The biomarker concept is considered as a breakthrough concept to complete the conventional approach for evaluating the environmental quality.
The concept offers opportunities to picturize holistic interactions between pollutants and pollutant-induced biological damages of sentinel organisms from
molecular, cellular to behavioral levels. It is acknowledged that a healthy organism exposed to increasing pollutant loads will suffer a continuum
deterioration in health which shows reversible to irreversible conditions that culminate on the death of organisms Depledge and Fossi 1994. Biomarkers
have capability to recognize in which point of the continuum pollutant-exposed organisms are located so that they offer potentially an early warning system for
environmental deterioration induced by pollutants Depledge and Fossi 1994. Last but not least, biomarkers can also detect prevented adverse effecs of
xenobiotic compounds on living organisms Wu et al. 2005. Therefore, biomarkers can be used conceptually as valuable tools in detecting adverse effects
of xenobiotic compounds both in laboratory and field scales Figure 1.
1.3. Problem Formulation
Biomarkers can be used either in early step of the ERA or in the further risk characterization both in field and laboratory scales. The applicability of
biomarkers in both laboratory and field scales should fulfill the requierements as rapid, sensitive, easy and cost-effective tools. ChE and phagocytic activities
which are miniaturized in micro-plate application are two biomarkers that fulfill the requirements Dizer et al. 2001; Blaise et al. 2002. Therefore, the experiment
that used the two biomarkers to detect the neuro-immune disruption induced by OP pesticides using blue mussels is needed to be studied as a strategy of exposure
in laboratory scale for assessing the pesticide effects. In fact, the use of biomarkers for detecting effects of pollutants can be
derived along continuum of biological integrity from molecular to behavioral levels. In general, the lower levels of biological compartments such as molecular
and cellular levels show sensitivity to environmental stressors, but they have poor lingkage to the ecological levels. In contrast, higher level of biological integrity
such as behavioral level has relatively significant relationship to the ecological levels Hansen 2007. One source of uncertainties in ERA using lower level of
biomarkers such as cholinesterase and phagocytic activities is the lack of ecological perpective. To solve the problem establishment of quantitative
relationship between measurement of biomarker along the biological integrity is necessary Sibley et al. 2000. Hence, in terms of OP pesticide impacts
combining ChE activity that is a main target of the OP pesticide toxicity and siphoning rate as surrogate of behavioral level from blue mussels is necessary to
be studied. The study allows us to recognize a transformation of ChE activity inhibition which is induced by the pesticides to the behavioral level. Accordingly,
this study will facilitate the interpretation of cellular damage induced by contaminant to ecological perspective through the behavioral level.
As an early warning system, biomarkers can be inserted to early step of ERA to recognize and characterize the hazardous of environmental stressors. In
the context of early recognition of the effect of existing pollutants in the environment biomarkers should be applied to assess rapidly hot spots of pollution,
thereby stimulating and supporting more detailed risk assessment. To be implemented in Indonesian waters the selected biomarkers which are phagocytotic
and ChE activities should be applied in indigenous mussels i.e. green mussels, P viridis
. Based on the role of biomarkers in ERA of OP pesticides four studies on
the selected biomarkers from two well-accepted eco-sentinel organisms namely green mussel Perna viridis and blue mussel Mytilus edulis for tropical and
temperate regions were conducted. The following are the structures of the studies. 1. In vivo test of dimethoate using ChE and phagocytic activity from blue
mussel, M. edulis, as biomarkers. 2. In vivo test of trichlorfon using ChE activity and siphoning rate from
blue mussel, M. edulis as biomarkers. 3. Cholinesterases ChEs characterization of green mussel, P. viridis,
from Pangkep district South Sulawesi Indonesia. This enzyme characterization was performed using two approach i.e. substrates and
inhibitors differentiations. 4. Hot spot biomonitoring using ChE and phagocytic activity from green
mussel, P. viridis as biomarkers.
Dimethoate is one of organophosphate OP pesticides that are in fact deliberately fabricated to inhibit ChE activity of target organisms. Albeit the
pesticide frequently usage in upland the presence of the pesticides in aquatic habitat from river Abdel-Halim et al. 2006 to coastal waters Hernandes et al.
1993 has been detected. Some OP pesticides have also been recorded to induce immune system of mobile invertebrate such as lobster De Guise et al. 2004.
Hence, the use of selected biomarkers that elucidate neuro-immune response of non-point source eco-sentinel organisms such as blue mussel, M. edulis to detect
dimethoate effects is of interest. The current study was set up to deal with laboratory test to recognize a potential extendable effect of dimethoate on marine
organism by using the selected biomarkers. One of the challenges to the use of biochemical or cellular biomarkers is
the lack of ecological relevance due to the ability of organisms to recover from the neurological damages after being exposed to such contaminants McHenery et al.
1997. Hence, it is demanding to study by integrating neurological response such as ChE activity and a higher level biological integrity that has a closed reasonable
relation to the induced enzyme like feeding activity. The study also attempted to record the ability of the trichlorfon-exposed mussels to recover from the
neurological and behavioral failures after incubation in artificial and natural seawater.
A characterization of ChEs from preferred sentinel organisms is a prerequisite of the use of ChEs from intended organisms as biomarker either in
laboratory tests or field investigations Bocquene et al. 1990; Strum et al. 1999; Rodryguez-Fuentes and Gold-Bouchot 2004. The characterization of these
enzymes provides us information at least on types of the enzymes and their parameters by which misinterpretation on data that were derived from undefined
ChEs as response to contaminants can be avoided. The ChE and phagocytic activity are two biomarkers that have been
employed frequently in stressor effects biomonitoring by using blue mussel, M. edulis
in temperate regions. There are few investigations in tropical regions that used the two biomarkers by employing green mussel, P. viridis.
Geographically M. edulis is distributed widely throughout boreal and temperate waters of both northern and southern hemispheres Soot-Ryen 1955.
In contrast, P. viridis is distributed widely in the Indo-Pacific region, from Japan to New Guinea and from Persian Gulf to South Pacific Islands Siddall 1980.
Although, the two mussels have different geographical distribution, their local distributions are similar. They generally live in marine intertidal, subtidal waters
though occasionally inhabit deeper water particularly where there is notable water movement Seed 1976; Rajagopal et al. 1998. They also share common
characteristics by living and growing in cluster using well-developed byssal apparatus on a variety of substrata, such as rock, wood, concrete, metal, old
submerged logs, and boats Seed 1976; Rajagopal et al. 1998. The two mussels can be differentiated distinctly by the external color of
the shell. M. edulis’s shell is covered by the conspicuous, dark yellowish brown or black, proteinaceous periostracum, while the shell color of P. viridis is bright
green to dark brownish-green near the outer edge and olive-green near the attachment point. The color of the shell is influenced by several genes, the age,
and the habitat of the animal. Blue mussel that inhabits in the intertidal zone has a blue-black and heavy shell, while those that lives in the sublittoral zone possesses
a brown with dark brown radial markings and thin shell Gosling 2003. Old P. viridis
’s shell tends to have more brown, while younger animal has vivid green or blue-green shell Siddall 1980. Moreover, M. edulis is characterized by the
presence of an anteriror adductor muscle, while this organ is absent in P. viridis Gosling 2003.
As a filter feeder, both M. edulis and P. viridis feeding on phytoplankton, small zooplankton and other suspended organic materials. As a temperate animal,
blue mussel has an optimum temperature and salinility for filtration rate are 5-20
o
C and 15-30 ppt, respectively Bayne et al. 1976. The optimum filtration rate of green mussel occurs at temperature 30
o
C and salinity 30-35 ppt Rajagopal 1991. Accordingly, the growth of the two animals is influenced by temperatures. The
optimum range of the growth of M. edulis is 3-20
o
C Almada-Villela et al. 1982, whereas P. viridis can grow appropriately on temperature 27-32
o
C Asikin 1982.
Both in M. edulis and P. viridis sexes are separate without external sign of dimorphism Seed 1976; Rajagopal et al. 2006. However, hermaphrodites may
occur in blue mussel population. Male and female gonads are distinguishable either in M. edulis or P. viridis. Ovaries are reddish in M. edulis and bright
orange in P. viridis whereas testes are cream in M. edulis and milky white in P. viridis
. The hot spot monitoring in this present study attempted to apply the two
selected biomarkers i.e. ChE and phagocytic activities which are originated from M. edulis
in Indonesia waters which is populated by P. viridis. The use of P. viridis
as eco-sentinel organism in stressor effects investigation campaigns in Indonesia is efficacious due to widely distribution of the animal from expected
pristine to heavily polluted waters. The hot spot monitoring was conducted in three different sites. The expected pristine site is located at coastal area of
Pangkajene Kepulauan Pangkep district, while the heavily polluted sites are located in Jakarta Bay, namely Kamal Muara and Cilincing. The three extreme
environments are considered to be appropriate location models for applying the biomarkers to picturize adverse effects status of the deteriorated coastal
environments.
1.4. Objectives of the Studies
