Human activities constitute the largest threat, followed by climatic conditions that affect the snails’ biodiversity and population of snails in a given region. Some of those activities include but not limited to the following:
– Deforestation i.e. the falling of trees for various purposes such as urbanization, road construction, building of industries, houses and schools.
– Use of pesticides, fertilizers, nematocides by crop farmers in weeds and nematode control in the farming. The use of agrochemicals such as pesticides in crop production also contributed in the change in the soil pH and the snail’s ecosystem and biodiversity.
– Slash and Burn agricultural practices of rural farmers during planting seasons. This displaces the snails in their natural habitat and exposes their eggs to harsh weather conditions such as sunlight and rain.
– Bush burning/ fires occasioned by the hunters of wild life animals e.g. bush meat
– Population growth and demand for cheap sources of animal protein
– Indiscriminate snail hunting in the forest (Ikojo et al., 2014).
– Lack of suitable foundation stock for large scale and commercial snail farming
– Unavailability of commercial snail feeds and concentrates
Commercial and intensive crop production systems, which uses inorganic fertilizers as a source of soil nutrients supplementation for profitable crop production. The use of inorganic fertilizers and compounds has destroyed the natural snail ecosystem and habitat suitable for snail growth, development and reproduction in their wild.
Read Also: Breeds of Snails and their Origins
• If the management practices are not strictly followed, there could be atmospheric pollution as a result of dead snail not removed from the pen. Dead snail has very offensive odour. It is more offensive than poultry droppings odour. The offensive odour could lead to diarrhea or cholera in man if not properly checked.
• The soil could be polluted if the pen is not well managed. If the soil inside the pen is not removed or turned regularly the soil may be polluted as a result of excreta from the snail, mouldy feed and decayed fruits, etc. Dead snail will rapidly decay turn to liquid within 2 or 3 days after death and the effluent could pollute the soil. The rusting of iron used to build the pen could also be a source of pollution.
• The dropping and the decayed snail (only the fleshy part of the snail can decay) could be washed into the nearby stream or rivers and could result into water pollution.
• The fleshy part of the snail is slippery and if not well processed could lead to stomach disorder. Eating of snail from Endemic area, or polluted soil i.e. lead accumulated soil could be hazardous to man. Over cooking and frying could reduce the nutritional quality of the snail. Taking up of toxic materials from the soil.
v) The Shell:
• The shell of the snail after processing if not well disposed could litter the surrounding.
vi) Cutting of Mulching Materials:
• Indiscriminate cutting of leaves (Plantain, banana, cocoa) for mulching snail pen could directly or indirectly affect the productivity of the plan or lead to the death of the plant.
vii) Inedible Part:
• The viscerals i.e. intestine, kidney, etc. constitute the inedible part. If the visceral is not properly taken care off i.e. by burning, burying or use for other beneficial purposes, it could decay and have adverse effect or the environment.
Snail as Metal Pollution Bio-Indicator:
• Snail could be used to detect presence of heavy metal such as:
• Lead (Pb),
Positive Impact of Rearing Snails under Domestication on the Environment
• Extinction: Snail farming under domestication will prevent extinction of snail from the wild.
• Earthworm population: There is symbiotic relationship between snails and earthworm. The latter feeds on the excreta of the former while earthworm helps in turning the soil of the pen.
• Soil fertility: The soil fertility inside the pen is improved as a result of decay leaves inside the pen. The presence of earthworm in the soil is an indication of fertile soil.
Climatic Factors Affecting African Land Snail Population in the Humid Tropics
Unfavorable climatic conditions and climate change poses a serious problem to snail population and farming in West African region. Climatic influence and its effects on snails have an associative effect on temperature, humidity, wind/air movement and light intensity. Snails are susceptible to infections and diseases caused by environmental contaminations and pollutants (Ebenso and Ologhobo, 2009).
Temperature: It is a major factor that influences the activities of snails. Snail requires lower and moderate temperature for normal feeding and body functions. Temperature ranges of between 23 – 28oc are suitable for snails’ growth and development. During hotter periods with high ambient environmental temperature, snails may experience heat stress. Heat stress poses a serious economic threat to snails population and snails under domestication.
The effect of heat occasioned by high temperatures on snails could be in the form of reduced feed intake and utilization, reduced egg production, reduce growth rate, low body weight, poor hatchability and fertility. Snails hibernates and aestivation especially during dry hot unfavorable seasons. Air, environmental and noise pollutions affects snails.
Humidity: Snails enjoy moist and cooler environments, which is usually achieved when it rains, the atmospheric air become moist with high relative humidity. Snails are active at a relative humidity of between 70 – 90%. However acidic rains in some areas caused by high air pollutants adversely affect snails’ population.
If the air is drier and hot, for longer periods, snails may dry up and die or hibernate. Snail pens and the top soils should be sprinkle with water regularly during hot periods especially in the dry seasons to maintain adequate damp environment.
Excessive air movement and winds: This is another climatic factor that may result in severe dehydration in snails and may cause them to retract into their shells, rather than feeding to gain weight and to breed. Prolong periods may cause the snails to go into aestivation which is a period of inactivity or dormancy in the life of snails.
Light Intensity: Snail requires light for their activities such as feeding and breeding. Though snails are nocturnal animals, however they require light for some photo-biological processes essential in the energy level and food chain e.g. cellular digestion and photosynthesis. Day light is usually from the sun, longer periods of light stimulate and prompt snails into reproduction under favorable conditions.
Soil Type: Snails depend very much on the soil for their food and reproduction e.g. egg laying. They can hardly survive or thrive effectively in the absence of a suitable soil-type. They require moist, aerated, easily drained, non waterlogged and non acidic soils. Soil rich in minerals contents and organic matters are good as too soil for snail farming after being sterilized to kill pathogens in the soils.