Climatic forcing and larval dispersal capabilities shape the replenishment of fishes and their habitat‐forming biota on a tropical coral reef

Fluctuations in marine populations often relate to the supply of recruits by oceanic currents. Variation in these currents is typically driven by large‐scale changes in climate, in particular ENSO (El Nino Southern Oscillation). The dependence on large‐scale climatic changes may, however, be modified by early life history traits of marine taxa. Based on eight years of annual surveys, along 150 km of coastline, we examined how ENSO influenced abundance of juvenile fish, coral spat, and canopy‐forming macroalgae. We then investigated what traits make populations of some fish families more reliant on the ENSO relationship than others. Abundance of juvenile fish and coral recruits was generally positively correlated with the Southern Oscillation Index (SOI), higher densities recorded during La Niña years, when the ENSO‐influenced Leeuwin Current is stronger and sea surface temperature higher. The relationship is typically positive and stronger among fish families with shorter pelagic larval durations and stronger swimming abilities. The relationship is also stronger at sites on the coral back reef, although the strongest of all relationships were among the lethrinids (r = .9), siganids (r = .9), and mullids (r = .8), which recruit to macroalgal meadows in the lagoon. ENSO effects on habitat seem to moderate SOI–juvenile abundance relationship. Macroalgal canopies are higher during La Niña years, providing more favorable habitat for juvenile fish and strengthening the SOI effect on juvenile abundance. Conversely, loss of coral following a La Niña‐related heat wave may have compromised postsettlement survival of coral dependent species, weakening the influence of SOI on their abundance. This assessment of ENSO effects on tropical fish and habitat‐forming biota and how it is mediated by functional ecology improves our ability to predict and manage changes in the replenishment of marine populations.     

The influence of postnatal nutritional deprivation on the phospholipid content of developing rat lung.

It has been previously reported that fasting may result in decreased lung surfactant production. In order to investigate this relationship and the role of nutrition in lung phospholipid synthesis, 21-day-old rats were exposed for 60 h to one of five dietary regimens: standard rat chow (controls), fasting, pure glucose, pure fat, or pure protein. After the period of fasting there was a 33% decrease in lung protein content, but there was no change in DNA content. Exposure to any of the experimental diets resulted in a decrease in tissue total phospholipid and phosphatidylcholine content per lung, but not per unit lung protein. Similarly lung lavage phospholipid and phosphatidylcholine content was decreased by 25% after fasting when expressed per lung or per unit DNA, but not per unit protein. Pulmonary cholinephosphotransferase (EC 2.7.8.2) activity was decreased in the fasted animals and those fed the protein diet, but not in the glucose or fat-fed animals. The activities of acetyl-CoA carboxylase (EC 6.4.1.2) and microsomal fatty acid elongation were decreased in all the experimental groups except for the glucose-fed group. It is concluded that fasting results in a decrease in lung cell size but not in lung cell number. Total phospholipid and phosphatidylcholine content in lung tissue and lung lavage is decreased per cell but not per unit cell mass.