Christopher Deacutis

Publications (5) View all

• Source

  Available from: Christopher Deacutis

  Article: Narragansett Bay Hypoxic Event Characteristics Based on Fixed-Site Monitoring Network Time Series: Intermittency, Geographic Distribution, Spatial Synchronicity, and Interannual Variability

  Daniel L. Codiga, Heather E. Stoffel, Christopher F. Deacutis, Susan Kiernan, Candace A. Oviatt
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  ABSTRACT: Low dissolved oxygen events were characterized in Narragansett Bay (NB), a moderate-size (370km2) temperate estuary with a complex passage/embayment geometry, using time series from 2001 to 2006 at nine fixed-site monitoring stations. Metrics for event intensity and severity were the event-mean deficit relative to a threshold (mg O2 l−1) and the deficit-duration (mg O2 l−1 day; product of deficit and duration [day]). Hypoxia (threshold 2.9mg O2 l−1) typically occurred intermittently from late June through August at most stations, as multiple (two to five per season) events each 2 to 7days long with deficit-duration 2 to 5mg O2 l−1 day. Conditions were more severe to the north and west, a pattern attributed to a north–south nutrient/productivity gradient and east–west structure of residual circulation. Spatial patterns for suboxic and severely hypoxic events (thresholds 4.8 and 1.4mg O2 l−1) were similar. The view that different processes govern event variability in different regions, each influenced by local hydrodynamics, is supported by both weak spatial synchronicity (quantified using overlap of event times at different sites) and multiple linear regressions of biological and physical parameters against event severity. Interannual changes were prominent and season-cumulative hypoxia severity correlated with June-mean river runoff and June-mean stratification. Benthic ecological implications for areas experiencing events include: NB hypoxia classifies as periodic/episodic on a near-annual basis; highest direct mortality risk is to sensitive and moderately sensitive sessile species in the northern West Passage and western Greenwich Bay, with some risk to Upper Bay; direct risk to mobile species may be ameliorated by weak spatial synchronicity; and indirect impacts, including reduced growth rates and shifts in predator–prey balances, are very likely throughout the sampled area due to observed suboxic and hypoxic conditions.
  Estuaries and Coasts 04/2012; 32(4):621-641. · 2.11 Impact Factor
• Chapter: Evidence of Ecological Impacts from Excess Nutrients in Upper Narragansett Bay

  Christopher F. Deacutis
  01/2008: pages 349-381;
• Chapter: Summer Bottom Water Dissolved Oxygen in Upper Narragansett Bay

  Emily Saarman, Warren L. Prell, David W. Murray, Christopher F. Deacutis
  01/2008: pages 325-347;
• Source

  Available from: Christopher Deacutis

  Article: Hypoxia in the upper half of Narragansett Bay, RI, during August 2001 and 2002

  Christopher F Deacutis, David Murray, Warren Prell, Emily Saarman, Larissa Korhun
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  ABSTRACT: Narragansett Bay, RI, is considered to be a relatively well-mixed estuary not subject to extensive seasonal stratification and hypoxia. However, results of surveys of dissolved oxygen (DO) for the upper half of Narragansett Bay on August 15, 2001 and on August 6, 2002 have documented evidence of wide-area intermittent subpycnoclinal hypoxia (≤ 3 mg l -1). For the August 2001 survey, severe hypoxic to near-anoxic levels were confined to the Providence River, the western side of Greenwich Bay, and a small area of Mount Hope Bay, but hypoxic levels below 2 mg l -1 were also experienced on the western side of the Upper Bay in an extensive, shallow oxygen minimum. Hypoxic bottom waters (≤ 3 mg l -1) extended from the Upper Bay into the upper West Passage. Hypoxic waters covered approximately 66 km 2 (36%) of the survey area for August 15, 2001. A more extensive and severe hypoxic event occurred during the August 2002 survey, when near-bottom waters of the entire Providence River and a large area of the Upper Bay and upper East Passage were severely hypoxic to near-anoxic, while other parts of the Upper Bay, upper East Passage and upper West Passage were hypoxic at depths greater than 5 m. Limited data for Mount Hope Bay in August 2002 documented small hypoxic areas of the southern end of that subembayment. The total hypoxic area for August 6, 2002 was approximately 93 km 2 (65%) of the total area surveyed. Decreased estuarine circula-tion due to a severe drought may have contributed to the wider extent of hypoxic and near-anoxic waters in large areas of the upper half of Narragansett Bay recorded in the August 6, 2002 survey as compared with the August 15, 2001 survey. Results of the oxygen surveys affirm sediment profile camera work and limited benthic studies that previously suggested parts of the Mid Bay have become subject to increased organic loading impacts. These impacts can take place even under drought condi-tions, when only point source nutrients are the major contributors to nutrient loadings entering the upper half of Narragansett Bay.
  Northeastern Naturalist 01/2006; 13:173-198. · 0.50 Impact Factor
• Conference Proceeding: Use of a long endurance solar powered autonomous underwater vehicle (SAUV II) to measure dissolved oxygen concentrations in Greenwich Bay, Rhode Island, U.S.A

  D. Crimmins, C. Deacutis, E. Hinchey, M. Chintala, G. Cicchetti, D. Blidberg
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  ABSTRACT: As hypoxic water masses increase worldwide in duration and extent due to coastal eutrophication, advanced technology water quality monitoring by autonomous vehicles can increase our capability to document and respond to these environmental perturbations. We evaluated the use of a long endurance autonomous underwater vehicle (AUV) to map dissolved oxygen levels to determine the extent of hypoxia in a small bay (Greenwich Bay, USA.) known to experience summertime hypoxic episodes that have resulted in massive fish kills. During a 7.5 hr nighttime/early morning period in September 2004, the AUV collected dissolved oxygen, conductivity, temperature and depth data along three transects in the Greenwich Bay. The AUV utilized was a new solar powered vehicle designed for continuous survey operations. This vehicle, referred to as the SAUV II, was recently developed for the US Office of Naval Research for long endurance missions requiring monitoring, surveillance, and/or station keeping with real-time bi-directional communications to shore. The vehicle was pre-programmed to transit to designated waypoints at various depths. Following each transect, the vehicle surfaced, maintained a watch circle, and transmitted data to shore via an RF link. The survey provided the participating scientists with near real-time access to the physical characteristics of the water column with improved spatial and temporal resolution over traditional sampling for dissolved oxygen concentrations. This pilot study served as a test of the SAUV II to collect high resolution, near real-time water quality data in a nearshore, shallow embayment. Water column temperature and conductivity was relatively uniform over the survey path (temperature varied from 22-23 °C; conductivity varied from 43030-43981 μS). The depth of the vehicle varied from near-surface to a maximum of 9.5 m. Depth and dissolved oxygen concentrations were correlated. Dissolved oxygen concentrations ranged from approximately 2.4 to 6.0 mg/L over the course of the survey; mildly hypoxic conditions were encountered. The lowest concentrations of dissolved oxygen occurred at the deeper depths (>6 m). As the pilot study was performed in September, the late stage of a hypoxic event was most likely observed- . Using the SAUV II to increase spatial sampling of dissolved oxygen in Greenwich Bay and conducting more frequent SAUV II surveys during the summer months will improve our understanding of hypoxia in this complex coastal estuary.
  Oceans 2005 - Europe; 07/2005