Impacts of human beings on the ecosystem

Human beings impacts on ecosystems form the largest threat due to continued deterioration of the abiotic factors and decline of biodiversity that ultimately undermines sustainability.  Lakes are highly sensitive and fragile ecosystems because they depend on a complexity of highly interdependent aquatic and terrestrial activities.  In their conclusion which coheres with Hiromi (2009) argument, Kota et al (2009) points the need to look at the problem of the human impacts on lakes from a holistic point of view as opposed to an isolated system.  It is from this consideration that this paper provides a critical analysis of the Lake Saroma ecosystem in Japan to establish the human impacts, future implications and mechanisms of addressing the same problem.

Description of the ecosystem
a) Geography of Lake Saroma
Lake Saroma forms the third greatest lake in Japan and is located on the shores of Hokkaido in North Eastern part about thirty kilometers from the City of Abashiri (Takata, Takayasu and Hasegawa, 2006).  The lake has a total surface area of about 150 square kilometers and 82.4 kilometers shoreline (Bernhard and Petra, 2004).  Notably, the lake is separated from Okhotsk Sea by a sandbar that extends about 20 kilometers.  Besides, this ecosystem is further bound by agricultural and forested land which forms part of its major catchment.

Figure I Lake Saroma (South Eastern shore view).Bernhard and Petra, 2004.

b) Biotic and abiotic components of the lake
Lake Saroma as Rashid, Scholes and Neville (2005) explain, has great biodiversity that inhabit the emergent as well as the deeper regions.  Emerged macrophytes include phragmites largely located on the shallower regions while submerged ones include Potamogeton crispus and Zostera marina.  Other plants include phytoplanktons like diatoms that inhabit different depths of the fragile ecosystem (Gonen and Wolfin, 2005).  These plants as - Kota et al (2009) emphasize, play a very critical role in balancing carbon dioxide and oxygen requirements of the aquatic ecosystem.

According to Bernhard and Petra (2004), fauna in Saroma Lake ecosystem can be divided into three categories.  First the zooplanktons include veliger, gastropoda and bivalvia.  Then, Benthos constitutes the Littorina squalida, Corbicula japonica, Macoma incongrua, Batillaria multiformis and Nuttalia olivicea.  Finally, fishes include Cottus pollux, Eleginus gracillus, Clupea pallasi, Pretius japonicas and Oryzias latipes (Gonen and Wolfin, 2005).  Other animals include over 150 migratory birds species that shift between Lake Saroma, Lake Chilika and other wetlands in the greater Asia continent.  It is worth noting that due to this diversity of flora and fauna, the ecosystem has largely been exploited for fishing and touristic purposes.    

In their view, Kota et al (2009) point that abiotic factors in any ecosystem are very crucial because they support the living component to create the needed sustainability.  The water volume in the lake is about 1.3 cubic kilometers with a mean and maximum depth of 8.7 meters and 19.5 meters respectively (Kota et al, 2009).  The average water temperatures ranges from 12 C between the months of May to November and less than 6 C during the colder months of December to April.   Mean PH of the water is about 8.1 while dissolved oxygen ranges between 8.1 to 8.8 mg l-1 in the Western and Eastern side of the lake respectively.  Gonen and Wolfin (2005) postulate that carbon oxygen demand (COD) ranges between1.1 to 2.0.  Though data on the ground sediments is missing owing to minimal researches focusing on it, Kota et al point that it is largely basic a factor contributed by interchange of the lake and Okhostk Sea waters.

Current impacts by the human beings
a) Eutrophication
As indicated earlier, Lake Saroma catchment area constitute largely of agricultural communities whose excess organic additives are easily washed down the lake.  Takata et al (2006) explain that to increase their yields, farmers intensified use of nitrogenous fertilizers has been a major source of nutrients enrichment especially at the river entry points.  However, eutrophication has largely been linked to intensive scallop culturing that began in 1996.  Takata et al (2006) further point out that the lake receives intensive organic loads at the bottom which result to reduction in benthic diatoms.

b) Pollution
Notably, scientific studies on Saroma Lake appear to differ on the levels of pollution in this fragile ecosystem.  However, they concur that though pollution levels are relatively low their effects are widely felt far up in the food chain.  Kota et al (2009) and Yale University (2009) indicate that pollution largely involves intensification of hydrogen sulfide which causes massive fatalities of microscopic organisms especially those in the primary food chain level.  

c) Decline fauna and flora in the lake
The human effects on the lake ecosystem is perhaps more evident from the daily social-economic activities.  Large number of Siroma region people is dependent on the lake for supply of proteins.  As a result, massive fishing has seen major fish species such as Clupea pallasi and Pretius japonicas rapidly decrease.  In addition, Kazuto and Isamu (2010) explain that preference of aquaculture has seen large sections of the lake along the sandbar between the two gates to Okhostk Sea being cleared the natural species.  Besides, aquaculture farming has seen eelgrass from the lake further cleared to create the needed environment for faster production (Julio and lvaro, 2006).  The holistic functioning of the ecosystem is therefore shifting from a self sustaining unit to a human controlled system and therefore less sustainable.

d) Migration of some species and invasion of alien species
Liba amd Harold (2009) concur with Miranda (2004) that following the intensive human influence on water quality in the lake, great changes in the type of species have been recorded.  To begin with, eutrophication and pollution greatly reduced the levels of oxygen available at the bottom levels a factor that made microorganisms and fish move to shallower waters and neighboring Okhostk Sea.  Of particular concerns, as Liba amd Harold (2009) further point out is the invasion of the lake by alien species that were introduced as ornamental plants in the country.  Unlike, the local plants, invasive species lack the necessary evolutionary natural enemy and therefore easily outdo the local organisms.  Such species in the lake include Eichhornia crassipes and Myriophyllum aquaticum (Liba amd Harold (2009).  Unless the problem of invasive species is addressed, scholars predict doom to this important ecosystem.

Prediction on future impact on Lake Saroma
The current status of Lake Saroma is worrying as Gonen and Wolfin (2005) and Hiromi (2009) concur.  Failure to address it will ultimately lead to massive loss of flora and fauna especially through adoption of aquaculture by the commercial communities.  Increasing levels of pollution as indicated earlier may cause greater losses of biodiversity while alien species further outdo them in the lake.
In their view, Julio and lvaro (2006) point out that the high levels of pollution and eutrophication also risk complete loss of water quality to support human services.  With communities adjacent to the lake dependent on fishing, poorer water quality will ultimately point at the inability of the lake to provide the needed resources for domestic and commercial purposes.  Of critical importance, is the possibility of aggravated poisoning to the people through biomagnification and bio-accumulation upper in the food-chain (Julio and lvaro, 2006).

The fast rising quantities of alien species in Lake Saroma is perhaps the greatest threat to the lake ecosystem.  According to Kota et al (2009), invasive species not only fast replace other macrophytes in the lake, but they also create poor penetration of oxygen by covering the surface and therefore further endangering phytoplanktons in the lower levels.  A special point to note at this instance is that some alien species such as Eichhornia crassipes easily thrive in the enriched waters and therefore manage to vegetatively propagate with speed (Kota et al, 2009).  

Guidelines on human activities to assist in preserving Saroma Lake
Over the years scholars and analysts appear to agree on the need for a holistic approach as the main platform towards sustainability achievement in different ecosystems.  How can the same be achieved in Lake Saroma  To begin with, there is need for strong involvement of the local communities in any efforts aimed at restoring and maintaining the necessary sanctity of Saroma Lake ecosystem.  Involving the local communities as Hiromi (2009) explains creates an internal force and a check point for sustainability.  To effect this involvement, the communities should further be trained on the need for preservation and its ultimate benefits to them.

Miranda (2004) argues that Saroma Lake ecosystem cannot be preserved without employing the necessary legislative frameworks.  The government should therefore establish laws to guide fishing in the lake a consideration that would allow replenishment of different species when quantities go down.  Besides, policies would further create a policy framework that allows polluter pays principle for all toxic effluents sources.

At any time, the understanding of Saroma Lake ecosystem components and their levels form the basis of deriving the correct models to address resilient problems.  Therefore, an effective assessment model should be established to regularly assess pollution levels and determine the numbers of flora and fauna in supporting responsive mechanisms.  Laura, Klaus and Richard (2008) explain that it is only through effective assessments that all stakeholders can be brought aboard in contributing both professional and technical support in mitigating the negative effects.

Finally, the lake could be designated as a ramsar site and therefore calling for international standards in maintaining its ecological and social-economic considerations.  According to Gonen and Wolfin (2005), ramser sites are wetlands that have international importance are specially conserved to facilitate better stakeholders understanding of the need for conservation, direct involvement of the local authorities and most importantly an international watch to facilitate high integrity of the ecosystem.

Conclusion
It is from the above discussion that this conclusion supports the thesis statement, human beings impacts on ecosystems form the largest threat due to continued deterioration of the abiotic factors and decline of biodiversity that ultimately undermines sustainability. It came out from the discussion that Lake Saroma ecosystem is under critical human impacts threats from the catchment regions and aquaculture units along its shores.  Further more, introduction of alien species as ornamental plant is fast spreading and threatening to outdo the local species.  With failure to address these impacts being projected to have a possible total damaging effects on this ecosystem, there is need to involve the local communities, establish the needed legislations and most importantly designate the lake as a wetland of international importance.

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