http://www.aslo.org/lo/toc/vol_42/issue_5_part_2/1119.pdf

Florida Bay Nutrients: Perspectives on the July 1-2, 1996 workshop

Report of the  Florida Bay Science Oversight Panel Ad Hoc Committee on Nutrients, National Academy of Science 

D.F. Boesch (Chair), J.M. Caffrey, J.E. Cloern, C.F. D’Elia, D. M. DiToro and W. W. Walker,Jr.
Submitted to the  Program Management Committee, Florida Bay Research Program 15 July 1996

This was the first official recognition that the Everglades plan to increase the flow of polluted water from the mainland into Florida Bay was flawed and could have serious impacts on Florida Bay and the downstream coral reefs of the Florida Keys.

SUMMARY
An Ad Hoc Committee on Nutrients convened under the auspices of the Florida Bay Science Oversight Panel participated in a two-day workshop of investigators and program managers on nutrients in Florida Bay. It was asked to evaluate the adequacy of databases and research and monitoring programs for deriving inferences about nutrient sources and processes in Florida Bay and how they may change as freshwater inflows increase in association with hydrological restoration of South Florida. The Committee’s main perspectives and recommendations are summarized below:

An important determinant of the supply of nutrients to the Bay is water flow and circulation, the most poorly quantified element of which is the exchange between western and central Florida Bay. There should be a concerted effort using salinity modeling, tracers and flow measurements to quantify these exchanges and their importance in supplying phosphorus (from deeper Gulf waters) and nitrogen (from the Shark Slough plume into western and central Florida Bay).

Although nutrient concentrations in freshwater effluents from the Everglades are now adequately monitored, because of the limited duration and high variability of the record recent variations in nutrient concentrations cannot be confidently attributed to water-management practices. The transport and transformation of nitrogen across the mangrove/estuarine transition and in the coastal flows toward Florida Bay remain important unknowns.

Box models of nutrient budgets for Florida Bay should be developed which include the major forms of N and P and at least three different geographic segments – western (west of Everglades National Park boundary), central and eastern – as a parallel and contributory exercise with the planned numerical simulation model.

In the shallow, warm, well lit Florida Bay cycling and transformation of nutrients may be as important as sources and concentrations in affecting plant growth. The current research on phytoplankton and biogeochemical processes should be expanded to focus on mechanisms of nutrient cycling rather than simply making inferences from nutrient distribution patterns.

Studies of nutrient limitation have shown that nitrogen limits phytoplankton growth in the western Bay, several nutrients may co-limit growth in the central Bay, and phosphorus typically limits growth in the eastern Bay. Understanding the causes of algal blooms now requires process studies using modern tracer and enzymatic techniques, intense time-series rather than semi-annual or monthly measurements, and field or mesocosm, as well as in vitro, experiments. The Program Management Committee (PMC) should explore opportunities for engaging experts in such approaches and facilitating the intense multidisciplinary studies required. The data and observations in support of the divergent perspectives offered regarding the effect on the coral reefs of export of nutrients from Florida Bay of the Florida Keys Marine Sanctuary are sketchy and anecdotal. Nutrient transport mechanisms and concentrations and grazing pressure on macroalgae must be considered together in addressing this question. The Florida Bay Research Program could contribute to the first of these factors.

Concerns about the comparability of chlorophyll and nutrient data were raised. Data comparability is essential and quality assurance/quality control exercises now being undertaken should be expanded and maintained.

Inconsistency of geographic references contributes confusion and interferes with the development of scientific consensus. The PMC should oversee an effort to develop a common set of names and boundaries for regions of Florida Bay. To the extent practicable, a common set of reference sites should also be selected for field measurements and experiments.

A nutrient-plankton bloom team of investigators should be formed to facilitate interpretation and use of monitoring and research data.

The Committee fully supports the PMC’s efforts to develop a coupled circulation-ecosystem model of Florida Bay as a tool to systemize data, pose hypotheses, and anticipate the effects of different water management scenarios. The coupled model should be designated to describe the dynamics of these key features of the Florida Bay ecosystem: (1) coupled hydrodynamic-nutrient-phytoplankton-water quality variability, (2) suspended sediments and their influence on turbidity, and (3) seagrass populations and their influence on sediment resuspension, nutrient cycling and geochemistry.
Although hydrologic flow and water level goals guide the restoration of the Everglades, no specific restoration goals for Florida Bay have been set which could guide research as well as management activities. A subcommittee or task force of specifically address the restoration goals for Florida Bay.

Because the freshwater effluent of the Everglades has very low concentrations of phosphorus and phytoplankton and macroalgal growth in the northeastern Florida Bay is strongly phosphorus limited, the Committee’s provisional judgement is that the planned redistribution of fresh water into the Taylor Slough system will not lead to or worsen acute symptoms of over-enrichment in Florida Bay. However, the consequences of this plan have not been assessed with even simple mass balance models and must be regarded as uncertain as this point.

For more info, go to:  http://www.nap.edu/openbook.php?record_id=10479&page=9  Florida Bay Research Programs and their relation to the Everglades Restoration Plan (2002).

Roland E. Ferry, Ph.D.-Water Management Division/Coastal Programs Section

Note:  Reef Relief’s Craig Quirolo provided vessel and technical support for this study, which helped us finally end ocean dumping in Key West. This outfall has been replaced with advanced nutrient-stripped wastewater treatment and a deep injection well.

Summary:
The US Environmental Protection Agency, Region4, directed and conducted a series of studies of the Key West Florida wastewater treatment plant ocean outfall from August 1993 to November 1994: The studies examined local hydrographic conditions, effluent transport and dilution in the receiving waters, geochemical and biological fate of effluent constituents, wastewater contributions to the benthos and to local eutrophication and impacts to macrobenthic communities.

Hydrodynamic conditions in the immediate area around the outfall on the ebb tides tend to transport effluent to the east, roughly parallel to the southern shorelines of the lower Keys and to the north into the Gulf of Mexico on the flood tide. High velocity tidal currents appear to confine the effluent largely to areas east of the Key West navigation channel. Effluent dilution exceeds 90:1 within 750 meters of the outfall and approaches 1000:1 within 2500 meters. Modeling results predict dilutions exceeding 32,000:1 at offshore bank reefs.

Nitrogen and carbon stable isotope studies indicate that outfall particulates are not a major component of particulate matter in benthic environments near the outfall or offshore bank reefs and that seagrass inputs are a primary source of sediment nitrogen in the area. The isoptopic dissimilarity between effluent and sediments suggest weak pelagic-benthic coupling in the area, probably due to strong currents and high rates of dilution. Outfall particulates do, however, appear to comprise a major component of the diet of some filter feeding macrobenthic organisms near the outfall, but not a major contributor of nitrogen to marine macrophyes around the outfall.

Coprostanol (fecal sterol) analysis of area sediments indicated sewage contamination of the benthos for several kilometers north and south of the outfall and along the southern shore of Key West. The outfalls relative contribution to sediment contamination cannot be distinguished from that of other likely (live-aboards mooring fields) and potential (ship discharges) sources of domestic wastes.

Benthic infaunal community analysis determined that there is no significant structural differences in macroinfaunal between communities in a sewage contaminated area by wastes and communities in an uncontaminated reference location.

The results of this series of studies indicate that wastewater effluent impacts from the Key West ocean outfall are mainly limited to localized eutrophication and contributions to some sewage contamination of the benthos in the vicinity of the outfall. The probability of transport of any significant amounts of outfall contaminants to offshore bank reefs appears to be low.

Trends in Ecology and Evolution, Volume 13, Number 11, 1 November 1998 , pp. 438-443(6) 

Laurie L. Richardson
Department of Biological Sciences, Florida International University, Miami, FL 33199, USA
(ricardl@fiu.edu)

Reports of new and emerging coral diseases have proliferated in recent years. Such coral diseases are often cited as contributing to coral reef decline. Many of these diseases, however, have been described solely on the basis of field characteristics, and in some instances there is disagreement as to whether an observed coral condition is actually a disease. A disease pathogen has been identified for only three coral diseases, and for only two of these has the pathogen been shown (in the laboratory) to be the disease agent.. In one case, the same disease name has been used for several widely varying coral syndromes, whereas in other multiple disease names have been applied to symptoms that may have been caused by a single disease. Despite the current confusion, rapid progress is being made.

Coral disease emergence in the 1990s
There have been many reports of new coral diseases in the 1990s. These include red band disease, yellow band disease, yellow blotch disease, dark spot disease, white pox, sea fan disease and rapid wasting disease. The emergence of theses dideases was broadcast in the popular literature, on coral reef websites and on coral-reef related internet servers as anecdotal observations. For most of these diseases, supporting data were limited to photographs of afflicted coral colonies. In many cases, it is not clear that what is being shown is actually a disease. The status of these new diseases is extremely confusing.

Only one of the recently emerging new coral diseases has been systematically characterized. Asperillogosis of sea fans (gorgonian corals) rapidly swept through the reefs of the Caribbean and the Florida Keys in 1995 and 1996, resulting in mass mortalities as result of tissue-degrading lesions. A team of investigators, using both laboratory and field techniques, showed that the lesions were caused by the terrestrial fungus Apergillus sydowii (proven in laboratory experiments that fulfilled Koch’s postulates, see Koch’s postulates for demonstrating the identity of a pathogenic microorganism), and that disease incidence was correlated with water depth and protection from wave exposure. The disease still persists throughouht the western Atlantic. These investigators have postulated that an unexplained, but well documented, mass mortality of sea fans that occured throughout the Caribbean during the 1980s was an earlier epizootic of the same disease. This conjecture is based on photographs of diseased sea fans from the 1980s event that reveal the same lesions now known to be caused by A. sydowii. The effect of this extensive sea-fan mortality on the reef ecosystem is not known.

Results of Studies of individual coral diseases
A summary of what is currently known about coral diseases (including only peer-reviewed literature that contains original data) is presented in Koch’s postulates (see Koch’s postulates for demonstrating the identity of a pathogenic microorganism). The main conclusions are as follows:

• There are currently only four diseases for which both coral tissue destruction leading to mortality, and the presence of a consistent, characteristic microorganism (or microbila consortium) associated with the disease are known. These are aspergillosis, black band disease, white band disease type II and plague type II. This is in contrast to the 13 individual coral diseases put forth by various investigators.
• Only 3 diseases (aspergillosis, black band disease and plague type II) have an associated microorganism (or microbial consortium) that has been demonstrated to be the disease pathogen.
• The mechanism of coral tissue death is known only for black band disease.
• Only white band disease has been shown to restructure a reef on a regional scale.

Most coral diseases, including new ones and some new ones that were first described in the 1970s and 1980s, have been only partially characterized. These include white band type I, plague type I, shut down reaction, red band disease, yellow blotch, rapid wasting disease, dark spot disease and white pox. No pathogens have been identified for nay of these diseases, and confusion is prevalent. Despite this, many of these syndromes are currently included in monitoring programs designed to evaluate coral reef health.

Current research by many of the investigators cited in this review is focusing on new areas, such as discerning mechanisms of aspergillosis resistance in sea fans, applying molecular probes to confirm identities of pathogens in outbreaks in different regions, and experimental manipulations to trigger disease activity from reservoir populations. Moreover, much current research is aimed at determining the relationship, if any between increased nutrients and coral disease.

The continuation of rigorous research efforts of recent years, specifically those that go beyond descriptive studies, is of critical importance for a complete understanding of coral diseases. A word of caution, however: until a pathogern has been identified for each of the uncharacterized coral diseases (including fulfillment of Koch’s postulates), these syndromes should be clearly identified as potential disease states and not coral diseases.

Koch’s Postulates

Disease related research in other areas of scientific endeavor always includes strict attention to fulfillment of Koch’s postulates ( a procedure set forth by Robert Koch in the 1870s) by which a presumed disease pathogen is demonstrated to be the cause of a disease. To demonstrate unequivocally the identity of a pathogenic microorganism, the following must be carried out:

• The microorganism must be documented as always being found associated with a particular disease.
• The microorganism must be isolated from the disease state and grown in pure culture under laboratory conditions.
• The pure culture of the microorganism must produce the disease when inoculated into a healthy animal.
• The microorganism must be re-isolated from the newly diseased animal and identified as the same microorganism as the presumptive pathogen.

Satifaction of Koch’s postulates when the host is a coral is challenging for several reasons. First, duplication of the normal reef environment in library aquaria is difficult, especially in terms of water movement (currents vs. Aeration) and microorganisms present in the water column. Second, the natural mode of infection is not known as a coral disease. Consequently, inoculation by syringe or after wounding the host tissue could be as unnatural as exposure to concentrated suspensions of pathogen in aquarium water of placement of colonies on pathogen-inoculated plates. Finally, it is difficult to prove the re-isolation of the pathogen by sampling the newly diseased experimental coral. Because some diseases are present on the surface of coral tissue, and experimental inoculation usually involves inoculation of the aquarium environment, recovery of the test microorganism could be compromised by the presence of contaminated aquarium water.

Microbial Pests–Coral Disease in the Western Atlantic

Proc. 8th Int. Coral Reef Symp. 1:607-612.  1997

D.L. Santavy and E.C. Peters
U.S. Environmental Protection Agency, Gulf Ecology Division, 1 Sabine Dr., Gulf Breeze, Florida 32561, U.S.A
Tetra Tech., Inc. 10306 Eaton Place, Suite 340, Fairfax, Virginia 22030, U.S.A

ABSTRACT

Diseases of sceleractinian corals have increased significantly over the last decade, affecting greater number of species around the world. Gross signs of coral disease are often observed in tissue loss on the skeleton, making differential diagnosis difficult. Using the histopathological and infrastructural techniques, coupled with microbiological analyses, the importance of microorganisms as pathogens in coral diseases is becoming more apparent.

This paper addresses the ecology of pathogens on reefs, specifically bacreria and cynobacteria that produce disease in scleractinian and acyonarian corals.

We review the nature of the disease and the influence of adverse environmental conditions. An update is presented on research concerning the bacteria associated with black- and white- band diseases; observations are presented concerning other coral diseases in the western Atlantic that appear to be caused by bacteria. We conclude with suggestions for improving the recognition that include research to identify bacterial pathogens and the role of environmental factors in the development of coral disease.