Effects of Stormwater Nutrient Discharges on Eutrophication Processes in Nearshore Waters of the Florida Keys, by Brian E. Lapointe and William R. Matzie © 1996 Coastal and Estuarine Research Federation. Estuaries Vol 19 No.28 pp422-435 http://www.erf.org/estuaries-coasts

Abstract

Rainfall events cause episodic discharges of groundwaters contaminated with septic tank effluent into nearshore waters of the Florida Keys, enhancing eutrophication in sensitive coral reef communities. Our study characterized the effects of stormwater discharges by continuously (30-min intervals) measuring salinity, temperature, tidal stage, and dissolved oxygen (DO) along an offshore eutrophication gradient prior to and following heavy rainfall at the beginning of the 1992 rainy season. The gradient included stations at a developed canal system (PP) on Big Pine Key, a seagrass meadow in a tidal channel (PC), a nearshore patch reef (PR), a bank reef at Looe Key National Marine Sanctuary (LK), and a blue water station (BW) approximately 9 km off of Big PIne Key. Water samples were collected at weekly intervals during this period to determine concentrations of total nitrogen (TN), ammonium ( NH₄⁺), nitrate plus nitrite ( NO₃^- plus NO₂^-), total phosphorus (TP), total dissolved phosphorus (TDP), soluble reactive phosphorus (SRP), and chlorophyll a (chl a). Decreased salinity immediately followed the first major rainfall at Big Pine Key, which was followed by anoxia <latex>$(\text{DO}<0.1\ {\rm mg}\ {\rm l}^{-1})$</latex>, high concentrations of NH₄⁺ (∼24 μM), TDP (∼1.5 μM), and chl a (∼ 20 μ g l^-1). Maximum concentrations of TDP (∼0.30 μM) also followed the initial rainfall at the PC, PR, and LK stations. In contrast, NH₄⁺ (∼4.0 μM) and chl a (0.45 μg 1^-1) lagged the rain event by 1-3 wk, depending on distance from shore. The highest and most variable concentrations of NH₄⁺, TDP, and chl a occurred at PP, and all nutrient parameters correlated positively with rainfall. DO at all stations was positively correlated with tide and salinity and the lowest values occurred during low tide and low salinity (high rainfall) periods. Hypoxia (DO < 2.5 mg l^-1) was observed at all stations following the stormwater discharges, including the offshore bank reef station LK. Our study demonstrated that high frequency (daily) sampling is necessary to track the effects of episodic rainfall events on water quality and that such effects can be detected at considerable distances (12 km) from shore. The low levels of DO and high levels of nutrients and chl a in coastal waters of the Florida Keys demand that special precautions be exercised in the treatment and discharge of wastewaters and land-based runoff in order to preserve sensitive coral reef communities.

Nutrient couplings between on-site sewage disposal systems, groundwaters, and nearshore surface waters of the Florida Keys

BRIAN E. LAPOINTE, JULIE D. O’CONNELL, & GEORGE S. GARRETT

Biogeochemistry (10) 1990. 289-307

Abstract
We performed a one-year study to determine the effects of on-site sewage disposal systems (OSDS, septic tanks) on the nutrient relations of limestone groundwaters and nearshore surface waters of the Florida Keys. Monitor wells were installed on canal residences with OSDS and a control site in the Key Deer National Wildlife Refuge on Big Pine Key. Groundwater and surface water samples were collected monthly during 1987 and analyzed for concentrations of dissolved inorganic nitrogen (DIN = NO3- + NO2- + NH5-), soluble reactive phosphate (SRP), temperature and salinity.

Significant nutrient enrichment (up to 5000-fold) occurred in groundwaters contiguous to OSDS; DIN was enriched and average of 400-fold and SRP some 70-fold compared to control groundwaters. Ammonium was the dominate nitrogenous species and its concentration ranged from a low of 0.77 uM in control wells to 2.75 mM in OSDS-enriched groundwaters. Concentrations of nitrate plus nitrite were also highly enriched and ranged from 0.05 uM in control wells to 2.89 mM in enriched groundwaters. Relative to DIN, concentrations of SRP were low and ranged from 30 nM in control wells to 107 uM in enriched groundwaters. N:P ratios of enriched groundwaters were consistantly > 100 and increased with increasing distance from the OSDS suggesting significant, but incomplete, adsorption of SRP by subsurface flow through carbonate substrata.

Nutrient concentrations of groundwaters also varied seasonally and were approximately two-fold higher during the winter (DIN = 1035 uM; SRP = 10.3 uM) compared to summer (DIN = 470 uM; SRP = 4.0 uM). In contrast, surface water nutrient concentrations were two-fold higher during the summer (DIN = 5.0 uM; SRP = 0.50 uM) compared to winter (DIN = 2.5 uM; SRP = 0.15 uM).

Direct measurement of subsurface groundwater flow rate indicated that tides and increased groundwater recharge enhanced flow some two-fold and six-fold respectively. Accordingly, the observed seasonal coupling of OSDS-derived nutrients from groundwaters to surface water waters is maximum during summer because of seasonally maximum tides and increased hydraulic head during summer wet season. The yearly average benthic flux of anthropogenic DIN into contiguous canal surface waters is 55 mmolm day value some five-fold greater than the highest rate of benthic N-fixation measured in carbonate-rich tropical marine waters.

Health Dangers Arise From Pumping Of Sewage Into Deep Sea
From Ocean Update September 1999 Vol. 4, No. 9

Paul R. Epstein, Center for Health and the Global Environment, Harvard Medical School. Tel (617) 432-0493
An outbreak of cholera on the southern Coast of Bangladesh in 1992 may presage the risks posed to developed and less-developed countries alike from deep-sea dumping of human sewage, according to some researchers. Scientists have noted that the 1992 outbreak was accompanied by an upwelling that brought deep-sea water to the surface near the Bangledeshi coast. In recent years, researchers have discovered a variety of pathogenic microbes, many usually found only in human feces, at unexpected depths of the ocean. Marine scientist D. Jay Grimes of the University of Southern Mississippi says that a variety of viruses that infect the human gastrointestinal tract – including poliovirus and rotavirus – have been identified in ocean water samples taken below 1,0000 meters (3,300 feet). In the late 1980’s, Sagar M. Goyal of the University of Minnesota isolated gut bacteria from samples obtained as sewage-sludge dumping sites more than 170 kilometers offshore from New York City, 30 months after the sites were closed to dumping. The bacteria were resistant to several antibiotics, showing that they originated from humans who were taking the drugs.

Although the scenario by which such microbes could reach the surface is unclear, Dr. Paul Epstein of the Harvard School of Medicine has expressed concern about the presence of pathogens in the deep ocean, particularly the given proliferation of projects such as miles long pipelines to take sewage out to sea.

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 Coral Reefs 18 (1): 1997.

by D.L. Santavy*, E.C. Peters, C. Quirolo, J.W. Porter, C.N. Bianchi.
Corresponding author: U.S. Environmental Protection Agency, Gulf Ecology Division, Gulf Breeze, FL., 32561, USA. e-mail: santavy.debbie@epamail.epa.gov

Esther C. Peters
Tetra Tech, Inc.
10306 Eaton Place, Suite 340
Fairfax, VA 22030
(703) 385-6007

Reef Relief’s Craig Quirolo first observed yellowband disease on corals near Key West in 1994 as part of his ongoing multi-year Coral Survey.  He documented the outbreak and alerted Reef Relief Scientific Advisor Dr. James Porter of UGA who arrived with a team that investigated the outbreak and named it yellow band disease.  Some scientists have since determined that it should be called yellow blotch disease.  To see survey images go to:  http://www.reefreliefarchive.org/cgi-local/ImageFolio31/imageFolio.cgi?direct=Yellow_Band_Disease

An extensive outbreak of coral disease was observed affecting the scleractinian corals Montastrea Faveolata and M. Annularis at San Blas, Panama, in the eastern Caribbean region. The first report of this disease referred to it as “yellow-band disease”, and it was observev on colonies of M.faveolata on reefs off Key West, Florida (Reeves 1994). Santavy and Peters (1997) proposed the name “yellow-blotch disease” (YBD based on the unusual pattern of yellowish tissue lightening, and to distinguish it from the yellow band disease reported by Korrubel and Reigl (1998) in the Arabian Gulf. Yellow-blotch disease is characterized by circular to irregularly-shaped patches or wide streaks of lightened transluscent tissue, occuring in no particular pattern on the surface of the colony, but more common on the uppermost surfaces. The color of affected tissue is yellow, not pale brown to white as occurs in bleaching.

Occasionally, bright white transluscent patches of tissue appear adjacent to yellowish ones. The affected tissues otherwise appear grossly normal. The lightened patches frequently, but not always, are adjacent to or form a margin around algal/sediment accumulations on dead coral skeleton. No “band” of clean, denuded skeleton is usually present.

The disease was present on most reefs examined at San Blas in 1996. At the western tip of the Salar Islands group (approximately 78 degrees 48.5’W,9 degrees 31’N), 6 to 18 m deep on the forereef, about 5% of all M. faveolata colonies were affected. Affected colonies had from one small patch of discolored tissue to numerous large patches of algal/sediment accumulations adjacent to yellowish tissues with extensive tissue tissue loss. Yellow-blotch disease was not observed here 25 years ago. The reefs are considered to be relatively spared from anthropogenic pollution and diving pressures. However, our assessment is that a major die-off of M. Faveolata is occurring in San Blas, which is of geological significance since it is the primary reef builder.

Similar signs of disease have been observed on Montastrea spp. Elsewhere, including the severly affected Netherlands Antilles (TJ Goreau and JM Cervino, AW and RJ Bruckner, per. Commm.); Key West; Negril, Jamaica; Isla Cocos and Marie La Gorda, Cuba; and Guanaja and Bay Islands, Honduras. However, the presence of unaffected large and small colonies of M. faveolata suggests that some colonies might be resistant or have not been exposed in a manner that results in an active infection.

Acknowledgement We thank Ken Clifton, the Captain and crew of the Daiquiri, the Smithsonian Tropical research Institute, and the Kuna Indians for their assistence in San Blas. Key West observations were supported by Reef Relief.