Joseph E. Salisbury

Coastal Acidification by Rivers:A Threat to Shellfish?

Increasing atmospheric CO2 is likely to cause a corresponding increase in oceanic acidity by lowering pH by 0.20.5 pH units by the end of the 21st century [Royal Society, 2005]. In light of increasing acidity, there are growing concerns about the future health of a variety of marine organisms, particularly shellfish, which in the United States is a

Ocean acidification in the coastal zone from an organism's perspective: multiple system parameters, frequency domains, and habitats.

1.6 billion industry. Shellfish predominantly inhabit coastal regions, and in addition to the projected stress caused by the global trend in ocean acidification, some coastal ecosystems receive persistent or episodic acid inputs as a result of interactions with river water, bottom sediments, or atmospheric deposition of terrigenous materials. Most river plumes are acidic relative to the receiving ocean, and river water is mixed extensively over the continental shelf. Moreover, the chemical nature and magnitude of discharge are changing rapidly due to climate change and land-use practices.

The United States' next generation of atmospheric composition and coastal ecosystem measurements : NASA's Geostationary Coastal and Air Pollution Events (GEO-CAPE) Mission

Multiple natural and anthropogenic processes alter the carbonate chemistry of the coastal zone in ways that either exacerbate or mitigate ocean acidification effects. Freshwater inputs and multiple acid-base reactions change carbonate chemistry conditions, sometimes synergistically. The shallow nature of these systems results in strong benthic-pelagic coupling, and marine invertebrates at different life history stages rely on both benthic and pelagic habitats. Carbonate chemistry in coastal systems can be highly variable, responding to processes with temporal modes ranging from seconds to centuries. Identifying scales of variability relevant to levels of biological organization requires a fuller characterization of both the frequency and magnitude domains of processes contributing to or reducing acidification in pelagic and benthic habitats. We review the processes that contribute to coastal acidification with attention to timescales of variability and habitats relevant to marine bivalves.

Dynamics of the Coastal Zone

The Geostationary Coastal and Air Pollution Events (GEO-CAPE) mission was recommended by the National Research Councils (NRCs) Earth Science Decadal Survey to measure tropospheric trace gases and aerosols and coastal ocean phytoplankton, water quality, and biogeochemistry from geostationary orbit, providing continuous observations within the field of view. To fulfill the mandate and address the challenge put forth by the NRC, two GEO-CAPE Science Working Groups (SWGs), representing the atmospheric composition and ocean color disciplines, have developed realistic science objectives using input drawn from several community workshops. The GEO-CAPE mission will take advantage of this revolutionary advance in temporal frequency for both of these disciplines. Multiple observations per day are required to explore the physical, chemical, and dynamical processes that determine tropospheric composition and air quality over spatial scales ranging from urban to continental, and over temporal scales ranging from diu...

Demonstration of ocean surface salinity microwave measurements from space using AMSR-E data over the Amazon plume

Earth’s coastline has evolved for many thousands ofyears, experiencing changes to habitat, coastal dynam-ics and the supply of sediment from the continentalinterior. Relative sea level has risen in some areas, butfallen elsewhere. There is an acknowledged range innatural variability within a given region of the globalcoastal zone, within a context of longer-term geologicalprocesses.Many of the regional controls on sea level involvelong-term geological processes (e.g., subsidence, iso-stasy), and have a profound influence on controllingshort-term dynamics. As sea levels fluctuate, the mor-phology of a coastal zone will further evolve, changingthe boundary conditions of other coastal processes: cir-culation, waves, tides and the storage of sediment onflood plains.Human development of coastal regions has modifiedpristine coastlines around the globe, by deforestation,cultivation, changes in habitat, urbanisation, agriculturalimpoundment and upstream changes to river flow.Humans can also influence changes in relative sea levelat the local scale. For example, removal of groundwaterand hydrocarbons from subterranean reservoirs maycause subsidence in nearby areas, with a concomitantrise in relative sea level. Our concern in LOICZ is notjust in the magnitude of change, but also in the recentand accelerated rate of change. Our interests extendto whether alterations on the local level can cumula-tively give rise to coastal zone changes of global signifi-cance.Climate warming may also contribute significantlyto sea level fluctuations. Predictions by the InternationalPanel on Climate Change (IPCC) suggest that sea levelis rising globally (15 to 95 cm by 2100) as a result of therecent warming of the ocean and the melting of ice caps(Houghton et al. 2001). As sea levels rise, coastal desta-bilisation may occur due to accelerated beach erosion,trapping of river sediment on flood plains and increas-ing water residence during floods. The predicted IPCCclimate-warming scenario will undoubtedly impactsome regions more than others. The Siberian coast isexperiencing a reduction in offshore sea-ice cover, witha associated increase in ocean fetch, leading to highersea levels during the open-water summer and accelera-tion of coastal erosion. Recent studies also suggest thattropical and temperate coastal environments are expe-riencing stormier conditions (i.e., increased numbersand severity of hurricanes). Will local storm surges mag-nify the impact of a global sea-level rise, increasing risksto humans and their infrastructure? Are there negativefeedbacks to engineering options for the protection ofcoastal settlements?Perhaps the largest impact on coastal stability is dueto modification to the global flux of sediment to thecoastal zone. Changes in global hydrology have modi-fied the timing and intensity of floods, and thereforethe effective discharge available for sediment transport.Climate shifts have varied the contributions from melt-water (snow, ice), altered the intensity of rainfall,changed drainage basin water-storage capacity, and al-tered precipitation and evaporation rates. Human influ-ences have also greatly modified downstream flow. Overhalf of the world’s rivers have seen stream-flow modi-fication through the construction of large reservoirs.These and other rivers have also been impacted by wa-ter withdrawal for agriculture, industry and settlements.Our understanding of the importance of submarinegroundwater discharge in the coastal zone and of itsprocesses has improved markedly in recent years; asignificant impetus has been given to this understand-ing by the LOICZ-associated SCOR Working Group 112.The outcomes of its work are summarised in this chap-ter.Human migration to the coastal zone and consequentland-use changes have also greatly impacted the stabil-ity of our coastal areas. Human impacts on the coastalzone ranges from massive (e.g., reduction in wetlands,urbanisation) to non-existent (e.g., many polar coast-lines). This chapter synthesises how climate shifts andhumans can affect and have affected our coasts on a glo-bal scale.

Ocean Acidification Disrupts Prey Responses to Predator Cues but Not Net Prey Shell Growth in Concholepas concholepas (loco)

Microwave Sea Surface Salinity (SSS) measurements can be performed by isolating the emissivity response to salinity changes from numerous geophysical effects, including surface temperature and wind waves. At L-band frequencies (1 to 2 GHz), the sensitivity to SSS is sufficient but it falls off quickly as frequency is increased. Nevertheless, methods using higher microwave frequencies with much lower SSS sensitivity than at L band, can already be tested. In particular, combining 6 and 10 GHz data in vertical polarization efficiently minimizes sea surface roughness and thermal impacts. Using AMSR-E data, the retrieved bi-monthly maps of SSS at 0.5 degrees resolution over the region of the Amazon plume show relative accuracy in-line with the future L-band dedicated mission objectives. Citation: Reul, N., S. Saux-Picart, B. Chapron, D. Vandemark, J. Tournadre, and J. Salisbury (2009), Demonstration of ocean surface salinity microwave measurements from space using AMSR-E data over the Amazon plume, Geophys. Res. Lett., 36, L13607, doi:10.1029/2009GL038860.

Removal of terrestrial DOC in aquatic ecosystems of a temperate river network

Background Most research on Ocean Acidification (OA) has largely focused on the process of calcification and the physiological trade-offs employed by calcifying organisms to support the building of calcium carbonate structures. However, there is growing evidence that OA can also impact upon other key biological processes such as survival, growth and behaviour. On wave-swept rocky shores the ability of gastropods to self-right after dislodgement, and rapidly return to normal orientation, reduces the risk of predation. Methodology/Principal Findings The impacts of OA on this self-righting behaviour and other important parameters such as growth, survival, shell dissolution and shell deposition in Concholepas concholepas (loco) were investigated under contrasting pCO2 levels. Although no impacts of OA on either growth or net shell calcification were found, the results did show that OA can significantly affect self-righting behaviour during the early ontogeny of this species with significantly faster righting times recorded for individuals of C. concholepas reared under increased average pCO2 concentrations (± SE) (716±12 and 1036±14 µatm CO2) compared to those reared at concentrations equivalent to those presently found in the surface ocean (388±8 µatm CO2). When loco were also exposed to the predatory crab Acanthocyclus hassleri, righting times were again increased by exposure to elevated CO2, although self-righting times were generally twice as fast as those observed in the absence of the crab. Conclusions and Significance These results suggest that self-righting in the early ontogeny of C. concholepas will be positively affected by pCO2 levels expected by the end of the 21st century and beginning of the next one. However, as the rate of self-righting is an adaptive trait evolved to reduce lethal predatory attacks, our result also suggest that OA may disrupt prey responses to predators in nature.

Ocean color and river data reveal fluvial influence in coastal waters

Surface waters play a potentially important role in the global carbon balance. Dissolved organic carbon (DOC) fluxes are a major transfer of terrestrial carbon to river systems, and the fate of DOC in aquatic systems is poorly constrained. We used a unique combination of spatially distributed sampling of three DOC fractions throughout a river network and modeling to quantify the net removal of terrestrial DOC during a summer base flow period. We found that aquatic reactivity of terrestrial DOC leading to net loss is low, closer to conservative chloride than to reactive nitrogen. Net removal occurred mainly from the hydrophobic organic acid fraction, while hydrophilic and transphilic acids showed no net change, indicating that partitioning of bulk DOC into different fractions is critical for understanding terrestrial DOC removal. These findings suggest that river systems may have only a modest ability to alter the amounts of terrestrial DOC delivered to coastal zones.

Examining organic carbon transport by the Orinoco River using SeaWiFS imagery

A critical yet poorly quantified aspect of the Earth system is the influence of river-borne constituents on coastal biogeochemical dynamics. Coastal waters contain some of the most productive ecosystems on Earth and are sites of intense downward particle fluxes and organic accumulation. Also, in many parts of the world, coastal ecosystems are experiencing unfavorable changes in water quality some of which can be linked directly to the transport of waterborne constituents from land. These include the well-publicized, increasing frequency of hypoxia events in the Gulf of Mexico [Goolsby, 2000], harmful algal blooms [Smayda, 1992], diminished water quality and changes in marine biodiversity [Radach et al., 1990].

Comparison of spaceborne measurements of sea surface salinity and colored detrital matter in the Amazon plume

[1] The Orinoco River is the fourth largest in the world in terms of water discharge and organic carbon export to the ocean. River export of organiccarbon is akey component of the carbon cycle and the global carbon budget. Here, we examined the seasonal transport of organic carbon by the Orinoco River into the eastern Caribbean using the conservative relationship of colored dissolved organic matter (CDOM) and dissolved organic carbon (DOC) in low salinity coastal waters influenced by river plumes. In situ measurements of CDOM absorption, DOC, and salinity were used to develop an empirical model for DOC concentration at the Orinoco River Plume. Satellite remote sensing reflectances were used with empirical models to determine DOC and Particulate organic carbon (POC) river transport. Our estimates of CDOM and DOC significantly correlated with in situ measurements and were within the expected ranges for the river. Total organic carbon transport by the Orinoco River during the period of 1998 to 2010 was 7.10 � 10 12 gCy � 1 , from 5.29 � 10 12 gCy � 1 of DOC and 1.81 � 10 12 gCy � 1 of POC, representing � 6% increase to previous published estimates. The variability in organic carbon transport responded to the seasonality in river flow more than to changes in organic carbon concentration in the river. Our results corroborate that is possible to estimate organic carbon transport using ocean color data at global scales. This is needed to reduce the uncertainties of land–ocean carbon fluxes.