Earthworms (Lumbricus terrestris) acclimated at 2 degrees C above their habitat temperature (10-12 degrees C) showed about 5% increase in basal rate of oxygen consumption, which increased to about 38% in 14-16 degrees C- and 40% in 16-18 degrees C-, but decreased by 84% in 20-22 degrees C-acclimated worms. Temperature also increased the blood hemoglobin (Hb) concentration, which decreased slightly in 20-22 degrees C-acclimated worms. The worms acclimated at 20-22 degrees C showed their blood to be hypovolemic than that of 10-12 degrees C worms indicating dehydration. Pre-exposure of 10-14 degrees C-acclimated worms to sublethal concentrations of zinc, copper, and lead did not significantly affect the rate of respiration. However, at higher temperatures all these metals inhibited oxygen consumption; zinc, lead, and cadmium by approximately 11% and copper by approximately 18% of that at 14-16 degrees C. At 20-22 degrees C, the respiration was further inhibited, 36% by copper, 18% by cadmium, and approximately 10% by lead and zinc. Copper, lead, and zinc decreased the temperature-enhanced increase in blood Hb concentration at all temperatures. In 20-22 degrees C-acclimated worms heavy metal exposure slightly lowered the oxygen affinity of Hb as well as caused shifts in carbon monoxide difference spectra. The acute toxicity of these metals was not affected by a 2 degrees C rise in acclimation temperature but increased by 17% (lead), 33% (copper), and 5% (zinc) in 14-16 degrees C- and by 40% (lead), 149% (copper), and 132% (zinc) in 20-22 degrees C-acclimated worms. The increase in toxicity of metals caused by high temperatures may be due to limiting the scope of aerobic metabolism (oxygen extraction, transport, and utilization) via quantitative and qualitative effects on Hb. This terrestrial species appears to be tolerant of slight increases in habitat temperature, such as that expected with current global climate change.

Survival, growth and proximal body composition of juvenile Farfantepenaeus californiensis (Holmes) were examined at two dissolved oxygen concentrations (mean 5.8 and 2.6 mg L−1) and three temperatures (19 °C, 23 °C and 27 °C) for 50 days. Three replicate experiments were performed with a 12 h light/dark photoperiod. Survival was 68–85% at the lower dissolved oxygen level and 77–82% at the higher level and was not significantly affected by the treatments (P > 0.01). Growth at the lower oxygen concentration was significantly less (P < 0.01) than at the higher concentration, with growth rates of 2, 12 and 24 mg day−1 from the lowest to the highest temperature and 4, 17 and 26 mg day−1 for the three temperatures at the higher dissolved oxygen level. Body lipids were 1.2% wt/wt at the higher temperature and 2.1% wt/wt at the lower temperature, while proteins were 15.1% wt/wt at the higher temperature and 12.5% wt/wt at the lower temperature. These results indicate that low oxygen levels and low temperature significantly depress growth at this particular stage of life.

Se estudió la composición y distribución del fitoplancton en el río Amacuzac. El fitoplanc­ton fue colectado en diferentes localidades del río, Se reconocieron un total de 16 especies correspondiendo 11 a la clase Chlorophyceae y cinco a la clase Cyanophyceae.

Los estudios nictimerales son particularmente importantes en los trópicos para conocerlas variaciones ecológicas en ciclos diurnos, y no sólo en estacionales, y lo son no sólo desde el punto de vista conceptual, sino para la aplicación de planes de manejo en diferentes ambientes. El objetivo fue analizar las variaciones del oxígeno disuelto, porcentaje desaturación y temperatura en la columna de agua durante ciclos nictimerales, en los lagos Zempoala y Tonatiahua ubicados en el Parque Nacional Lagunas de Zempoala. Los mayores valores oxígeno disuelto, se presentaron en Zempoala, y la temperatura fue análoga en ambos lagos de acuerdo a los valores promedio totales. La variación de los parámetros estuvo directamente influenciada por la estacionalidad, su morfometría y entorno. El lago Zempoala se consideró como meromictico con tendencias a monomíctico cálido y Tonatiahua comomonomíctico cálido.