scale of the nanoparticles (Hanna et al. 2013). In the case of
nAg, the uptake rate was observed to increase with a change
in the size of the ENP (Pan et al. 2012; Banerjee and
Choudhury 2019). Zhao and Wang (2012) have noted a
contrary reverse trend, however. Related data were well
accessible (Handy et al. 2008; Klaine et al. 2008). Various
nanomaterials, particularly silver, indicate bactericidal
properties (Sondi and Salopek-Sondi 2004; Morones et al.
2005; Banerjee and Choudhury 2019). The titanium dioxide
also shows strong antimicrobial activity (Wolfrum et al.
2002).
3.2 Toxicity to Aquatic Plants
Less research has been done on the impact of the ENPs on
aquatic plants. Synchrotron-based micro X-ray fluorescence
mapping and extended X-ray absorption structure spectroscopy revealed deposits of the fraction of Ag 2 S and silver
thiol species in the roots of duckweed after exposure to 24 h
of ENP (Stegemeier et al. 2017; Banerjee and Choudhury
2019). The development of Ag derivatives in the plant roots
was possibly due to the plant molecular defence system to
retort the intake of Ag-ENPs (Stegemeier et al. 2017). Kim
et al. (2011) reported hindrances to the development of
Lemna paucicostata plants exposed to Ag-ENP (even at a
low concentration of 1 ppm) and TiO 2 -ENP (at a higher
concentration of 250 ppm).
3.3 Toxicity to Phytoplankton
Phytoplanktons are an essential means of the marine food
web system and are the most significant consumers in
aquatic habitats. Where ENPs have significant toxic effects
on phytoplankton, the whole ecosystem is affected due to
phytoplankton toxicity as they hold crucial importance in the
aquatic food chain. The toxicity to phytoplankton and
reduction in their growth will automatically allow the entire
food system to fail or collapse. Therefore, ecotoxicological
studies on phytoplankton are of particular importance for
aquatic systems. As expected, the algae were the most sensitive group of aquatic organisms to ENP. It was found that
ZnO exhibited maximum toxicity in freshwater plankton
Pseudokirchneriella subcapitata among other metal and
metal oxide ENPs, with substantial growth reduction (EC 50 )
at 42 mg l
−1 (Aruoja et al. 2009; Banerjee and Choudhury
2019). In the marine algae, Thalassiosa pseudonanathe EC 50
for ZnO was found to be 4.6 mg L
−1 (Wong et al. 2010).
Particles of Nano-C 60 impaired the growth of P. subcapitata
at a concentration of 90 mg L
−1 nearly 30%. The C 60 ENPs’
contact with the algal cells has facilitated the entrance into
the cells of other contaminants. This stimulated more
significant damage to algal cells and improved cellular
apoptosis (Sigg et al. 2014; Banerjee and Choudhury 2019).
Toxic effects of NiO ENPs on the alga Chlorella vulgaris
have been tested. The tests showed 32.28 mg L
−1 EC 50
values with 72 h sensitivity to NiO. NiO toxicity of thylakoid systems in Chlorella vulgaris has caused plasmolysis,
cell membrane damage, and disorder. The most alarming
discovery was that the NiO effects could be transmitted to
herbivores at a higher trophic level, devouring the NiO effect
(Gong et al. 2011; Banerjee and Choudhury 2019).
The exposure of nanomaterials to phytoplankton and the
deposition in phytoplankton will directly or indirectly impact
the whole marine environment because they are the primary
consumers of the nutrient in aquatic environments. Phytoplanktons are the primary producers, so the nanocrystals
lying on the exteriors of this biota enter up in the food chain.
The iron nanoparticles hamper the growth of marine phytoplankton. There is also inhibition of development of
marine phytoplankton species Isochrysis galban due to
presence of iron nanoparticles (Keller 2012). In photosynthesis of phytoplankton, chlorophyll is of a, b, and c types
(Chen et al. 2012). As the Fe 3 O 4 nanoparticle intensity
enhanced, the chlorophyll a matter tends to decline in C.
vulgaris (Chen et al. 2012). There has been a significant
toxic effect of Fe 3 O 4 nanoparticles on CO 2 absorption and
the net photosynthetic rate. In lipid peroxidation and cellular
oxidative, the malondialdehyde (MDA) is an important
marker in C. vulgaris, which steadily rises as the Fe 3 O 4
nanoparticle concentration rises (Chen et al. 2012). This has
demonstrated that the MDA content in C. vulgaris has been
increased due to stress-induced by Fe 3 O 4 nanoparticles
(Chen et al. 2012).
3.4 Fish Nanotoxicity
Fish is a common aquatic vertebrate, serving an essential
ecological role in aquatic systems. It is also an important
food source for humans—a study on the toxicity and behaviour of ENPs in fish directly related to human safety. To
forecast the toxicity of a specific material, different stages in
the fish life cycle are studied. Harmful ENPs can be highly
toxic to many invertebrate organisms, including fish species
which are also part of the aquatic food chain. Marine
invertebrates such as Hediste diversicolor and Scrobicularia
sp. had been chosen for the study of their behavioural and
biochemical reactions to Cu NPs. Impaired coping habits
were found at Scrobicularia sp. for Cu-ENPs or Cu soluble
as well; however, H. diversicolor reflected harmful effects
only on soluble Cu. All species showed no variations in their
cholinesterasic behaviour, demonstrating that either the
Cu-ENPs or the soluble Cu did not induce neurotoxicity
(Buffet et al. 2011; Banerjee and Choudhury 2019). When
Nano-toxicity and Aquatic Food Chain
193
nAg, the uptake rate was observed to increase with a change
in the size of the ENP (Pan et al. 2012; Banerjee and
Choudhury 2019). Zhao and Wang (2012) have noted a
contrary reverse trend, however. Related data were well
accessible (Handy et al. 2008; Klaine et al. 2008). Various
nanomaterials, particularly silver, indicate bactericidal
properties (Sondi and Salopek-Sondi 2004; Morones et al.
2005; Banerjee and Choudhury 2019). The titanium dioxide
also shows strong antimicrobial activity (Wolfrum et al.
2002).
3.2 Toxicity to Aquatic Plants
Less research has been done on the impact of the ENPs on
aquatic plants. Synchrotron-based micro X-ray fluorescence
mapping and extended X-ray absorption structure spectroscopy revealed deposits of the fraction of Ag 2 S and silver
thiol species in the roots of duckweed after exposure to 24 h
of ENP (Stegemeier et al. 2017; Banerjee and Choudhury
2019). The development of Ag derivatives in the plant roots
was possibly due to the plant molecular defence system to
retort the intake of Ag-ENPs (Stegemeier et al. 2017). Kim
et al. (2011) reported hindrances to the development of
Lemna paucicostata plants exposed to Ag-ENP (even at a
low concentration of 1 ppm) and TiO 2 -ENP (at a higher
concentration of 250 ppm).
3.3 Toxicity to Phytoplankton
Phytoplanktons are an essential means of the marine food
web system and are the most significant consumers in
aquatic habitats. Where ENPs have significant toxic effects
on phytoplankton, the whole ecosystem is affected due to
phytoplankton toxicity as they hold crucial importance in the
aquatic food chain. The toxicity to phytoplankton and
reduction in their growth will automatically allow the entire
food system to fail or collapse. Therefore, ecotoxicological
studies on phytoplankton are of particular importance for
aquatic systems. As expected, the algae were the most sensitive group of aquatic organisms to ENP. It was found that
ZnO exhibited maximum toxicity in freshwater plankton
Pseudokirchneriella subcapitata among other metal and
metal oxide ENPs, with substantial growth reduction (EC 50 )
at 42 mg l
−1 (Aruoja et al. 2009; Banerjee and Choudhury
2019). In the marine algae, Thalassiosa pseudonanathe EC 50
for ZnO was found to be 4.6 mg L
−1 (Wong et al. 2010).
Particles of Nano-C 60 impaired the growth of P. subcapitata
at a concentration of 90 mg L
−1 nearly 30%. The C 60 ENPs’
contact with the algal cells has facilitated the entrance into
the cells of other contaminants. This stimulated more
significant damage to algal cells and improved cellular
apoptosis (Sigg et al. 2014; Banerjee and Choudhury 2019).
Toxic effects of NiO ENPs on the alga Chlorella vulgaris
have been tested. The tests showed 32.28 mg L
−1 EC 50
values with 72 h sensitivity to NiO. NiO toxicity of thylakoid systems in Chlorella vulgaris has caused plasmolysis,
cell membrane damage, and disorder. The most alarming
discovery was that the NiO effects could be transmitted to
herbivores at a higher trophic level, devouring the NiO effect
(Gong et al. 2011; Banerjee and Choudhury 2019).
The exposure of nanomaterials to phytoplankton and the
deposition in phytoplankton will directly or indirectly impact
the whole marine environment because they are the primary
consumers of the nutrient in aquatic environments. Phytoplanktons are the primary producers, so the nanocrystals
lying on the exteriors of this biota enter up in the food chain.
The iron nanoparticles hamper the growth of marine phytoplankton. There is also inhibition of development of
marine phytoplankton species Isochrysis galban due to
presence of iron nanoparticles (Keller 2012). In photosynthesis of phytoplankton, chlorophyll is of a, b, and c types
(Chen et al. 2012). As the Fe 3 O 4 nanoparticle intensity
enhanced, the chlorophyll a matter tends to decline in C.
vulgaris (Chen et al. 2012). There has been a significant
toxic effect of Fe 3 O 4 nanoparticles on CO 2 absorption and
the net photosynthetic rate. In lipid peroxidation and cellular
oxidative, the malondialdehyde (MDA) is an important
marker in C. vulgaris, which steadily rises as the Fe 3 O 4
nanoparticle concentration rises (Chen et al. 2012). This has
demonstrated that the MDA content in C. vulgaris has been
increased due to stress-induced by Fe 3 O 4 nanoparticles
(Chen et al. 2012).
3.4 Fish Nanotoxicity
Fish is a common aquatic vertebrate, serving an essential
ecological role in aquatic systems. It is also an important
food source for humans—a study on the toxicity and behaviour of ENPs in fish directly related to human safety. To
forecast the toxicity of a specific material, different stages in
the fish life cycle are studied. Harmful ENPs can be highly
toxic to many invertebrate organisms, including fish species
which are also part of the aquatic food chain. Marine
invertebrates such as Hediste diversicolor and Scrobicularia
sp. had been chosen for the study of their behavioural and
biochemical reactions to Cu NPs. Impaired coping habits
were found at Scrobicularia sp. for Cu-ENPs or Cu soluble
as well; however, H. diversicolor reflected harmful effects
only on soluble Cu. All species showed no variations in their
cholinesterasic behaviour, demonstrating that either the
Cu-ENPs or the soluble Cu did not induce neurotoxicity
(Buffet et al. 2011; Banerjee and Choudhury 2019). When
Nano-toxicity and Aquatic Food Chain
193