Trawling for solutions

Hi there, welcome back to standing room only.

To reduce that Tryptophan induced coma resulting from 3 days of constant turkey intake let's dive right in with some positivity regarding our impacts on the marine environment of Hong Kong:

WWF-Hong Kong has been at the vanguard of environmental impact issues for 33 years and has been partially responsible for many of the environmental reforms across Hong Kong. Its Save Our Seas (SOS) campaign saw a focus on the protection of marine biodiversity. Perhaps the most prevalent result of the SOS campaign is the instigation of a trawling ban inside HK waters. Between 2004 and the ban's commencement on the 31st of December 2013 the SOS campaign applied concerted pressure on the Hong Kong SAR government through a program of public petitions and open letters from highly regarded members of academia (WWF-HK open letter) all aimed at raising awareness of the marine environments fragile state and providing researched evidence that changes need to be made quickly.

"The ban increases the public’s interest in and commitment to the sea. It will have a major positive impact on the whole ecosystem. Banning trawling is the best single action to help Hong Kong’s fishery on the road to recovery. It also shows that the government is beginning to listen to stakeholders other than the fishermen."

Prof. Yvonne Sadovy, Department of Ecology and Biodiversity, The University of Hong Kong (WWF-HK Save Our Seas supplement, 2011).

Prior to the trawling ban the management of fishery practices around Hong Kong was pretty minimal. Not surprising when we consider that, as noted in our initial fisheries post, after WW2 the primary focus for Hong Kong was to rebuild and enhance its fishing fleet in order to fulfil the growing demand for fresh fish in an increasingly competitive market (Cheung and Sadovy, 2005). Until relatively recently there simply wasn't a whole-hearted consideration of the sustainable nature of new fishery practices being adopted in HK and the situation manifested itself as a decrease in overall capture fisheries since the 1980s. In a broader perspective Hong Kong was suffering an exaggerated version of  the contemporary decreasing trend observed globally by Pauly et al (2002) whereby increasing fishery technology and expansion of fleet size resulted in over-exploitation of fishery resources and a major drop in the actual number of fish being caught per trip.

Cheung and Sadovys (2005) determination of  the variations of 'Total inshore landings' (total quantity of fish caught) and the  Catch Per Unit Effort (CPUE, basically how many fish were caught per trip compared to 1950 catches) in Hong Kong waters between 1950 and 1997.  

"Throughout the 1950s and 1960s, this huge increase of global fishing effort led to an increase in catches ... encouraging an entire generation of managers and politicians to believe that launching more boats would automatically lead to higher catches."

Shots-fired! Pauly's (2002) rhetoric places the blame for global over-exploitation of fishery resources squarely at the feet of the upper-echelons of power. 

The exclusion of Hong Kong waters to trawling practices is hoped to allow the local aquaculture to restore itself to its former glory. Samantha Lee, Senior Marine Conservation Officer for WWF-Hong Kong, expects marine stocks to recover by up to 30% inside of 5 years (Marine Science Today, 2013).

As well as increasing in numbers the decline in the mean-trophic value of catches, caused by the loss of larger slow growing species and highlighted in Mortons editorial (2005), is also estimated to reverse itself with a 10-20% increase over 5 years (WWF-HK 'submission to the Legislative Council', 2011: page 3).

Only time will tell if these changes can be maintained and have their desired effects, but for now I personally think that we can take this as evidence that the human race is beginning to take responsibility for its impacts and invest seriously in taking steps to lessen and hopefully reverse them.

TED Talk Time

Hi there,

Thought I'd throw a quick movie your way; 4 years ago Johan Rockström, a professor at Stockholm University and (at the time of filming) the executive director of the Stockholm Resilience Centre, gave a TED talk describing his 9 recently identified 'Planetary Boundaries'.

The boundaries represent limits on human impacts on the environment. Johan explains within these limits the earth can remain at a level that maintains our current global environmental state, whilst exceeding these limits (or possibly only a number of them) could cause an abrupt change in the global environmental state from which it is likely we could never return.

The talk immediately identifies human population growth as a primary pressure on the earth's environmental conditions and the identified planetary boundaries encompass the majority of the topics we have investigated so far. Although his talk takes a much wider global and temporal viewpoint than that of this blog, I think its a great piece of media that conveys how the issues we are investigating all contribute to a much larger problem.

Interestingly, although perhaps unsurprisingly, Johan suggests that many aspects of human impact need to be initially addressed on a smaller cultural scale which will then allow incremental improvements of our environmental impacts to combine and result in global scale changes. I think this is a valid observation; the solutions to excess nutrient pollution and fishery resource exploitation impacts I mentioned in earlier posts both appear to have their beginnings at grassroots level. Guidelines for the control of agriculturally derived water pollution, released last year by the FAO, noted that there has been ''considerable success'' (Food and Agriculture Organisation of the United Nations - Water Pollution Guidelines, page 13: 2013) in decreasing nutrient pollution through educating farmers in best practises and demonstrating financial savings through lower, correctly timed applications of fertiliser.

As yet we haven't broached the subject of 'reducing impacts' but I think this video offers us a great excuse to start looking at the more positive side of the subject in my next post.

Take care and don't stress about Christmas shopping to much.

Blooming Hell!

Hello again,

Today's post is going to be a little different and self indulgent; as a member of the Environmental Modelling MSc course at UCL I was particularly interested in a paper I referenced last week by Lai and Yin (2014). The paper investigated the potential for Algae Blooms to derive from physical accumulation via the application of a coastal circulation model.

Typically, algae blooms are considered to result from excess agricultural nutrients entering the aquatic system and promoting the growth of diatoms or other single celled algae to an exaggerated level (eutrophication). As the concentrations of algae increase they reach toxic levels (referred to as 'Harmful Algae Blooms' or HABs), ingestion of which can increase mortality rates of marine life and cause illness in those that eat the affected fish/shellfish etc. Backer and McGillicuddy's (2006) study on the relationship between humans and the ocean contains a plethora of illnesses that can be caused by ingestion, although I wouldn't advise reading it if you're at all partial to seafood!

Delicious! a glass of Microcystis bacteria (this is a surface sample of a HAB affected freshwater lake). These bacteria excrete neuro-toxins which can kill humans (Oberholster et al, 2004). Photo credited to T. Bridgeman in (Backer and McGillicuddy, 2006). Presumably Mr Bridgeman is no longer with us.

Lai and Yin's (2013) study theorised that, aside from nutrient pollution, blooms can arise from a combination of physical factors causing an accumulation of the single celled algae. Their theory was based on observations in Port Shelter bay in north-east Hong Kong; the bay suffers from frequent HAB's of Dinoflagellates that tend to occur in the same area each time (a band mirroring the coastline). Water samples from the bay indicate that nutrient levels are too low to produce a eutrophication event and hence a second, physical factor seemed likely.

In order to understand the complex mechanisms at play a Finite Volume Community Ocean Model (FVCOM) was used in combination with a series of water samples that were taken during a bloom event and identified Algae concentrations. The model was utilised in 3 experiments, each increasing in complexity by the application of new variables, with assessment of the potential for aggregation:

• Experiment 1 involved two model runs: Both utilised the morphology of the coastal region and the effects of the tidal forcing on the movement of algae in the bay. However, 1A was performed under a homogenous water profile (basically ignoring the effects of changing temperture and salinity levels based upon water depth), whilst the 1B was performed under a stratified water profile whereby the temperature and salinity (which both affect algae concentrations) were utilised to aid aggregation of the Dinoflagellates.
• Experiment 2 maintained the stratified water profile and tidal forcing but included the effects of wind conditions on the surface of the water.
• Experiment 3 enhanced Experiment 2 with the inclusion of the ability for the Dinoflagellates to swim upwards, against flow in order to promote photosynthesise. This ability results in amplified accumulation as the flagellates are suspended in the same location, swimming against the current, for longer periods of time.

The experiments proved that by applying several variables:

• An accurate approximation of the coastal topography
• Tidal forcing
• Wind effects
• A stratified, saline/temperature dependent water profile
• A potential for the modelled particles (in this case the Dinoflagellatte algae) to vertically migrate towards the surface

The FVCOM model can simulate the physical aggregation effects observed across Port Shelter bay! Woohoo! Modelled cross-sections across portions of the bay that have been observed to contain HAB's clearly indicate that there is a convergence of currents (and hence Dinoflagellates).

Cross sections of the modelled bay indicating convergence of currents. Larger arrows on the surface indicate position of observed HABs whilst smaller arrows indicate current direction (Lai and Ying, 2014. page 73).

Cartoon representation of the modelled process (Lai and Ying, 2014. page 74).

I hope this sortie into my preferred discipline has given you a little more insight into how we can begin to enhance our understanding of the environment. I feel that mitigation of human impacts on the environment must begin with a good understanding of how the environment works and how our impacts actually affect it. As we have seen in this post, natural processes can cause similar outcomes as those derived from humans. Without this further investigation we may have assumed that such HAB events are solely due to our influence, giving us a misguided sense of our impact.

As a thanks for joining me again, here's another Harmful Bloom.

Courtesy of lotr.wikia.com.

Teach a man to fish a lot!

Hi there, welcome back.

Last week we had a run through the evolution of Hong Kong's fishery practises over the last 80 years. We observed that Hong Kong's fishing fleet evolved from low tech, mostly wind powered, vessels to a predominantly mechanised fleet. This mechanisation, and the newer fishing practises that it enabled, resulted in yearly increases in fishery yields. Although these increases are associated with an actual decrease in per unit yield (basically catches are becoming smaller so an increased number of catches is require to meet the demand).

This post is going to have a quick look at three dominant fishery methods utilised by the Hong Kong fleet:

Gei Wai (fish ponds):

Gei Wai are large bunded ponds that can be either replenished tidally or through deviation of freshwater sources dependent upon the culture (Lai et al, 1999). They are effectively nurseries where young fish, shrimp etc. are introduced and allowed to mature in a relatively protected, and easily farmed habitat (www.wwf.org, 2014).

As I'm sure you've already realised, this method requires a large areas of coastal land (perpetually at a premium in Hong Kong) and as such the practise is slowly being ousted in favour or less spatially demanding methods. Gei Wai now predominately survive in the very northern portion of the new Territories (Lai et al, 1999) on government owned land.

Marine Culture Cages:

Culture cages are large, fine grated cages suspend from rafts in coastal waters. The practise was adopted in the 1960s after growing population demands required a greater output from marine resources.

Gei Wai and Fish Culture Zones in 1998, courtesy of www.afcd.gov.hk.

Although the method thrived for approximately 20 years (Morton, 2005) this flourishing new industry couldn't sustain itself for very long. Typically the farms were situated in protected environments (shallow coastal bays etc.) in order to allow the livestock to growth as quickly and easily as possible.

However, the low current energy of these protective areas prevented the excess chum and supplements that were fed to the fish from being transported away from the farm area resulting in a rising levels of local nutrient pollution.


The increasing levels of marine population deriving from Hong Kong's rising population also had a severe impact on Cage fishery. Perhaps most notable impact event is the 1998 'Red tide': a significant algae bloom swept across Hong Kong and decimated caged cultures and corals. The bloom affected 25 of the culture zones in HK and resulted in a loss of approximately 2,500 tonnes of fish culture at an estimated HK$250,000,000 impact on the Hong Kong economy (Yang et al, 2003).

Capture fisheries:

A quick referal to the ever useful 'Hong Kong: The Facts' government released fact sheet (www.gov.hk, 2014) gives us a summation of Hong Kong's modern fisheries fleet:

• 33% of vessels are >15m and carry out activities outside HK local waters, along the northern continental shelf of south china sea: Trawling, Line fishing and Gill netting.
• The remaining two thirds of the fleet comprise smaller vessels whose activities are generally carried out inside HK local waters (Gill-Netting, Line fishing, Purse Seiners and Cage Trapping).

For the sake of brevity I am going to focus on, arguably, the most impactful of these capture methods: Trawling. I feel that the other techniques, whilst clearly impacting the environment, can pretty much be regarded as a single entity that represents the exploitation of shallow marine ecology. Although many of the techniques are similar to trawling, they typically do not disturb the seabed envrionment to the same degree.

The trawling method involves dragging large nets across, or near, the seabed in order to catch fish and Crustacea.

Basic trawling method, courtesy of web.duke.edu.

The environmental impacts of trawling have long been recognised (Van Dolah et al, 1987) and consist of two primary effects:

• Huge plumes of sediment are disturbed by the nets. Similar to the side effects of reclamation the spread of the disturbed sediment can spread across huge areas preventing phytoplankton photosynthesis (Yan et al, 2013). Fish species also have 'varying tolerances of suspended solids' (Newell et al, 1998. Page 25) and may suffer clogging of the gills eventually preventing feeding and causing death.
• The second impact is a much more obvious and severe matter; the act of dragging a net (complete with ballast to maintain negative buoyancy) literally scours a path across the sea floor destroying habitats in its way. Coral reefs are particularly susceptible to this destruction due to the slow growth rate. Years of growth can be removed in a single pass (Hall-Spencer et al, 2002).

The severity of trawling impact on marine ecology is such that in early 2013 the practice was banned inside HK local waters, given Hong Kong's establishment and ubiquitous association with fishery practises the acknowledgement of trawling's destructive capability was a huge step. An article, released on the day of the bans commencement by the South China Morning Post (www.scmp.com, 2013) stated that HK$1.7 billion were due to be paid out as compensation to affected companies and fishery families.

Above is a quick Youtube clip issued by www.seafish.org. It's not an immensely exciting clip but I think it really allows you to comprehend just how much damage trawling could do across delicate marine ecologies. Scary!

Teach a man to fish

Unsurprisingly, a major reason for Hong Kong's original settlement and early expansion is due to it's exceptional marine resources. The East China Sea, South China Sea and freshwater outflow from the Pearl River provide large expanses of varied aquaculture.

The increasing population of Hong Kong and its demand for these fishery resources has resulted in their severe over-exploitation with little to no evidence of improvement. A study, commissioned by the Agriculture, Fisheries and Conservation Department of the HK government, identified that over the last 25 years catches have decreased by almost 50%. In addition 12 of 17 commercial species in HK waters have been identified as being "heavily over-exploited" whilst the remaining 5 species are "fully exploited". The study is referred to in  the Fisheries Protection (Specification of Apparatus) (Amendment) Notice (2011) by LegCo (Hong Kongs Legislative Council), although the original document seems to be elusive, if you come across it please let me know.

Perhaps its the years I spent in my previous discipline of archaeology speaking but I feel that to appreciate the current state of affairs we really need to step back a little and take a quick look at how HK reached this situation. An article by Morton (2005) describes HK fisheries evolution from larger, slow growing species that are worth more to smaller, faster growing species that are worth less. The article, whilst not referenced, touches upon some of the land marks in this evolution, with a little fleshing out we can develop clearer idea of how the HK's fleet has evolved:

• The 'Fisheries Research Unit' (FRU) was conceptualised in the late 1930's (Morton 2005), although the its official establishment appears to have occured some 20 years later (Mellor 1981, pg 198). The FRU's aim was to determine how HK's technologically inferior fishing fleet could compete with Japans relatively mechanised, larger fleet which shared portions of the same waters and targeted the same species, effectively directly competing with China and HK for marine resources.

Late 19th Century Chinese fishing 'Junk', Courtesy of hongwrong.com

• The 2nd Sino-Japanese war saw the occupation of China. During this time the Japanese possessed a monopoly on fishery resource exploitation in the East China Sea. As a result supplies of fresh fish to HK were reduced to near zero (and as we have already seen Hong Kong is heavily dependent on imports from China). HK fishery was forced to deal with an overnight increase in demand, fairly at odds with its current, at the time, methods.
• However, Japanese occupation of HK towards the end of the war sparked a technological renovation of the local fishing fleet allowing  larger catches from larger areas to be acquired (Morton 2005).
• In 1960 a refreshed governmental focus on the state of HK's fleet began. The government assumed control of, and invested in,  the FRU (Chan et al, pg 4: 1996). Representing an official governmental recognition of the potentially troubling situation. This governmental interest and investment continued steadily for around twenty years.
• After governmental intervention the catch totals of the HK fleet were noted to rise annually from 53,000 to 224,000 in 1990. However, whilst fishery totals increased year on year it is reported that the catch per capita began to steadily decline from the late 1980's onwards. These declines are noted not only in Hong Kong but worldwide. Anderson et al's (2011) studies of trends in the expansion of invertebrate fisheries reflects Mortons conclusions of a declining trend in marine catches, albeit on a global scale, noting that total catches of marine invertebrates rose from 2 million in 1950 to 12 million present day (2011). Whilst the factors governing each decline are not identical (as we may venture into next time) they both involve a core theme of increased activity and exploitation reaching a tipping point, beyond which the environment cannot cope with the strain.

Join me next time when we will take a look at the methods that Hong Kong utilised during the enhancement of its fisheries.

After reading Anderson et al's (2011) on invertebrate fishery trends I started to read up on Sea Cucumbers.... I urge you to do the same: LOOK HOW CRAZY THEY ARE!

Courtesy of NationalGeographic.com

Land Reclamation

Welcome back, I'm assuming you're here for more porpoise and dolphin pics? Ok, but not until we've explored some of our impacts on their marine environment!

The  population, commercial and industrial expansion of Hong Kong, particularly over the last 60 years, has resulted in a degradation of its coastline and marine environment. Perhaps the most notable activity that has caused this degradation is Land Reclamation.

As we identified early on in this blog, Hong Kong possesses a huge, expanding population that is requiring more and more land in order to live, work and survive. To fulfil this demand Hong Kong has frequently utilised land reclamation techniques.

What?

Simply put, it is the building up of the sea bed to create an above sea-level surface that is stable enough for further construction or other development. There are various methods used for achieving this build up but broadly speaking they involve the replacement of the soft silt sediments on the seabed with large deposits of rocks (Yan et al, 2013).

When?

The earliest reports of land reclamation in China originated from the Western Han Dynasty where coastal areas were reclaimed in order to create terraces for the recovery of salt from sea water.
Modern reclamation, as we would consider it (i.e. the creation of land for industry etc), began in Hong Kong during the mid 19th Century (Jiao, 2000) shortly after the beginning of the British occupation. Large areas of marshland close to the harbour were bought and reclaimed by traders wishing to create easy access to the harbour.

Since those initial projects, land reclamation has been undertaken on much larger scales culminating in an estimated 10% increase in land surface across Hong Kong by 2000. Furthermore, this increase is due to accelerate with the recent commencement of several larger scale industrial projects (Jiao et al, 2000). The graphic below gives an impression of how reclamation projects have advanced from their humble beginnings and have predominantly been focused on both sides of Victoria harbour with more recent undertakings towards the western edges of Lantau and the New territories.

Estimates of the evolution of land reclamation across Hong Kong, courtesy of www.scmp.com

Where?

Two of the most recent reclamation projects carried out (and in fact still being carried) in Hong Kong are the construction of the HK International Airport and the construction of the Macau-Zhuhai-Hong Kong Bridge:

Hong Kong International Airport

Take another quick look at our 'evolution of land reclamation' graphic; you see the huge area on the northern edge of Lantau? That's the site of Hong Kong's newest airport and home to over 12km^2 of reclaimed land, Hong Kong's largest, completed reclamation project so far (Plant et al, 1998).

If you're desperate for a little more on reclamation methods here's a link for a promo video released on Hong Kong International airports offical youtube channel, I won't embed the video because its seriously cheesy and saccharine with the positive (marketing) aspects of reclamation, but it does offer a brief synopsis of the reclamation project: HK Airport Reclamation.

Hong Kong - Zhuhai - Macau Bridge (HZMB)

A little further west from the airport is the bridge project which aims to be the first step in connecting three of the largest population centres of the Pearl River Delta (China's industrial centre) through a combination of bridge and tunnel networks. A large portion of this project is the creation of a series of new islands.

Preparatory construction work for the bridge commenced in late 2009 and has a predicted completion data of 2016  (ARUP website, 2010) .

Route of the New bridge, courtesy of www.NCE.co.uk

Impacts

It seems logical that the deposition of 1000s of tons of material into a coastal area is perhaps one of the most powerful impacts to which we could subject a marine environment.  Jefferson et al, (2009) created an informal hierarchy of  'development activities' associated with the industrialisation of Hong Kong and their respective impacts on the marine environment which placed land reclamation at the top of the list.

Those of you who tuned in last week may also notice that these two examples are placed, at least partially, within the same zone that the WWF Hong Kong identified as containing White Dolphin populations. Hung et al (2004) confirm that the ranging area of the dolphin populations identified across the Pearl River Estuary extend across western Hong Kong waters, although they go on to state that further investigation of true numbers are required. Regardless, it is clear that the reclamation being undertaken for these projects will have an impact upon these local cetacean populations.

Aside from the complete removal of swathes of environment, there are additional impacts relating to the upcast sediments and potential contaminants sealed within these deposits. Yan et al (2013) provide a case study for the future off-shore airport at Jinzhou Bay that models the impacts of two reclamation methods: Underwater Explosion and Silt dredging.

• As the name implies the 'Underwater Explosion' method of soft silt removal is through the explosion of Trinitrotoluene (TNT) packages that are placed deep within the sediments. The explosion leaves the sediment, and any previously sealed contaminants suspended in the water allowing rock deposits, that were previously dumped on top of the sediment, to enter the newly cleared area. This method can have two catastrophic effects on marine ecology: the primary explosion can disorientate, or even kill marine life, particularly those that possess carefully balanced swim-bladders (Jefferson et al, 2009), within a given radius whilst the dense spread of suspended sediment can extend across huge areas destroying the ability of phytoplankton to photosynthesise and negatively affecting zooplankton growth (Yan et al, 2013).

• The 'Silt Dredging' method involves the construction of dredgers which suck up the silt and deposit it elsewhere. This method lacks the severe impact of the former, but possesses the same risk of disturbing contaminated sediments whilst also requiring an additional area for dumping of the extracted deposits.

A quick aside: for any Environmental Modelling MSc people out there I really recommend having a look over the case study I mentioned earlier (Yan et al, 2013). It's a good example of a modern project involving comparisons, predictions and evaluations through model application and is the kind of work that any of us may be involved with in the future.

And now, as promised....porpoises!

D'AAAAAW!!!! courtesy of www.china.org.cn

Won't somebody please think of the porpoises???

This post marks the introduction of a new theme here at standing-room-only: Impacts on Marine Ecology.

The 263 islands forming Hong Kong boast an incredible 733km of coastline leading to the expanse of the South China Sea. This setting provides an multitude of habitats for various marine fauna. WWF Hong Kong provides a great synopsis of marine biodiversity across the islands.

Perhaps the most noteworthy members of HK's marine ecology are the Chinese White Dolphin (Sousa chinensis) and the Finless Porpoise (Neophocaena phocaenoides). Whilst a total of 16 Cetacea species (Wikipedia) have been recorded in Hong Kong waters the White Dolphin and Finless Porpoise are the only members of this group that are spotted with enough frequency to be considered local species (Jefferson et al, 2009).

The Finless Porpoise, courtesy of the WWF.

• The Finless Porpoise is highly distinctive due to it lack of a dorsal fin (bet you didn't see that coming?), a unique trait amongst porpoises.

A distribution study carried out by Jefferson et al, 2002 observed that in the Hong Kong area the porpoises are limited to the southern and south-eastern waters and appear to traverse this area on a seasonal basis. It is thought that the porpoises' aversion to freshwater prevents their movement from straying further west where the freshwater outflow from the Pearl River Delta has a stronger influence on local salinity levels.  The study also notes that coastal areas with seasonally increased freshwater input (Southern Lantau island for example) cause the populations to avoid the area until salinity levels are recovered.

Between 1995 and 2000 the same study recorded that the abundance of the mammals in the HK area varied seasonally from approximately 55 observed members in autumn to over 150 in spring-time. It is thought that this fluctuation is caused by porpoise groups moving north-east into Chinese waters during the summer.

Chinese white dolphin, courtesy of actionasia.com

• The Chinese White Dolphin (also known as the Indo-Pacific Humpback Dolphin) has a light pink skin, a result of blood vessels close to the skin surface that are used to regulate the internal temperature of the mammal.

The White Dolphin appear to be the antithesis of the Finless Porpoise in regards to preferred habitat: they are present across all of Hong Kong's western waters and are rarely observed in HK's central-southern or south-eastern waters. The dolphin population is also known to extend north from western Hong Kong, following the freshwater influence of the Pearl River Estuary (Jefferson et al, 2009).

Further studies by the, now ubiquitous, Jefferson and Hung, 2004 recorded that although dolphin numbers in, and adjacent to, Hong Kong waters varied between 103 in spring to 193 in autumn, these variations were not reflected in the overall population. This suggests that, unlike the Finless Porpoise, the White Dolphin is a year round resident of HK waters.

The two species are known to coincide in just one area: the Soko Islands. Which may account for the recent government proposed plans to create a new marine park in the vicinity (Hong Kong Government, 2014).

Soko Islands (image courtesy of South China Morning Post). Read article here.

It is widely accepted that Hong Kong's marine ecology has suffered massive deterioration and is potentially on the verge of collapse (WWF website). The impact of large scale development across Hong Kong and China is negatively affecting, and in some cases completely obliterating the habitat for Cetaceans. Join me next time when we take a look at these impacts and how they are affecting the marine ecology.

Can't get enough Porpoises!

Agriculture 2 - Nitrogen: too much of a good thing?

Last time on Standing Room Only....

• Due to its lack of adequate arable land Hong Kong relies upon imports from China for 90% of its fresh food.
• Annually increasing applications of nitrogen chemical fertilisers (CF-N) allow China to supply not only its world leading population but export the excess to Hong Kong and numerous other countries.
• Of late China accounts for 30% of the worlds yearly total Nitrogen fertilisers (CF-N's) used.

and now Part 2...

Clearly using larger and larger amounts of CF-N can result in higher yields being produced more quickly and therefore enable multiple crop cycles within a time frame that previously would have only allowed a single harvest. 

The downside is that the efficiency of the fertilisers decreases substantially when greater volumes are applied: physical factors such as the proportion of nitrogen that a soil can retain and the methods used to apply the fertiliser place hard limits on how much nitrogen (N) is actually utilised by the plants. Perhaps it's a little easier to explain this by thinking in terms of a 'nitrogen balance' within a soil:

Known input of CF-N = N present within harvested crop + Unaccounted N. 

This unaccounted N is 'lost' through the crop process in a variety of manners,  Zhu and Chen, 2002 provide a great quantitative assessment of how this 'Unaccounted N' is distributed, although it's a little dry if you're not into numerous statistical comparisons etc. so here's my take on it:

• Up to a third of the applied N is retained in the soil. This proportion is dependent upon crop type, irrigation and the history of N application (longer periods of fertiliser use result in greater accumulation of N). Potentially this retained nitrogen can be used up by the next crop cycle but only if the N remains in the root zone.
• Potentially a fifth of the CF-N can leach out of the root-zone (again this is highly dependent upon soil type, depths, irrigation etc). Predominantly this leaching occurs during the crops' initial growing process when there is a lot of water flowing through the ground but the plants have not developed sufficiently to use the majority of the fertiliser. 
• A small amount of the excess nitrogen can be lost due to above ground run-off. As with leaching this generally occurs early on in the crop cycle, flooding or excess irrigation carries nitrogen rich silts away from the crop-land and into local watercourses.
• The primary cause of nitrogen loss is denitrification and may account for up to a massive 50% of unaccounted nitrogen. Dentrification refers to the the microbial reduction of CF-N producing gaseous emissions which are subsequently lost to the atmosphere.

Visual representation of the nitrogen balance courtesy of the FAO.

So, we know that the application of increasing quantities of CF-N can lead to larger quantities of N escaping the agricultural system and reaching the natural environment. Now we need to consider what are the effects of dumping an excess of nitrogen into a carefully balanced ecosystem?

We've seen that the unaccounted N is basically transported in two ways: hydrologically (leaching and run-off) and through gaseous emission (denitrification). 

Hydrologically lost CF-N have an incredibly high chance of reaching local water systems where they can cause large scale contamination.  This form of contamination is so common and wide spread that the World Health Organisation denotes agricultural application of nitrogen as a primary cause for nitrate water pollution (WHO, 2011). They go on to state that drinking water sourced from agricultural areas often exceeds 50mg/l (that's 5 times the level generally observed from drinking water derived from surface water in non agricultural areas). 

Nitrogen that finds its way into lake systems also leads to a substantial increase in 'Algae Blooms'. The eutrophication of algae has a hugely destructive effect on lake ecology and is potentially irreversible in some cases (Carpenter et al, 1999).

Chemical fertilisers (including CF-N) causing eutrophication and its resultant impact on lake ecology. Courtesy of sciencebitz.

The major emissions resulting from microbial reduction of CF-N (denitrification) are nitric oxide (NO), nitrous oxide (N2O) and di-nitrogen (N2) (Zhang et al, 2009).  Perhaps the most important of these to consider within the scope of this blog is nitrous oxide. Emissions of N2O are a major contribution to the greenhouse effect (which is widely documented so let's not dive into its intricacies at the moment) Wikipedia. Although agriculturally derived quantities of nitrous oxide are currently considered to be relatively low (around 0.2kg N/ha./year) the amount is increasing each year (Kim et al, 2007). More importantly the IPCC has predicted that N2O has nearly 300 times the global warming potential of CO2 over the next 100 years!

OK, I feel that we've identified that we have the ability to drastically enhance a soil's naturally sustainable output to a level that can cope with the demands of an ever increasing population. We've also determined that this prolific productivity comes with a price: two significant impacts upon the environment. Let's put a pin in agriculture for now so that next time we can explore some other environmental impacts caused by an increasing population.

Even Paul Walker and Vin Diesel are obsessed with NOS (Nitrous oxide for the uninitiated)!

P.S....

If you fancy a bit of further reading Gruber and Galloway, 2008 have an informative and accessible article in 'Nature' that explains some more of the nitrogen cycle. I strongly recommend checking it out.

Agriculture Part 1

Hi, welcome back.

Last time I, hopefully, gave you an impression of where this blog would take us as well as a few facts and figures to get us rolling. Today I’d like to introduce my first theme in environmental impacts of an increasing human population…..AGRICULTURE.

Hong Kong has a total area of approximately 1100km² consisting of Hong Kong Island, Kowloon Peninsula and the New Territories (including Lantau Island and over 260 smaller islands). The Hong Kong Government estimate that only a quarter of the total area represents ‘developed’ land and it is within this 275km² that the majority of Hong Kong’s 7.2 million strong population live and work.

A false-colour satellite image of Hong Kong depicting developed (pink) and natural (green) landscapes (Courtesy of Wikipedia, annotated by the author).

Clearly the areas of ‘developed land’ are predominantly highly urbanised or industrialised in order to accommodate the local population. Unfortunately outside of this area Hong Kong’s geography mainly comprises mountainous topography that prevents the development of large scale agricultural activity. It is estimated that at the beginning of 2014 there was only 7km² of active farmland in the whole region! (Hong Kong Government, 2014).

So how do they pick up the slack? They look to the north...CHINA! According to the HK Food and Health Bureau 90% of their fresh food is sourced directly from China.

Currently, and historically, China possesses the world’s largest population with 1.3 Billion people in 2013 (you guessed it: World Bank). However, as of 1998 the country only had 0.1 Hectares of arable land per person - that's less than half the world average at the time (Zhu and Chen, 2002). Given their population and low percentage of arable land how do they produce enough to subsist? Let alone have an excess with which to help out other countries?

Well, a major aspect of the country’s high productivity from a limited area is due to the introduction of Nitrogen based chemical fertilisers (CF-N) (Wikipedia). After the Second World War the application of these fertilisers allowed China’s overall food production to increase by over 450% in 50 years (1950-2000) (Chinese Agriculture Yearbook 1980-1999 cited in Zhu and Chen, 2002). This massive growth was achieved in spite of an overall decrease in the total arable area of the country, predominantly due to increasing levels of construction and industrialisation (People's Republic of China Government website).

There we have it: a clear example of an increasing population placing a severe impact on an environment. Complete with an anthropogenic solution of chemically altering the environment in order to inflate its naturally sustainable production level.

However, there are a couple of sides to this story that we have not yet covered: Firstly is the fact that achieving this immense output is requiring higher and higher applications of CF-N's each year. For a little context (by now I hope you realise that this means ‘here are some numbers’) these yearly increases mean that in 1998 China used 30% of the total Nitrogen fertilisers used in the world (Zhu and Chen, 2002).

Ok, that seems like a good place for a cliff-hanger. I’ll get another post up over the next few days where we can further this analysis and have a look at the impact that this massively increased quantity of Nitrogen is having on the natural environment and what steps could/can be taken to mitigate its effects.  Much like Stallone’s chef d'œuvre it’s sure to be a post filled with thrills.

Let's get started!

Hi, thanks for visiting!

First let's get some admin out of the way: This blog forms the assessment of the Global Environmental Change MSc module GEOG3057. My general aim over the next few months is to use this site as a vehicle to investigate the environmental impact caused by an increasing human population.

OK, time for a few facts and figures (this may get a little dry but once we’re all on the same page we can look at the ‘fun’ stuff):

Right now there are an estimated 7.2 billion people in the world, (World Bank website), a number that has increased by over 30% in the last 20 years (IAP Statement on Population Growth, 1994). Recently new projection (Gerland et al, 2014) have been published suggesting that rather than, as previously expected, levelling off in the near future the world’s population is actually expected to maintain its upward trend and has the potential to reach a colossal 12.3 billion people by the end of 2100.

Distribution of world population (2014). Courtesy of Wikipedia.

So now we know there are a lot of people around and even more are coming. Acquiring the resources to sustain the this population has long been recognised as a serious environmental issue (Reed College) and over the next few months you and I will investigate some of the effects of our population on the environment as well as established and proposed methods to combat these impacts.

All well and good but the world’s a big place, so in order to maintain a common thread throughout the blog my investigations will focus predominantly on Hong Kong with further examples drawn from China (although I may occasionally stray out of this locale if exterior examples crop up during my research).

Why focus on Hong Kong? Well, after visiting the ‘Special Administrative Region’ several years ago I was immediately struck by the sheer scale of the city: the huge skyscrapers across Central framed every view, hordes of people swarmed the streets of Kowloon at all hours and extensive shopping malls jam packed with every consumable imaginable line the streets of Tsim Sha Tsui (‘Tsimsy’ as its locally known).

The whole city seemed to be straining against its physical, resource and environmental limits. Clearly the demands and output of this city have substantial implications on the environment, indeed even a quick moment of research into Hong Kong’s recent events indicate that extensive land reclamation projects (SCMP, 2013) are currently being undertaken (an impact that we shall be looking into further in the near future).

The juxtaposition of this 7.2 million strong population and the numerous national parks across Hong Kong provides an ideal ‘front line’ between human population and the natural environment for our investigations. Extending our sphere of investigation to include China allows me to include a wider range of environmental and population scenarios that perhaps are so demonstrative when focusing on HK alone.

The skyscrapers of Central Hong Kong clustered the foot of Victoria Peak

(courtesy of mrwallpaper.com)

So that's the plan! I hope that you will join me for future posts, next time we can get right down to business.

Please don’t hesitate to contact me in the comments. If you like/hate/disagree with what you read or if you have any suggestions of relevant papers and articles that you find interesting then let me know. The whole point of this blog is to learn something new, if we can do that together then fantastic!

Thanks for reading this first instalment, here is me on the HK waterfront with a statue of Bruce Lee, because.....Bruce Lee!