1234

1 Chapter 1 INTRODUCTION Water pollution is today’s one of the greatest problems in our society. The quality of water sample from the concerned area is threatened by increasing bacteriological counts, presence of toxic and hazardous substances and the salination of the water. Moreover, incidence of oil spills and trash brought by the boats, ships

and other sea transportation these pollutants contributes to the

deterioration of the quality of water may be also transported to other countries by the sea or ocean. (EMB Manual Report 1985). Water pollution offers the greatest threat in the people’s health and aquatic life. Incidents like death and water contamination could become more and more frequent as population grows Water Pollution Control Act of 1972 established a national program to protect the quality of both interstate and intrastate waters. The general aesthetic requirements are that all surface waters should be capable of supporting aquatic life and should be free of substances attributable to waste discharges. When a river or lake is classified in accordance with intended uses, specific, physical, chemical, biological and temperature quality standards are established to ensure that the most beneficial use will not be deterred by pollution. (Hammer, 1999). Lately, the presence of heavy metals is also posing a big threat to our marine environment. Although the presence of heavy metals occur naturally in the water higher levels are usually detected near the populated coastal areas and rivers discharges. It was found out that pollution from industries and households as well as pollution induced by

2 natural processes contribute to the elevated levels of metals in these areas. It is alarming that human activities are releasing these materials at rates matching or even surpassing the natural processes. (Bruland, Koide and Goldberg 1974). A biological indicator is a plant or animal species that is known to be particularly tolerant or sensitive to pollution. Based on the known association of an organism with a particular type or intensity of pollution, the presence of the organism can be used as a tool to indicate polluted conditions relative to an impacted reference conditions. Sometimes a set of species or the structure and function of an entire biological community may function as a bio indicator. One indicator of seawater intrusion is an increased chloride concentration in a freshwater aquifer, because chloride, a major constituent of seawater, is chemically stable and moves at about the same rate as intruding seawater. For the purposes of this study, chloride concentrations of 100 milligrams per liter (mg/L) or more were assumed to indicate seawater intrusion.

Biological

indicator species are unique environmental indicators as they offer a signal of the biological condition in a watershed. Using bio indicators as an early warning of pollution or degradation in an ecosystem can help sustain critical resources. While indicator species is a term that is often used, it is somewhat inaccurate. Indicators are actually groups or types of biological resources that can be used to assess environmental condition. Within each group, individual species can be used to calculate metrics such as percent Achnanthes minutissima (a diatom species) or groups of species (e.g., EPT taxa) or

3 individual orders (e.g., Caddisfly larvae - Order Trichoptera) in an effort to assess water quality conditions. The

major

groups

include:

Fish,

Invertebrates,

Periphyton,

and

Macrophytes. Marine environments also utilize biological indicators. While this site focuses predominately on freshwater resources, marine/tidal indicators are also quite important in sustaining biodiversity and preserving and restoring marine and estuarine resources. Not only their presence can be used to detect pollution but pollutants such as lead and cadmium are eaten by tiny animals. Although a bio- indicator however is capable of preventing and reducing the threats of pollutants to our health. Biological indicators species are unique environmental indicators as they offer a signal of the biological condition in a watershed. Using bio indicators as an early warming of pollution or degradation in an ecosystem can help sustain critical resources. The Bacoor - Paranaque coastal area is one of the major sources of sea foods. This area is facing a great amount of strain because of growing population along its coastline. The increasing of numbers of squatters, industrial establishments and widening of roads and vehicles are some reasons why some parts coastal areas are considered biologically dead and missing. This may be attributed to the unabated disposal of untreated domestic sewage. The continuing urbanization of Metro Manila occupied with the illegal

4 construction of squatter shanties in esteros and other waterways also contribute to its deterioration. This study would also like to find out the extent of lead and cadmium contamination along Bacoor-Parañaque coastal area using Sow Bugs (Oniscus Asellus) as the potential biological indicators. 1.1 Objectives of the study This study is aimed to determine the concentration level of lead and cadmium along Bacoor-Parañaque coastal area. Specifically it aimed to: •

Determine the Lead and Cadmium contamination using Sow Bugs as a potential biological indicator.

•

Compare the concentration levels of lead and cadmium from the three sampling sites.

1.2 Significance of the Study The result of the study was provided vital information about the potential of sow bugs (Oniscus Asellus) to act as biological indicator of the marine environment. This study can also be used for the further investigation of other pollutants that maybe present in the area. 1.3 Scope and Limitation The sample, sow bugs was collected at Bacoor-Paranaque Coastal Area in ( Maliksi, Las Pinas, Paranaque ) This study was focused mainly on the

5 possible utilization of Sow Bugs (Oniscus Asellus) as potential bio-indicator from coastal area. Sow Bugs collected along Bacoor-Paranaque coastal area was used as a potential biological indicator of Lead and Cadmium. The sow bugs that were study are in the growth stage. This study was conducted in DENR - EMB Laboratory East Avenue , Quezon City . Atomic Absorption Spectrophotometer (GBC Aavanta Australia ) was used to analyze the lead and cadmium content of the samples.

6 Chapter 2 REVIEW OF RELATED LITERATURE AND STUDIES 1.1. Sow Bugs (Oniscus Asellus) Sow Bugs (Oniscus Asellus) belong to the Animalia Kingdom , phylum Arthropoda, Subphylum Crustacea, Class Malacostraca, Order Isopoda, Family Oniscidae, Genus Oniscus, and Species Oniscus Asellus. Oniscus asellus, the common woodlouse, is one of the largest and commonest species of woodlouse in the British Isles and Western Europe , growing to lengths of 16 mm and widths of 6 mm. They are generally flatter than other large woodlice, and their bodies are usually brownish-black in colour, with paler mottling and very pale edges to their segmental plates. Their carapace is usually rather shiny, while the underside is pale. The species can also be identified by its long pointed telson. Oniscus asellus has a strong exoskeleton and seven pairs of legs, but are born with six pairs. They have antennae that reach about half of their body length, which they use to feel around in their dark environment. Other common names of oniscus asellus include the common shiny woodlouse and more colloquially tiggyhogs, God's little pigs, parsons-pigs, grammer sows and sow bugs. Sow bugs are not insects, as s evident by the number of legs, seven pairs as opposed to the three pairs that insects have. Sow bugs are actually crustaceans, so their closet relatives include things like fresh water shrimp, crabs, crayfish and lobsters

7 The species is particularly fond of rotting wood and are one of the commonest species found under garden logs and stones in their range. They are also likely to be found in houses which have damp porches, in outhouses, back kitchens and so on. These woodlouse eat vegetables, various types of detritus such as dead plant and animal matter, including rotting wood. They are very effective decomposers; this means they are often an integral part of a compost heap. Oniscus asellus predators include toads; shrews, hedgehogs, young owls and foxes, centipedes and spiders such as the woodlouse spider (Dysdera crocata), which has evolved fangs which are well-suited for piercing the woodlouse's exoskeleton and injecting poisons. Sowbugs are interesting, armadillo-like creatures. Strangely enough, they belong to the same class of animals as lobsters and shrimps. These tiny land crustaceans require moist conditions to survive and like to live under rocks or debris such as damp, decaying leaf litter. 2.2 Biological Indicator Biological Indicator is an organism which can indicate pollution and the degree of pollution by their presence in the environment. These organisms are capable of accumulating significant amounts of toxic pollutants in their system which return reduces the amount of the pollutants emitted in the environment.

8 Biological indicator refers to organisms, species or community whose characteristics show the presence of specific environmental conditions. Other terms used are indicator organism, indicator plant and indicator species Biological indicators are used to monitor and evaluate the effectiveness of sterilization. They are designed for use with ethylene oxide gas, dry heat, steam or radiation. Ethylene oxide gas is used to kill bacteria, mold and fungi in medical supplies such as bandages and food stuffs such as spices. Dry-heat sterilization uses an oven to raise the temperature of items that are wrapped in foil or fabric. Steam sterilization uses an autoclave, a self-locking machine that sterilizes its contents with steam under pressure.

Biological indicators that are suitable for

use with gamma and electron beam radiation techniques are also available. Biological indicator use the ability of organisms to detect and monitor changes of any particular factors in the ecosystem, including contamination by pollutants the greatest advantage of bioindicators is they detect real or total affects of any pollutants under natural conditions whereas the chemical and physical measurements can detect only the dose or the concentration of the pollutants (www.scene,cmu.ac.th, 2003) 2.3 Heavy Metals In chemistry heavy metals is often referred to as a type of chemical element, which are poisonous to humans. The further metals that pose greatest environmental hazardous due to their extensive used, their widespread distribution are lead, mercury and arsenic. None has yet pervaded the

9 environment to such an extent as to constitute widespread changes. However, each has been discovered to occur at toxic levels in certain locales in recent times. Heavy metals differ from the toxic organic compounds in that they are totally non- biodegradable, since most elements cannot be transmitted except under extra ordinary conditions, they are practically speaking, indestructible and so they accumulate in the environment. (Bierd, 1995). Heavy metals that occur naturally may become mobilized as a result of natural processes as well as activities. Industrial processes are often cited as one of the notable causes of heavy metal destabilization that usually results to severe degradation of the aquatic environment. The concentration of heavy metals in ground water can easily be increased to levels, which aquatic organisms are not previously encountered. Heavy metals which a higher concentrations are proven to be toxins to aquatic organism. 2.3.1 Lead Toxicity Lead is one of the oldest metals known and one of the most seven metals used in the ancient world. Lead is bluish gray metal that has no taste or smell, namely occurs naturally in drinking water and at some point in the water delivery system. This occurrence as the result of corrosion is the reaction between the water and lead in parts of the water delivery system. Lead is the most ubiquitous toxic metal and is detectable in practically all phases of the inert environment and in all biological system.

10 Lead reaches the aquatic environment through precipitation, fallout of lead dust, and municipal and industrial wastewater discharges. The toxic effects from lead form a continuum from clinical and overt effects to subtle or biochemical effects. Lead has been used by humans for at least 7000 years, because it is widespread, easy to extract and easy to work with. It is highly malleable and ductile as well as easy to smelt. In the early Bronze Age lead was used with antimony and arsenic. In the aquatic environment, lead may be complex with organic ligands yielding soluble, colloidal particulate compounds. Soluble lead is released from the solution by association with sediments and suspended particulates such as organic matter, hydrous oxide and clay. Lead is bio-accumulated by aquatic organisms including benthic bacteria, plants, invertebrates and fishes. Lead causes neurological problems, with organolead compounds, being more toxic than simple lead salts. Children can suffer mental retardation, lower performance in IQ test and hyperactivity. Severe exposure in adults causes irritability, sleeplessness and irrational behaviour. The appetite is depressed and death can occur due to starvation (Bunce 1994). Lead is non essential for plants and animals. It is toxic by ingestion and is accumulative poison. 2.3.2 Cadmium Toxicity A soft, bluish-white metallic element occurring primarily in zinc, copper, and lead ores, that is easily cut with a knife and is used in low-friction, fatigue-

11 resistant alloys, solders, dental amalgams, nickel-cadmium storage batteries, nuclear reactor shields, and in rustproof electroplating. Atomic number 48; atomic weight 112.41; melting point 320.9°C; boiling point 765°C; specific gravity 8.65; valence 2. Cadmium is an extremely toxic metal commonly found in industrial workplaces, particularly where any ore is being processed or smelted. Due situations where trace quantities of cadmium are found in the parent ore or smelter dust. Cadmium is used extensively in electroplating, although the nature of the operation does not generally lead to overexposures. Several deaths from acute exposure have occurred among welders who have unsuspectingly welded on cadmium-containing alloys or worked with silver solders. Cadmium is also found in some industrial paints and may represent a hazard when sprayed. Operations involving removal of cadmium paints by scraping or blasting may similarly pose a significant hazard. Cadmium is also present in the manufacture of some types of batteries. Cadmium emits a characteristic brown fume (CdO) upon heating, which is relatively non-irritating, and thus does not alarm the exposed individual. Cadmium is a metal found in natural deposits as ores containing other elements. The greatest use of cadmium is primarily for metal plating and coating operations, including transportation equipment, machinery and baking enamels, photography, television phosphors. It is also used in nickel-cadmium and solar batteries and in pigments.

12 Exposures to cadmium are addressed in specific standards for the general industry, shipyard employment, the construction industry, and the agricultural industry. This page highlights OSHA standards, preambles to final rules (background to final rules), Federal Registers (rules, proposed rules, and notices),

directives

(instructions

for

compliance

officers),

and

standard

interpretations (official letters of interpretation of the standards) related to cadmium. Hazards are present in every work environment; being unaware of them, especially when dealing with cadmium, can have critical, even fatal, consequences. Included among the references listed below are most of the major activities in which cadmium exposure can or has occurred. These links also aid in recognizing cadmium and cadmium compounds and the health effects associated with them. This is a fact sheet about a chemical that may be found in some public or private drinking water supplies. It may cause health problems if found in amounts greater than the health standard set by the United States Environmental Protection Agency (EPA). In 1974, Congress passed the Safe Drinking Water Act. This law requires EPA to determine safe levels of chemicals in drinking water which do or may cause health problems. These non-enforceable levels, based solely on possible health risks and exposure, are called Maximum Contaminant Level Goals.

13 From 1987 to 1993, according to EPAs Toxic Chemical Release Inventory, cadmium releases were primarily from zinc, lead and copper smelting and refining industries, with the largest releases occurring in Arizona and Utah . Some cadmium compounds are able to leach through soils to ground water. When cadmium compounds do bind to the sediments of rivers, they can be more easily bioaccumulated or re-dissolved when sediments are disturbed, such as during flooding. Its tendency to accumulate in aquatic life is great in some species, low in others.The regulation for cadmium became effective in 1992. Between 1993 and 1995, EPA required your water supplier to collect water samples once and analyze them to find out if cadmium is present above 5 ppb. If it is present above this level, the system must continue to monitor this contaminant every 3 months.If the levels of cadmium exceed the MCL, the system must notify the public via newspapers, radio, TV and other means. Additional actions, such as providing alternative drinking water supplies, may be required to prevent serious risks to public health. 2.4 RELATED STUDIES MONIT. ZOOL. ITAL. (1989). Study the Terrestrial isopods as biological indicators of zinc pollution in the Reading area, south east England . The concentrations of zinc were determined in samples of soil, and whole specimens of the woodlice

Porcellio scaber Latreille, 1804 and Oniscus asellus Linne,

1758, collected from 63 sites within an area of 30 x 30 km centered on reading, South East England. No major regional source of zinc pollution could be

14 identified on maps prepared from concentration of this metal in soil or woodlice samples collected 5 km apart. The concentrations of zinc in P. scaber were about twice those of Q. asellus at each site. This stressed the importance of accurate identification of species in biological indicator studies. G. Walker1 (2004) analyzed the Copper granules in the barnacle Balanus balanoides. The sample was collected from an area with high heavy-metal run-off contained two different types of granule within the parenchyma cells of the prosoma. X-ray microprobe analysis shows one to be the familiar zinc granule made up of concentric layers and giving major peaks for phosphorus and zinc, and the other to be homogeneous and giving peaks for sulphur and copper. This latter granule is designated the copper granule. Whilst zinc granules are known to be composed of inorganic phosphate, various tests on copper granules in sections and in a granule-rich pellet have shown that the copper is probably complexed with organic matter. The tests also demonstrated the relatively, insoluble (inert) nature of these granules. Although zinc and copper granules were present together in the prosoma, atomic absorption analyses of whole bodies (prosoma+thorax) have shown the level of zinc (50.28 g/mg dry weight) to be much higher than that of copper (3.75 g/mg dry weight). Clay Sassaman, Ronald Garthwaite (1984) study the The Interaction between the Terrestrial Isopod Porcellio scaber Latreille and One of Its Dipteran Parasites, Melanophora roralis (L.) (Rhinophoridae. Melanophora roralis (L.), a rhinophorid fly, was reared from naturally infected sowbugs, Porcellionides

15 pruinosus (Brandt) and Porcellio scaber Latreille, collected at several locations in the eastern United States , the majority from P. scaber. Aspects of the hostparasite interaction were studied in a large sample of isopods from North Carolina . The flies were sexually dimorphic for body size, and varied in size as a function of individual host size. Differences between the fly sexes were due to their differential utilization of a common range of host sizes rather than to the use of

different

host

sizes;

this

result

was

directly

confirmed with laboratory rearings of full sibships. Two potential indicators of individual fitness, adult longevity, and female fecundity, were direct functions of parasite, and hence host, size. The size dimorphism in Melanophora roralis, and physiological features associated with it, may reflect adaptations in this parasite for population persistence at low population densities.

16 Chapter 3 METHODOLOGY 3.1 Materials, Reagents and Apparatus Materials such as Erlenmeyer flasks, beaker, volumetric flasks, burettes, pipette, graduated cylinder, wash bottles polyethylene bottles, and pestle and mortar were sterilized. Reagents of hydrochloric acid, nitric acid and 30% hydrogen peroxide are of analytical grade. Atomic Absorption Spectrophotometer (GBC Avanta, Australia ) was used for the determination of the amount of metals absorbed. 3.2 Collection of Sample Thirty pieces of sow bugs (Oniscus Asellus) were randomly collected from Maliksi, Las Pinas and Paranaque . It was hand-collected and place in a small bottle of mineral water; the samples was brought to the laboratory and clean thoroughly. The sample tissue was taken out from the container and dried in an oven at 70ºC for 2 hours. Sample was cooled in the desiccators, and then ground using a mortar and pestle to obtain a pulverized sample. Thesample was used to test the presence of lead, and cadmium content in seawater along BacoorParanaque coastal area. 3.3 Preparation of Sample Nitric acid digestion method was used in the study was adapted from the Department of Environmental Natural Resources, Environmental Management Bureau –National Capital Region (EMB –NCR).

17 Two grams of pulverize sample was digested in Erlenmeyer flask at 10 ml of 70 % with 1:1 nitric acid was added and heated for 10-15 minutes. Then, 2 ml of distilled water and 3 ml 30% hydrogen peroxide was added and cooled. Afterwards, 10mL of distilled water and 5 ml hydrochloric acid was added and heated again to reduce the volume to 5 ml solution then cooled again. The digested sample was filtered and was transferred to 100 ml volumetric flask. In preparation for the blank, same procedure was done in an empty flask as with a flask containing the sample. 3.4 Analysis of Samples through AAS Atomic Absorption Spectrophotometer (GBC Avanta Australia ) was used in the analysis of lead and cadmium. It uses high-pressure combustible gas (acetylene, hydrogen) and aesthetic gas (nitrous oxide). The solution from the acid digestion method was used for the analysis of lead and cadmium. Parameters such as wavelength, light sources, slit width and flame type was set before the analysis of heavy metals. Standard solution was prepared. This standard solution serves as valid calibration curves and was used in the calculation of the concentration of lead and cadmium in the samples. The solution and the blank were aspirated directly into the instrument and the absorption was read.

18 CHAPTER 4 RESULTS AND DISCUSSION 4.1 Collection and Preparations of Sow Bugs (Oniscus Asellus)

The collection of the sow bugs was done by hand- picking. Randomly sampling of sow bugs were collected at the downstream portion of Maliksi, Las Piñas and Parañaque and it was placed in a small bottle of mineral water provided with enough sea water to make sure that the sow bugs are still fresh before digestion. Three sampling in one site was done. The samples obtained five meters away from each sites. The sample was brought from the small bottle of mineral water and put it to the news paper to drain the sea water in sowbugs, and was dried within four hours from the sunlight and dried in an oven at 70 ºC for 2 hours. And after the preparation, the sample tissue grind with mortar and pestle and they becomes pulverized, the color turns to brown. 4.2 Nitric Acid Digestion When nitric acid was added they form bubbles and the color turns to yellow and they have an unpleasant odor. 4.3 Color The color of fresh sow bug (oniscus asellus) was dark brown if they are in water and black if they are under the stone. The color of the sample tissue after drying is brown.

19 4.2 AAS Analysis of Lead The lead contents of the digested samples were determined by atomic absorption of both metals at the DENR Laboratory. The concentration of both metals in the dried samples in ppm (mg/L) was calculated. .

The data presented in Table 4.1 shows that the samples obtained from

Maliksi and Las Piñas have the same amount of lead with a concentration of 0.002ppm. The sample obtained from Parañaque has the least amount of lead which is <0.001 ppm. The lead concentration in the three sites exceeds the maximum lead concentration which is 0.05 mg/L. Table 4.1. Lead Content in a Dried Tissue Sample Tissue of Sow Bugs

Pb Concentration Sampling Site concentration

(ppm)

Trial 1 Maliksi

Trial 2

Average

Trial 3

0.002

0.004

0.002

0.002

0.002

0.002

<0.001

<0.001

<0.001

0.003* Las Piñas 0.002* Parañaque <0.001*

* Allowable limit (0.05mg/L)set by DENR

20 4.3 AAS analysis of Cadmium Table 4.3 shows the concentration of cadmium in the three sampling sites along the Bacoor- Parañaque coastal area. The samples obtained from Las Piñas have the highest degree of cadmium contamination. The samples gathered from Maliksi have the least amount of cadmium contamination. Table 4.3 Cadmium Content in a Dried Sample Tissue of Sow Bugs Cd concentration Sampling Site

(ppm)

Average

concetration Trial 1

Maliksi

Trial 2

0.04

Trial 3

0.029

0.023

0.031* Las Piñas

0.078

0.019

0.017

0.038*

Parañaque

0.025

0.021

0.018

0.021*

*Allowable limit (0.01mg/L) set by DENR This study has confirmed and conducted by Arapo and Ariño (2005) who gave also a similar study in Pb, Cd, and Hg contamination along BacoorParañaque coastal area. The sampling area was also the same. The samples were immediately preserved after collection and analyzed using an Atomic

Absorption Spectrophotometer. Seawater sample needed for lead and cadmium analyses underwent wet acid digestion. Seawater sample for mercury analysis 21 was diluted 1:9 with 1 N nitric acid. The average concentrations of lead were 0.2129, 0.1742, and 0.1327 ppm respectively. Mercury found at concentration of 5.1327, 6.8490, and 33.1668 ppb. Analyses gave a negative result for cadmium. Cadmium in seawater is either not present or below detectable limit. The three sampling sites were generally high in mercury and lead. Seawater from Parañaque contains the greatest concentration of mercury and seawater from Maliksi has the greatest concentration of lead. Results of the analyses for lead and mercury exceeded the DENR maximum limit for heavy metals Pb, and Hg in seawater which are 0.05 ppm and 2 ppb respectively.

22 Chapter 5 CONCLUSION AND RECOMMENDATIONS The main focus of this study was to determine the lead and cadmium contents of Sow Bugs (Oniscus Asellus). Sow Bugs (oniscus aellus) a crustacean, was collected from BacoorParañaque coastal area during the 1st week of December, 2006. The samples were analyzed using Atomic Absorption Spectrometer. The results showed that cadmium are present in the sow bugs collected from Bacoor- Parañaque coastal area. The lead concentrations in Maliksi, Las Pinas and Parañaque was less absorbance. The samples obtained from Maliksi and Las Pinas have the higher amount of cadmium concentration and the samples obtained from Paranaque have the least amount of cadmium concentration. From the three sampling sites the lead concentration was not detected. With the notable results of the study, the following recommendations are drawn. •

Continuous study / monitoring of cadmium concentration in the sea water along Bacoor- Parañaque coastal area.

•

Further similar study could be conducted using other environmental technique to determine the heavy metals concentrations of the samples.

23 BIBLIOGRAPHY American Public Works Association, Water Pollution Aspects of Urban Runoff (Washing, 1964) A.P.H.A Standard Methods for the Examination of Water and Wastewater, Washington D.C 13th edition Black and Veatch International, Master Plan for Sewage System Manila Metropolitan Area. Final Report for World Health Organization (WHO) Dec.1969 Ellis, M.M.A., B.A Westfall and Marion D. Ellis, 1946, Determination of Water Quality U.S fish and Wildlife Service Res. Report 9 Environmental Management Bureau Report; Principles for developing Coastal Water Quality Criteria (1976) Rep. Study GE SAMP EMB Report, Background on water Pollution, A manual for Municipal, State and Federal Planners (1978) EMB Report, Water and Pollution Control (1985) Funk, Thomas A. The Law and Water ( St. Louis 1967) Grava, Siguid, Urban Planning Aspect of Water Pollution Control ( New York 1969) Hynes, H.B.N. 1960. The biology of Polluted Waters, Liverpool University Press. Liverpool Leland, H.V. et.al. Heavy Metals and Other Trace elements, Water Pollution Federation. Literature Review Issue EMB. June 1975 Tanswell, C.M. (ed) 1965. Biological Problems of Water Pollution. Third seminar Public Health Service, Public No.999-WP-25 Wilbur, Charles C. The Biological Aspects of Water Pollution ( Springfield 1969) Warren, Charles E. 1971. Biology and Water Pollution Control W.B. Saunders

Company Philadelphia Willrica, Ted.L.,and Hines N. William. Water Pollution Control and Abatement ( Ames , IOWA ) 19 24 REFERENCE Bigornia, A.t. (2002). Analysis of lead, in clams, mussels and oysters. Undergraduate thesis, U.P., Diliman Q.C Calica JR 1980. Zinc uptake of some freshwater, plants under state Conditions,Unpublished B.S Thesis, UP at Los Banos Christman, R.F (ed) 1977. Where Might Heavy Metals in the aquatic Environment end up., Environmental Science and Technology (7), 643 Darwin, L.C, 1999. The use of water hyacinth as biological indicator chromium Levels in Laguna de Bay. Unpublished M.S Thesis U.P Los Banos QH 365 Panda A.K (1997). The removal of Nickel and Zinc using water Lettuce ( Pistia stratioles) under static conditions. QL1 Brusca, R. C. 1984. Phylogeny, evolution and biogeography of the marine isopod subfamily Idoteinae (Crustacea: Isopoda: Idoteidae). Trans. San Diego Soc. Nat. Hist. 20: 99-134. Brusca, R. C. and E. W. Iverson. 1985. A Guide to the Marine Isopod Crustacea of Pacific Costa Rica . Revista de Biologia Tropical 33, Supplement 1:1-77. Brusca, R. C. and G. D. F. Wilson. 1991. A phylogenetic analysis of the Isopoda with some classificatory recommendations. Mem. Queensland Mus. 31: 143-204. Brusca, R. C., R. Wetzer, & S. France . 1995. Cirolanidae (Crustacea: Isopoda: Flabellifera) of the Tropical Eastern Pacific. Proc. San Diego Soc. Nat. Hist. 30: 1-96. Cohen, B. J. & G. C. B. Poore. 1994. Phylogeny and biogeography of the Gnathiidea (Crustacea: Isopoda) with descriptions of new genera and species most from south-eastern Australia . Mem. Mus. Victoria 54: 271-397.

Delaney, P. M. 1989. Phylogeny and biogeography of the marine isopod family Corallanidae (Crustacea, Isopoda, Flabellifera). Contrb. Sci., L.A. Co. Nat. Hist. Mus. 409: 1-75.

25 Grassle, J. F. & N. J. Maciolek. 1992. Deep-sea species richness: Regional and local diversity estimates from quantitative bottom samples. Am. Nat. 139:313341. Hessler, R.R. and G.D.F. Wilson. 1983. The origen and biogeography of malacostracan crustaceans in the deep sea. in, R.W. Sims, J.H. Price and P.E.S. Whalley, 1983, Evolution, Time and Space: The Emergence of the Biosphere, Academic Press, N.Y. [Systematics Assoc. Special Vol. No. 23]. pp. 227-254. Hopkin, S. P. 1989. Ecophysiology of Metals in Terrestrial Invertebrates. Elsevier Applied Science, Barking. Kensley, B. 1984. The role of isopod crustaceans in the reef crest community at Carrie Bow Cay, Belize . Mar. Ecol. 5(1):29-44. Kensley, B. and R. C. Brusca (eds.) 2001. Isopod Systematics and Evolution. Balkema, Rotterdam . Kensley, B. & M. Schotte. 1989. Guide to the Marine Isopod Crustaceans of the Caribbean . Smithsonian Institution Press, Washington , D.C. Kensley, B. In Press. Estimates of species diversity of free-living marine isopod crustaceans of coral reefs. Coral Reefs. Kensley, B. & M. Schotte. 1995. World List of Marine and Freshwater Isopods. Smithsonian Institution Gopher Server, accessible via Smithsonian Home Page on WWW. Moore, W. ms. Historical biogeography of the central tropical Pacific based on anthuridean isopod crustaceans. In draft version. Perry, D. M. and R. C. Brusca. 1989. Effects of the root-boring isopod Sphaeroma peruvianum on red mangrove forests. Mar. Ecol. Prog. Ser. 57: 287292. Poore, G. C. B. & G. Wilson. 1993. Marine species richness. Nature, London 361: 587-583.

Wallerstein, B. R. & R. C. Brusca. 1982. Fish predation: A preliminary study of its role in the zoogeography and evolution of shallow-water idoteid isopods (Crustacea: Isopoda: Idoteidae). J. Biogeography 9: 135-150.