INTRODUCTION Corbicula fluminea is a freshwater species of clam that is invasive to the United States. This clam is often used as a food source in the Asian countries to which it is native, and is postulated to have been introduced in the late 1930s to the state of Washington by Chinese immigrants (Dresler 1980). C. fluminea has since spread throughout the majority of the U.S., and has become particularly prolific in the Chesapeake Bay region since the 1970s (Dresler 1980). While C. fluminea may be an invasive species, its presence can be beneficial to the waterways in which it is found. These clams play an important role in nutrient cycling and the filtration of phytoplankton and seston out of the water column (Hakencamp and Palmer 1999). …show more content…
C. fluminea are unique from many other species of clams in that they are able to not only filter-feed using their siphons, but also pedal-feed, using their foot to consume organic matter found within the sediments of streambeds (Hakencamp, et al. 2001). The upper limit of C. fluminea’s filtration abilities is believed to be at an approximate particle size of 20-25 µm (Boltovskoy, et al. 1995). However, in a study conducted by Boltovskoy, there was no evidence that C. fluminea preferentially selected the smallest algae species it was fed over the largest algae (1995). Although studies have been performed on C. fluminea, there is still a great deal of information that is unknown regarding its life cycle and its feeding habits. It is currently contested whether the presence of this invasive is overall beneficial or harmful to the ecosystems that it is occupying. This makes learning more about C. fluminea essential to management plans for the dense populations found throughout the United States. The objective of this study was to observe how filtration rates in Corbicula fluminea were impacted by exposure to different species of algae of varying sizes. I hypothesized that both the smallest and largest species of algae would be filtered at lower rates than species that were in the middle of the size range. MATERIALS AND METHODS CULTURING & MEASURING ALGAE Four species of green algae were grown in culture in a lab for use in this study: Chlorella sp., Haematococcus sp., Chlamydomonas sp., and Scenedesmus sp. Prior to preparing cultures, artificial freshwater was placed in a culture vessel (volume was dependent upon the size of the vessel, see appendix table 2) and sterilized in an Autoclave set to a p12 15 minute liquid cycle. To culture algae, the appropriate volume of water and culture medium (see appendix table 1) were pipeted into the culture vessel and swirled to combine. Cultures were stored in an environmental chamber with a 12 hour dark: 12 hour light photoperiod at approximately 21°C. Algal cells were measured by using a compound microscope with an ocular micrometer in the lens and using a stage micrometer to create a conversion factor for measurements at each objective.
Algae were then measured using the ocular micrometer and the previously determined conversion factor was used to calculate the true algal cell size. The diameter of the cell was measured in the species Chlorella sp., Haematococcus sp., Chlamydomonas sp. The length and width of the cell were measured in Scenedesmus sp. Average cell size and the standard deviation were then calculated for each species of algae, based upon the longest dimension of the …show more content…
cell. OBTAINING & MAINTAINING CORBICULA FLUMINEA Corbicula fluminea used in this study were obtained from Carroll Creek and Owens Creek, both located in Frederick County, Maryland. Clams were maintained in a laboratory setting in a tank containing artificial freshwater and held at approximately 21°C. C. fluminea were divided amongst 6 separate containers within the tank to ensure that random sampling would occur and the same animals would not be used repetitively in the experiment. FILTRATION RATE EXPERIMENT Seven 250 mL beakers were filled with 100 mL artificial freshwater and a pipet was used to add 10 mL of one species of algae to each beaker. Five Corbicula fluminea were selected for the experiment, each of which was measured using a digital caliper and weighed on a scale prior to experimentation. One C. fluminea was placed in five of the beakers, while two were used as controls and received no animal. A Pasteur pipet was used to disturb the water and mix the solution. An initial sample of 8mL was extracted from each of the controls using a pipet and dispensed in a test tube. A set of serial dilutions (½, ¼, 1/8) was then created. A hemocytometer and compound microscope were used to count cell density at each stage of the dilution for both controls. The fluorescence readings and cell density values for each control were regressed to create a standard curve. Time 0 began when each of the C. fluminea exposed their siphons, indicating that filtration had begun; the experiment was conducted for 90 minutes. At 10 minute intervals, the solution was mixed to ensure that algal cells were in suspension and a 2 mL sample was extracted to measure a fluorescence reading using a fluorometer. DATA ANALYSIS The cell density present in each of the experimental containers was then determined using the equation of the line from the previously created standard curve (where x=fluorescence value and y=cell density (cells/mL)). The cell density was multiplied by the total volume of solution used in the beaker to find the total number of cells. To determine the number of cells each of the C. fluminea filtered, cell density at time 10 was subtracted from time 0; this was repeated between each time interval. Cell density was then multiplied by total volume (110mL) to find the total number of cells and divided by 10 minutes to determine the rate of filtration at each interval. This was then divided by the weight of the clam to find the rate of filtration per gram body weight. A one-way analysis of variance was performed to determine significant differences in the average rates of filtration based upon the species of algae being filtered. A Tukey HSD test was then used to determine amongst which species significant differences occurred. RESULTS Figure 1. The average algal cell size (based on the longest dimension of the cell) of each of the species of algae cultured and used in the experiment. Error bars represent +/- 1 standard deviation of the mean. Figure 2. The average Corbicula fluminea uptake rate of filtration for each species of algae used in the experiment over the course of 10 minutes. Error bars represent +/- 1 standard deviation of the mean. A one-way ANOVA indicated that filtration rates were significantly different based on the species of algae (p=4.59 x 10-3). Lines at the top of the graph represent significant differences amongst species of algae determined by a Tukey HSD test at p<0.01). However, the difference in the rate of filtration between Haematococcus sp. and Chlamydomonas sp. was insignificant. DISCUSSION There appears to be a range in algal cell size that C. fluminea are disposed to filter. Particle size must cross a certain threshold, but not be greater than a particular size, for C. fluminea to readily filter it out of the water. Based on the cell size of the algae used in this experiment, I would approximate this range to be between 2 µm and 25 µm. When C.
fluminea were placed in water containing Chlorella sp., the filtration rate decreased in comparison to clams given Chlamydomonas sp. and Haematococcus sp. This was unexpected, as I anticipated filtration rates of Chlorella sp. to be higher than Chlamydomonas sp., but lower than Haematococcus sp. Because Chlorella sp. is of a spherical shape, similar to Chlamydomonas sp. and Haematococcus sp., and is within the size range of particles that C. fluminea are capable of filtering, it is likely that particle size is not the only factor that influences particle selection. The presence of chemoreceptors has been noted in other species of bivalves (Ten Winkel and Davids 1982). While no studies have confirmed the presence of chemoreceptors in C. fluminea at this time, the low filtration rates of Chlorella sp. in this study indicate that C. fluminea may be selecting algae for filtration based upon chemical signals in conjunction with cell size. Scenedesmus sp. was also filtered at a lower rate than Chlamydomonas sp. and Haematococcus sp. In addition to this species being at the upper end of the range of cell size that C. fluminea is known to filter, Scenedesmus sp. was the only species of algae used in the study that had a non-spherical cell shape. It is unknown at this time if the shape of algal cells significantly impacts filtration capabilities in C.
fluminea. In future studies, it would be interesting to present cells of varying shapes to determine if cell shape impacts the clams’ ability to filter. It would also be wise to present more than one species of algae at a time to determine if the C. fluminea are preferentially selecting particular cell sizes/shapes over others. Additional research would need to be conducted to confirm or refute the presence of chemoreceptors in C. fluminea.
The Artemia franciscana can survive in extreme conditions of salinity, water depth, and temperature (Biology 108 laboratory manual, 2010), but do A. franciscana prefer these conditions or do they simply cope with their surroundings? This experiment explored the extent of the A. franciscanas preference towards three major stimuli: light, temperature, and acidity. A. franciscana are able to endure extreme temperature ranges from 6 ̊ C to 40 ̊ C, however since their optimal temperature for breeding is about room temperature it can be inferred that the A. franciscana will prefer this over other temperatures (Al Dhaheri and Drew, 2003). This is much the same in regards to acidity as Artemia franciscana, in general thrive in saline lakes, can survive pH ranges between 7 and 10 with 8 being ideal for cysts(eggs) to hatch (Al Dhaheri and Drew, 2003). Based on this fact alone the tested A. franciscana should show preference to higher pH levels. In nature A. franciscana feed by scraping food, such as algae, of rocks and can be classified as a bottom feeder; with this said, A. franciscana are usually located in shallow waters. In respect to the preference of light intensity, A. franciscana can be hypothesized to respond to light erratically (Fox, 2001; Al Dhaheri and Drew, 2003). Using these predictions, and the results of the experimentation on the A. franciscana and stimuli, we will be able to determine their preference towards light, temperature, and pH.
The Zebra Mussel (Dreissena polymorpha), is a small freshwater mollusk that is an invasive species. It has slowly been making its way into the United States. It has done this by showing up in lakes and in rivers. The mussels get their name due to the striped pattern on their shells. They are a relatively small species, only growing to the size of a human finger nail but there have been cases of larger (“Zebra Mussels,” 2013, para. 2). Mussels live a short life span of 4-5 years and most do not make into adulthood. They live in freshwater at depths of 6 to 24 feet. The female produces 30,000 to 1,000,000 eggs per year starting at the age of two. Zebra Mussels are free moving and can move with an external organ called the byssus (“Zebra Mussels,” 2013, para. 3). But they can be moved around by currents and other objects too. Zebra Mussels are a threat to ecosystems. They damage the natural habitat of lakes and rivers and cause negative effects to the native aquatic life. They multiply in vast majority casing a lake of food and space for other animals. And also the U.S. has spent millions on the removal of these pests from our water (“Zebra Mussels,” 2014, para. 8). The Zebra Mussel has now made its way into Colorado. Just a few has been found in the waters of Colorado but a few is enough to cause a big stir. Extreme precautions have now been put into effect to make sure that the threat of Zebra Mussels is under control.
A common inference made by scientists predicts that the zebra mussel will continue spreading passively, by ship and by pleasure craft, to more rivers in North America. Trailered boat traffic is the most likely cause for invasion into North America. This spread can be preventable if boaters thoroughly clean and dry their boats and associated equipment before transporting them to new bodies of water. Since no North American predator or combination of predators has been shown to significantly reduce zebra mussel numbers, such spread would most likely result in permanent establishment of zebra mussels in many North American waterways.
Known as Pterois Volitans in the animal kingdom, also called the red lionfish, is a sight to behold in the tropical waters as they swim like an underwater butterfly in the sea. In waters not native to their origin, as they are from the Pacific and have predators that will have them for a snack. Invasive to the Caribbean Sea they have rapidly reached the Gulf of Mexico and far south, spreading to parts of South America. The lionfish has become a persistent pest that’s more trouble than what it appears to be, attractive yet deceptive with a striking pattern of white and red stripes. In the New York Times article, A Call to Action… and Even Rodeos, scientists say that, “from 2005 onward, lionfish have become the most numerous nonnative invasive species in the world.” The average pound fish is one of nature’s clever creations, a venomous foe with spines and an infinite appetite that reproduce quickly. Invasive species are notorious because they have no or almost nonexistent natural predators and they are adapt to their new home very well. The biological adaptations of this fish has caused both ecological and economical mayhem, serious measures have been taken up to control their population as well as to protect our coral reefs.
One of the Bays biggest resources is its oysters. Oysters are filter feeders which mean they feed on agley and clean the water. The oysters feed on agley and other pollutants in the bay turning them into food, then they condense the food down to nutrients and sometimes developed pearls. Filtering the water helps the oysters to grow, and also helps clean the Chesapeake Bay. One oyster can filter 50 gallons of water a day, Oysters used to be able to filter the Bay in about a week. However, these creatures are now scarce in the bay. The Chesapeake Bays Oyster (crassostrea virginica) Population has declined severely because of over harvesting, agricultural runoff, and disease. Now the Chesapeake Bay is becoming polluted without the oysters and the water is not nearly as clean as it once was. The Chesapeake Bay was the first estuary in the nation to be targeted for restoration as an integrated watershed and ecosystem. (Chesapeake Bay Program n/d). This report will show the cause and effect of the Chesapeake Bay's Oyster decline on the Bay.
Tropicalia is not only know as a form of music in Brazil but as a rebellion. Its theme of cultural non conformity was strengthened by the idea that Brazil had lost its way. Tropicalia took a stand against the social and musical hierarchy of Brazil. Though mainly known as a form of Brazilian pop music Tropicalia is deeply rooted in the political and cultural background of Brazil.
They also look after the quality of coastal waters by watering down, sifting, and settling deposits, left-over nutrients and contaminants. They are highly productive ecosystems and provide habitats and act as nurseries for all manner of life.
The outer layer of a reef consists of living animals, or polyps, of coral. Single-celled algae called zooxanthellae live within the coral polyps, and a skeleton containing filamentous green algae surrounds them. The photosynthetic zooxanthellae and green algae transfer food energy directly to the coral polyps, while acquiring scarce nutrients from the coral. The numerous micro habitats of coral reefs and the high biological productivity support a great diversity of other life.
The understanding of Saballaria cementarium's diet has not been thoroughly examined in much detail. Qian and Chia (1990) examined the role of detritus, form of eelgrass, as a food source for developing larvae of the organism. It is not known whether they are food limited. The experiment was conducted to reveal some facts about the feeding habits of the larvae in determining the development and growth of it. The invertebrate larvae's primary food source comes from the phytoplankton that is found in abundance at the bottom of the sea floor. The larvae fed with detritus were compared with those fed on equal concentrations of phytoplankton. Other tests were conducted to compare the degrees of survivorship among the larvae using varying concentrations of phytoplankton. Higher concentrations of phytoplankton, consumed by the larvae, yielded
... ethanol present. Due to the fact that there has been a distinct correlation between the levels of ethanol present and the mortality rate of certain aquatic life forms, it was expected that when a higher concentration of ethanol was present in the artificially constructed environment, the brine shrimp would have a lower rate of hatching and a higher mortality rate. It was anticipated that if the brine shrimp cysts were exposed to levels of ethanol in 0%, 0.1%, 0.15%, and 0.2%, than the brine shrimp cysts exposed to higher levels of ethanol would develop more slowly due to the fact that ethanol changes the shape of proteins when it permeates the membrane of a call. Thus, the brine shrimp’s exposure to 0.2% ethanol would yield higher mortality rates and more developmental problems than when the brine shrimp were exposed to 0.15% ethanol, 0.1% ethanol, and 0% ethanol.
Reason Two: Daphnia are also an able to be used in bioassays because they are very sensitive to any changes within the water and a very simple and cheap. They mature in a very short period of time, so it does not take long to grow them to maturity and test. ”Bioassays are procedures that can determine the concentration, purity, or biological activity of a substance such as vitamin, hormone, or plant growth factor by measuring the effect on an organism, tissue, cells, enzyme, or
Coral reefs are the most biodiverse ecosystem on the planet. There are more than 25,000 known species of organisms and countless others that have yet to be identified (Helvarg, 2000). Reefs thrive on the shallow edge of tropical seas, most often on the eastern edge of continents along warm water currents that brush the coasts. Reefs cannot live in cold waters and are limited by ocean depth and available sunlight. Coral is the foundation of the reef community, providing a three-dimensional structure where thousands of species of vertebrates and invertebrates live and feed. Some species of coral are hard, while others soft. Some are branched, yet others are compact and rounded. Coral is made up of large communities of tiny jellyfish like polyps. These polyps absorb calcium from the sea water and secrete a hard limestone skeleton. At night the polyps extend sticky, stinging tentacles from their skeletons to capture and consume small floating organisms such as zooplankton. Every coral has a two-stage life cycle: the larva, and the polyp. The larval stage is free swimming, and the polyp is stationary. Ocean currents carry the larva from the stationary parent polyp to any hard, clean, silt-free surface where, if the conditions are perfect, the larva grows into a coral forming polyp, never to move again (Levin, 1999). One of the most valuable resources for coral polyps are algae. Some live on the coral skeletons, but one type in particular, zooxanthellae, lives inside the tissue of the polyps. Zooxanthellae makes up about half the weight of the fleshy polyps and are not only a valuable food resource, but they are responsible for the brilliant colors associated with coral. When coral looses these prec...
There are several types of treatment methods present but biological treatment methods have gained much traction in the recent years due to their low operation costs, comparatively benign effects on the environment and their ease of handling and maintenance. Biological wastewater treatment methods can be subcategorized into dispersed growth systems and attached growth systems. Biofilms fall under the latter category (Sehar & Naz, 2016)
Introducing exotic species has been a highly debated issue. Why should we bring another animal or plant into a region to eradicate another species? That’s the question that people have been asking for ages. Of course, there are positives to bringing in another species, but many times, there are just as many negatives. Also, these species can be introduced accidentally or intentionally. The new organism may cause no obvious problems and eventually, it will be considered “native” to the area. For example, corals are “perhaps the oldest animals on the planet, and these long-lived corals have evolved in one of the Earth’s most stable environments” (Eichenberg, p.2). If a new type of fish were to be put into the ecosystem with the corals, the coral would be affected. First, the fish might eat the coral. Second, they could use the coral for shelter, and possibly damaging it that way. Third, the fish could bring predators that might also eat the coral. Introducing an exotic species has the “rippling affect” of dropping a stone into a pool of water. Everything outside the epicenter is affected. A study was done at Cornell University, and they estimated that $120 billion per year are spent fixing the problems caused by exotic species” (Chiras, p.