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August 10, 2003
 
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Lake Descriptions [back]  

Lake Laysan

The uninhabited island of Laysan (25° 46' N, 171° 44' W) comprises a sandy ridge of about 1.45 sq. miles (Fig. 2). At the center of the island there is an hypersaline lagoon that may attain 10 m in depth, depending on local precipitation. Laysan is the only Hawaiian lake not principally of volcanic origin and thus not situated in a volcanic crater (Maciolek, 1982). The central lagoon may occupy 20% of the island's entire area and appears to have no direct connection to the ocean. More than seven million seabirds use the island annually, and there are a number of endemic species, including over 40 endemic insect species. (Ely and Clapp, 1973; Bakus, 1978). The composition of the lagoon's microbial flora is likely driven by the presence of so many birds, just as large avian populations in other areas affect local waters (Lindeboom, 1984; Pietr, 1986; Roser et al., 1993).

 

Lake Kauhako, Moloka‘i

Lake Kauhako is located on the Kalaupapa Peninsula on the north shore of Moloka‘i (Fig. 3, Fig. 4). The lake is the fourth deepest lake in the United States and that with the highest ratio of depth (248 m) to surface area (3500 sq. meters) of any lake in the world (zr = 374%). Previous work has shown the upper 4.5 m to be stratified (T = 23 - 26 °C; salinity = 6 - 24.5), but below a pycnocline at ~4.5 m the water column is homogenous (T = ~26.25 °C; salinity = 32) (Donachie, et al., 1999; and unpubl.). An oxycline was recorded at 2 m, and hydrogen sulfide that was undetectable at 4 m attained ~130 mM by 5 m. Through flow cytometry, Donachie et al. (ibid.) also reported large populations of heterotrophic and autofluorescent bacteria at the surface (2 x 109 L-1 and 9 x 109 L-1, respectively), with chlorophyll a in excess of 150 mg L-1.

 

Lake Waiau, Hawai‘i

Situated in a cinder cone at an elevation of 3969 m (13021 ft.) on the summit of volcanic Mauna Kea, Hawai‘i, Lake Waiau is the highest and shallowest lake in the state of Hawai‘i, and also the third highest in the United States (Fig. 5). The lake is considered cold mono- or polymictic. Lake depth and surface area depend very much on precipitation, but should the entire 7300 sq. meter cinder cone be occupied then maximum depth would be ca. 3 m (Woodcock, 1980; Laws and Woodcock, 1981). The lake's high altitude exposes it to levels of ultraviolet radiation well above those of any other Hawaiian lake, and benthic mats in the lake produce mycosporine-like amino acids (MAA) compounds that protect them from UVB radiation (Kinzie et al., 1998).

Lake Wai'ele'ele, Maui

The only other high-elevation lake in Hawai‘i is Lake Wai‘ele‘ele (Fig. 6). It is also the state's deepest and smallest freshwater lake (ca. 6.4 m and 2200 sq. meters, respectively) (Maciolek, 1982). The lake sits in a heavily vegetated crater at 2040 m (6693 ft) in an area that receives 800 cm of rainfall per year. Water in the lake has low concentrations of minerals but high levels of humic acids. The aquatic biota comprises few species, but differs from that of Lake Waiau in that it contains two Odonata (damselflies).

Green Lake, Hawai‘i

At just over one mile from the Pacific Ocean and 25 miles from the active Kilauea volcano, Green Lake is both the farthest south and east lake in Hawai‘i. The lake first appeared in the literature only twenty years ago (Maciolek, 1982). The lake's small surface area (8000 sq. meters), its crater location and the dense overhanging vegetation protect the lake from prevailing winds (Fig. 7). As a result, the deeper water may become seasonally anoxic. As the lake only attains a depth of 6 – 7 m, however, stratification probably breaks down with the onset of the seasonal Trade winds. The lake might thus alternate between stratified and holomixis. Water from the lake has been reported as brackish and to fluctuate with tides in the nearby ocean.

Other site(s)

We aim also to explore other Hawaiian aquatic habitats that may host unusual microorganisms. For example, during the NOW-RAMP II cruise that took us to Laysan we were informed of an unreported brackish pond on 0.5 sq. mile Southeast Island in the Pearl and Hermes Atoll (27° 47' 23" N, 175° 49' 20" W) (Fig. 8). Pearl and Hermes Atoll comprises several uninhabited, low, sandy islands that cover ca. 0.32 km2 around a central lagoon of 300 km2. Southeast Island is the largest in the atoll at ~0.14 km2. We sampled this 30 cm deep, 20 m diameter anchialine pool some 100 m from the ocean since its remote location is consistent with our belief that geographically remote and unspoiled areas may host novel microorganisms.


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