Environmental Engineering Reference
In-Depth Information
(Martinez et al.
2001
), Hydropsyche (Sol` et al.
2004
) and a range of macroinver-
tebrates (Goodyear & McNeill
1999
). However, a correlation between sediment
metal concentrations and invertebrate body burdens has not always been
found (Bervoets et al.
1997
,
1998
), which may be due to specific responses in
different species or groups. Macroinvertebrates source their food from a
number of niches within the freshwater environment and are generally
grouped into collector-gatherers, scraper-grazers, predators, shredders and
filterers (e.g., Begon et al.
1990
), so-called functional feeding groups. Research
has shown that the uptake of metals into organisms is strongly affected by the
feeding niche (Smock
1983
; Timmermans et al.
1989
; Kiffney & Clements
1993
).
Predatory insects in particular have been shown to obtain the majority of
bioaccumulated metal from food (Hare et al.
2003
), although food borne alu-
minium was found not to be important in the removal of predators down-
stream of mine drainage and the cause was thought to be related to direct
toxicity via gills (Soucek et al.
2002
). Van Hattum et al. (
1991
) found that,
for invertebrates of different feeding habits, Zn concentrations decreased in
the order predator
deposit feeder. In other studies, however,
no difference between herbivore-detritivores and predators was found in terms
of their body burdens of metals (Winterbourn et al.
2000
). Within metal-
contaminated environments metals are often at highest concentrations within
biofilms and sediments (Farag et al.
1998
). Biofilms are located at the bottom of
the food web, supporting, in conjunction with detritus, most of the aquatic
ecosystem, and often forming the interface between water toxicants and the
food web (Sabater et al.
2007
). This niche is utilised preferentially by shredder-
scrapers, and this group has been shown in many investigations to take up the
largest concentrations of metals such as Cd, Pb and Zn (Farag et al.
1998
; Rhea
et al.
2006
). Investigations of rivers in Idaho that receive mine drainage found
that the primary route of exposure of invertebrates to Cu was via periphyton
(Beltman et al.
1999
) and concentrations of metals in biofilms were a good
predictor of metals in invertebrates (Rhea et al.
2006
). In contrast, Borgmann
et al.(
2007
) showed that concentrations in epiphytic and detrital food did not
affect uptake of metal into Hyallela azteca. The prevalence of contradictory
information within the literature suggests that the sources and patterns of
uptake into macroinvertebrates may be both specific to the species and metal
involved. Although the majority of studies have focused upon sediment and
food concentrations it has also been suggested that invertebrates could collect
metals from the sediment pore water and the boundary layer between the
surface of the sediments and the overlying water column (Bervoets et al.
1998
)
adding another potential variable. Leaf litter deposited in mine waters also
accumulates large amounts of metals such as Fe, Mn and Zn (Nelson
2000
;
Batty & Younger
2007
), and this may be particularly associated with fine
particulate organic matter (FPOM) due its larger surface area in comparison
>
filter feeder
>
