling or upgrading programmes.

Seasonal variation in the abundance of marine plastic debris in the estuary of a subtropical macro-scale drainage basin in South China

Marine plastic debris, including microplastic debris (0.315-5mm) and large plastic debris (>5mm), was collected from 25 beaches in Hong Kong during a wet summer season (June-August 2014) and the following dry winter season (January-March 2015). Wilcoxon signed rank tests were used to compare the abundances and weights of seven categories of plastic debris between the two seasons. The results showed that the abundances and weights were significantly higher (p<0.05) in the wet season than in the dry season. Additionally, seasonal differences were detected only at the sites that were located on the west coast of Hong Kong and not at the sites on the east coast. These results suggest that the Pearl River Estuary on the west of Hong Kong plays a prominent role in the abundance and distribution of plastic debris in Hong Kong. In addition, the study indicates that estimates of microplastic abundance may be biased if samples are collected only during the wet or dry season if the sample locations are strongly influenced by a seasonal variation of riverine inputs, such as from the Pearl River.

Evidence of microbeads from personal care product contaminating the sea

Plastic microbeads in personal care products have been identified as a source of marine pollution. Yet, their existence in the environment is rarely reported. During two surface manta trawls in the coastal waters of Hong Kong, eleven blue, spherical microbeads were captured. Their sizes (in diameters) ranged from 0.332 to 1.015mm. These microbeads possessed similar characteristics in terms of colour, shape and size with those identified and extracted from a facial scrub available in the local market. The FT-IR spectrum of the captured microbeads also matched those from the facial scrub. It was likely that the floating microbeads at the sea surface originated from a facial scrub and they have bypassed or escaped the sewage treatment system in Hong Kong. Timely voluntary or legislative actions are required to prevent more microbeads from entering the aquatic environment.

Hong Kong at the Pearl River Estuary: A hotspot of microplastic pollution

Large plastic (>5mm) and microplastic (0.315-5mm) debris were collected from 25 beaches along the Hong Kong coastline. More than 90% consisted of microplastics. Among the three groups of microplastic debris, expanded polystyrene (EPS) represented 92%, fragments represented 5%, and pellets represented 3%. The mean microplastic abundance for Hong Kong was 5595items/m(2). This number is higher than international averages, indicating that Hong Kong is a hotspot of marine plastic pollution. Microplastic abundance was significantly higher on the west coast than on the east coast, indicating that the Pearl River, which is west of Hong Kong, may be a potential source of plastic debris. The amounts of large plastic and microplastic debris of the same types (EPS and fragments) were positively correlated, suggesting that the fragmentation of large plastic material may increase the quantity of beach microplastic debris.