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Hurricane Harvey deposited over 90×109 m 3 of rainwater over central Texas, USA, during late August/early September 2017. During four cruises (June, August, September and November 2017) we observed changes in hydrography and nutrient and oxygen concentrations in Texas coastal waters. Despite intense terrestrial runoff, nutrient supply to the coastal ocean was transient, with little phytoplankton growth observed and no hypoxia. Observations suggest this was probably related to the retention of nutrients in the coastal bays and rapid uptake by phytoplankton of nutrients washed out of the bays, as well as dilution by the sheer volume of rainwater and the lack of significant carbon reserves in the sediments, despite the imposition of a strong pycnocline. By the November cruise conditions had apparently returned to normal, and no long-term effects were observed. [ABSTRACT FROM AUTHOR]

Hurricane Harvey deposited over 90 billion cubic meters of rainwater over central Texas, USA, during late August/early September 2017. During four cruises (June, August, September and November 2017) we observed changes in hydrography, nutrient and oxygen concentrations in Texas coastal waters. Despite intense terrestrial runoff, nutrient supply to the coastal ocean was transient, with little phytoplankton growth observed and no hypoxia. Observations suggest this was probably related to the retention of nutrients in the coastal bays, rapid uptake by phytoplankton of nutrients washed out of the bays, as well as dilution by the sheer volume of rainwater, and the lack of significant carbon reserves in the sediments, despite the imposition of a strong pycnocline. By the November cruise conditions had apparently returned to normal and no long-term effects were observed. [ABSTRACT FROM AUTHOR]

Abstract: A numerical hydrodynamic simulation of the Texas–Louisiana continental shelf circulation is compared with hydrographic and moored observations of temperature, salinity, and current velocity. The spatial and temporal structure of the model error suggests that the model is able to reproduce the observed broad-scale features and seasonal patterns faithfully. However, there are energetic features that have small spatial and temporal scales, 30–50km and 5–12days, that are not reproduced in the model. These small-scale features are not well resolved concurrently in both space and time by most modern hydrographic and moored measurements, and thus appear as observational noise when comparing observations with numerical simulations. We demonstrate that these features are reproduced statistically within the model in terms of mean and variance, but are not reproduced exactly. Thus, these features create a substantial noise floor that constrain assessments of model skill to large spatial and temporal scales. [Copyright &y& Elsevier]

Abstract: Here we report on spatial and temporal changes in the concentration and composition of total dissolved organic carbon (DOC) and dissolved lignin-phenols (sum 8) in surface and bottom waters in estuarine and inner shelf off the Louisiana coast (USA). DOC samples were collected at 6 stations on 3 cruises (April 2008, July 2008) for organic analyses along a transect that spanned from inside Terrebonne–Timbalier Bay estuary, Louisiana (7m water depth) to the outer-most station on the inner Louisiana shelf (18.5m water depth). An additional set of samples was taken for DOC and dissolved lignin-phenols in April 2009 in the upper marshes of the estuary in water depths typically ca. 1m. Hydrographic properties of shelf waters in April 2008 were drastically different than in July 2008 because of the higher river discharge from the Mississippi River (MR) and the opening of man-made water diversion structures in Louisiana in April. There were no significant differences in DOC concentrations between the inner bay and shelf stations, likely due to extensive mixing between the bay and shelf waters. However, there were significantly higher concentrations of dissolved lignin (sum 8) and Λ8 at the marsh stations (x̄ =0.28±0.15mgL−1 and x̄ =0.69±0.35), compared to the inner shelf (x̄ =0.16±0.06mgL−1 and x̄ =0.24±0.12) stations, respectively. Low S/V and C/V ratios observed in Terrebonne–Timbalier Bay estuary were likely the result of selective degradation of syringyl and cinnamyl over vanillyl lignin-phenols, and not inputs of woody gymnosperms. A gradient of decreasing S/V ratios along a transect from the upper marshes to the shelf was likely the result of photochemical breakdown of lignin and dilution effects from marine waters near the outer reaches of the estuary. Inputs of photochemically-altered DOC from estuaries such as Terrebonne–Timbalier Bay to the inner Louisiana shelf may provide an additional source of OC for microbial food webs in the northern Gulf of Mexico. [Copyright &y& Elsevier]

Abstract: The circulation and distribution of water properties in the water column of the Gulf of Mexico influence the flux of carbon to the benthic environment. The eddy field of the upper 1000m creates environmental conditions that are favorable for biological productivity in an otherwise oligotrophic subtropical ocean. This eddy field results in the transport of nutrients and organic matter into the photic zone through cross-margin flow of shelf waters, upwelling in cyclones, and uplift from the interaction of anticyclones with bathymetry. These conditions then allow the productivity that becomes a possible source of carbon to the benthos. Data from four cruises during summers of 2000–2002 are used to describe the currents and water property distributions in the deepwater Gulf of Mexico, which consists of water depths greater than 400m. Comparisons are made to historical data sets to provide an understanding of the persistence of the characteristics of the Gulf and the processes that occur there. The currents in the Gulf are surface intensified, have minimum in 800–1000m depths, and also exhibit bottom intensification, especially near sloping topography. Historical time series records show current speeds near-bottom reach 50–100cms−1. At basin scales, these currents tend to flow cyclonically (counter-clockwise) along the bathymetry. These near-bottom, episodic, high-speed currents provide a mechanism for the transport of organic material, in both large and small particle sizes, from one benthic area to another. The distributions of temperature, salinity, nutrients, and dissolved oxygen during the study appear to be unchanged from historical findings. The source waters for the deep Gulf are the water masses brought into the Gulf by the Loop Current system. The properties in the upper 100–200m are the most variable of the water column, consistent with their proximity to wind mixing, river discharge mixing, and atmospheric influences. Below 1500m, there are no major horizontal variations in these water properties. [Copyright &y& Elsevier]

Focuses on a study which summarized estimates of volume transport and property distributions through the Mozambique Channel and offered additional estimates and measurements based on acquired hydrographic and data. Historical background and interpretation; Results of the study; Float speed and velocity statistics.