Research
My main research interests revolve around the intersection between light and the function of tropical and subtropical
shallow-water ecosystems, particularly coral reefs. Visible light is the primary energy source for these ecosystems, but water
column optical properties alter both the quantity and quality of light available to the benthos for primary production. Thus,
knowledge of shallow water optical properties is fundamental to understanding ecosystem function. Light itself can also be
used as a tool, through inversion of remote sensing data, to measure various aspects of the ecosystem. In practice, much of my
research has focused on development and application of in situ optical and remote sensing methods to study various aspects of
coral reef system function, at scales of centimeters to hundreds of kilometers.
Coral Reef Remote Sensing
Quantification of benthic community structure is central to understanding coral reef ecosystem
function. For example, community structure determines rates of reef metabolism and indicates reef status, and different
bottom-types are important in life history strategies of reef-dwelling organisms. Conventional methods for determining benthic
community structure include the use of in situ quadrats, line transects, and manta tows, but these are not logistically
feasible for surveys over large areas. Digital remote sensing is the only available means to acquire quantitative reef
community structure data across large spatial scales. Coral reef remote sensing is inherently interdisciplinary. My work in
this area has included sensor design, satellite mission development, algorithm development and implementation, image
processing, optical calibration/validation, ecological calibration/validation, and scientific interpretation of image products
Reef Biogeochemistry
Measuring reef metabolism in situ has traditionally been confined to shallow reef-flats under limited environmental conditions,
generally utilizing flow respirometry over heterogeneous community assemblages or relatively small incubation chambers. Over
the past two years, I have begun to develop a remote sensing approach for estimating community- to reef-scale primary
production based on optical absorbance and light-use efficiency. (This type of model was first suggested by Monteith in the
early 1970's for crop plants and is now routinely used in terrestrial remote sensing studies.) Modeling results are very
encouraging, but a good deal of fundamental research is required to further this topic, as there are no published values of
photosynthetic light-use efficiency at the coral reef community scale. Again, it should be pointed out that this approach is
readily extendable to other ecosystems, including the open ocean.
Bio-Optics
The interaction of light with organisms continues to be an area of professional interest. To this end, I have constructed a
model that accurately predicts coral photosynthetic pigment concentration based on rapid, non-invasive measurements of optical
reflectance; I have developed a similar model to predict zooxanthellae density. These models are currently limited to a few
coral species, and further work is required to include other taxa. However, there is clear potential for these simple optical
measurements to provide for routine in situ monitoring of coral status. As technology and inversion algorithms advance, the
same models can eventually be used for remote sensing of "coral reef color." It should be noted that the same basic methods
used for corals are readily applicable to other plants.
Water Optical Properties
Shallow coastal waters are very complex optical environments, with more diverse types and concentrations of dissolved and
suspended materials than the open ocean. However, to date, there has been very little effort to parameterize optical
properties in these environments. One of my research interests is measuring spectral optical properties (absorption, beam
attenuation, volume scattering, diffuse attenuation) across space and time. My goal is to link these measurements with
physical forcings to generate a model for predicting optical properties which, in turn, can be used to drive biogeochemical
models.
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Selected Publications
(Complete publication list)
Hogrefe KR, Wright DJ, Hochberg EJ (2008) Derivation and integration of shallow-water bathymetry: implications for coastal
terrain modeling and subsequent analyses. Marine Geodesy. 31: 299-317
Hochberg EJ, Atkinson MJ (2008) Coral reef benthic productivity based on optical absorptance and light-use efficiency. Coral
Reefs. 27: 49-59.
Denevi BW, Lucey PG, Hochberg EJ, Steutel D (2007) Near-infrared optical constants of pyroxene as a function of iron and
calcium content. Journal of Geophysical Research-Planets. 112: E05009.
Conger CL, Hochberg EJ, Fletcher CH, Atkinson MJ (2006) Decorrelating remote sensing color bands from bathymetry in optically
shallow waters. IEEE Transactions on Geoscience and Remote Sensing. 44: 1655-1660.
Hochberg EJ, Apprill A, Atkinson MJ, Bidigare RR (2006) Bio-optical modeling of photosynthetic pigments in corals. Coral Reefs. 25: 99-109.
Andréfouët S, Payri C, Hochberg EJ, Hu CM, Atkinson MJ, Muller-Karger FE (2004) Use of in situ and airborne reflectance
for scaling-up spectral discrimination of coral reef macroalgae from species to communities. Marine Ecology Progress Series.
283: 161-177.
Hochberg EJ, Atkinson MJ, Apprill A, Andréfouët S (2004) Spectral reflectance of coral. Coral Reefs. 23: 84-95.
Mumby PJ, Skirving W, Strong A, Hardy JT, LeDrew E, Hochberg EJ, Stumpf RP, David LT (2004) Remote sensing of coral reefs and
their physical environment. Marine Pollution Bulletin. 48: 219-228.
Andréfouët S, Kramer P, Torres-Pulliza D, Joyce KE, Hochberg EJ, Garza-Perez R, Mumby PJ, Riegl B, Yamano H, White WH,
Zubia M, Brock JC, Phinn SR, Naseer A, Hatcher BG, Muller-Karger FE (2003) Multi-site evaluation of IKONOS data for
classification of tropical coral reef environments. Remote Sensing of Environment. 88: 128-143.
Hochberg EJ, Andréfouët S, Tyler MR (2003) Sea surface correction of high spatial resolution Ikonos images to improve
bottom mapping in near-shore environments. IEEE Transactions on Geoscience and Remote Sensing. 41: 1724-1729.
Andréfouët S, Hochberg EJ, Payri C, Atkinson MJ, Muller-Karger FE, Ripley H (2003) Multi-scale remote sensing of
microbial mats in an atoll environment. International Journal of Remote Sensing. 24: 2661-2682.
Hochberg EJ, Atkinson MJ, Andréfouët S (2003) Spectral reflectance of coral reef bottom-types worldwide and implications
for coral reef remote sensing. Remote Sensing of Environment. 85: 159-173.
Hochberg EJ, Atkinson MJ (2003) Capabilities of remote sensors to classify coral, algae and sand as pure and mixed spectra.
Remote Sensing of Environment. 85: 174-189.
Andréfouët S, Payri C, Hochberg EJ, Che LM, Atkinson MJ (2003) Airborne hyperspectral detection of microbial mat
pigmentation in Rangiroa atoll (French Polynesia). Limnology and Oceanography. 48: 426-430.
Andréfouët S, Muller-Karger FE, Hochberg EJ, Hu CM, Carder KL (2001) Change detection in shallow coral reef environments
using Landsat 7 ETM+ data. Remote Sensing of Environment. 78: 150-162.
Hochberg EJ, Atkinson MJ (2000) Spectral discrimination of coral reef benthic communities. Coral Reefs. 19: 164-171.
Atkinson MJ, Barnett H, Aceves H, Langdon C, Carpenter SJ, McConnaughey T, Hochberg EJ, Smith M, Marino BDV (1999) The
Biosphere 2 coral reef biome. Ecological Engineering. 13: 147-171.
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