Temporal and spatial variability of dissolved organic and inorganic phosphorus, and metrics of phosphorus bioavailability in an upwelling-dominated coastal system

Author Posting. © American Geophysical Union, 2005. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 110 (2005): C10S13, doi:10.1029/2004JC002837.High-frequency temporal and spatial shifts in the various dissolved P pools (total, inorganic, and organic) are linked to upwelling/relaxation events and to phytoplankton bloom dynamics in the upwelling-dominated Oregon coastal system. The presence and regulation of alkaline phosphatase activity (APA) is apparent in the bulk phytoplankton population and in studies of cell-specific APA using Enzyme Labeled Fluorescence (ELF®). Spatial and temporal variability are also evident in phytoplankton community composition and in APA. The spatial pattern of dissolved phosphorus and APA variability can be explained by bottom-controlled patterns of upwelling, and flushing times of different regions within the study area. The presence of APA in eukaryotic taxa indicates that dissolved organic phosphorus (DOP) may contribute to phytoplankton P nutrition in this system, highlighting the need for a more complete understanding of P cycling and bioavailability in the coastal ocean.KCR acknowledges WHOI for rapid-response funding that made possible participation on this first COAST cruise, and NSF-OCE grant 0119134 for support of subsequent work on these and other COAST samples

Marine vs. terrigenous organic matter in Louisiana coastal sediments: The uses of bromine:organic carbon ratios

Recent data on the sources of organic carbon buried in the ocean have emphasized the probable importance of terrigenous organic matter in burial budgets of deltaic depocenters. The many markers used to assess relative importance of marine vs. terrestrial sources each have ambiguities. We use the ratio of bromine to organic carbon (Br:OC) as a source indicator for organic matter in the Mississippi delta. Progressive increases in bromine concentrations from the river to the slope indicate increasing content of marine-derived organic matter. Quantitative estimates of marine vs. terrigenous organic matter using Br:OC ratios in a two-endmember mixing model are consistent with recent estimates using a combination of three other source markers [Gordon, E.S., Goñi, M.A. 2003. Sources and distribution of terrigenous organic matter delivered by the Atchafalaya River to sediments in the northern Gulf of Mexico. Geochim. Cosmochim. Acta, 67:2359-2375]. The Br:OC vs. δ13C relationship indicates seaward increase in δ13C without proportionate incorporation of marine organic matter, consistent with recent arguments that isotopically depleted terrestrial detritus derived from C3 plants is separated from C4-derived terrigenous organic matter during transport. Decreasing Br:OC ratios downcore at many sites that have significant amounts of marine organic matter indicate that the marine organic matter is preferentially lost during burial diagenesis. This preferential loss constrains the contribution of organic matter burial in deltaic environments to global removal of Br. © 2007 Elsevier B.V. All rights reserved

Large-scale climatic effects on traditional Hawaiian fishpond aquaculture.

Aquaculture accounts for almost one-half of global fish consumption. Understanding the regional impact of climate fluctuations on aquaculture production thus is critical for the sustainability of this crucial food resource. The objective of this work was to understand the role of climate fluctuations and climate change in subtropical coastal estuarine environments within the context of aquaculture practices in He'eia Fishpond, O'ahu Island, Hawai'i. To the best of our knowledge, this was the first study of climate effects on traditional aquaculture systems in the Hawaiian Islands. Data from adjacent weather stations were analyzed together with in situ water quality instrument deployments spanning a 12-year period (November 2004 -November 2016). We found correlations between two periods with extremely high fish mortality at He'eia Fishpond (May and October 2009) and slackening trade winds in the week preceding each mortality event, as well as surface water temperatures elevated 2-3°C higher than the background periods (March-December 2009). We posit that the lack of trade wind-driven surface water mixing enhanced surface heating and stratification of the water column, leading to hypoxic conditions and stress on fish populations, which had limited ability to move within net pen enclosures. Elevated water temperature and interruption of trade winds previously have been linked to the onset of El Niño in Hawai'i. Our results provide empirical evidence regarding El Niño effects on the coastal ocean, which can inform resource management efforts about potential impact of climate variation on aquaculture production. Finally, we provide recommendations for reducing the impact of warming events on fishponds, as these events are predicted to increase in magnitude and frequency as a consequence of global warming

Time-series of He‘eia Fishpond and Kāne‘ohe Bay water temperature (cubic spline fit; see text) from March to December 2009.

<p>Red shaded areas = approximate dates of the fish kills.</p

Kāne‘ohe Bay sea-surface temperature from MOKH1 from May–November 2009 (El Niño Modoki), 2010 (La Niña), and 2015 (El Niño).

<p>Kāne‘ohe Bay sea-surface temperature from MOKH1 from May–November 2009 (El Niño Modoki), 2010 (La Niña), and 2015 (El Niño).</p

Time-series of Kāne‘ohe Bay Marine Core Base Air Station (KBMCB) data from September 15^th–October 15^th, 2009.

<p>The week before the fish kill was analyzed separately and is shaded in red. Fishpond temperatures from each station are as follows: Stake 13 = blue, Stake 15 = black, Stake 18 = pink.</p

Background meteorological conditions of Kāneʻohe Bay (observed at KBMCB, November 20^th 2004-November 20^th 2016) as compared to conditions during the fish mortality events (May and October 2009).

<p>Background meteorological conditions of Kāneʻohe Bay (observed at KBMCB, November 20^th 2004-November 20^th 2016) as compared to conditions during the fish mortality events (May and October 2009).</p

Time-series of air temperature, sea surface temperature, wind direction, and wind speed data from the National Buoy Data Center station ‘MOKH1’, November 20, 2008 –November 20, 2016.

<p>Red vertical lines = approximate fish kill dates.</p

Time-series of He‘eia Fishpond and Kāne‘ohe Bay water temperature (cubic spline fit; see text) from March to December 2009.

<p>Red shaded areas = approximate dates of the fish kills.</p