Nest Guard Replacement in the Antarctic Fish Harpagifer bispinis: Possible Altruistic Behavior

Nesting biology of the Antarctic plunder fish, Harpagifer bispinis (Schneider), was examined at Arthur Harbor, Antarctic Peninsula, during the austral winter, 1975. Females prepare nest sites, spawn, and guard the eggs for 4 to 5 months, the longest guarded incubation period reported for any fish species. If this guard is removed, it is soon replaced by a conspecific, usually male. If the second guard is removed, a third replaces it. Guards are essential to ensure nest survival. Selfish or parental acts or acts of kinship or reciprocity do not adequately explain guard replacement. The act may be altruistic.     

Human granulocyte collagenase

A collagenase, operative at neutral and alkaline pH, has been extracted from the granule fraction of human granulocytic leukocytes. It digests reconstituted collagen fibrils and reduces the viscosity of collagen solutions. Cleavage of collagen in solution with purified enzyme produces the discrete products characteristic of other animal collagenases.     

A century of transformation: fire regime transitions from 1919 to 2019 in southeastern British Columbia,Canada

Context

In fire-excluded forests across western North America, recent intense wildfire seasons starkly contrast with fire regimes of the past. The last 100 years mark a transition between pre-colonial and modern era fire regimes, providing crucial context for understanding future wildfire behavior.

Objectives

Using the greatest time depth of digitized fire events in Canada, we identify distinct phases of wildfire regimes from 1919 to 2019 by evaluating changes in mapped fire perimeters (>?20-ha) across the East Kootenay region (including the southern Rocky Mountain Trench), British Columbia.

Methods

We detect transitions in annual number of fires, burned area, and fire size; explore the role of lightning- and human-caused fires in driving these transitions; and quantify departures from historical fire frequency at the regional level.

Results

Relative to historical fire frequency, fire exclusion has created a significant fire deficit in active fire regimes, with a minimum of 1–10 fires missed across 46.4-percent of the landscape. Fire was active from 1919 to 1939 with frequent and large fire events, but the regime was already altered by a century of colonization. Fire activity decreased in 1940, coinciding with effective fire suppression influenced by a mild climatic period. In 2003, the combined effects of fire exclusion and accelerated climate change fueled a shift in fire regimes of various forest types, with increases in area burned and mean fire size driven by lightning.

Conclusions

The extent of fire regime disruption warrants significant management and policy attention to alter the current trajectory and facilitate better co-existence with wildfire throughout this century.

Graphical abstract