Bacterial Diseases of Marine Organisms

NB: We do not resell your papers. Upon ordering, we do an original paper exclusively for you.

NB: All your data is kept safe from the public.

Table of Contents

Introduction
Why I chose the topic
Corals
Dolphins
Fish
Conclusion
Works Cited

Introduction

The diversity of marine organisms has resulted in an increase in diseases reported affecting marine life. This increase is also attributed to the increasing interest in marine research, changes in the quality of water and associated human impact. Among the many diseases implicated in marine organisms, infectious diseases, particularly those caused by bacterial organisms largely affect aquatic organisms impacting negatively on their existence, and the extinction of others (Rowan742). In the aquatic environment, ocean water contains over 10⁵ bacteria in a milliliter of water. Some of these bacteria are pathogenic and reside in warmer regions of the water body reaching about 37^oC. In this regard, the presence of these bacteria and their potential to cause disease in marine organisms is directly dependent on the prevailing environmental temperatures.

Why I chose the topic

This topic is essential based on the fact that, in the recent past, many emerging infectious diseases affecting marine organisms have been increasing with little knowledge about the inducing bacteria. Thus, it would be important to understand the various microorganisms that impact negatively on the lives of the various creatures in marine systems. This article explores bacterial diseases in marine organisms with a focus on diseases affecting the corals, dolphins and fish.

Corals

Bacterial diseases are claiming the lives of many small-polyp stony and Acropora corals. The bacterial infections to these corals mainly lead to rapid tissue death and tissue necrosis, symptomatology that describes conditions where Acropora corals and related SPS corals lose tissues through sloughing from their skeletons (Rosenberg, Omry, Leah, Rotem and Ilana 356). Coral tissue loss follows several patterns, including rapid tissue loss from the skeleton, or sloughing of tissues from the skeleton due to the effects of currents. The bleaching of corals is a result of Vibrio species, some of which luminesce, while others elicit bioluminescence with deep-sea fish intracellularly. In the same way, Vibrio species induce zooxanthellae characteristics in corals in some specific conditions (Rosenberg et al 357; Rowan 742).

Dolphins

Dolphins are largely infected by Brucella species. In addition, Brucella species have been isolated in whales and seals. Although the organism has been mainly isolated in dolphins eliciting no disease signs, several health outcomes have been linked to infection with Brucella species including meningoencephalitis, pneumonia, abortions, blubber abscesses, and osteoporosis (Rowan 742). Among the prevalent species of Brucella isolated in dolphins include the Brucella ceti and Brucellag pinnipedialis (Hernández-Mora et al 1430). Similarly, the cetacean species primarily infected with Brucella species include the Atlantic white-sided dolphin, identified as Lagenorhynchus acutus, bottlenose dolphin, botanically known as Tursiops truncates, common dolphin, known as Delphinus delphi, Harbor porpoise, Phocoena phocoena, and the striped dolphin, also known as Stenella coeruleoalba.

Studies regarding Stenella coeruleoalba on Costa Rican Pacific coast have shown a high prevalence of meningoencephalitis among the dolphins. Additionally, antibodies directed to Brucella organisms, especially B. ceti, were highly eminent in the cerebrospinal fluid of marine animals (Hernández-Mora et al 1430). The striped dolphin is a highly susceptible host of the bacteria and poses and the most potent reservoir and source of transmission of the infectious agent. Isolation of B. ceti from body fluids of dolphins such as fetal tissues and milk in pregnant marines defines conclusions that the organism is tropic to fetal tissues and placental materials. In this regard, the transmission may take either the vertical form or horizontal to other susceptible marines.

Fish

Several bacterial pathogens have been identified to cause diseases among the Pisces including Pseudomonas fluorescens, Aeromonas hydrophila (MAS), and Aeromonas salmonicida. The P. fluorescens is the primary cause of pseudomonas septicemia in pond fish. It is a secondary invader with similar attributes to A. septicemia (Rowan 742). The infection is huge although it has a good prognosis considering its low severity. The bacterium is a ubiquitous organism of water but can also be found in the soil, and in foods that are vulnerable to spoilage. Its biochemical characteristics include a positive catalase test and cytox test with strict aerobic characteristics. The organism has a worldwide distribution in both fresh water and salty waters infecting nearly all fish although it elicits severe infections in aquarium fish. Its transmission from mud, carrier fish or other aquatic organisms such as frogs is primarily vertical with the temperature being the main environmental factor supporting transmission (Rowan 742). The pathophysiology of P. fluorescens especially in catfish entails hemorrhagic symptomatology with necrosing internal organs. In some cases, external lesions are evident and lead to loss of pigmentation. Diagnosis is through kidney isolation on BHI with the test results confirmed serologically. Disease control is via the use of drug therapy and removal of the stressor since there is no available vaccine yet.

Infection with A. hydrophila (MAS) mainly results in motile Aeromonas septicemia, which renders severe complications to the affected fish species. The organism is opportunistic in nature and induces red legs in frogs. The virulence of the organism is aided by its production of endotoxins. It grows best in TSA at 18 to 25^oC forming white colonies that are circular with a convex elevation. The bacilli organism is motile with polar flagella, and is positive of oxidase test, catalase test, and results in the fermentation of glucose. Pathophysiologically, the organism causes hemorrhagic reactions with necrosis of internal organs. Additionally, the skin and muscle tissues may necrose where G septicemia is the primary infection. The occurrence of superficial ulcerations that are circular and grey to red in color is predominant. Lesions are mainly present around the mouth with the fish hemorrhaging from the fins. An internal look reveals soft, swollen kidney pathology with petechiae forming in the musculature of the fish. The diagnosis of the infection is via TSA isolation of the kidney, and managing the disease with chloramphenicol or therapy with oxygen (Rowan 742).

Lastly, infections of fish with A. salmonicida results in furunculosis, which is characterized by boil-like lesions on the skin. Following strict management of the disease in the UK, the prevalence of the infection has declined drastically. The A. salmonicida is the most common of the three subspecies causing the disease. The bacilli are characterized by pigment production during their growth, producing bipolar staining characteristics (Rowan 742). Cultural characteristics of the organism include brown pigmentation, with the cells growing best at 18 to 25^oC producing raised colonies that are tiny and white in color. Biochemically, the organism is positive to oxidase test and does not produce any gas while fermenting glucose. Its pathogenicity is aided by the production of endotoxins. The organisms primarily infect fish and are found in carrier fish or in infected water bodies forming abundant reservoirs. Following horizontal transmission in contaminated water or carriers, A. salmonicida causes subacute to acute lesions that may be chronic depending on the virulence of the infecting strain, environmental temperature dose and host resistance to the organism.

Conclusion

Bacterial infections adversely affect marine life. Some bacterial infections result in diseases that may cross to humans from the marine organisms as zoonotic diseases, especially those affecting corals and fish. Identification of the correct bacteria causing the disease is important for correct treatment and proper management options. Research into bacterial diseases in marine organisms is indispensable to increase knowledge on the prevailing diseases, infectious agents and define methods of designing therapeutic options to curb the infections.

Works Cited

Hernández-Mora, Gabriela., González-Barrientos Rocío., Morales Juan-Alberto., Chaves-Olarte Esteban., Guzmán-Verri Caterina., Baquero-Calvo Elías., De-Miguel María-Jesús., Marín Clara-María., Blasco José-María., and Moreno Edgardo. “Neurobrucellosis in stranded dolphins, Costa Rica.” Emerg Infect Dis 14.9 (2008): 1430-1433. Print.

Rosenberg Eugene., Koren Omry., Reshef Leah., Efrony Rotem., and Zilber-Rosenberg Ilana. “The role of microorganisms in coral health, disease and evolution.” Nature Reviews Microbiology 5 (2007): 355-362. Print.

Rowan, Rob. “Coral bleaching: thermal adaptation in reef coral symbionts.” Nature 430.7001 (2004): 742-742. Print.

Click Here To Order Now!