Rhodoliths, free-living calcareous red algae, create large and diverse habitats worldwide. Although these plants are abundant and ecologically important, little is known about their growth rate. We determined the growth rate for an individual rhodolith, Lithothamnium crassiusculum, from the southern Gulf of California through 14 C analysis using accelerator mass spectrometry (AMS) to be 0.6 mm yr Ϫ1 . This growth rate suggests large L. crassiusculum, which have been found with radii in excess of 6 cm, may live over 100 yr. Declines in the ⌬ 14

ABSTRACT. This paper describes the methods used to develop the Cariaco Basin PL07-58PC marine radiocarbon calibration data set. Background measurements are provided for the period when Cariaco samples were run, as well as revisions leading to the most recent version of the floating varve chronology. The floating Cariaco chronology has been anchored to an updated and expanded Preboreal pine tree-ring data set, with better estimates of uncertainty in the wiggle-match. Pending any further changes to the dendrochronology, these results represent the final Cariaco 58PC calibration data set.

Atmospheric testing of thermonuclear devices during the 1950s and 1960s created a global radiocarbon (14C) signal that has provided a useful tracer and chronological marker in oceanic systems and organisms. The bomb-generated 14C signal retained in fish otoliths can be used as a time-specific recorder of the 14C present in ambient seawater, making it a useful tool in age validation of fishes. The goal of this study was to determine 14C in otoliths of the age-validated yelloweye rockfish (Sebastes ruberrimus) to establish a reference time series for the coastal waters of southeast Alaska. Radiocarbon values from the first year's growth of 43 yelloweye rockfish otoliths plotted against estimated birth year produced a 14C time series (1940–1990) for these waters. The initial rise of 14C occurred in 1958 and 14C levels rose to peak values (60–70‰) between 1966 and 1971, with a subsequent declining trend through the end of the record in 1990 (–3.2‰). In addition, the 14C data confirmed the longevity of the yelloweye rockfish to a minimum of 44 years and strongly support higher age estimates. This 14C time series will be useful for the interpretation of 14C accreted in biological samples from these waters.

The longevity of organisms is intrinsically interesting and can provide useful information on their population structure and dynamics and the dynamics of associated communities. With the exception of perennial Laminariales that have rings in the stipe, the life spans of most perennial macroalgae are unknown or based on anecdotal observations. Using morphological analyses combined with the location and time of the rise in 14 C from atmospheric nuclear testing within the thallus, we determined that the growth rate of a specimen of Clathromorphum nereostratum Lebednik from Adak Island was 0.30 mm . yr À 1 , the 3 0 bands within the thallus were annual, and the specimen sampled was 61-75 years old. Living crusts of this species from the same geographic region are reported to be up to 20 cm thick. Assuming our growth rate is typical, C. nereostratum can be approximately 700 years old, the oldest known living alga. This longevity and consistent banding within the thallus suggest that smaller scale sampling and additional chemical analyses of this alga could provide a detailed long-term record of environmental variation at high latitudes in the North Pacific.

Indigenous people possess information of animals’ habitat use and behaviour; information essential for management and conservation of species affected by climate change. Accessibility of species that are important to Indigenous hunters may also change with environmental conditions. We documented Indigenous Knowledge of bearded (ugruk in Iñupiaq), ringed (natchiq), and spotted seals (qasigiaq) in Utqiaġvik, Alaska, using semi-directed interviews with Iñupiaq hunters. This study originated from discussions with an agency of the regional municipal government to serve co-management efforts and understand habitat use of species subjected to climate change. Results indicated that ringed seals are associated with higher ice concentrations in winter than bearded seals and changes in sea ice retreat in spring may have greater impact on ringed seal habitat use because they are more likely to haul out on ice in spring. Additionally, all three species have foraging hotspots, used over several days by multiple individuals. Bearded seals, and to a lesser extent spotted and ringed seals, will use currents to forage. Results also revealed the use of inland water bodies and terrestrial habitat, which may become more important for bearded and ringed seals with changing ice concentrations and should be considered in management and conservation of these species.

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