Phyllorhiza punctata threatens large commercial fisheries of shrimp and crab in the Gulf of Mexico. It is feared this species will feed directly on the eggs and larvae of fish, crab and shrimp, having serious economic implications for commercial fishing. Similar invasive jellyfish have been known to cause major disruptions in marine fisheries in Europe and in some instances have driven out certain marine species. Whether or not P. punctata has this potential is yet to be determined (Martin, 2000). P. punctata's greatest economic impact thus far has been the clogging of shrimp nets. Estimated economic losses range in the millions of dollars. The indirect effect of predation on eggs and larvae of commercially important finfish and shellfish remains intangible (Graham et al. 2003). P. punctata also damages boat intakes and fishing gear, and have caused the closure of productive areas to fishing activities (Perry, 2005).
In their research, Graham et al. (2003) believe that P. punctata may have had an indirect effect on zooplankton production through changes in chemical or physical properties of the water. The manifestation of surface foam streaks down-wind of a super-swarm were likely due to high dissolved organic material (DOM) loading by the swarm. Mucus shed into the water when jellyfish are concentrated increases the viscosity of the water and may also elevate toxins as mucus-bound nematocysts are discharged (Graham et al. 2003).
Location Specific Impacts:
Gulf of Mexico (Atlantic Ocean)
Modification of nutrient regime: Graham et al (2001) observe that there is potential for negative impacts both economic and ecological from invasions of P. punctata. P. punctata are large consumers of fish eggs and larval fish. During the 2000 invasion, both fish eggs and dominant copepods (primarily Acartia tonsa) were being cleared at a rate of nearly 100% per day. Clearance rates were estimated on the order of 50m3 ind-1 d-1, which suggests that, at their most concentrated, these medusae were turning over the water about 5 times each day (Graham et al 2001).
Mississippi Sound (United States (USA))
Economic/Livelihoods: Graham et al (2001) observe that there is potential for negative impacts both economic and ecological from invasions of P. punctata. The concentrated aggregations of P. punctata in the Mississippi Sound in July and August 2000 coincided spatially and temporally with shrimping activities (Graham et al 2001).
There is circumstantial evidence that P. punctata reduced the white shrimp harvest in Mobile Bay, Alabama and Mississippi Sound by 26.7 % (Graham et al 2003) (Perry, 2005).