Romberg Tiburon Center for Environmental Studies

Paradise, CA, United States

Romberg Tiburon Center for Environmental Studies

Paradise, CA, United States
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Woodson C.B.,Stanford University | Barth J.A.,Oregon State University | Cheriton O.M.,University of California at Santa Barbara | McManus M.A.,University of Hawaii at Manoa | And 20 more authors.
Geophysical Research Letters | Year: 2011

Internal waves of depression were observed propagating along-shelf and into northern Monterey Bay, California (CA) on the inner shelf. These waves had amplitudes approximately equal to the thermocline depth (∼4 m), and were unstable to shear and mix the thermocline. Isopycnal gradient spectra showed that the wave packets lead to an elevated mean dissipation rate of 2.63 × 10-5 m3 s-2 for up to 2 hours after wave passage. The proximity to the surface created strong surface convergences that can actively transport buoyant material, such as plankton, back into the bay. The wave packets were observed regularly over the upwelling season across multiple years suggesting they may have large effects on the documented spatial variation of phytoplankton and larvae on the inner shelf. The timing of the waves suggests they are not formed by tides interacting with bathymetry, but are generated by buoyant plume propagation. © 2011 by the American Geophysical Union.

Benner I.,Alfred Wegener Institute for Polar and Marine Research | Benner I.,Romberg Tiburon Center for Environmental Studies | Passow U.,Alfred Wegener Institute for Polar and Marine Research | Passow U.,University of California at Santa Barbara
Marine Ecology Progress Series | Year: 2010

Coccolithophores play a prominent role in the marine, and by extension the global, carbon cycle. The ability of coccolithophores to thrive on organic nutrients is assumed to be a key reason for their ecological success, as Emiliania huxleyi grows well on a variety of organic nutrients. The ability of other coccolithophores to utilize organic nutrients has, however, not been investigated. We conducted experiments to compare the ability of E. huxleyi, Coccolithus braarudii, and Calcidiscus leptoporus to grow on environmentally common organic nitrogen and phosphorus sources (glycine, L-alanine, L-proline, L-serine, L-glutanic acid, L-histidine, urea, glycerophosphate, adenosine monophosphate, adenosine triphosphate, and β-nicotinamide adenine dinucleotide). The nitrogen and phosphorus additions (200 μM and 14 μM, respectively) were higher than naturally occurring in the ocean, as our goal was to test the ability of coccolithophores to utilize these substances. E. huxleyi was able to grow on all tested organic nutrients. C. braarudii grew on 7 out of the 10 tested nutrient sources, but did not grow on 3 amino acids. C. leptoporus grew on only 3 out of the 7 tested Nsources, with no growth on the 4 amino acids. Similarities in the coccolithophores' ability to utilize specific organic sources suggest common transport systems and enzymes, whereas differences emphasize the presence of species-specific nutrient uptake mechanisms. Such species-specific differences in the ability to utilize certain nutrients may provide explanations for biogeographic distribution patterns and substantiate the suspicion that E. huxleyi may not be a good representative of coccolithophores, e.g. for Earth system models. © Inter-Research 2010.

Teh L.S.L.,University of British Columbia | Teh L.C.L.,University of British Columbia | Hines E.,Romberg Tiburon Center for Environmental Studies | Junchompoo C.,Eastern Marine and Coastal Resources Research Center | Lewison R.L.,San Diego State University
Ocean and Coastal Management | Year: 2015

We apply an integrated and interdisciplinary conceptual framework to assess the potential for uptake of bycatch reduction measures by small-scale fisheries along the Andaman coast and eastern Gulf of Thailand, and in Sabah, Malaysia. Specifically, we characterize the current governance, socio-economic, ecological, and scientific context for marine megafauna bycatch, and identify the enabling and limiting factors to bycatch reduction at each location. Enabling factors are those that motivate or facilitate conservation actions among resource users, managers, and other stakeholders, while limiting factors are those that act as barriers to conservation. We conduct a comparative analysis of the strength of enabling and limiting factors at the two study locations by using a qualitative scoring system. Overall, conditions in Thailand appear to be relatively more supportive of bycatch reduction than Sabah. Many enabling factors, such as community based marine management and positive attitudes towards conservation, occur at the local scale, suggesting potential marine megafauna bycatch reduction approaches can be implemented successfully from the bottom-up. We show that intervention points for reducing marine megafauna bycatch lie within a much broader realm than conventionally considered in bycatch reduction schemes. Effective policies for reducing marine megafauna bycatch thus have to address multifaceted drivers of small-scale fishing behaviour in addition to ecological considerations. © 2015 Elsevier Ltd.

Jensen C.M.,San Francisco State University | Jensen C.M.,Romberg Tiburon Center for Environmental Studies | Hines E.,San Francisco State University | Hines E.,Romberg Tiburon Center for Environmental Studies | And 4 more authors.
Coastal Management | Year: 2015

Shipping traffic poses a worldwide threat to many large whale species. Spatially explicit risk assessments are increasingly being used as a tool to minimize ship-strike risk. These assessments often use static representations of shipping patterns. We used Automatic Identification System data to quantify variability in cargo shipping traffic entering and exiting San Francisco Bay, which contains some of the busiest ports in the United States, at three temporal resolutions: (1) before and after implementation of the California Air Resources Board's Ocean-Going Vessels Fuel Rule, (2) among seasons, and (3) day versus night. We used the nonparametric Mood's Median test to compare median daily distance traveled because the data were not normally distributed and the variance was not homogeneous. Our analyses show that shipping traffic off San Francisco is dynamic at both interannual and daily temporal resolutions, but that traffic was fairly consistent among the seasons considered. Our analyses emphasize the importance of economic and regulatory drivers on interannual shipping traffic patterns. Shipping traffic is expected to continue to change off the U.S. West Coast and to increase globally. These changes in shipping traffic could have implications for the risk of ships striking whales and should be included in risk assessments. © 2015, Taylor and Francis Group, LLC.

Dransfield A.,Romberg Tiburon Center for Environmental Studies | Hines E.,Romberg Tiburon Center for Environmental Studies | Hines E.,San Francisco State University | McGowan J.,Romberg Tiburon Center for Environmental Studies | And 5 more authors.
Endangered Species Research | Year: 2014

Understanding habitat preferences for endangered species is a high priority for management strategies to ensure minimum conflict between human uses and wildlife conservation. The purpose of this study was to identify oceanographic variables that predict occurrences of humpback whales Megaptera novaeangliae within the Cordell Bank and Gulf of the Farallones National Marine Sanctuaries, California, USA, to assess potential conflict with vessel traffic. We used data collected by Applied California Current Ecosystem Studies (ACCESS) conducted from 2004 to 2011. Using zero-inflated negative binomial regression, we developed predictive models and identified locations highly used by whales to characterize humpback whale habitat. We analyzed whale encounter rates at 3-km bin intervals in relation to bathymetric, surface and midwater hydrographic predictor variables and temporal variables characterizing oceanographic conditions. Our models included variables that accounted for detectability of whales. Two models were compared and contrasted: (1) a surface-only model, using only surface oceanographic variables, and (2) a surface + mid-water model, using both surface and mid-water variables. The surface + mid-water model performed significantly better than the surface-only model, which underestimated the amount of suitable whale habitat in the northern half of our study area. We compared resulting predicted habitat areas with previous and current San Francisco Bay Area shipping lane poly gonal footprints to investigate whether newly accepted changes in routes reduced areal overlap with humpback whale habitat. Although our analyses show that the area occupied by shipping traffic has decreased in areas of high predicted humpback whale habitat use, changes in vessel lane footprints do not account for several important aspects of ship-strike risk, including vessel frequency, speed, size and density patterns within the shipping lanes and variability between lanes. © The authors 2014.

Paganini A.,Romberg Tiburon Center for Environmental Studies | Kimmerer W.J.,Romberg Tiburon Center for Environmental Studies | Stillman J.H.,Romberg Tiburon Center for Environmental Studies
Aquatic Biology | Year: 2010

Invasive species can have large impacts on food webs if their metabolic demands are higher than those of extant species. The clam Corbula amurensis is believed to have caused a large shift in the pelagic food web in the northern reach of the San Francisco Estuary (USA) since its introduction in the 1980s. This shift has been attributed to the clam's high density, high suspension-feeding rates, and ability to thrive in a wide range of salinities. To understand how environmental salinity alters the potential metabolic impacts of C. amurensis on the pelagic food web, we investigated clam metabolism following acclimation to constant low, constant high, and fluctuating salinities. We measured growth rate, feeding rate, respiration rate, activity of the metabolic enzyme malate dehydrogenase (MDH), and osmoregulatory performance. Clams did not grow during a 3 mo period at either high or low salinity, although they fed more rapidly following acclimation to high salinity than low. C. amurensis had higher metabolic rates in both high and low salinity than in fluctuating salinities. Activity of MDH was positively correlated with salinity in both foot and mantle tissues. MDH activities of C. amurensis were twice those of other clam species. Osmotic pressure of C. amurensis tissues was always lower than that in the acclimation water, but clams hyporegulated to a greater extent in high-salinity conditions. Overall, our results suggest that clams experiencing higher salinities increase metabolic rates to support greater osmoregulation and compensate by increasing their filter-feeding rate. © Inter-Research 2010.

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