How Symbiosis between Fish and the Jellyfish is affected by Ocean Acidification
Introduction on ocean acidification
Ocean acidification is described as one of the major daunting challenges that are currently a major threat to the marine life. This dubious situation is created when the ocean absorbs approximately one forth and one half of all the anthropogenic CO2 gas emissions (Nagelkerken et al. 2016). The unprecedented uptake of CO2 by the ocean is followed by the formation of carbonic acid through the dissolution of the absorbed CO2 gas.
Relationship between jellyfish and fish under normal conditions
Ocean acidification is also known to result to tremendous harmful changes on the ocean chemistry which in turn affects the entire marine ecosystem. Aside from the negative effects caused on the shellfish and coral reefs, increased ocean acidity has also been discovered to have a significant interference on the relationship between the jellyfish and fish. Furthermore, researchers have found that ocean acidification has lead to an alarming increase in jellyfish population that threatens to lead to a loss in fish biodiversity (Richardson et al., 2009).
The marine life is characterized by several interrelationships between different organisms living in the ocean. Some of the organisms that have been known to have a great correlation are the jellyfish and fish. The jellyfish and some few species of fish have a symbiotic relationship where fish benefits on its association with the jellyfish without causing any harm to the jellyfish. A large vast of fish that have been known to have a symbiotic relationship with the jelly fish are described as juvenile fish. Most of these juvenile fish usually swim around the belly of the jellyfish while a few others can be found swimming among the tentacles of the jellyfish (Nagelkerken et al. 2016). Only a few species of juvenile fish are able to survive around the tentacles of jellyfish which is believed to produce toxic compounds that are essentially harmful to most marine organisms inclusive of the predator fish. Thus, the juvenile fish that are in a symbiotic association with the jellyfish, are able to survive and grow as they are protected from the predators who would have otherwise preyed upon the juvenile fish were it not for the presence of the jellyfishes’ poisonous tentacles. Juvenile fish are able to evade the toxicity poised by the tentacles of the jellyfish by avoiding swimming in close proximity to the tentacles of the jellyfish. In addition, the jellyfish is able to provide safe habitat or shelter to the growing but vulnerable juvenile fish. The juvenile fish is also able to obtain food from its association with the jellyfish by either feeding directly on the jellyfish, on the zooplankton present on the jellyfish, on the amphipod parasites present on the jellyfish host or on the prey encountered by the fish as the jellyfish swims through the water column (Purcell & Dror, 2010). Therefore, the juvenile fish is able to get ample conditions and protection by living in symbiosis with the jellyfish. Symbiotic relationship between the jellyfish and the juvenile fish is eminently essential not only in enhancing the survival of the juvenile fish but also in promoting the activity of reproduction by the fish. Therefore, from this symbiotic association, the juvenile fish is able to significantly increase in its species population. The newly born juvenile fish are thereafter able to utilize their both their sight and sense of smell to reach out to the jellyfish so as to continue with the symbiotic relationship (Pitt & Purcell, 2009). Thus, the facultative symbiotic relationship between the jellyfish and the juvenile fish is known to increase the rate of survival of the juvenile fish which will have higher chances of progressing and reaching their maturity and adult stage.
In normal conditions, filter-feeding pelagic fish are regarded as better feeders of planktonic food as compared to jellyfish. Thus, small filter-feeding pelagic fish are known to outcompete jellyfish thus controlling the outbreak of jellyfish population (Richardson et al., 2009).
Effects of Ocean acidification on jellyfish and juvenile fish
Blooming of Jellyfish and its effects on the competitive pelagic fish
Increase in ocean acidity is known to have a positive impact jellyfish which spontaneously increases in its population. On the other hand, ocean acidification has been found to have detrimental effects of the juvenile fish. Increase in jellyfish population has been mostly attributed to the low pH that is usually attributed by the increase in water acidity (Mills, 2001). Jellyfish are mostly known to feed on both adult and larval fish. Therefore, as jellyfish continue to thrive in population, so does the population of fish continues to decrease significantly. In essence, ocean acidifications negatively affect calcifying plankton thereby opening ecological space for non-calcifying species such as the jellyfish (Richardson & Gibbons, 2008). In addition, research studies have indicated that there exists a positive correlation between increase in water acidity and the population of jellyfish species such as pelagic Cnidarians and Ctenophore. Jellyfish are also able to survive in disturbed marine ecosystems such as ocean acidity since they are characterized with a broad diet, fast growth rates, ability to shrink when starved, ability to tolerate hypoxia and their capacity to fragment and regenerate (Richardson et al., 2009).
Thus, jellyfish are able to survive better under low pH conditions as compared to fish which are harshly affected by high acidity levels of the ocean waters. It is with this profound reason that the local jellyfish increase in population thus displacing fish and ultimately forming an alternate ecosystem state (Richardson et al., 2009). However, in some cases where filter-feeding pelagic fishes are plenty in the ocean, the population of jellyfish is always kept in check due to the fact that filter-feeding pelagic fishes are better competitors for planktonic foods as compared to jellyfish (Richardson et al., 2009). However, since ocean acidification causes adverse effects to the small filter-feeding pelagic fish, their population is likely to decrease drastically. It is with this profound reason that the jellyfish population increase significantly as they no longer have to compete with the filter-feeding pelagic fish for planktonic food. An outbreak in jellyfish population results to a rapid self-enhancing feedback loop in which the jellyfish invade habitats where the fish might have formerly controlled jellyfish numbers (Richardson et al., 2009). Therefore, jellyfish bloom may result to a significant shift in the ecosystem culture where the competitive and diverse fish species become replaced by a monoculture of jellyfish population (Richardson et al., 2009).
Predation of juvenile fish by jelly fish
Most of these juvenile fish which are usually at their early-life stages get negatively affected by increase in water acidity due to the non-maturity of their physiological systems which limit their acclimation capacities (Mills, 2001). Since most of the juvenile fish are vulnerable to the harsh conditions caused by an increase in ocean acidity, their probability of surviving and reaching the maturity and adult stage is greatly obstructed. Thus, ocean acidification does not only interfere with the symbiotic relationship existing between the jellyfish and juvenile fish but also results to an increase in mortality levels of the juvenile fish. In addition, the disruption caused by ocean acidification to the symbiotic relationship between jellyfish and juvenile fish also results to the juvenile fish being prone to predation by other existing marine predators (Pitt & Purcell, 2009). Thus, most of the juvenile fish get exposed to the normal food web which consists of different trophic levels whose organisms would readily feed on the juvenile fish. According to recent research studies, the disruption of the association between the jellyfish and juvenile fish has also led to the circumstances where the jellyfish ends up feeding on the juvenile fish. This is primarily attributed by the rampant death and decrease in population of the juvenile fish that had been caused by an alarming increase in the ocean acidity (Purcell & Dror, 2010).
Intraspecific competition of jellyfish and increased mortality rates of fish
Since ocean acidification results to a blooming population of jellyfish, the juvenile fish become at risk of being eaten by the jellyfish that they once had a facultative symbiotic association with. This situation can be elucidated using the fact that an increase in population of a given single species of organisms is likely to result to competition among same species of organisms which is commonly described as intraspecific competition. The rapid increase in population of jellyfish as a result to ocean acidification thereby results to intraspecific competition for space, food and other resources (Richardson et al., 2009). It is with this profound reason that amid a state of increased ocean acidity, the jellyfish population will be forced to feed on the juvenile fish so as to compete effectively with the other vast jellyfish population. The jellyfish causes massive death of the juvenile fish by releasing stinging filaments in the water column which causes an irritation on the fishes’ gills thereby resulting to the juvenile fish dying from hemorrhage and subsequent suffocation. Therefore, jellyfish bloom has been found out to have deleterious effects as through intraspecific competition and predation, the jellyfish results to a significant loss of abundance on fish (Richardson et al., 2009).
Interference with the juvenile fishes’ sensory organs
Increase in ocean acidity is also known to cause a significant alteration of the ocean chemistry. This causes an abnormality on the ocean chemistry which interferes with the normal life of the existing marine plant and animal life. An example of organism whose normal life gets interfered by the increase in ocean acidity is the juvenile fish. Ocean acidification is known to have a negative impact on the juvenile fish as the altered ocean chemistry interferes with the normal sense of smell, vision and hearing capabilities of the juvenile fish (Nagelkerken et al., 2016). Interference with the normal sense of smell and hearing capabilities of the juvenile fish in turn disrupts the normalcy of the juvenile fish forming a facultative symbiotic association with the jellyfish. This is primarily due to the fact that the affected species of juvenile fish would find it extremely daunting and challenging for them to dodge the stinging tentacles of the jellyfish. Therefore, alteration caused by ocean acidification on the juvenile fishes’ sense of smell will eventually result to the increase in mortality levels on the juvenile fishes’ population. This is because juvenile fish like all the other myriad of marine organisms existing in the ocean are not immune to the toxic effect caused by the poisonous compounds that are released by the tentacles of the jellyfish (Richardson & Gibbons, 2008). Therefore, an increase in ocean acidity interferes with the existing relation between the jellyfish and the juvenile fish as the sensory organs of the juvenile fish fails to function properly thereby resulting to the juvenile fish having physical contact with the poisonous tentacles of the jellyfish. Ocean acidification thus makes the normal symbiosis between the jellyfish and the juvenile fish to be a dangerous association that results to massive death of the juvenile fish.
Consequences of a disrupted relationship between jellyfish and juvenile fish
Furthermore, interference of the facultative symbiotic association between the jellyfish and juvenile fish limits the survival rate of the juvenile fish. This is because, under normal circumstances, the juvenile fish would not only rely on the jellyfish for shelter and protection but also for food. Ocean acidification which destroys the symbiosis between the juvenile fish and the jellyfish causes the juvenile fish to have limited access to food. Since the vulnerable juvenile fish are unable to compete effectively with the existing wide array of robust existing marine organisms, most of them tend to die due to lack of food among other important resources that they had access to during the period that they were in a symbiotic relationship with the jellyfish (Pitt & Purcell, 2009). This thereby results to death of the juvenile fish which ultimately causes a loss of fish diversity in the ocean.
Table 1: A table showing how ocean acidification has affected both fish and jellyfish
|An increase in population||High mortality rates including species of small filter-feeding pelagic fish and juvenile fish|
|Intraspecific competition among jellyfish||Inadequate shelter and protection; fed by marine predators|
|Due to competition among jellyfish for food, they fed on the juvenile fish and on the fishes’ eggs||The sensory organs of the fish were disrupted by increased water acidity|
|Increased levels of reproduction due to the good oceanic condition as a result of ocean acidification; High reproductive rates; Increase in population||Hemorrhage and subsequent suffocation of fish due to the effect of acid water on the fishes’ gills|
This table has been made by me as a synthesis of various sources
Ocean acidification process has been discovered to have massive effect on the relationship between fish and jellyfish. A decrease in pH of the oceanic waters has been found to stimulate reproductive rates among the jellyfish which later on results to a blooming population of jellyfish. This leads to intraspecific competition among the jellyfish which then feed on the juvenile fish and the fishes’ eggs. This drastically affects both the present and future population of juvenile fish. In addition, ocean acidification negatively affects the sense organs of juvenile fish thus hindering the fish from sensing the toxic tentacles of the jelly fish (Pitt & Purcell, 2009). This results to a dangerous association between juvenile fish and jellyfish because of the fact that an obstructed sense of smell and sight will lead to the juvenile fish getting in contact with the poisonous tentacles of the jellyfish. In addition, juvenile fish lose the protection and shelter that they once had while in association with the jellyfish. Thus the fish becomes exposed to various marine the increased population of jellyfish that prey and feed on them. Therefore, as the population of jellyfish rises due to ocean acidification, the population of juvenile fish reduces at an alarming rate due to factors including a broken symbiotic association between fish and the jellyfish.
Jellyfish bloom may also result to a significant shift in the ecosystem culture where the competitive and diverse fish species become replaced by a monoculture of jellyfish population. This is because ocean acidification leads to a decrease in filter-feeding pelagic fish where as the jellyfish population increase due to availability of planktonic food. Therefore ocean acidification results in loss of fish species diversity where as different species jellyfish increases in abundance.
In conclusion, ocean acidification evidently causes more harmful effects to the marine life as opposed to the positive effects. One of the negative effects that an increase in ocean acidity has on marine life is with regard to the destruction of the symbiotic relationship existing between the jellyfish and the juvenile fish. Even though jellyfish bloom is largely associated with an increase in ocean acidity levels, the juvenile fish are unfortunately unable to withstand such harsh conditions (Purcell & Dror, 2010). Due to ocean acidification, a large vast of juvenile fish die and this tremendously affects the entire marine ecosystem
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Nagelkerken, I., K. A. Pitt, M. D. Rutte, and R. C. Geertsma, 2016: Ocean acidification alters fish–jellyfish symbiosis. J. Phys. Oceanogr., 283, 20161146, doi:10.1098/rspb.2016.1146.
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