Rise of the Jellyfish!!!

Are the Jellyfish taking over the oceans? 

Picture: Richard et al. 2009

Factors leading to rise in jellyfish:

While there are multiple factors that influence the abundance in the jellyfish in coastal areas, especially off the coast of Japan, but there is evidence that changes in ocean stratification leading to abundance in dinoflagellates and anthropogenic changes may have the biggest influence. (Richardson et al. 2009)

Anthropogenic Factors:

One anthropogenic cause that has lead to rise of jellyfish is due to overfishing (Richardson et.al). Many fish compete for the same zooplankton prey as jellyfish, with fish being also predators of jellyfish. However, removal of certain fishes opens up the ecological fish for the jellyfish to bloom (Richardson et al. 2009).

Picture: Richard et al. 2008

Eutrophication:

Coastal eutrophication (the hypertrophication of an ecosystem in response to the addition of artificial or natural substances such as nitrates and phosphate through fertilizers or sewage) has encouraged the bloom of certain types of phytoplankton (Richardson et Al. 2009). Certain nutrients added to the coast zones are rich in nitrates and phosphate, but low on silica and it is this decrease in silica that non-siliceous phytoplankton that dinoflagellates are able to bloom and replace diatoms (Richardson et Al. 2009). These changes in abundance in phytoplankton has resulted in decrease in primary and secondary producers (Richardson et. Al).  Such disruption could have catastrophic environmental consequences and affect delivery of importance ecosystem services, especially food production (Thackery). With such disturbances in food webs, can lead to not having enough food to support large amounts of marine mammals and can lead to change in overall ecosystems (Richardson et Al. 2009 & Thackery).

Click on image to enlarge.
Picture: Richardson et. al

Stratification impacts on the rise of jellyfish:

Click on image to enlarge
Richardson et al. 2009

With increasing stratification leading to nutrient-poor surface waters, leading some planktons moving lower in the column to find food. Flagellates on the other hand, due to their ability to migrate vertically into nutrient-rich deeper waters, can outcompete diatoms who are unable to actively migrate vertically (MBARI & Richardson et Al. 2009). This bloom in flagellates can lead to favorable environments for jellyfishes to thrive rather for other fishes. Certain jellyfish species can also increase in abundance as the temperatures increase and ocean warming occurs (Richardson et. Al).

Climate change, eutrophication, and overfishing are acting synergically to create environments that are favorable for jellyfish, but harmful for other marine organisms (Richardson et Al. 2009). Jellyfish outbreaks can have many deleterious consequences such as; loss of tourism revenue via beach closures and death of bathers and reduction in commercial fish abundances through competition and predation. All these climate changes are causing blooming of dinoflagellates and jellyfishes today which were similar to condition seen 550 million ago (Richardson et Al. 2009).