Examining the Effects of pH and Macrophyte Diversity on Benthic Macroinvertebrate

Assemblages in Adirondack Lakes

by

Jacob A. Gaskill
Candidate for Bachelor of Science
Environmental Science
With Honors

May, 2014

APPROVED

Thesis Project Advisor: ______________________________

Dr. Kimberly Schulz

Second Reader: ______________________________

Dr. Neil Ringler

Honors Director: _____________________________

William M. Shields, Ph.D.

Date: ______________________________

1
Abstract:
Acidification in ecosystems, such as water bodies of the northeastern United States, causes

significant changes in their biological communities. Changes in lower trophic levels significantly affect

the structure and function of higher trophic levels. Benthic macroinvertebrates are useful when

examining the effects of acidification because different species are tolerant or sensitive to particular

conditions and can act as indicators of water quality. Macrophyte diversity is another explanatory

variable influencing macroinvertebrates. Many studies have examined macroinvertebrate assemblages

in streams related to water quality, but macroinvertebrates in lakes are less well studied.

We compared the benthic macroinvertebrate assemblages in four Adirondack lakes with

differing pH. We predicted that as pH decreased, the abundance and diversity of the macroinvertebrates

would decline. To test this, we measured pH and collected 40 benthic samples from four Adirondack

lakes using a PONAR samler. Macroinvertebrates were sorted, identified to the lowest possible taxon

(generally family or genus) and tallied. Macrophytes were identified and diversity was estimated with

the Shannon Diversity Index.

Benthic macroinvertebrate richness decreased with lower pH (p = 0.03) and increased with

greater macrophyte diversity (p =0.02). However, total macroinvertebrate abundance was not

statistically correlated with pH (p = 0.08) or macrophyte diversity (p = 0.07). Diversity is often considered

a strong indicator of ecosystem health, thus our results suggest that further reduction of acidification

may restore diversity of lower trophic levels in Adirondack lakes and improve their ecological conditions.

2
 Table of Contents

Introduction..................................................................................................................................................1

Objective and Hypotheses...............................................................................................................2

Methods........................................................................................................................................................3

Analysis...........................................................................................................................................4

Results..........................................................................................................................................................5

Discussion.....................................................................................................................................................8

Effects on Higher Trophic Levels....................................................................................................8

Disturbances..................................................................................................................................10

Continuity with Streams................................................................................................................11

Importance for Management........................................................................................................13

Potential Sources of Error..............................................................................................................13

Continuation of Study....................................................................................................................14

Conclusion..................................................................................................................................................14

Works Cited................................................................................................................................................16

Appendix.....................................................................................................................................................18

3
Figures:

Figure 1: Average benthic macroinvertebrate taxon richness per lake.

Figure 2: Average benthic macroinvertebrate abundance per lake.

Figure 3: Ephemeroptera and Trichoptera Order trends with changing pH.

Table:

Table 1: Percent composition by lake of each Order of benthic macroinvertebrates found.

Appendix:

Figure 1: Benthic macroinvertebrate abundance versus pH. Each of the ten sites sampled in each lake is
represented.

Figure 2: Benthic macroinvertebrate taxon richness versus pH. Each of the ten sites sampled in each lake
is represented.

Table 1: Percent composition by lake of each Family of benthic macroinvertebrates found in each lake.

Acknowledgments:

This study would not have been possible without the help of several individuals. I would like to

thank Dr. Neil Ringler for agreeing to review this report and providing very valuable insight. I would also

like to thank Dr. Kimberly Schulz for her instruction and support, as well being available to answer my

questions and sign my many forms. Finally, I would like to thank Andrew Brainard. As main collaborator

on the project, his guidance and direction cannot be overstated. As a friend , his advice and insight was

invaluable. The assistance of these three individuals has sparked my enthusiasm in the scientific process

and I am incredibly thankful for their contributions to my education.

4
Introduction:

Acidification in ecosystems causes significant changes, especially to species that inhabit those

ecosystems. Its effects are especially felt in the Northeastern United States (Geller and Schultze, 2009).

The southwestern region of the Adirondack Park is one of the most affected areas in the country

(Driscoll et al., 1991), because this area receives high amounts of rainfall, and the granite and gneiss

bedrock has little cation exchange capacity with which to neutralize acids (Cumming et al., 1991).

However, the percentage of acidified lakes in this region is dropping. Since the implementation of the

Acid Rain Program, a 1990 amendment to the Clean Air Act that reduced sulfate emissions, and the

Nitrogen Budget Program, a 2003 cap and trade program designed to regulate NOx emissions, Waller et

al. (2012) found that the percentage of severely acidified lakes in their study sample dropped from

15.2% to 8.3%. Furthermore, Driscoll et al. (1998) showed that sulfate concentrations have decreased

since 1983 in both precipitation and lake water. This coincides with a reduction in sulfate emissions in

the Midwest, largely attributed to the 1990 amendment to the Clean Air Act. Many believe that these

pieces of legislation have been some of the most successful environmental policies in the United States,

and they are widely thought to have decreased acid deposition.

Despite reductions, acid deposition in the Adirondack Park is still occurring and causes a range

of pH values in different bodies of water. Baldigo et al. (2009) conducted a comprehensive study of

Western Adirondack streams, finding that while there has been some recovery, many streams and lake

outlets are still acidified. Their study compared present water quality and benthic macroinvertebrate

communities with similar data collected in 1980. Macroinvertebrates are useful when examining the

effects of acidification because of the high diversity that they exhibit. Different species are able to

survive different conditions, and therefore can act as indicators to water quality. Furthermore, as

stressors (such as pH or changing habitat) increase and the environment becomes less habitable,

5
diversity decreases (Rapport and Whitford, 1999). Many believe that an ecosystem's health is directly

related to the biodiversity it supports (relative to the ecosystem if it were undisturbed). Thus, it is

possible to assess the health of similar ecosystems based on biodiversity. A decrease in benthic

macroinvertebrate diversity also has a great potential to affect higher taxonomic levels negatively.

Shifting macroinvertebrate regimes have a great potential to affect fish by altering the availability and

concentrations of energy and nutrients, especially amino acids (Forster, 2011). This would make it more

costly for some species to meet nutritional requirements and might ultimately open the door for other

species to flourish (Lento et al., 2008).

Many studies (for example, Baldigo et al., 2009) examine stream acidification in the Adirondack

Park. Much attention is given to the effects of acid deposition on streams, because they are more prone

to acidification than lakes. Streams receive water from shallow soils with little buffering capacity and

have few in-stream processes with which to buffer acid (US Geologic Survey, 2009). Consequently, much

less work has been put into studying the effects of acid deposition in lakes, where cations are typically

present in slightly higher concentrations than streams and thus are able to buffer acid inputs more

effectively. This is significant because management for both water bodies should not be the same if the

effects of acidification on each are different. Both are very prevalent throughout the Adirondack Park,

making management implications widespread. This study attempts to bridge the gap in the current

understanding of acidification in Adirondack waters by examining lake benthic macroinvertebrates.

Objective and Hypotheses:

This study investigates how environmental disturbances like changes in pH and macrophyte

diversity affect the abundance and taxa richness of benthic macroinvertebrates in four Adirondack

Lakes. We predict that benthic macroinvertebrate abundance and richness will be greater in lakes with

higher pH values and a greater diversity of macrophytes.

6
Methods:

Four Adirondack lakes were sampled for this study: Cranberry Lake, Lake Flower, Long Lake, and

Raquette Lake. Lakes were selected using two main criteria: the availability of a boat launch for public

access and the existence of public use data required for a second study on non-native macrophytes that

was being conducted at the same time. Sites were selected by measuring the total length of shoreline

around each lake and dividing it by ten (since ten sites were sampled in each lake). This was the distance

between each site. The first site was always placed at the boat launch and then subsequent sites were

marked off around the lake. Theoretically, this is a sound method for making sure that the whole lake

was evenly sampled. In practice, some sites were not able to be sampled because of unnavigable

physical features. A handheld GPS unit was used to record the coordinates of the location of each

sample site. At each site, pH was measured using a YSI 6600 Sonde. The pH for each lake was calculated

by averaging the measured pH at each site. The lakes we sampled were relatively small, so averaging the

measured pH values at each site is an appropriate way to accurately reflect the dominant ph of each

lake.

At each site, four benthic samples were collected using a petite PONAR (15.5 cm x 15.5 cm).

Samples were taken from between a one and three meter depth. This was done to maximize the

number of benthic macroinvertebrates collected. On calm days, samples were collected from different

sides of the boat to ensure an even sampling of the site. This was not necessary when the boat was

drifting. Within 24 hours of collection, a 70-80% ethanol solution was added to the samples to preserve

the benthic macroinvertebrates. A 70-80% ethanol, Rose Bengal (C20H2Cl4I4Na2O5) solution was added to

each sample to preserve and to dye all of the organic matter in the samples a bright pink. This facilitated

the sorting process and increased its accuracy as well.

7
 Dyed samples were run through a 0.50 millimeter sieve and rinsed. These rinsed samples were

sorted through using forceps. All benthic macroinvertebrates were removed and placed in a vial with 70-

80% ethanol solution. Any remains (shells, cases) were also removed and taken note of, but were not

used in analysis.

For macroinvertebrate identification, we used the key by Peckarsky et al., (1990). Sorted

samples were examined using a stereo microscope (though occasionally a dissecting microscope was

also used for smaller organisms). Organisms were identified to the furthest possible taxon, typically

family or genus. The exceptions to this were Oligochaeta, Amphipoda, and Chironomidae which were

just identified to order (or in the case of chironomid, Family). This was done because these three taxa

are known for their tolerance to environmental stressors and were very difficult to identify to any finer

taxonomic resolution. All identified organisms were counted and returned to the 70-80% ethanol

solution. This allowed for the creation of a list of taxa present, and abundance of each taxon in each

sample.

Analysis:

Total abundance was calculated for each lake by summing up the abundances of all benthic

macroinvertebrates present in each site (for a total of ten sites). This number was averaged (divided by

ten) to find the relative abundance per site. Taxon richness was calculated by averaging the number of

taxa present in the four samples of each site. This was done for each site (for a total of ten values). The

taxon richness of each lake was the average of these ten sites. The pH of each lake was found by

averaging the measured pH values of each site (ten total values). Macrophyte diversity was measured

using the Shannon Diversity Index, which takes into account the abundance and evenness of species

present in the community. A high Shannon Diversity Index value is representative of a diverse

community with an even species distribution.

8
Results:

Benthic macroinvertebrate richness increased with pH (p = 0.034) and macrophyte diversity (p =0.015) (Figure

1). However, total macroinvertebrate abundance was not statistically correlated with pH (p = 0.077) or macrophyte

diversity (p = 0.071) (Figure 2).

Both Ephemeroptera and Trichoptera increased in percent composition of benthic macroinvertebrates per lake

as pH increased (Figure 3). Otherwise, there were few other noticeable trends in percent composition of different

macroinvertebrate orders with pH (Table 1).

A. B.
18 Macroinvertebrate Richness vs. pH 18 Macroinvertebrate Richness vs.
Adirondack Lakes, Summer 2013 Macrophyte Diversity
16 16 Adirondack Lakes, Summer 2013
Lake Lake
Average Number of Taxa

Average Number of Taxa

14 14
Flower Flower
12 12

10 Raquette 10 Raquette
Lake Lake
8 Long Lake 8 Long Lake
Cranberry Cranberry
6 Lake R2 = 0.9222 6 Lake R2 = 0.9706
4 p = 0.034 4 p = 0.015
2 2
0 0
6.5 7 7.5 8 8.5 0 0.5 1 1.5 2
pH Macrophyte Total Shannon Diversity Index

Figure 1: A. Benthic macroinvertebrate richness increases as pH increases (p = 0.034). B. Benthic macroinvertebrate

richness increases as macrophyte diversity increases (p = 0.015).
A. B.
Macroinvertebrate Abundance vs. pH Macroinverebrate Abundance vs.
190 Adirondack Lakes, Summer 2013 Macrophyte Diversity
190
180 Adirondack Lakes, Summer 2013
180
Lake
Total Macroinvertebrates

Lake

Total Macroinvertebrates
170 Raquette Flower 170 Raquette Flower
Lake
160 Lake
160
150 150
Long Lake Long Lake
140 140
2
R = 0.8638 R2 = 0.8514
130 130
p = 0.071 p = 0.077
120 120
Cranberry Cranberry
110 Lake Lake
110
100 100
6.5 7 7.5 8 8.5 0 0.5 1 1.5 2
pH Macrophyte Total Shannon Diversity Index

Figure 2: A. There are no significant correlations between benthic macroinverebrate abundance and pH (p = 0.071) B. or
macrophyte diversity (p = 0.077).

3.5
Ephemeroptera and Trichoptera Trends
3 Adirondack Lakes, Summer 2013 R² = 0.8688

2.5
% Composition of Lake

Ephemeroptera
R² = 0.9152
2 Trichoptera

1.5

0.5

0
6.8 7 7.2 7.4 7.6 7.8 8 8.2
pH

Figure 3: Both Ephemeroptera and Trichoptera increased as pH increased. Many Ephemeroptera species are very
intolerant of acidic condition and are used as an indicator species for water quality.

10
Table 1: Percent composition of each taxon in each lake. Here, taxa are displayed as orders or classes (as denoted by
"C"). For a percent composition table with finer identification, please refer to the Appendix. Also shown are the average
pH values of each lake.

Cranberry Lake Long Lake Raquette Lake Lake Flower

(pH = 7.00) (pH = 7.42) (pH = 7.58) (pH = 8.05)

Ephemeroptera 0.2 0.7 1.8 2.5

Odonata 0.1 0.1 0.1 0.1

Plecoptera 0.1 0.0 0.0 0.0

Trichoptera 1.0 1.3 1.6 3.3

Coleoptera 0.4 0.1 0.1 0.1

Megaloptera 0.4 1.3 0.3 0.3

Diptera 44.4 54.7 26.9 38.1

Amphipoda 15.3 3.1 22.0 3.9

Isopoda 9.4 3.6 2.7 13.3

Gastropoda (C) 3.0 2.9 2.3 5.9

Bivalvia (C) 3.4 6.4 4.0 3.2

Oligochaeta (C) 22.3 25.1 31.0 33.3

11
Discussion:

Hypothesis 1 was supported. Benthic macroinvertebrate richness is significantly correlated with

both pH (p = 0.034) and macrophyte diversity (p = 0.015). Both of these variables partially explain the

change in taxon richness between lakes.

Hypothesis 2 must be rejected. We found no significant correlation between the decrease in

benthic macroinvertebrate abundance with pH (p = 0.071) or macrophyte diversity (0.077), indicating

that these two variables do not explain changes in abundance between lakes. Macroinvertebrate

abundance levels off at higher pH than macrophyte richness, so there is not a linear relationship

between these variables.

Our results indicate that certain environmental stressors (in particular pH and degrading habitat)

may directly affect the richness of lower trophic levels (Figure 1). However, pH and macrophyte diversity

do not have a statistically significant effect on the abundance of benthic macroinvertebrates (Figure 2).

There are several probable explanations for this. As the number of taxa decrease, it appears that the

percent composition of a few specific taxa increases, most notably Diptera (comprised mostly of

chironomids), Isopoda, and to a limited extent, Amphipoda (Table 1). This suggests that more tolerant

species are able to replace sensitive ones, causing a shift in the benthic macroinvertebrate assemblages

in the lake. The tolerant taxa not affected by the pH or macrophyte changes increased in number, and so

replaced individuals from taxa that were negatively affected by low pH or macrophyte diversity. Even if a

particular species is able to survive at a decreased pH, individuals may be less successful procuring

enough energy to thrive and reproduce at the rate experienced in less stressful conditions. This creates

an opportunity for other taxa not affected by the increasing stressors to flourish. So, overall numbers of

macroinvertebrates may not change even though the taxonomic diversity changes.

12
Effects on Higher Trophic Levels:

Many species of fish feed on benthic macroinvertebrates at one point in their life history and

may favor specific taxa due to their nutritional and energetic value. As these are replaced by increased

abundances of other taxa, fish must shift their diets or starve. This makes it harder (and sometimes

impossible) for the fish to acquire the nutrients they require. This phenomenon has been well

documented and has significant reverberations throughout the ecosystem (McNickle, Rennie, and

Sprules, 2006; Schaeffer, Diana, and Haas, 2000).

For example, McNickle, Rennie, and Sprules (2006) observed significant changes in abundance

of Diporeia (a genus in the Order Amphipoda) following the introduction of the zebra mussel in Lake

Huron. A study sponsored by the Cooperative Institute for Limnology and Ecosystem Research observed

similar trends in Lake Michigan, Erie, Huron, and Ontario. Diporeia abundance has declined dramatically

in deeper zones as zebra mussel and later quagga mussel populations have increased. McNickle, Rennie,

and Sprules (2006) believe that this will reduce whitefish populations in the lake unless the whitefish are

able to switch their diets to other food sources. If this switch is not made, whitefish diets are predicted

to contain only 57-84% of their former energy content (McNickle, Rennie, and Sprules, 2006). Schaeffer,

Diana, and Haas (2000) used an energetic model to explain declines in Yellow Perch in Saginaw Bay (Lake

Huron). They found yellow perch to be food limited as a result of subsistence feeding on small

Chironomid larvae. Formerly, yellow perch used to feed on Hexagenia larvae, but these were extricated

from the bay by 1965. Since then, yellow perch growth rates and lifespan have declined and mortality

has increased (Schaeffer, Diana, and Haas, 2000). Yellow perch are fished commercially in the Great

Lakes region, especially in Lake Erie, and were valued at over $4.8 million in 2007 (Moy and Kinnunen,

n.d.). In our study, we observed Ephemeroptera reductions (mainly consisted of Hexagenia) in

conjunction with decreased pH (Figure 3). This, combined with the fact that the percent composition of

Diptera in our study lakes (which was mostly made up of chironomids) consisted of anywhere from 26.9-

13
54.7% makes the negative effects of changes in benthic macroinvertebrates on fish in Saginaw Bay a

very real possibility in acidic Adirondack lakes (Table 1).

Disturbances:

While any changes in the Adirondacks will be much smaller than those in the Great Lakes, it is

important that environmental stressors be minimized in order to preserve greater diversity at low

trophic levels, as it has been found that stressors such as low pH decrease diversity in Adirondack

ecosystems. Smith et al. (1989) found that benthic macroinvertebrate assemblages immediately

downstream of beaver dams were much different than assemblages upstream of the same dams. They

concluded that disturbances due to the dam changed benthic macroinvertebrate structure and function

and suggested several causes of the changes including high concentrations of trace metals and low

dissolved oxygen. They also observed decreases in Ephemeroptera and increases in larval densities of

Trichoptera and Chironomid (Smith et al., 1989). These observations remain largely consistent with what

we observed in our analysis of Adirondack lakes, except that instead of studying beaver dams, we found

that reductions in pH and macrophyte diversity are correlated with decreased benthic

macroinvertebrate richness. This means that two ways to maintain benthic macroinvertebrate richness

will be to prevent pH from dropping too low (a larger sample of lakes will need to be conducted to

pinpoint this number, but the four lakes sampled in this study suggest a significant drop in richness

between a pH of 7.00 and 8.05) and to maintain productivity and habitat structure in Adirondack lakes,

as indicated by macrophyte diversity. As observed by Smith et al. (1998), we saw an increased sensitivity

of Ephemeroptera to even slight environmental stressors. Unlike Smith et al. (1998), we saw the

opposite trend in Trichoptera species, observing declines as disturbances increased (Figure 3). However,

Trichoptera drift increased within an hour of reaching a pH of 5.9 (Robertson-Bryan 2004). This finding is

consistent with the findings of our study.

14
 The range of pH values we measured in our study is relatively small. Cranberry Lake was the

lowest pH lake we sampled, but average pH of the lake was 7.00. Lake Flower was the highest pH lake

we sampled and it had a pH of 8.05 (Table 1). Many species would probably be able to withstand these

changes in pH because they are relatively small and organisms must continually survive some amount of

environmental change. This is exemplified by the percent composition changes found in each of the four

lakes we studied (Table 1). Many taxa do not show any dramatic changes, notable trends with changes

in pH, or make up such a small percentage of total abundance that it is difficult to observe any relevant

changes to percent composition. Courtney and Clements (1998) conducted an experiment to see how

benthic macroinvertebrates in streams responded to changes in pH. They had three treatment trials

with pH values of 4.0, 5.5, and 6.5 and one control trial with pH of 7.4 and found that only the lowest pH

trial showed any significant change in benthic macroinvertebrate diversity or abundance. They also cited

a study by Johnson et al., (1993) that found the pH value at which half of the tested species died was

between 2.45 and 5.38, much lower than even the lowest pH measurement in Cranberry Lake. Since our

most acidic lake was between the two highest pH values in the study by Courtney and Clements (1998),

we could expect not to observe any dramatic shifts in macroinvertebrate communities. However, even

disturbances that do not extirpate a particular taxon might cause it to suffer. This makes it possible for

other taxa to increase, ultimately creating the potential for minor shifts in benthic macroinvertebrate

assemblages. This seemed to be the case with two exceptions. We observed a direct increase in percent

composition of mayflies (Ephemeroptera) and caddisflies (Trichoptera) as pH increased (Figure 3). This is

partially consistent with prevailing literature. Mayflies are widely accepted to be one of the most

sensitive orders to acidification, consisting of many important indicator species. Simpson, Bode, and

Colquhoun (1985), Courtney and Clements (1998), and Smith et al. (1989) all observed significant

declines in Ephemeroptera abundance as pH declined, though Courtney and Clements (1998) found that

declines of other genera occurred at a finer level than Order.

15
 It is also important to note that several other factors might describe the patterns observed in

our study. The four lakes we studied are small in comparison to the Great Lakes (United States) where

much of the existing research in lentic ecosystems is centered. Furthermore, the shape and size of the

lakes in our study sample vary. Lake Flower is shallow, small, and ovate while Cranberry Lake is much

larger, deeper, and is oddly shaped, containing several dendritic arms. Substrate size and detritus

content also plays a very large role in determining benthic macroinvertebrate composition (Parker,

1989). Since it is virtually impossible to find a set of lakes identical in all aspects except pH, manipulation

experiments are a useful way of isolating specific variables. This type of experimentation could provide a

greater level of confidence to degree of influence pH and macrophyte diversity have on determining

benthic macroinvertebrate assemblages. However, the oversimplification associated with manipulation

experiments detracts from the complex relationships in natural ecosystems. This is why it is important to

use both the observations and analyses from sampling natural ecosystems in conjunction with

experimentation that eliminates the uncontrollable variation found in natural ecosystems. Future

experimentation concerning this topic should continue to focus on determining the degree of influence

different variables (pH, macrophyte diversity, lake size, substrate) have on determining benthic

macroinvertebrate assemblages in the Adirondacks.

Continuity with Streams:

The effects of acidification on streams in the Adirondacks have been well studied. Simpson,

Bode, and Colquhoun (1985) examined two Adirondack streams, one with a moderate pH (5.8-7.32) and

the other with a lower pH (4.4-5.0). They found that the site with the moderate pH had a higher

diversity of benthic macroinvertebrates than the site with the lower pH. They also found that species

regimes change with pH. This is in agreement with our study. They observed an increase in

Chironomidae abundance during September sampling. Our sampling was done late in the year (between

late August and early October), but since we have no samples from earlier in the year with which to

16
compare, any connections drawn between our study and theirs is speculative. Between 2003 and 2005,

the Western Adirondack Stream Survey (WAAS) (Baldigo et al., 2009) sampled benthic

macroinvertebrates in 36 streams in the Oswegatchie and Black River basins. The WAAS Project is

unique because it compared results to the results of a similar survey conducted in the early 1980s

(Baldigo et al., 2009). They found that macroinvertebrates were moderately to severely affected in 52%

of assessed streams (US Geologic Survey, 2009). Both the WAAS Project and the study done by Simpson,

Bode, and Colquhourn (1985) support the findings of our study: increased acidification is strongly

correlated with a decline in the number of benthic macroinvertebrates that are able to survive. The

biggest difference we found is the degree of sensitivity. We believe that macroinvertebrates in the lakes

we sampled were more sensitive to small changes in pH and might have a higher threshold than those in

streams. However, several other factors might contribute to this instead. Increasing our sample size of

lakes will help to provide some insight to this hypothesis.

Often, Adirondack streams are more acidic than lakes since streams continually receive water

from shallow soils with little buffering capacity. Furthermore, there are few in-stream processes with

which to buffer acid deposition while lakes tend to have a greater concentration of cations. Lakes are

also generally composed of more homogeneous water. In streams, discharge and water chemistry is

almost completely dependent on upstream occurrences. This means that benthic macroinvertebrates

living in streams have to face a wider range of disturbances that occur at a greater frequency than

benthic macroinvertebrates in lakes. It is very possible then that benthic macroinvertebrates in lakes are

more vulnerable to handling disturbances than those in streams since disturbances are not as common

in lakes. The fact that many stream studies have found the threshold for declines in benthic

macroinvertebrate diversity to be a much lower pH value for macroinvertebrates in streams further

supports this hypothesis.

17
Importance for Management:

Ultimately, this means that management of lakes and streams in the Adirondacks should be

similar and should focus on mitigating acidification and preventing dramatic changes in the diversity of

macrophytes. Acidification of many Adirondack water bodies has slowly decreased since the legislation

of the 1970's was passed, but many more water bodies are still affected (Baldigo et al., 2009). Acid

deposition is particularly difficult to manage since pollutants originate from out of state and several of

the other factors are out of human control (bedrock composition, wind patterns, precipitation trends).

Current education programs exist that inform boaters about the dangers of invasive species and provide

information about how to take precautions to stop their spread. This will be important to continue since

many of the invasive macrophytes of concern in the Adirondacks are commonly known to reduce

diversity of different water bodies. Finally, many lakes are heavily trafficked by boats traveling from

sometimes great distances. This poses a unique issue for managers trying to stop the spread of invasive

macrophytes that is not present in many streams, as boat traffic on small streams is much lower than

that on lakes). Ultimately, it is important that managers know that while benthic macroinvertebrates in

streams and lakes both experience declines in diversity due to increased acidification, the

macroinvertebrates in lakes probably are more sensitive to these changes. This will enable them to

create and implement appropriate regulations with the goal of maintaining the health and productivity

of Adirondack systems.

Potential Sources of Error:

There were several sources of error in this study. Samples were collected between late August

and early October. This late into the season, cold might have become a factor in the mortality of some

benthic macroinvertebrates. Furthermore, sampling over such a wide time frame allows for some error

in benthic macroinvertebrate assemblages due to the emergence of some species. Finally, a few samples

18
were lost or mislabeled (one sample from Cranberry Lake, one sample from Raquette Lake, and two

samples from Long Lake). This would affect the abundance of benthic macroinvertebrates found in each

lake, but the effects of this are expected to be marginal since our sample size was so large.

Continuation of Study:

We plan to continue this study by examining three more lakes (Lake Placid, Arbutus Pond, and

Fourth Lake).Samples have already been procured from these lakes but have not yet been prepared and

analyzed. These lakes will strengthen our data set by increasing our sample size and will extend the high

end range for pH values to 8.11 (Fourth Lake).

Conclusion:

Our study indicates that benthic macroinvertebrate taxon richness in Adirondack lakes is

affected by pH and macrophyte diversity. Conversely, abundance did not share a significant relationship

with either pH or macrophyte diversity. It appears that as sensitive taxa (namely Trichoptera and

Ephemeroptera) declined, more tolerant taxa increased in number to take their place. This has a

potential to cause disruptions up the food chain as some species of fish might not be able to acquire

sufficient nutrients or energy from these alternative prey. When compared to the results of similar

analyses of streams, the results of our study remain consistent. The most notable difference is that

benthic macroinvertebrates in lakes appear to be more sensitive to disturbances, experiencing

significant changes in richness over a 7.00 to 8.05 range in pH values. In streams, the literature reports

significant changes at much lower pH values. Ultimately, our study attempts to learn more about the

effects of acidification on Adirondack lakes, in which benthic macroinvertebrates are largely unstudied,

especially compared to the vast amount of work put into understanding more about Adirondack

19
streams. It is important for managers to know the similarities and differences of acidification in lakes

and streams so that they can implement regulations accordingly.

20
Works Cited:

Baldigo, Barry P., Gregory B. Lawrence, Robert W. Bode, Howard A. Simonin, Karen, M. Roy, and Alexander J.
Smith. “Impacts of Acidification on Macroinvertebrate Communities in Streams of the Western
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Appendix:

450 Macroinvertebrate Abundance vs. Ph; Adirondack Lakes, Summer 2013

400

350 Long Lake

Raquette Lake
300
Total Abundance

Lake Flower
250
Cranberry Lake
200

150

100

50

0
6 6.5 7 7.5 8 8.5
pH

Figure 1: The total number of benthic macroinvertebrates found at each of the ten sample sites within
each lake. pH was measured at each site and averaged for all four lakes, but the pH of each site is
depicted here.

Macroinvertebrate Diversity vs. pH; Adirondack Lakes, Summer 2013

30

Long Lake
25
Raquette lake
Average Number of Taxa

20 Lake Flower

Cranberry Lake
15

10

0
6 6.5 7 7.5 8 8.5
pH

23
Figure 2: The average number of taxon found at each of the ten sample sites within each lake. pH was
measured at each site and averaged for all four lakes, but the pH of each site is depicted here.

Table 1: Percent composition of each taxon in each lake. Here, taxa are displayed to the family level,
with a few exceptions. Many organisms were identified as far as genus, but are displayed to the family
level here because the degree of confidence in correct identification is much higher for family than
Genus.
"O" indicates that this taxon is identified to the Order level.
"C" indicates that this taxon is identified to the Class level.
"U" indicates that members of the family Unionidae were found in this lake.

Cranberry Lake Long Lake Raquette Lake Lake Flower

Ephemeroptera Ephemeridae 0.08 0.64 1.42 1.04
Ephemeroptera Ephemerellidae 0.00 0.00 0.42 1.43
Ephemeroptera Polymitarcyidae 0.00 0.06 0.00 0.00
Ephemeroptera (unidentified) 0.08 0.00 0.00 0.00
Odonata Anisoptera 0.08 0.00 0.58 0.05
Odonata Zygoptera 0.00 0.00 0.00 0.44
Odonata (unidentified) 0.00 0.00 0.00 0.33
Plecoptera (unidentified) 0.08 0.00 0.00 0.00
Trichoptera Brachycentridae 0.00 0.13 0.11 0.00
Trichoptera Glossosomatidae 0.08 0.00 0.00 0.00
Trichoptera Hydroptilidae 0.00 0.00 0.00 0.27
Trichoptera Lepidostomatidae 0.00 0.06 0.00 0.00
Trichoptera Leptoceridae 0.08 0.06 0.68 1.32
Trichoptera Limnephillidae 0.00 0.19 0.00 0.00
Trichoptera Odontoceridae 0.00 0.19 0.00 0.00
Trichoptera Philopotamidae 0.08 0.13 0.00 0.00
Trichoptera Phryganeidae 0.08 0.00 0.16 0.22
Trichoptera Polycentropidae 0.24 0.13 0.37 0.82
Trichoptera Psychomyiidae 0.00 0.00 0.11 0.49
Trichoptera Sericostomatidae 0.00 0.19 0.11 0.00
Trichoptera (unidentified) 0.40 0.00 0.11 0.11
Coleoptera Dytiscidae 0.24 0.00 0.00 0.00
Coleoptera Elmidae 0.00 0.00 0.05 0.00
Coleoptera Hydrophilidae 0.00 0.00 0.00 0.05
Coleoptera Psephenidae 0.00 0.06 0.00 0.00
Coleoptera (unidentified) 0.16 0.00 0.00 0.00
Megaloptera Sialidae 0.40 1.34 0.32 0.33
Diptera Chaoloeridae 0.96 11.47 0.26 2.14
Diptera Chironomidae 43.11 43.28 26.61 35.91
Diptera Culicidae 0.32 0.00 0.00 0.00
Amphipoda (O) 15.30 3.06 21.97 3.79
Isopoda Asellidae 9.38 3.57 2.74 13.34
Gastropoda (C) 3.04 2.87 2.32 5.93
Bivalvia (C) 3.45 6.37 3.48 3.12 (U)
Oligochaeta (O) 22.28 25.11 30.93 33.28

24