Using nowcast model currents to explore transport of non-indigenous jellyfish into the Gulf of Mexico

Abstract

In the spring of 2000, millions of the non-endemic jellyfish Phyllorhiza punctata were found in coastal regions of the Mississippi Bight in the northern Gulf of Mexico. The aggregations were large enough to seriously impact local fisheries by clogging shrimp nets and damaging gear. More importantly perhaps, the impact on plankton biomass and hence on fishery resources were potentially large, since P. punctata is a voracious filter feeder. In this study, we examine a hypothesis for their sudden appearance which involves advection from the Caribbean in an intruding Loop Current and subsequent flux onto the Mississippi Shelf through eddy-shedding processes which interact with the continental shelf/slope. Surface current data were obtained from an archived finite difference model of the Gulf of Mexico which used altimeter data assimilation and real wind forcing covering the time of the invasion. Model and satellite data showed that an exchange event occurred in late April at a time appropriate for the invasion. The results from tracing transport pathways suggest that mass redistribution of Caribbean populations into the northern Gulf of Mexico can be accomplished via Loop Current intrusion and flux of deep basin water onto the shelf. As such, the occurrence of the invasive species P. punctata in the northern Gulf in 2000 can be explained by a natural, but not necessarily common, sequence of events. This hypothesis is discussed as a means of redistribution of a species by invasion as opposed to redistribution by diffusive spreading. KEY WORDS: Gulf of Mexico · Jellyfish · Non-indigenous · Numerical model Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 305: [139][140][141][142][143][144][145][146] 2005 of P. punctata interfered with commercial shrimping along coastal Mississippi and Louisiana and could have been responsible for the unusually low shrimp harvests in 2000 (Graham et al. 2003a).Although Graham et al. (2003a) provided the first published report of the invasion of Phyllorhiza punctata in the Mississippi Bight, there are a number of credible anecdotal reports that smaller aggregations of these medusae had been occurring for several years prior to 2000 along southern Louisiana west of the mouth of the Mississippi River, specifically in Terrebone Bay. While the potential for spreading from this source exists, we must still consider the possibility of periodic introductions of expatriate medusae from a Caribbean source with or without establishment of a population of scyphistomae in the northern GOM. The suddenness and magnitude of the 2000 event suggests that more than local spreading is involved. The purpose of this study was to investigate the possibility that the summer 2000 population of P. punctata medusae could have been transported from the Caribbean into the northern GOM over a relatively short period of time consistent with the biological constraints of these jellyfish (i.e. life-history and survival). This was accomplished by employing a re...

Integrating Biogeochemistry and Ecology Into Ocean Data Assimilation Systems

“…This type of oceanic information was identified in the early stages of GODAE as potentially very valuable to different applications related to the "living ocean, " such as the fishing industry and fisheries management (Griffin et al, 2002). Numerous examples of GODAE products used for environmental applications are found in the literature, ranging from real-time temperature products for monitoring seasonal fish migration (Hobday and Hartmann, 2006) and ecological regime shifts (Brander, in press), to ocean currents and velocities used to understand the transport and spread of fish larvae (Bonhommeau et al, 2009;Johnson et al, 2005), to sources and sinks of atmospheric CO 2 . Some of these examples will be discussed in the following sections.…”

Inflow of shelf waters into the Mississippi Sound and Mobile Bay estuaries in October 2015

“…[15][16][17][21][22][23] The MSS is primarily a vertically well-mixed semienclosed estuary, also showing characteristics of a partially well-mixed estuary and locally a stratified estuary. 12 August-October is a low-inflow/high-salinity period and the persistent southerly and southeasterly winds and low discharge cause strong vertical stratification in the Mobile Bay and MSS.…”

Loop Current Spin-off Eddies, Slope Currents and Dispersal of Reef Fish Larvae from The Flower Gardens National Marine Sanctuary and The Florida Middle Grounds

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