The study aimed to determine if invasive largemouth bass were negatively impacting the survival of native western pond turtles at the Bernard Field Station. The researchers analyzed the stomach contents of 21 bass caught from a lake at the field station. None of the bass stomachs contained turtle hatchlings. However, the bass' diets included other species like crayfish and amphipods, indicating they still impacted the ecosystem. Additional data suggested seasonal diet changes and that bullfrogs may be a more significant threat to the turtles. While the results did not support the initial hypothesis, they provided insights into species interactions and potential conservation methods.
Crayfish Predation on Snails in Different Environments diontaedm
This project was ran at Kellogg Biological Station in the summer of 2015. The project was conducted questioning if snails could better survive in habitats composed of different substances. This question came about as we were searching for snails and continuously found dead snails in sandy areas and more living sands in areas with Detritus
Ratio « number of males on number of females » for the mass production of Sar...Innspub Net
The appropriate proportion of male and female parents that give a highest number of juveniles is a major concern in tilapia culture Sarotherodon melanotheron due to the oral incubation by males. A study of the ratio “number of males to number of females” on fingerlings production has been performed in order to determine the optimal ratio for S. melanotheron. Five ratios were tested : R1 (1 male to 2 females), R2 (1 male to 3 females), R3 (2 males to 2 females), R4 (2 males to 4 females) and R5 (2 males to 6 females). The experimental device consists of five concrete tanks (1m x 1m x 60cm) filled to 2/3, about 0.17m3 of water. The fish are fed three times a day with a diet containing 35% crude protein. Once a week, the fertilized eggs are collected and incubated in a tank. The hatching rate and larval growth are followed. The experiment was duplicated and lasted 6 weeks to harvest eggs and 40 days to track the growth of larvae. The results show that the number of egg laying is significantly different from a ratio to each other (p ˂ 0.05) and increases with the number of males and females. The highest number of egg laying is obtained with R5 ratio “2 males to 6 females” that seems best for the mass production of juveniles of S. melanotheron. These results provide a basis for the intensive production of S. melanotheron for the aquaculture development in lagoon.
Zebrafish (Danio rerio) are a small freshwater fish belonging to the cyprinid family (Spence, 2006). The species is native to warm water streams in the Ganges and Brahmaptura River basins located in India, Bangladesh, and Nepal (Barman, 1991; Laale, 1977). They are thought to be an annual species that breeds during the monsoon season, when food such as aquatic insects are most plentiful (Spence, 2006). Zebrafish are considered to be omnivorous having been observed feeding throughout the water column, from the surface to the benthos, on a varied diet (Spence et al 2008).
POPs in the Galapagos Islands-Juan Jose Alava-Fall2012-ENSC100Juan José Alava
A description of the Galapagos Islands and the first assessment of Persistent Organic Pollutants (POPs) in the Galapagos Marie Reserve with emphasis on DDT in endangered Galapagos sea lions.
Diversity and dispersion patterns of echinoderms in Babanlagan, Talisayan, Mi...Angelo Mark Walag
Echinoderms are fundamentally good indicators of health and status of coralline communities in marine waters. In this study, the diversity and distribution of echinoderm species were determined in Babanlagan, Talisayan, Misamis Oriental. In total, 387 individuals were collected coming from classes Echinoidea, Holothuroidea, Asteroidea, and Ophiuroidea. The majority of individuals collected were Protoreaster nodusus, which is a good indicator of reef health while the least abundant echinoderm species was Acanthaster planci. The pattern of distribution of majority of echinoderms was a clumped distribution while the other groups followed regular/uniform distribution, which may be due to limited dispersal ability and availability and available food sources. Moderate species diversity was also observed and species were rather similar in abundance, shown by the evenness index. This suggests good marine health, even under the threat of gleaning activities, active fishing, and habitat destruction. It is recommended that follow-up studies are conducted especially regarding monitoring of echinoderm species, to further assess the health of the intertidal zone in Babanlagan, Talisayan, Misamis Oriental.
"Integrated science for integrated management: fairy tale or finally here?" by Phillip Levin, Northwest Fisheries Science Center, USA
ICES ASC Plenary lecture Thursday 18 September 2014
Effect of Stocking Density on the Resistance to Fasting, Growth and Survival ...Agriculture Journal IJOEAR
Abstract— After artificial reproduction of African catfish Heterobranchus bidorsalis, larvae of two days old and 2.18 ± 0.35 mg of mean weight were used to perform two experiments in order to assess the effect of stocking density on their fasting resistance, growth and survival. During the first experiment which lasted 11 days with four batches of larvae at densities of 1, 2, 3 and 4 individuals/ml, results showed that density did not significantly affect (p˂0,05) the resistance to fasting of larvae. However, first mortalities were observed at D5 for all the densities, the higher daily mortality was recorded at D10 and the last mortalities were obtained at D12.
Results of the second experiment revealed that the weight and growth performance of larvae decreased with the increasing of the density after 28 days of rearing. In contrast, the larval survival rate increased with the density. The values of survival rate were respectively 30.53 ± 4.32 and 55.30 ± 21.70 % for the densities 1 ind./l and 20 ind./l.
We investigated the effects of fish protein hydrolysate (FPH) on zootechnical performance and immune response of the Asian Seabass Lates calcarifer Bloch. Experimental fish were fed with 3 diets: a local commercial diet (control), coated or not, with 2 and 3% FPH (w/w). Twelve thousand Asian Seabass juveniles (5.88±0.56 g) were divided into three groups and two replicates reared in nursery tanks (2000 L). The remaining fish were then used for grow-out experiment in floating net cages (1m x 1 m x 3 m). Zootechnical performances were assessed at both stages with following indicators: total weight gain (TWG), % relative weight gain (% RWG), % specific growth rate (% SGR), final weight (g) and final length (cm). At the end of each trial period, fish immune status was assessed through blood sampling and the measurement of Neutrophile (%), Monocyte (%), Lymphocyte (%), Macrophage (105 cell/mL), Leukocyte (103 cell/mL) and Phagocytes activity (%). At the end of the nursery trial, an immersion bacterial challenge with Vibrio parahaemolyticus (105 cells mL-1) was implemented. The results showed that dietary FPH supplementation significantly influenced the growth and immune status of Asian Seabass when compared to the control group. Fish fed FPH supplemented diet yielded higher growth rates and survival rates than non supplemented group. Fish phagocytic activity and resistance to a bacterial challenge were also improved by dietary FPH supplementation. These results may be related to the significant changes observed in fish leukocyte profiles, when fed FPH supplemented diets. Altogether, these results show the positive contribution of FPH to the sustainability of Asian seabass farming.
Crayfish Predation on Snails in Different Environments diontaedm
This project was ran at Kellogg Biological Station in the summer of 2015. The project was conducted questioning if snails could better survive in habitats composed of different substances. This question came about as we were searching for snails and continuously found dead snails in sandy areas and more living sands in areas with Detritus
Ratio « number of males on number of females » for the mass production of Sar...Innspub Net
The appropriate proportion of male and female parents that give a highest number of juveniles is a major concern in tilapia culture Sarotherodon melanotheron due to the oral incubation by males. A study of the ratio “number of males to number of females” on fingerlings production has been performed in order to determine the optimal ratio for S. melanotheron. Five ratios were tested : R1 (1 male to 2 females), R2 (1 male to 3 females), R3 (2 males to 2 females), R4 (2 males to 4 females) and R5 (2 males to 6 females). The experimental device consists of five concrete tanks (1m x 1m x 60cm) filled to 2/3, about 0.17m3 of water. The fish are fed three times a day with a diet containing 35% crude protein. Once a week, the fertilized eggs are collected and incubated in a tank. The hatching rate and larval growth are followed. The experiment was duplicated and lasted 6 weeks to harvest eggs and 40 days to track the growth of larvae. The results show that the number of egg laying is significantly different from a ratio to each other (p ˂ 0.05) and increases with the number of males and females. The highest number of egg laying is obtained with R5 ratio “2 males to 6 females” that seems best for the mass production of juveniles of S. melanotheron. These results provide a basis for the intensive production of S. melanotheron for the aquaculture development in lagoon.
Zebrafish (Danio rerio) are a small freshwater fish belonging to the cyprinid family (Spence, 2006). The species is native to warm water streams in the Ganges and Brahmaptura River basins located in India, Bangladesh, and Nepal (Barman, 1991; Laale, 1977). They are thought to be an annual species that breeds during the monsoon season, when food such as aquatic insects are most plentiful (Spence, 2006). Zebrafish are considered to be omnivorous having been observed feeding throughout the water column, from the surface to the benthos, on a varied diet (Spence et al 2008).
POPs in the Galapagos Islands-Juan Jose Alava-Fall2012-ENSC100Juan José Alava
A description of the Galapagos Islands and the first assessment of Persistent Organic Pollutants (POPs) in the Galapagos Marie Reserve with emphasis on DDT in endangered Galapagos sea lions.
Diversity and dispersion patterns of echinoderms in Babanlagan, Talisayan, Mi...Angelo Mark Walag
Echinoderms are fundamentally good indicators of health and status of coralline communities in marine waters. In this study, the diversity and distribution of echinoderm species were determined in Babanlagan, Talisayan, Misamis Oriental. In total, 387 individuals were collected coming from classes Echinoidea, Holothuroidea, Asteroidea, and Ophiuroidea. The majority of individuals collected were Protoreaster nodusus, which is a good indicator of reef health while the least abundant echinoderm species was Acanthaster planci. The pattern of distribution of majority of echinoderms was a clumped distribution while the other groups followed regular/uniform distribution, which may be due to limited dispersal ability and availability and available food sources. Moderate species diversity was also observed and species were rather similar in abundance, shown by the evenness index. This suggests good marine health, even under the threat of gleaning activities, active fishing, and habitat destruction. It is recommended that follow-up studies are conducted especially regarding monitoring of echinoderm species, to further assess the health of the intertidal zone in Babanlagan, Talisayan, Misamis Oriental.
"Integrated science for integrated management: fairy tale or finally here?" by Phillip Levin, Northwest Fisheries Science Center, USA
ICES ASC Plenary lecture Thursday 18 September 2014
Effect of Stocking Density on the Resistance to Fasting, Growth and Survival ...Agriculture Journal IJOEAR
Abstract— After artificial reproduction of African catfish Heterobranchus bidorsalis, larvae of two days old and 2.18 ± 0.35 mg of mean weight were used to perform two experiments in order to assess the effect of stocking density on their fasting resistance, growth and survival. During the first experiment which lasted 11 days with four batches of larvae at densities of 1, 2, 3 and 4 individuals/ml, results showed that density did not significantly affect (p˂0,05) the resistance to fasting of larvae. However, first mortalities were observed at D5 for all the densities, the higher daily mortality was recorded at D10 and the last mortalities were obtained at D12.
Results of the second experiment revealed that the weight and growth performance of larvae decreased with the increasing of the density after 28 days of rearing. In contrast, the larval survival rate increased with the density. The values of survival rate were respectively 30.53 ± 4.32 and 55.30 ± 21.70 % for the densities 1 ind./l and 20 ind./l.
We investigated the effects of fish protein hydrolysate (FPH) on zootechnical performance and immune response of the Asian Seabass Lates calcarifer Bloch. Experimental fish were fed with 3 diets: a local commercial diet (control), coated or not, with 2 and 3% FPH (w/w). Twelve thousand Asian Seabass juveniles (5.88±0.56 g) were divided into three groups and two replicates reared in nursery tanks (2000 L). The remaining fish were then used for grow-out experiment in floating net cages (1m x 1 m x 3 m). Zootechnical performances were assessed at both stages with following indicators: total weight gain (TWG), % relative weight gain (% RWG), % specific growth rate (% SGR), final weight (g) and final length (cm). At the end of each trial period, fish immune status was assessed through blood sampling and the measurement of Neutrophile (%), Monocyte (%), Lymphocyte (%), Macrophage (105 cell/mL), Leukocyte (103 cell/mL) and Phagocytes activity (%). At the end of the nursery trial, an immersion bacterial challenge with Vibrio parahaemolyticus (105 cells mL-1) was implemented. The results showed that dietary FPH supplementation significantly influenced the growth and immune status of Asian Seabass when compared to the control group. Fish fed FPH supplemented diet yielded higher growth rates and survival rates than non supplemented group. Fish phagocytic activity and resistance to a bacterial challenge were also improved by dietary FPH supplementation. These results may be related to the significant changes observed in fish leukocyte profiles, when fed FPH supplemented diets. Altogether, these results show the positive contribution of FPH to the sustainability of Asian seabass farming.
When a population of spotted salamanders in an area of vernal pools re.pdfaadyaenterprisesnoid
When a population of spotted salamanders in an area of vernal pools remains stable for many
years and the population has stabilized because of resource limits, then carrying capacity has
been reached. density dependence is not involved. predation has decreased. density independence
occurs. Exponential growth, when graphed, appears as a(n) straight line. "S" curve. "J" curve.
wavy line that goes up and down regularly. A biologist wants to estimate the size of a population
of turtles in a lake. She captures 18 turtles on her first visit to the lake, and marks their backs
with paint. A week later she returns to the lake and captures 18 turtles. Five of these 18 turtles
have paint on their backs, indicating that they are recaptured animals. Using this information,
biologist calculate the total salamander population in the lake is about 5 15 2 10 What pattern of
population growth corresponds to the principle of a carrying capacity? S-shaped bell-shaped J-
shaped a straight line To measure the population of lake trout, 4 Q individual trout were netted
and marked with a fin clip, then returned to the lake. The next week, the lake was netted again,
and out of the 480 lake trout that were caught, 5 had fin clips. Using the markrecapture estimate,
the lake trout population size could be closest to which of the following? 1680 408 50 320
Which of the following methods will provide information to an ecologist about both the size and
density of a population? mark and release quadrat life table mark and recapture Ants living in
acacia trees attack any predators of the tree. In return, the ants live protected in the thorns of the
tree and eat the nectar and protein-rich secretions of the tree. What term describes this
relationship? competition commensalism mutualism parasitism A community ecologist might
study: all the members of a single species that live together in a single geographic area. the
interactions among species living in a single area. the behavior of a species in its natural
environment. the rates of increase or decrease in the population size of individual species in
different environments. Which term best describes the relationship between leaf cutter ants and
the plants? Leaf Cutter Ants Jangle: How Nature Works Frnm Title: (3) Intobase. All rights
Reserved. Lengtn: 03:03 mutualism communism commensalism predation Cattle egrets hitch a
ride on domestic cows and eat insects that are stirred up by their activity. What term describes
this relationship? competition commensalism parasitism predation What role would an owl that
eats a seed-eating mouse perform in a food chain? secondary consumer producer primary
consumer tertiary consumer The North Atlantic Right Whale, Eubalaena glacialis, was called the
"right whale" because they were the best whale for early whalers to kill. They have long baleen
and lots of blubber and oil. When killed, they could be towed back to land for processing
because they float. They once numbered in the millions, but.
Growth and protein content of mud crabs (Scylla serrata) fed with different n...Innspub Net
Mud crab (Scylla serrata) farming is one of the main sources of livelihood in Calauag, Quezon. Commonly, they use trash fish as their major source of feeds for mud crabs. However, fluctuation on its prices happen because of supply and demand, thus the use of other natural feeds were conceptualized. This aimed to determine if there are significant differences on the weight, protein content and meat characteristics of mud crabs fed with different natural feeds. It also aimed to assess the profitability of mud crab farming in plastic cages using different natural feeds. The experiment was laid out in Complete Randomized Design with three treatments replicated thrice: T1 – trash fish, T2 – horn snail meat and T3 – yellow corn. Results revealed that mud crabs fed with horn snail had the highest weight and protein content as compared to the other treatments. Hence, had the highest ROI. While, in the sensory analysis of its meat characteristics, mud crabs fed with yellow corn had the highest mean which was rated as very much juicy, flavorful and very much acceptable.
The culture of maintenance ornamental fish among Iranian people is developing every day. One of the most important factors in selection aquarium fish is behavior of feeding. The feeding behavior of Guppy is poorly documented. In this experiment we study feeding behavior in P. reticulata by six treatments. Six aquariums with the same dimension were used and two points A & B with the maximum distance from each other were selected in each aquarium. In aquarium No.1 hand move with feeding in point A, in aquarium No.2 hand move without feeding in point A, in aquarium No.3 hand moves in point A and feeding in point B, in aquarium No.4 feeding without hand move in point B, in aquarium No.5 in semi dark conditions hand move with feeding in point A and finally in aquarium No.6 in darkness conditions hand move with feeding in point A were done. In aquarium No.1, 94% of fish moved to point A and in aquarium No.2 it was about 92%. In aquarium No.3, 95.5% of fish moved to point A and in Aquarium No.4, 74.5% of fish moved to point B. In aquarium No 5 and 6, 96% and 99.5% of fish moved and didn’t move to point A, respectively. Our results showed that this species is a visual feeder and a good aquarium fish for their feeding behavior.
Article Citation:
Rajaei M, Nematollahi MA, Bahmaninezhad A and Lotfizadeh A.
Behavior of Feeding in Guppy: Poecilia reticulata.
Journal of Research in Animal Sciences (2012) 1(1): 001-006.
Full Text:
http://janimalsciences.com/documents/AS0004.pdf
The culture of maintenance ornamental fish among Iranian people is
developing every day. One of the most important factors in selection aquarium fish is
behavior of feeding. The feeding behavior of Guppy is poorly documented. In this
experiment we study feeding behavior in
P. reticulata
by six treatments. Six
aquariums with the same dimension were used and two points A & B with the
maximum distance from each other were selected in each aquarium. In aquarium
No.1 hand move with feeding in point A, in aquarium No.2 hand move without
feeding in point A, in aquarium No.3 hand moves in point A and feeding in point B, in
aquarium No.4 feeding without hand move in point B, in aquarium No.5 in semi dark
conditions hand move with feeding in point A and finally in aquarium No.6 in darkness
conditions hand move with feeding in point A were done. In aquarium No.1, 94% of
fish moved to point A and in aquarium No.2
it
was about 92%. In aquarium No.3,
95.5% of fish moved to point A and in Aquarium No.4, 74.5% of fish moved to point B.
In aquarium No 5 and 6, 96% and 99.5% of fish moved and didn’t move to point A,
respectively. Our results showed that this species is a visual feeder and a good
aquarium fish for their feeding behavior.
Behavior of Feeding in Guppy: Poecilia reticulata .
Invasive+Species+Lab+Report-1 (1)
1. Micropterus salmoides from pHake
Lake Do Not Affect Actinemys
marmorata Survival Rates
Kian Bagheri
Dr. Nina Karnovsky
Bio 41E: Evolutionary and Ecological Biology
Pomona College
8 May 2015
2. Bagheri 1
Abstract
Invasive species have detrimental impacts on the ecosystems they invade. They can
indirectly change food webs, decrease biodiversity, and alter ecosystem conditions by preying on
native species (Marchetti et al., 2004). Largemouth Bass (Micropterus salmoides), an invasive
species at the Bernard Field Station, have been shown to prey on native species within the BFS.
These Bass are amongst the most advantageous organisms in the study of invasive species
because they are relatively easy to catch, anesthetize, and dissect. This experiment aimed to use
this invasive species to see if they were directly affecting the survival of the Western Pond Turtle
(Actinemys marmorata). We hypothesized that the presence of the Largemouth Bass were
causing these declines in the Western Pond Turtle population by consuming their hatchlings. We
tested our hypothesis by catching twenty-one Bass from pHake Lake and analyzing the contents
of their stomachs in the laboratory to see if there was any indication of turtle hatchlings. We
were able to determine that our results were not consistent with our hypothesis, as none of the
Bass that we caught showed any indication of having consumed turtle hatchlings. Though our
results refuted our hypothesis, we were still able to compare them to data collected in 2011 -
2012 to find that there were seasonal changes to the Bass’s consumption patterns, that they still
affected the BFS ecosystem by preying on other species and competing for resources, and that
there was another potential species affecting the survival of the Western Pond Turtle.
Introduction
Invasive species severely affect native communities through interspecific interactions
such as predation and competition between invaders and natives, thereby risking the extinction of
native species (Miyake and Miyashita, 2011). Not only do invasive species compete with native
species for resources, but they also upset the natural balance of an ecosystem, greatly reducing
its biodiversity. Worldwide, 20 percent of endangered vertebrates are imperiled as a result of
invasive species (MacDonald et al., 1989), and 42 percent of the species on the Endangered
Species List are at risk primarily because of invasive species (Pimentel et al., 1999). Invasive
species are also the second greatest threat to biodiversity after habitat loss. Studying invasive
species is important because their numbers are dramatically increasing in the United States, and
thus, they pose a serious threat to the health of native wildlife species and ecosystems.
In this experiment, we examined the Largemouth Bass (Micropterus salmoides), an
invasive species at the Bernard Field Station (BFS) and a native species to Midwestern and Gulf
3. Bagheri 2
Coast regions in the United States, to see if they were affecting the survival of the Western Pond
Turtle (Actinemys marmorata). These Bass were introduced to the BFS as a non-native species in
1981, and have been associated with a decline in native prey species (Hayes and Jennings, 1986).
Western Pond Turtles, on the other hand, are important because they are the only native
freshwater turtle in California, and are more endangered than previously thought. Based on
preliminary observations by Dr. Nina Karnovsky, the Western Pond Turtle population at the BFS
appeared to be in decline. We hypothesized that the Largemouth Bass were causing these
declines in the Western Pond Turtle population at the BFS by consuming their hatchlings. We
predicted to find turtle hatchlings within their stomachs. To test this hypothesis, we caught
twenty-one Largemouth Bass, and subsequently analyzed the contents of their stomachs in the
laboratory to see if they contained any indication of turtle hatchlings. Using data from 2011 -
2012 in addition to the data that we collected, we characterized the diets of the Largemouth Bass
in pHake Lake. By testing this hypothesis, we hoped to illuminate key insights to species
interactions and develop new methods for preserving native species at the BFS.
Materials & Methods
In this experiment, we tested whether an invasive species, the Largemouth Bass, was
influencing the survival of the Western Pond Turtle population at the BFS. We collected all of
our data at the BFS in Claremont, CA. We visited the BFS twice to catch the Bass, on April 7
and 11, 2015. We caught the Bass from pHake Lake, a manmade lake within the BFS. Each
member had a fishing rod with Fat Ika Bait, a net, and a bucket filled with water. Once we
caught the Bass, one member would lure it into the net while the other would unhook it from the
line. After we caught three to four Bass, we would go back to shore to offload the Bass. Dr. Nina
Karnovsky humanely anesthetized the Bass using MS-222 (Sigma Aldrich). After being put to
4. Bagheri 3
sleep, we took preliminary measurements of each Bass (weight, total length, fork length, and
standard length). We transported the Bass back to the Seaver South Laboratory, and stored them
in the freezer until we were ready to dissect them the following week. We caught a total of
twenty-one Bass.
In the laboratory, we dissected each Bass to analyze the contents of their stomachs. First,
using a scalpel, we cut open the Bass. Using scissors, we cut into the Bass to make a flap about 4
cm x 4 cm. After taking a preliminary look at the inside of the Bass, we sexed it. Females
generally had a clear indication of eggs (gooey orange color), and males had indication of
gonads. After sexing the Bass, we identified the stomach, and cut it out. In a bowl, we cut the
isolated stomach and washed its contents with 80% ethanol. To identify the exact contents of
each Bass’s stomach, we put the bowls under a microscope. Once we confirmed our findings, we
recorded them. We went on to dissect the next Bass until all twenty-one were dissected.
After finishing our dissections, we set up two motion-sensor cameras at pHake Lake to
determine if there was any evidence of the Western Pond Turtle. We put the cameras on opposite
sides of the lake near the shore and tied them to a tree. We allowed the cameras to run for five
days without interruption (from April 24 – 28, 2015), and programmed them to take a picture
every 45 seconds or every time there was significant movement. After five days had elapsed, we
removed the cameras and obtained the data.
Results
The objective of this experiment was to determine whether the invasive species
Largemouth Bass was driving the turtle population at the BFS to extinction. We caught a total of
twenty-one Bass from pHake Lake over the course of two visits, and characterized their diets by
dissecting their stomachs. Of the twenty-one Bass that we analyzed, none of them showed any
5. Bagheri 4
indication of having consumed turtle hatchlings (Table 1). We did, however, find other notable
remains within their stomachs, and their percentages relative to the sum total that the Bass
consumed are as follows: crayfish (2.72%), amphipod (76.65%), snail (19.1%), small fish
(0.78%), bait (0.39%), and unknown (0.39%) (Table 1 and Figure 1).
We then added our data to an already existing file on the Largemouth Bass stomach
contents from 2011 – 2012. We created a bar graph displaying percent occurrence of anything
found in the Bass’s stomachs (Figure 2). This graph revealed the three most popular
consumption choices for the Bass in pHake Lake: amphipods (94.77%), snails (1.55%), and
dragonfly larvae (1.18%) (Figure 2).
Finally, we made a bar graph revealing what percent of their diet was composed by each
category (Figure 3). This graph was separated based on the four sampling periods: Fall 2011,
Spring 2012, Summer 2012, and Spring 2015. From this graph, it was readily apparent that
amphipods were the preferred food of the Bass, with the only exception coming in Fall 2011,
when large damsal larvae predominated at 96.41%. This figure also indicates that snails
comprised a large portion of the bass diet beginning in Spring 2015.
6. Bagheri 5
Table 1: Contents found within the stomachs of the Bass for Spring 2015. Occurrences refers to
the number of Bass that we found to have that content within its stomach, amount refers to the
sum total of all the occurrences, and percentage refers to each amount divided by the total (257).
Content
Turtle
Occurrences
0
Amount
0
Percentage
0%
Crayfish 5 7 2.72%
Amphipod 5 197 76.65%
Snail 3 49 19.1%
Small Fish 2 2 0.78%
Bait 1 1 0.39%
Unknown
Total
1
17
1
257
0.39%
100%
Figure 1: Pie chart depiction of Bass diets for our data only (Spring 2015).
2.72%
76.65%
0.00%
0%
0%
0%
0%
19.07%
0.78%
0.39% 0.39%
Crayfish
Amphipods
Damsal Larvae
Dragon fly Larvae
Dragon fly
Hemiptera
Ants
Snail
Small Fish
Unknown
Bait
7. Bagheri 6
Figure 2: Graphical depiction of Bass diets using our data (Spring 2015) and the data obtained
from 2011 - 2012. The x-axis represents prey consumption, and the y-axis represents percent
occurrence.
0.00%
10.00%
20.00%
30.00%
40.00%
50.00%
60.00%
70.00%
80.00%
90.00%
100.00%
PercentOccurance Largemouth Bass
Summer 2012
Fall 2011
Spring 2012
Spring 2015
8. Bagheri 7
Figure 3: Bar graph depiction revealing what percent of the Bass’s diet was composed by each
category for the pooled data (Fall 2011, Spring 2012, Summer 2012, and Spring 2015).
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Total Summer
2012
Fall 2011 Spring
2012
Spring
2015
Percent of Diet Composed By
Categories
Bait
Unknown
Small Fish
Snail
Ants
Hemiptera
Dragon fly
Dragon fly Larvae
Damsal Larvae
Amphipods
Crayfish
9. Bagheri 8
Discussion
In this experiment, we were concerned with determining how much of an impact the
Largemouth Bass were having on the survival of the Western Turtle Population at the BFS
through a careful analysis of the Bass’s stomach contents. From our results, we were able to
conclude that the Largemouth Bass did not have an impact on the Western Pond Turtle at the
BFS, as none of them had any indication of turtle hatchlings within their stomachs. With that
being said, however, our results indicated that they were still affecting the BFS ecosystem in
other ways and that there was also another potential species affecting the survival of the Western
Pond Turtle.
Although our results did not support our hypothesis, they did reveal that the Bass are not
selective in what they choose to consume. This is supported by the fact that in five out of the
twenty-one Bass that we caught (23.81%), there was evidence of crayfish consumption. We
found one of these Bass to have even consumed three crayfish. In the data from previous years,
there was also significant evidence indicating that the Bass had consumed crayfish, as nineteen
out of the seventy-three (26.03%) Bass had shown evidence of crayfish consumption. Crayfish
are freshwater crustaceans that resemble small lobsters. Their hard, shell-like covering
exoskeleton reveals that the Bass have flexible diets. The fact that one of our Bass showed
evidence of having consumed three crayfish also indicates that the Bass can consume a
significant amount of food relative to their body size during one feeding period. In addition, in
one of the Bass that we caught, its stomach contained the Fat Ika bait that we used to catch it.
This finding again reaffirms that the Bass are able to consume large objects. All of these findings
suggest that they are more than capable of consuming turtle hatchlings, especially since turtle
10. Bagheri 9
hatchlings are anywhere between 2.5 – 3.0 cm, whereas crayfish can grow to be between 5.0 –
12.0 cm in length and the Fat Ika Bait that we used was about 10.0 cm in length.
We can attribute our result that none of the Bass had turtle hatchlings within them to our
small sample size. We only caught twenty-one Bass, which is not a substantial amount, given
that there are an estimated 1,000 Bass in pHake Lake according to Dr. Karnovsky. Our small
sample size makes our data less reliable. We thus cannot conclusively state that the Bass are not
consuming Western Pond Turtle hatchlings, because it is likely that with a larger sample size, we
would have found evidence of turtle hatchling consumption. In addition, we did see potential
evidence of the Western Pond Turtle (Figure 4), so we cannot confidently attribute our results to
a lack of turtles in the lake.
It has also been shown that the biggest threat to the endangered Western Pond Turtle is
the bullfrog (Durham, 2010). A voracious predator, this amphibian has been known to feed on a
wide range of prey including insects, fish, and even turtle hatchlings (Kiesecker and Blaustein,
1998). The hatchlings are particularly vulnerable due to their small size and limited mobility. It
is hard to control or eradicate bullfrogs because they have a high fecundity and broad diet. We
can thus rationalize our results by claiming that the bullfrog is perhaps the main predator of the
Western Pond Turtle at the BFS. Our motion sensor camera even caught an image of the bullfrog
(Figure 5) and we observed them a few times ourselves while we were out fishing for the Bass.
Finally, our results reveal that there is strong evidence showing that seasonal changes
drive Bass consumption patterns (Figure 2). In warm-weather climates, amphipods are more
abundant. Warmer temperatures make them more active, increasing their feeding and
reproduction rates (Lane, 2002). Our Bass consumption patterns support this fact (Figure 2), as
nearly 95% of their diet in the Summer 2012 comprised of amphipods. In Spring 2012 and 2015,
11. Bagheri 10
there were high numbers of amphipod consumption in the Bass diets as well. In addition, our
only results in colder temperatures were from Fall 2011. During this time, damsel larvae
comprised of nearly 100% of their diet (Figure 2). An explanation for this consumption pattern
can be attributed to the fact that the damselfly lays its eggs during cold temperature periods so
that they hatch in warmer temperatures. Since the larvae are immobile during the fall, the Bass
are much more readily able to consume the larvae.
By understanding the consumption patterns of the Bass, we are more readily able to
predict when they will consume certain type of prey, and this could have huge ramifications for
the conservation of certain species at the BFS. In the future, we recommend that the Bass be
completely removed from pHake Lake. We could also catch and dissect the bullfrogs at pHake
Lake to see if they are affecting the survival of the turtle population. All of these factors would
contribute to the preservation of native species at the BFS.
Figure 4: Image taken by our motion-sensor camera indicating possible evidence of the Western
Pond Turtle. The boxed image is what seems to be evidence of a turtle. The figure at the bottom
of the picture appears to be the back of a bird.
12. Bagheri 11
Figure 5: Image taken by our motion sensor-camera indicating evidence of a bullfrog.
Acknowledgements
We would like to thank Dr. Nina Karnovsky for her tireless work in helping make this
experiment a success. Dr. Karnovsky helped catch, anesthetize, and analyze the Bass, and
dedicated countless hours to making sure that the experiment was conducted in an efficient and
thorough manner. We would like to thank our laboratory TA’s, Mimi Starr and Molly Shallman,
for coming to the BFS to help us catch the Bass and also for helping us analyze the contents of
their stomachs in the laboratory. We would like to thank Max Karnovsky and Christian Settles
for also helping us catch Bass at the BFS. We would like to thank Yonghong Ren for driving us
to and from the BFS and for helping us set up our motion-sensor cameras. Finally, we would like
to thank the manager of the BFS for allowing us to use the facility in order to collect our data and
Pomona College for allowing us to use its facilities.
13. Bagheri 12
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