ABSTRACT
Our understanding of the trophic transfer of pollutants in marine subtropical ecosystems remains limited due to the complexity of their food webs. Thus, we aimed to evaluate Cd, Cu, Mn, Pb, and Zn sources, incorporation, and trophodynamics throughout the food web of the southeastern Gulf of California by stomach content analysis, stable isotope analysis, isotope mixing models, and trace element analysis in biological and environmental matrices. The food web comprised three main trophic guilds (TG1, TG2, and TG3). The bioaccumulation of Cd and Zn from seawater was efficient (> 1000) in TG2 and TG3. Bioaccumulation factor from sediment (BSAF >1) evidenced of Cd in all trophic guilds. In addition, non-trophic Cd relationships were identified in the food web. Based on the trophic magnification factor (TMF), Mn and Pb showed biodilution (TMFMn = 0.38; TMFPb = 0.16), while Cu and Zn exhibited biomagnification (TMFCu = 2.08; TMFZn = 3.31).
Subject(s)
Cadmium , Trace Elements , Bioaccumulation , Ecosystem , LeadABSTRACT
Environmental changes have been associated with natural climatic variability or human activity. Water resources management is, perhaps, the most drastic change observed in the coastal environment. However, external forcings such as the El Niño event have important implications in the global and regional hydrological balance. These environmental changes have an impact on the density and biomass of the ichthyofauna in the Terminos Lagoon (TL) for the past 30 years, presumably, associated with variations in the temperature and surface salinity of the sea. Therefore, in the present study, δ18O was quantified in otoliths of two important species due to their dominance: Stellifer lanceolatus and Eucinostomus gula, and to understand the environmental changes reflected in both species. The δ18O was analyzed in otoliths of these two species captured in 1998/1997, 2006/2007 and 2016/2017 and were compared with in situ temperature and salinity data. Sea surface temperature and salinity increased by 2 °C and 9, respectively, between 1997 and 2017. Stellifer lanceolatus δ18O values was in isotopic equilibrium with seawater calcite; while, E. gula is not in isotopic equilibrium. The δ18O of S. lanceolatus and E. gula varied significantly with the increase in salinity (R2 = 0.8987 and R2 = -0.2964) and not with the sea surface temperature. S. lanceolatus is an excellent bioindicator of changes in sea surface salinity in this region of the Gulf of Mexico.
Subject(s)
Otolithic Membrane , Seawater , Animals , Gulf of Mexico , Humans , Mexico , SalinityABSTRACT
RATIONALE: The jumbo squid Dosidicus gigas is a fishery resource of considerable economic and ecological importance in the Mexican Pacific. Studies on its habitat preferences are needed to understand recent fluctuations in the abundance and availability of the species. Stable isotope analysis allows us to infer ecological aspects such as spatial distribution and trophic preferences. METHODS: We used an isotope ratio mass spectrometer, automated for carbonate analysis, and coupled to an elemental analyzer, to determine the isotopic composition of statoliths (δ18 O and δ13 C values) and beaks (δ13 C and δ15 N values) from 219 individuals caught over two fishing seasons (2007 and 2009) off the coast of Santa Rosalía, in the central Gulf of California. We used these isotopic ratios to assess variation in spatial and trophic preferences by sex, size, and fishing season. RESULTS: In the 2009 group, we observed significant differences in statolith δ13 C values and beak δ13 C and δ15 N values between males and females. Between size groups, we observed significant differences in statolith δ18 O and δ13 C values in 2007 and in beak δ13 C and δ15 N values during both seasons. Both seasons were characterized by high overlap in δ18 O and δ13 C values between sexes and in 2009 between size groups. We observed low trophic overlap between sexes in 2009 and between size groups during both seasons. CONCLUSIONS: The isotopic ratios from statoliths and beaks indicate that D. gigas has changed its spatial and trophic preferences, a shift that is probably related to changes in the species' diet. This intraspecific variation in preferences could be related to characteristics such as size, which may influence squid distribution preferences.
Subject(s)
Carbon Isotopes/analysis , Decapodiformes/chemistry , Decapodiformes/physiology , Nitrogen Isotopes/analysis , Animal Distribution , Animals , Beak/chemistry , California , Female , Male , Mass Spectrometry/methods , Mexico , Pacific OceanABSTRACT
The most important clinical and epidemiological aspects of the lymphogranuloma venereum as a sexually-transmitted disease are described. We present a summary of the clinical history of an HIV-positive patient who presented with a tumoral lesion in the inguinal region presumptive of lymphogranuloma venereum. The diagnostic value of the polymerase chain reaction (PCR) technique for the establishment of an accurate diagnosis is stressed the epidemiological importance of the report of this sexually-transmitted disease in an HIV-positive patient for the first time in Cuba is also pointed out. A good response was attained with Doxycycline.
