Juneau Nature

Natural & cultural history of Juneau & Southeast Alaska

Juneau Nature - Natural & cultural history of Juneau & Southeast Alaska

Auke3 biocultural

This is the content of the third in a 3-part sign array on Auke Lake Trail. See also the other 2 panels: Auke1 intro and Auke2 geo

Life of the lake

In biology as in geology, Auke Lake is surprisingly dynamic for a bedrock-controlled basin enclosed mostly by old-growth forest. Here are some trends that have been noted:

• western toad–formerly abundant, now almost extinct

• common loon–declining

• prickly sculpin–dramatic increase

• freshwater mussel (Anodonta) & stickleback–declining

• pond lily (Nuphar polysephalum)–declining

• sockeyes, cutthroats, Dolly Varden–declining

• dates of ice-out–earlier

We can guess at reasons for some of these trends; the others remain mysterious. Several of the trends are probably interrelated. As recently as the 1970s, tiny toadlets used to crawl out of the marshy margins in uncountable thousands at summer’s end. Their crash is attributed in part to a chytrid fungus. But could those 6-inch prickly sculpins swarming in the pond-lily fringe–rare or absent in the 1970s–have vacuumed up the last western toad larvae?

6musselcycle

Biologists have only begun to map the distributions of freshwater mussels in Alaskan lakes. These mollusks have a bizarre life history. Their tiny, toothed larvae attach to gills of sticklebacks, sculpins or salmonids and are sometimes carried to new lakes before the spat release and drop to the bottom. Formerly abundant on loose flocculent covering the shallow margins of Auke Lake, mussels are now hard to find. Mussels are sensitive indicators of water quality.

When hunting season commences, Auke Lake becomes a daytime loafing area for hundreds of Canada geese and mallards. At night, they often fly directly over the runway approach space to feed on salt marsh vegetation in the Mendenhall Wetlands State Game Refuge.

Home for 10 millennia

Auke Lake didn’t exist when the first humans paddled into “Mendenhall Bay.” Sagebrush-covered hills descended to berg-strewn beaches. Since the time of those Paleomarine seal-hunters, climates, landforms, habitats and species have been in continual flux, but people always adapted.

7knopf

1912 USGS Tlingit place names have been added to this early map. In 1910 there were no coastal roads. Trails (dashed lines) led inland to mines. The Auk village at today’s picnic beach still supported gardening and subsistence. Cabins on Auke Creek were smoke houses of Sheep Creek Mary, 1835-1922, L’eeneidí clan, Big Dipper House. Her land became a cannery, then a NMFS research facility.

Today, the rate of change is faster than humans have ever experienced. Survival depends more than ever on intimate knowledge of terrestrial and marine environments. Four decades of research by the National Marine Fisheries Service (NMFS) at Auke Lake–a “benchmark” study site–has contributed to this understanding.

8-1929

The road from Juneau reached Auke Bay in 1918, and the back loop connection had been freshly completed in this 1929 aerial oblique. The original road crossing, right on the lake outlet, was re-routed to its current position below the lagoon in 1951. In left distance, Mendenhall Glacier still covered the future Visitor Center site, and outwash ran through future Dredge Lake.
The largest building on the beach was the Carlsons’ Auke Bay Salmon Cannery. (Their first cannery–1919 to 1921–was right on Auke Creek.) On the future site of Auke Bay School the land was open and boggy. Small-tree forest with smooth, interlocking canopy was recovering from a major blowdown in 1883.

OLYMPUS DIGITAL CAMERA

Lakeshore changes Intensive use (red) and residential development (orange) reached a plateau in the 1980s. The biggest recent change is perhaps the loss of wild, little-traveled lake shore, critical for easily displaced wildlife such as mink, otter and shore-nesting waterbirds.

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