Donald E. Dragoo | USGS Science

USGS2018

At-sea observations of marine birds and their habitats before and after the 2008 eruption of Kasatochi volcano, Alaska

Kasatochi volcano, an island volcano in the Aleutian chain, erupted on 7-8 August 2008. The resulting ash and pyroclastic flows blanketed the island, covering terrestrial habitats. We surveyed the marine environment surrounding Kasatochi Island in June and July of 2009 to document changes in abundance or distribution of nutrients, fish, and marine birds near the island when compared to patterns observed on earlier surveys conducted in 1996 and 2003. Analysis of SeaWiFS satellite imagery indicated that a large chlorophyll-a anomaly may have been the result of ash fertilization during the eruption. We found no evidence of continuing marine fertilization from terrestrial runoff 10 months after the eruption. At-sea surveys in June 2009 established that the most common species of seabirds at Kasatochi prior to the eruption, namely crested auklets (Aethia cristatella) and least auklets (Aethia pusilla) had returned to Kasatochi in relatively high numbers. Densities from more extensive surveys in July 2009 were compared with pre-eruption densities around Kasatochi and neighboring Ulak and Koniuji islands, but we found no evidence of an eruption effect. Crested and least auklet populations were not significantly reduced by the initial explosion and they returned to attempt breeding in 2009, even though nesting habitat had been rendered unusable. Maps of pre- and post-eruption seabird distribution anomalies indicated considerable variation, but we found no evidence that observed distributions were affected by the 2008 eruption. ?? 2010 Regents of the University of Colorado.

Arctic, Antarctic, and Alpine Research↗

USGS2005

Seabird, fish, marine mammal, and oceanography coordinated investigations (SMMOCI) in Sitka Sound, Alaska, July 2000

Surveys for seabirds and marine mammals were conducted in and near Sitka Sound, Alaska (Fig. 1) from the M/V Tiĝlax̂ during 12-16 July 2000 (Table 1, Fig. 1). The objective was to characterize the marine environment in the vicinity of St. Lazaria Island, one of ten seabird colonies monitored annually by the Alaska Maritime National Wildlife Refuge (See Dragoo et al. 2003). In addition to censusing seabirds and mammals encountered on line transects, local oceanography was characterized by measuring water temperature and salinity continuously at the sea surface, and by taking profiles of the water column on a series of CTD transects. The relative abundance of zooplankton and fish biomass was measured using a dual -frequency echosounder. Significant acoustic targets were sampled with a m id-water trawl net. Long-lines were se t twice to catch and characterize diets of large demersal fish species. Rosenthal et al. (1981 and 1982) studied the bottomfish component of the nearshore habitats in southeastern Alaska including the Sitka Sound area during the summers of 1980 and 1981, allowing comparisons of our findings to those from the earlier works. There are no previous surveys for seabirds or marine mammals in this area with which we can compare our surveys.

Alaska↗