An Investigation Into the Effects of Varying Seawater Concentrations on Two Marine Invertebrates’ Osmoregulatory Abilities; Carcinus Maenas and Arenicola Marina.

Alterations of environmental conditions appear constant to aquatic organisms that live within rocky shore ecosystems. The Zebra-top Snail was examined species within the following report, found on intertidal rocky shores of south-east and West Australia. The reaction and mass change of the Zebra-top Snail was examined whist carrying out this experiment. It was hypothesised that the Snails placed into higher salinity water will attempt to find higher ground, and their mass will be less than their original weight. The Snails were placed in water, each containing different amounts of salinity, as the rate of reaction was examined. The Snails placed in greater salinity showed a significant response in reaction within 10 minutes of observations.

Therefore this experiment was to determine that lobsters in various salinities will osmoconform to their environment. In order to test that lobster's osmoconform, we had to extract approximately 1.0 ml hemolymph from their hemocyannin on the ventral first section of the pre-branchial region. The hemolymph was spun for three minutes in a microcentrifuge and the serum was then tested on an osmometer, which determined the osmolarity of the hemolymph. The results substantiated the hypothesis, in that, lobsters internal osmoles fluctuate with the salinity of the external environment. The two lobsters in the low salinity tank had the lowest osmolarity 0.746 osmoles; the two lobsters in the normal salinity had 0.873 osmoles. The last tank with the highest salinity had the lobsters with the highest osmolarity at 1.445 osmoles. Therefore our data suggests that lobster's osmoconform, with respect to the salinity of their environment by readjusting their intracellular solute concentration to prevent swelling or dehydration because the osmolarity of their hemolymph dictates that of the environment.

The procedure for this experiment followed the steps as shown in the flow chart (Figure 1) and will be expanded upon here. The oxygen-measuring probe in the test chamber was first turned on and required 10 minutes to warm up. During this time, two empty containers had 200mL of fish water added to them and then each was weighed using a scale that was tared to zero before use. Two pairs of goldfish were then collected from the large tank #1 in the lab room using the fish net provided, and one pair was placed in each container. Then, the containers were reweighed separately and the original weights were subtracted from the new weights in order to determine each pair of goldfish’s weight. Two trials were conducted and in each trial, each goldfish pair was subjected to two conditions, first a control condition where no factors were introduced, followed by an experimental condition where they were exposed

The experiment took place in a laboratory setting, and the first step was obtaining sixty individual Daphnia magna (that were neither adults nor tiny offspring) from a large tank in the lab. These individuals were equally divided into three groups; low density, medium density, and high density. The twenty Daphnia assigned to the low density group were split into four groups of five and pipetted into one of four tubes filled with 10mL of Chlamydomonas algae. The twenty Daphnia assigned to the medium density group were split into two groups of ten and placed into one of two tubes also filled up to 10mL with Chlamydomonas. The final twenty Daphnia were all placed into a single tube filled with 10mL of the algae. In order to avoid suffocation-related

For this experiment the independent variable is the crayfish and elodea while the dependent variable is the respiration rate measured in NaOH. The elodea and crayfish were placed into two different graduated cylinder containing 30ml and the volume displacement were than recorded. Once finished measuring, three beakers were obtained, labeled and 100ml of tap water was added to each beaker. The control group is beaker 3. The beaker containing elodea was completely covered in foil and placed into a dark cabinet to avoid photosynthesis from happening for 15 minutes. After 15 minutes, the crayfish and elodea were taken out and placed back into their tanks. Four drops of the pH indicator phenolphthalein were added to each beaker. NaOH was dropped

The Deep sea ecosystem has been classified as the largest ecosystem compared to all other ecosystems within the world (Martin, 2003). The main characteristics of this ecosystem is that it experiences very low oxygen levels, the water temperature is extremely cold, the pressure within this area is very high and sunlight do not penetrate to these depths. The species that do live within this environment are highly adapted to these harsh conditions such as the Cookie-cutter Shark (Isistius brasiliensis) (Figure 02). This essay will mainly focus on the Cookie-cutter Shark as well as

During the summers the oxygen content atop the water normally has a salinity level consistent with “more than 8 milligrams per liter”; but when oxygen content drops down to “less than 2 milligrams per liter” the water is then known to be in hypoxic state (CENR, 2000; USGS, 2006). Hypoxia is the result of oxygen levels decreasing to the point where aquatic organisms can no longer survive in the water column. Organisms such as fish, shrimps, and crabs are capable to evacuate the area but the fauna that cannot move either become stress and/or die. Due to this, many call the hypoxia zone the “dead zone” (Overview, 2008; USGS, 2006).

Providing electrolytes in the drinking water alters the birds’ osmotic balance in a way that enhances thirst (Teeter and Belay, 1996). Drinking saline water increases sodium concentrations in plasma which is capable, at certain levels, of changing the osmolality of body fluids. The osmolality of the extracellular fluid is controlled primarily by the concentration of sodium and its attendant anions (Verbalis, 2003). The increased tonicity of the extracellular fluid increases the osmotic pressure on the body cells that may result in drawing water from the cells into the extracellular fluid. To prevent this, certain neurons (osmo-Na+ receptors) detects the concentration of sodium in extracellular fluid and triggers osmotic thirst to help restore the body fluids to a normal state (Stachenfeld, 2008). In humans, a minimal change (2-3%) in plasma tonicity is capable of inducing thirst (Stachenfeld, 2008).

Oxygen availability is another abiotic factor that the A.tenebrosa adapts to on the rocky shore which affects their distribution. The A.tenebrosa uses the behavioural adaptation of their tentacles to collect water which contains oxygen whilst under water during a high tide. The A.tenebrosa then stores this water (as previously stated) in their tentacles and folds their tentacles into their mouths. This helps the A.tenebrosa to have sufficient amount of oxygen whilst exposed during the high tide. This affects the distribution of the A.tenebrosa as they are found in the low and mid tide zones of the rocky shore which gives them sufficient amount of time to collect the water and oxygen needed to survive during the short period of time they are

The varying levels of the tides create a very complicated microhabitat for the organisms. The organism must adapt to both underwater and terrestrial conditions in order to thrive.

Table 1: The table displays the weight of the shells in each water solution. The weights are shown, and the difference is taken by subtracting the weight after 16 days from the intial weight. The average difference is then calculated and standard deviation is calculated from the differences. Standard error of the mean is calculated and the value is multiplied by

They are relatively inexpensive and easy to acquire, have an extremely short incubation period (24 hours) and can be related to nutritional effects on other species (Sorgeloos et al 1998). Crustaceans make up a food source for the human population as well as being a widely accepted food source by many animals; they are also an economic source for crustacean farmers. To be able to find the most adequate diet for growth and production is crucial to the success of the aquaculture industry. Many factors influence the metabolic rate of a crustacean, including environmental temperature, salinity and osmosis as well as body size, reproductive state and nutrition. (Ansell,

It all has to do with the concentrations of solutes in the blood stream of the animal. Some crustaceans rely on cell

For example, swordfish values range <70% (Torres-Escribano et al., 2010; Cabañero et al., 2004, Maulvault et al., 2011). The same thing occurs for the atum considered with low bioaccessibility (9%) by Cabañero (2004), however Ouédragon and Amyot (2011) report 72%.

Changes to salinity can play an important role in the growth and size of aquatic life and the marine species