Marina Sánchez-Ramírez

Seasonal Occurrence of Opechona pyriforme Metacercariae (Digenea: Lepocreadiidae) in Eirene tenuis Medusae (Hydrozoa: Leptothecata) From a Hypersaline Lagoon in Western Gulf of Mexico

Abstract Seasonal occurrence of Opechona pyriforme metacercariae in the Eirene tenuis population from Laguna Madre, Mexico was analyzed in zooplankton samples collected in October 1997 and January, May, and July 1998. Eirene tenuis medusae were present in May, July, and October, although parasites were found only in October and July samples. Host population density was positively correlated with both surface water temperature and salinity. Total sample prevalence was 3.74%, mean abundance of the parasite was 0.06, and intensity of infection ranged between 1 and 59 metacercariae/host. Prevalence differed significantly among seasons, while intensity of infection did not. Parasite distribution was found to be highly aggregated. Although O. pyriforme infected hydromedusae of all sizes, prevalence was higher in sizes above 2.11 mm umbrella diameter. Additionally, a tendency towards increasing intensity of infection values with increasing umbrella diameter of medusae was observed. This is the first record of E. tenuis as a second intermediate host of O. pyriforme, as well as the first record of this helminth in the Gulf of Mexico.

Mesoscale distribution of Oikopleura and Fritillaria (Appendicularia) in the Southern Gulf of Mexico: spatial segregation

The mesoscale spatial distribution of Oikopleura and Fritillaria in the southern Gulf of Mexico was analyzed to know the existence of segregation between the...

Chromosome analysis of Aurelia aurita Linné, 1758 (Scyphozoa: Ulmaridae), southern Gulf of Mexico

Abstract Aurelia aurita is a cosmopolitan species that is common along the coasts of the Gulf of Mexico. It enters lagoon–estuarine systems where it is present in high densities. The karyotype of organisms from Estero Tenechaco, Tuxpan, Veracruz is described. Specimens were collected with a spoon landing net in March 2003. Marginal tentacle tissue was subjected to cytogenetic processing, including a mitostatic treatment previous to hypotonic shock. The chromosome numbers obtained were 2n=44 and n=22, and the fundamental number was NF:88.