Tropical decadal variability in nutrient supply and phytoplankton community in the Central Equatorial Pacific during the late Holocene.

We have reconstructed baseline δ15N and δ13C of export production at Kingman Reef in the Central Equatorial Pacific (CEP) at sub-decadal resolution, nearly continuously over the last 2000 years. The changes in δ15N reflects the strength of the North Equatorial Counter Current (NECC) relative to the South Equatorial Current (SEC), and to a lesser extent, the North Equatorial Current (NEC). Seasonal to multi-decadal variation in the strength of these currents, through the redistribution of heat, have global climate impacts and influence marine and terrestrial ecosystems. We use modern El Niño-La Nina dynamics and the Tropical Pacific Decadal Variability (TPDV) pattern, which is defined in the CEP, as a framework for analyzing the isotopic data. The CEP δ15N and δ13C records exhibit multi-decadal (50-60 year) variability consistent with TPDV. A large multi-centennial feature in the CEP δ15N data, within age-model uncertainties, is consistent with one of the prolonged dry-pluvial sequences in the American west at the end of the Medieval Climate Anomaly, where low TPDV is correlated with drier conditions. This unique record shows that the strength of the NECC, as reflected in baseline δ15N and δ13C, has at quasi-predictable intervals throughout the late Holocene, toggled the phytoplankton community between prokaryotes and picoplankton versus eukaryotes.

Yersinia enterocolitica is a common cause of gastroenteritis in Auckland.

AIMS: Infections with Yersinia enterocolitica are a significant cause of gastroenteritis in many countries, However, little information is available on the incidence of human disease in New Zealand. A study was performed between January 1988 and December 1993 to investigate aspects of the epidemiology of yersiniosis in the Auckland region including prevalence, age and sex distribution, strain definition and seasonal occurrence. METHODS: Culture of 231 128 faecal samples for enteric pathogens was performed at Diagnostic Laboratory, a community laboratory in Auckland, between January 1988 and December 1993. All yersinia isolates recovered were sent to the department of veterinary pathology and public health, Massey University for further typing. Relevant data were entered into a database and reviewed at the end of the study period. RESULTS: 1469 of the samples, representing 941 cases, were positive for strains of yersinia during the study period, a crude isolation rate of 0.6%. A single strain from each of the cases was further typed and yersinia enterocolitica was found to constitute the majority of the isolates (918), making it the third most common enteric pathogen isolated after campylobacter and salmonella. Of the strains isolated, 98% were recognised human pathogens, with biotype 4, serotype 0:3 being the most frequently recovered, as it is worldwide. No clear seasonal pattern emerged although most isolations were made in the autumn-winter period. The age distribution showed two peaks, 0-4 (17.6%) and 25-29 year olds (13%). Infections in males outnumbered those in females (56:44). CONCLUSION: The results of this study show that Y enterocolitica is an important enteric pathogen in the Auckland region, particularly in children and young adults and it has identified a need for a case-control study to assess the relevant risk factors for acquisition of Y enterocolitica infections in New Zealand.