Point Blue Conservation Science

About: Point Blue Conservation Science is a nonprofit organization based out in Petaluma, California, United States. It is known for research contribution in the topics: Population & Foraging. The organization has 151 authors who have published 330 publications receiving 11929 citations. The organization is also known as: Point Reyes Bird Observatory.

Modeling predator and prey hotspots: Management implications of baleen whale co-occurrence with krill in Central California.

Abstract: As global ocean-bound commerce increases, managing human activities has become important in reducing conflict with threatened wildlife. This study investigates environmental factors determining abundance and distribution of blue whales (Balaenoptera musculus), humpback whales (Megaptera novaeangliae) and their prey (Euphausia pacifica and Thysanoessa spinifera) in central California. We provide insights into environmental drivers of the ecology and distribution of these species, model whale distributions and determine coincident hotspots of whales and their prey that will help decrease human threats to whales and protect critical feeding habitat. We developed separate predictive models of whale abundances (using negative binomial regression on count data) and krill abundance (using a two-part hurdlemodel combining logistic and negative binomial regressions) over a 14 year period (2004-2017). Variables included in situ surface and midwater oceanographic measures (temperature, salinity, and fluorescence), basin-scale climate indices, and bathymetric- and distance-related data. Predictions were applied to 1 km2 cells spanning the study area for May, June, July, and September during each of the 14 years of surveys to identify persistent distribution patterns. Both whales and krill were found to consistently use the northeast region of Cordell Bank, the Farallon Escarpment, and the shelf-break waters. The main identified blue whale hotspots were also krill hotspots, while co-occurrence was more limited and varied seasonally for humpback whales and krill. These results are valuable in identifying patterns in important areas of ecological interaction to assist management of whales. Areas north of Cordell Bank are of particular management concern since they overlap with the end of the San Francisco Bay northern shipping lane. Our findings can help decrease threats to whales, particularly in important foraging areas, by supporting implementation of vessel management and informing potential conflicts with other human uses.

State of the California Current 2019–2020: Back to the Future With Marine Heatwaves?

Abstract: The California Current System (CCS) has experienced large fluctuations in environmental conditions in recent years that have dramatically affected the biological community. Here we synthesize remotely-sensed, hydrographic, and biological survey data from throughout the CCS in 2019-20 to evaluate how recent changes in environmental conditions have affected community dynamics at multiple trophic levels. A marine heatwave formed in the north Pacific in 2019 and reached the second greatest area ever recorded by the end of summer 2020. However, high atmospheric pressure in early 2020 drove relatively strong Ekman-driven coastal upwelling in the northern portion of the CCS and warm temperature anomalies remained far offshore. Upwelling and cooler temperatures in the northern CCS created relatively productive conditions in which the biomass of lipid-rich copepod species increased, adult krill size increased, and several seabird species experienced positive reproductive success. Despite these conditions, the composition of the fish community in the northern CCS remained a mixture of both warm- and cool-water-associated species. In the southern CCS, ocean temperatures remained above average for the seventh consecutive year. Abundances of juvenile fish species associated with productive conditions were relatively low, and the ichthyoplankton community was dominated by a mixture of oceanic warm-water and cosmopolitan species. Seabird species associated with warm water also occurred at greater densities than cool-water species in the southern CCS. The population of northern anchovy, which has been resurgent since 2017, continued to provide an important forage base for piscivorous fishes, offshore colonies of seabirds, and marine mammals throughout the CCS. Coastal upwelling in the north, and a longer-term trend in warming in the south, appeared to be controlling the community to a much greater extent than the marine heatwave itself.

Metabolism, Growth, and Activity in Adélie and Emperor Penguin Embryos

Abstract: The eggs of Adelie (Pygoscelis adeliae) and Emperor (Aptenodytes forsteri) penguins are smaller than those of large species in other orders. The incubation period in Adelie Penguins was as predicted based on egg mass, but in Emperor Penguins it was 50% longer than predicted. Although penguins have been described as semialtricial using the behavioral and morphological traits in Nice's (1962) classification, total oxygen consumption during incubation was similar to that of eggs of the same masses laid by precocial species. In both penguin species prepipping oxygen consumption was at a level predicted for precocial species. Adelie embryos grew continuously during the last two weeks of incubation, but the relative growth rate (%/day) of both wet and dry mass decreased steadily until day 32 of incubation. From day 21 to day 31 of incubation, there was no significant change in the wet mass, dry mass, or caloric content of yolk. The mass-specific caloric content of the embryos remained constant at 5.49 kcal/g dry mass. Activity of the embryo between pipping and hatching contributed importantly to measured oxygen consumption (10% of the total measured during incubation, -20% in pipped eggs from 3 days to 1 day before hatching, and -25% on the day of hatching). We suggest that the limited behavioral repertoire of hatchling penguins evolved as a response to the severity of the environment into which they hatch and because of the skilled predatory behavior that they must learn before they can feed themselves. Received 21 June 1985, accepted 6 January 1986. MANY investigators have measured the energy metabolism of avian embryos and discussed the empirical relationships between this and other functions, including embryonic growth, egg mass at laying, length of incubation, developmental type at hatching, adult mass, adult basal metabolic rate, and conductance of the eggshell (for recent reviews and discussions see C. Vleck et al. 1980, Rahn 1982, Bucher and Bartholomew 1984). A stated or an implicit assumption in most of these studies is that the contribution of activity to the total energy metabolism of avian embryos is minimal. Embryonic oxygen consumption usually has been measured in closed respirometry systems, except for very large eggs (D. Vleck et al. 1980) and in a few recent studies (e.g. Bartholomew and Goldstein 1984). Closed-system respirometry is integrative and gives only average values and rates of energy metabolism over relatively extended time periods. Recently, it has become possible to follow short-term fluctuations in energy metabolism by using flow-through respirometry and calculating instantaneous rates of oxygen consumption (Bartholomew et al. 1981). Continuous monitoring of rates of oxygen consumption of avian embryos over extended periods of time allows one to determine short-term variability in oxygen consumption of an individual due to activity as well as variation due to longer-term ontogenetic change. All members of the order Sphenisciformes are considered to be semialtricial (Nice 1962). Most lay their eggs in relatively to extremely cold environments characterized by low absolute humidity. Emperor (Aptenodytes forsteri) and Adelie (Pygoscelis adeliae) penguins breed on the Antarctic continent and its fringe islands and have a circumpolar distribution. There were no published data on embryonic growth and metabolism in penguins, so it was necessary to establish as broad a data base as possible from the combination of materials available to us (see Methods). We collected Adelie Penguin eggs of known age from colonies near Arctowski Station and Palmer Station in the Antarctic. We made physiological measurements on the eggs of Emperor Penguins and on the eggs and chicks of Adelie 485 The Auk 103: 485-493. July 1986 This content downloaded from 157.55.39.132 on Thu, 15 Sep 2016 06:17:50 UTC All use subject to http://about.jstor.org/terms 486 BUCHER ET AL. [Auk, Vol. 103 Penguins at Sea World in San Diego, California. Measurements of embryonic mass and accompanying yolk mass were obtained when possible to allow analysis of growth patterns and of energy allocation at specific times during incubation.