Thresholds for adding degraded tropical forest to the conservation estate

Logged and disturbed forests are often viewed as degraded and depauperate environments compared with primary forest. However, they are dynamic ecosystems1 that provide refugia for large amounts of biodiversity2,3, so we cannot afford to underestimate their conservation value4. Here we present empirically defined thresholds for categorizing the conservation value of logged forests, using one of the most comprehensive assessments of taxon responses to habitat degradation in any tropical forest environment. We analysed the impact of logging intensity on the individual occurrence patterns of 1,681 taxa belonging to 86 taxonomic orders and 126 functional groups in Sabah, Malaysia. Our results demonstrate the existence of two conservation-relevant thresholds. First, lightly logged forests (68%) of their biomass removed, and these are likely to require more expensive measures to recover their biodiversity value. Overall, our data confirm that primary forests are irreplaceable5, but they also reinforce the message that logged forests retain considerable conservation value that should not be overlooked

Hibernation in an Antarctic Fish: On Ice for Winter

Active metabolic suppression in anticipation of winter conditions has been demonstrated in species of mammals, birds, reptiles and amphibians, but not fish. This is because the reduction in metabolic rate in fish is directly proportional to the decrease in water temperature and they appear to be incapable of further suppressing their metabolic rate independently of temperature. However, the Antarctic fish (Notothenia coriiceps) is unusual because it undergoes winter metabolic suppression irrespective of water temperature. We assessed the seasonal ecological strategy by monitoring swimming activity, growth, feeding and heart rate (f H)inN. coriiceps as they free-ranged within sub-zero waters. The metabolic rate of wild fish was extrapolated from f H recordings, from oxygen consumption calibrations established in the laboratory prior to fish release. Throughout the summer months N. coriiceps spent a considerable proportion of its time foraging, resulting in a growth rate (Gw) of 0.1860.2 % day 21. In contrast, during winter much of the time was spent sedentary within a refuge and fish showed a net loss in G w (20.0560.05 % day 21). Whilst inactive during winter, N. coriiceps displayed a very low f H, reduced sensory and motor capabilities, and standard metabolic rate was one third lower than in summer. In a similar manner to other hibernating species, dormancy was interrupted with periodic arousals. These arousals, which lasted a few hours, occurred every 4–12 days. During arousal activity, fH and metabolism increased to summer levels. This endogenous suppression and activation of metabolic processes, independent of body temperature, demonstrates that N. coriiceps wer

Scavenging in Antarctica: intense variation between sites and seasons in shallow benthic necrophagy

The response of scavengers to a feeding cue at Adelaide Island, West Antarctic Peninsula was investigated using a baited video camera system. Fourteen experimental deployments, each lasting 72 h were conducted at two contrasting sites during the winter and summer of 2005. The rate of bait consumption varied between sites but not between seasons, and was low in comparison with studies at lower latitudes and greater depths. At the Hangar Cove site, the nemertean Parborlasia corrugatus was out-competed at the bait and displaced by the lysianassid amphipod Cheirmedon femoratus during winter. However, C. femoratus did not feed on the bait during summer, allowing P. corrugatus to monopolise the feeding opportunity. At the South Cove site the asteroid Odontaster validus dominated the bait in both seasons but sporadic feeding by the nototheniid fish Notothenia coriiceps considerably affected consumption rates during two of the six deployments. Scavengers were attracted to the bait in very high numbers and opportunistic necrophagy seems to be a successful strategy in an environment that is intensely disturbed by ice

Summer and winter comparison of hourly activity and <i>f</i>_H profiles in <i>N. coriiceps.</i>

<p>Panel A shows activity profiles from two separate fish remotely recorded by acoustic telemetry during summer months (black), and the activity profile for the same fish is also shown during winter months (red). The flat line indicates when the fish were sedentary. Panel B shows the mean hourly <i>f</i>_H from two sea-caged <i>N. coriiceps</i> during summer (black) and <i>f</i>_H for the same fish during winter (red).</p

The free-ranging metabolic rate of <i>N. coriiceps.</i>

<p>The mean monthly <i>M</i>O₂ of wild <i>N. coriiceps</i> (black line, n = 6) was extrapolated from continual field recordings of <i>f</i>_H using the equation given in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0001743#pone-0001743-g003" target="_blank">Fig. 3</a>. Water temperature was measured by an onboard temperature sensor (red).</p

Activity parameters for free-ranging <i>N. coriiceps.</i>

<p>Fish were tracked within a 1 km² area by acoustic telemetry and a static hydrophone array over a 365 day period (mean±S.E, N = 7).</p>a,b,c,d<p>indicates seasonal mean data that is significantly different as calculated by multivariate analysis (<i>P</i><0.05).</p