A SURVEY ON THE POPULATION OF POMACEA CANALICULATA (GASTROPODA: AMPULLARIIDAE), MELANOIDES TUBERCULATTA (GASTROPODA: COCHLICELLIDAE) & LUMBRICUS TERRESTRIS (OLIGOCHAETA: LUMBRICIDAE) AT SITIO SAN ROQUE, BRGY. STO. ROSARIO, CITY OF MALOLOS, BULACAN

A Research Presented to
The Faculty of College of Science
Bulacan State University
City of Malolos, Bulacan

In Partial Fulfillment to
The Requirements for the Course
BIO 123 and BIO 123L
2nd Semester, A.Y. 2014-2015

by

March 2015

Abstract

The study on the three species found in San Roque, Sto. Rosario, City of Malolos, Bulacan is undertaken: Pomacea canaliculata, Melanoides tuberculatta, Lumbricus terrestris which coincidentally are the most dominant in the community in terms of population. The common earthworm, Lumbricus terrestris turns out to be the most common on the researcher’s locality, Sto. Rosario, City of Malolos, Bulacan.

Introduction

In a residential community where majority of the area is covered by houses and rice fields, earthworms and snails are the most dominant form of invertebrates. Wet and damp areas like creeks, water irrigation and pusali that are found in the community also give rise to these organisms.

Pomacea canaliculata and Melanoides tuberculatta are both found in the area and are members of Class Gastropoda. Class Gastropoda, which means “stomach foot”, contains about 40,000 described species of snails, slugs, and similar animals. The class is primarily a marine group, but it also contains many freshwater and terrestrial mollusks. Most gastropods have shells, but some, like slugs and nudibranchs, have lost their shells through the course of evolution (Johnson & Raven, 2007).

The earthworms of Class Oligochaeta consist of 100 to 175 similar segments, with a mouth on the first and an anus on the last. A worm can eat its own weight in soil everyday (Johnson & Raven, 2007). Earthworms have an important role in the aeration and fertilization of soil. They seem to eat their way through the soil because they suck in organic and other material by expanding their strong pharynx. It brings organic matter down into their burrows from the surface, and the familiar 'worm casts' consist of soil excreted by earthworms (Nichols, Cooke & Whiteley, 1971). Lumbricus terrestris, the most common earthworm in the community, is included in the class.

The study aims to investigate the diversity of the common snails Pomacea canaliculata and Melanoides tuberculatta and the common earthworm Lumbricus terrestris at Sitio San Roque, Barangay Sto. Rosario, City of Malolos, Bulacan. The researcher will try her best to produce the most accurate estimates of the number of the three species she will be investigating.

The researcher limits the study to an area of 64m² that is to be divided to four quadrants for more precise results. The area where the species are gathered is a spacious, wet area for it is a fishery. Other species may be mentioned other than the three species being investigated, but it is just for the sake of comparison. Pomacea canaliculata, Melanoides tuberculatta, and Lumbricus terrestris will be the focus of the study, and them being dominant in the said community.

METHODS AND MATERIALS
The researcher looked for an area where she can gather the specimens she needed for the study. The survey was conducted on Sitio San Roque, Sto. Rosario, City of Malolos, Bulacan, the researcher’slocality. To get a more precise result, she divided the 64m^2 into four sites with 16m² each in terms of area. She used a metric tape for this, and the formula for calculating the area of a given square lot.

RESULTS

Site 1grass | Site 2damp grass area, water | Site 3damp grass area, water | Site 4water |

Site 1 Site 2 Name of species found | Number of the said species found | Lumbricus terrestris | 4 | Name of species found | Number of the said species found | Melanoides tuberculatta | 2 | Pomacea canaliculata | 4 | Lumbricus terrestris | 4 |

Name of species found | Number of the said species found | Lumbricus terrestris | 2 | Melanoides tuberculatta | 4 | Site 4 Name of species found | Number of the said species found | Lumbricus terrestris | 4 |

In terms of area, each site/quadrant is 16m². The researcher divided the area measured into four sites so that it would be easier to conduct a survey, and so that the results would be as accurate as possible. 64m² is the total land area where the specimens are gathered.

SITE DESCRIPTION

Every quadrant measures 16m². The location is a fishery.

SUMMARY BY SPECIES

Channeled applesnail is the common name for Pomacea canaliculata. It is the species of large freshwater snail with gills and an operculum, an aquatic gastropod mollusk in the family Ampullariidae. It is considered to be in the top 100 of the "World's Worst Invasive Alien Species" (Global Invasive Species Database, 2008).

Form
The shell of P. canaliculata is globular, from 40-60 mm high and 45-75 mm wide, but can reach 150 mm in length. These numbers vary depending on environmental conditions; the shell grows mostly in the spring and summer but growth slows in the fall and winter. The shell can be yellow, green or brown and has five to six whorls separated by a deep indented suture which gives it the “channeled” name. The aperture is large and oval shaped with males having a rounder aperture than females. However, females in the adult stage are overall larger than males. The operculum is moderately thick, corneous, concentric and light to dark brown in color. The operculum is retractable at the shell opening. The body of the snail can vary in color from yellow to brown and almost black. The siphon has yellow spots and its tentacles are curled under the shell when it is resting. The snail is closely related to other species in the canaliculata group, however, distinctions can be made by looking at the color of the eggs, shell size, angle of indented sutures and shell opening. (Ghesquiere, 2005a; Ghesquiere, 2005b; Tamburi and Martín, 2009)

Reproduction
Sexes are separate. Females lay clusters of bright pink eggs attached to solid surfaces (rocks, walls, logs, emergent vegetation, and trash) up to usually about 50 cm above the water surface. Eggs generally hatch within 7-15 days, but may take longer, probably depending on ambient temperature regime.
Reproductive output can be enormous. Clutch size is up to 1000, but averages probably 200-300. Clutches are laid every few weeks (Pagad, 2005)
Habitat description
Applesnails are found in freshwater habitats. This amphibious animal remains submerged during the day, hidden in vegetation near the surface. It is more active during the night, and leaves the water in search for fresh vegetation (The Apple Snail Website, 1998-2003). The temperature preferences for P. canaliculata range from 18 to 25 degrees C. Temperatures below 18 degrees or above 32 degrees C drastically increases the snail's mortality rate. (Cowie, 2005)

Distribution
Pomacea canalicualata was originally introduced from South America to south-east Asia around 1980, as a local food resource and as a potential gourmet export item. The markets never developed; the snails escaped or were released, and P. canaliculata became a serious pest of rice throughout many countries of south-east Asia. In the Philippines, it is considered the number one rice pest and has caused huge economic losses. It was introduced to Hawai‘i in 1989, probably from the Philippines, and for the same reasons as for its initial introduction to south-east Asia. Again, the snails rapidly escaped or were released and quickly became major taro pests. P. canaliculata can spread rapidly from agricultural areas into wetlands and other natural freshwater systems where it may have a serious impact. These potential impacts could involve destruction of native aquatic vegetation leading to serious habitat modification, as well as competitive interactions with the native aquatic fauna, including native snails. Already, introduced P. canaliculata has been implicated in the decline of native species of Pila apple snails in south-east Asia. Also, native species of Pila in the Philippines are reported to have declined as a result of extensive pesticide applications against introduced P. canaliculata. Climatic modeling has shown that it has the potential to spread to many as yet uninfested parts of the world, for instance the huge rice-growing areas of India. It has already been introduced to the USA and threatens the major rice-crops of Texas and California. Australia in particular is extremely concerned about its potential introduction to natural wetlands (e.g., Kakadu) as well as to rice-growing areas. (Pagad, 2005).

Economic Importance
The apple snail is eaten by people and animals, and used in aquariums, but not to the beneficial extent intended. It now has no commercial value as a food source (Pagad, 2005).

Possibly the most ubiquitous freshwater snail in Singapore, Melanoides tuberculata is a hardy species present in almost any kind of water bodies, including brackish drains near the sea. Also known as red-rimmed snail, it is a species of burrowing snails that are commonly found in freshwater aquarium tanks. These popular scavengers provide a useful function of breaking up the substrate therefore reducing anaerobic bacteria and eating decaying plant and dead animals. They also eat algae. They are extremely good cleaning crew for a tank with substrates (Theaquariumwiki.com).

Form
With an elongated conical shell that has regularly increasing whorls, the morphology of most of the adults include a pale to dark brown shell colour (Thomson, 1974) with many reddish-brown spots or "flame" looking like pattern (Pointier, 2001). The aperture always faces to the right. Prominent vertical ribs are usually present on the middle and upper whorls of the shell. Adult snails typically reach a shell length of 30–36mm.

It has a tongue-like head that is constricted on its ventral side to give rise to the foot. The tentacles are just above the constricted area and right at the base of each long and slender tentacle; the eyes are present there (Lee, 1973).

Reproduction
Contrary to common opinion, Malaysian Trumpet snails are not hermaphrodite (where each individual has both male and female organs). Malaysian Trumpet snails are gonochoric (either male or female). They cannot change sex, either. However, they are also apomictic parthenogenetic (females can produce young female clones without a male to fertilise the eggs). Usually a large proportion of the snails are female clones, commonly the entire population in some areas. They produce live young by parthenogenesis (Aquaspacingworld.com).

Habitat
The species is found in all types of permanent waters, from small springs to vast lakes, e.g. Lake Victoria, and from oligotrophic to eutrophic waters. It is a browser of microalgae and a detritivore, feeding on detritus, plant leaves and dead animals, and is able to survive in relatively alkaline and saline waters. The species is parthenogenetic and is spread by birds. The species is the intermediate host of several trematodes. (Van Damme D., 2014)

Distribution
This species has a global distribution. Its original range covers subtropical and tropical Africa (with exception of the Congo Basin and most of coastal western Africa) and southern Asia. During the 20th Century it was introduced, e.g. via rice cultivation, to many other regions and it is presently found over all of Africa, the entire Arabian Peninsula, western Asia, south and southeast Asia including southern China and also in Japan, Malaysia, and Australia (Liu et al. 1979, Brown 1994, Ramakrishna and Dey 2007). The last two decades it has been moving northwards into Europe, having crossed the Mediterranean, and has been found e.g. in southern Spain (Álvarez Halcón 1995). It was also introduced in North, middle and South America. In addition to the countries and regions listed, it also occurs in many Palaeartic countries indoors (aquariums, hothouses, garden shops) or outdoors in warm waters, either artificial ones such as cooling water ponds e.g. of nuclear power plants, or natural ones, such as a thermal spring outflow in Slovakia (Májsky 2000).

Lumbricus terrestris goes under a variety of name: dilly worm, green crawler, large crawler, night crawler, nitro crawler. Night crawlers are so named because they are usually seen feeding above ground at night. They burrow during the day—typically keeping close to the surface—capable of digging down as deep as 6.5 feet (National Geographic).

Form
Typically only a few inches (7 or 8 centimeters) in length, some members of this species have been known to grow to a serpentine 14 inches (35 centimeters). Earthworms’ bodies are made up of ring-like segments called annuli. These segments are covered in setae, or small bristles, which the worm uses to move and burrow (National Geographic). It has a reddish-brown back, a yellowish underside and an often prominent orange-red 'saddle' region known as the 'clitellum', close to the reproductive organs. Although this earthworm has a cylindrical body, the tail region may become flattened (Cloudsley-Thompson & Sankey, 1961). The body is segmented and has visible rings known as ‘annuli’; each segment bears small hairs known as 'chaetae', which help the worm to move through the soil (Nichols, Cooke & Whiteley, 1971). Earthworms travel underground by the means of waves of muscular contractions which alternately shorten and lengthen the body (peristalsis).

Reproduction
Night crawlers mate on the surface. Like all earthworms, they are hermaphroditic but do not self-fertilize (National geographic). It needs another worm to mate with and produce fertilised cocoons - it is obligatory biparental (National History Museum, …). They reproduce sexually with individuals mutually exchanging sperm. L. terrestris leaves its burrow to copulate on the soil surface. Sperm is stored, and mated individuals produce cocoons for up to 12 months after the mating. Earthworms lay cocoons which have an egg inside. A study on the hatchability of cocoons found a range of 76 to 62% hatched over the 5 months following mating, which decreased to about 11% in the sixth month, and cocoons after that failed to hatch. Median total production of viable cocoons was 5 per individual, with a range of 0-21. Sperm may be stored for as long as 8 months (Butt & Nuutinen, 1998).
Following mating, each worm forms a tiny, lemon-shaped cocoon out of a liquid secreted from its clitellum, the familiar-looking bulge seen near the first third of the earthworm’s body. The sperm and egg cells are deposited inside the cocoon, and it is buried. After a two- to four-week gestation period, the baby worms emerge (National Geographic, …).
Habitat description
Lumbricus terrestris can inhabit all soil types except coarse sands, bare rock and acidic peat (Frelich, 2011). It tolerate soils with pH values as low as 3.5–3.7 and as high as about 8. L. terrestris is not frost-tolerant indicating that it hibernates in deep soil layers during the winter (Addison, 2009; Tiunov et al., 2006; Wironen & Moore, 2006). Although often present in agricultural fields, it fares poorly due to herbicides, mechanical damage and lack of leaf litter (L. Frelich, pers. comm.).
L. terrestris occurs in agricultural areas, natural forests, planted forests, range/grasslands, riparian zones, ruderal/disturbed, scrub/shrublands, urban areas, wetlands.

Distribution
In the northern regions of Europe, Asia and North America, the Lumbricidae are the earthworms of forest, grassland, sown pasture, cropland and gardens (Lee, 1985). Once present in an environment, its activities can radically alter forest floor litter decomposition regimes and the soil-litter communities based on forest floor litter. It is considered invasive as it is widespread globally, tolerant to a range of transport and climatic conditions and, being a hermaphrodite, only two individuals are needed in a founding population. However, little is known about the properties which make this species so invasive. (Hendrix, 2008).
In many ecosystems and in agricultural systems earthworms are highly beneficial to soil processes (Hendrix & Bohlen, 2002). However in forest ecosystems with few or no native earthworms, introduced species can have negative effects. Earthworms are keystone detritivores that can act as “ecosystem engineers” and have the potential to change fundamental soil properties, with cascading effects on ecosystem functioning and biodiversity (Frelich et al., 2006; Eisenhauer et al., 2007; Addison, 2009)

LOCATION

The blue circle indicated where the study was held. The specimens needed were also gathered in the area, Sitio San Roque, Sto. Rosario, City of Malolos, Bulacan.
Conclusion
All the four sites within the area contain the common earthworm, Lumbricus terrestris.
In the first site where the area is fully grass, Lumbricus terrestris is the only one of the three species found. In the second site that is wet, the three is present. It’s just the common earthworm, Lumbricus terrestris again in Site 3 where the area is damp for it is the fishery itself. Melanoides tuberculata and Lumbricus terrestris are present in the fourth site.
The common earthworm is the most diverse on the area of the three species investigated. The applesnail, or kuhol ranks next, and the red-rimmed snail is the least diverse in the community.

Literature Citated
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Nichols, D., Cooke, J. and Whiteley, D. (1971) The Oxford Book of Invertebrates. Oxford University Press, Oxford.
Buczacki, S. (2002) Fauna Britannica. Hamlyn, London.
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100 of the World's Worst Invasive Alien Species. Global Invasive Species Database http://www.issg.org/database, accessed 27 October 2008.
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© Natural History Museum, London