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Rosenberg 2002), although the cause of such infections is not uniquely linked to a
specific pathogen (Polson et al. 2008). Studies of pathogens attached to atmospheric
particulates suggest that deposition of fungi and bacteria to the Park from outside by
aerosol means is quite likely to occur. Some concerns have been raised for this to be a
driving force for the coral declines seen in recent years but proof is inconclusive.
Microbial contamination from terrestrial sources does occur and is a potential problem
for Biscayne National Park. Given that data is sparse so the threat is inferential.
Pesticides and herbicides
Key et al. (2003) examined pesticides attributed to contaminated canal discharge
levels in grass shrimp and found correlation between reduced levels of
acetylcholinesterase enzyme and canal chemicals at Military and North Canals. Cantillo
and Lauenstein (2004) analyzed samples from South Biscayne Bay and Manatee Bay
for contaminated marine sediment. Eight types of pesticide were found in seawater
samples including atrazine, metolachor, CEAT, CIAT (metabolized herbicides),
chlorpyrifos, diazinon, malathion, and 4,4’DDE (DDT metabolite). The majority was
found at highest levels at the upstream sites associated with the canal network, at the
mouths of the canals. Metolachlor was present at all sites sampled. Two sites, Princeton
Canal mouth and Florida City Canal mouth had high levels of ethoxylates which can be
an endocrine disruptor. Carriger and Rand (2008) assessed the aquatic risk caused by
atrazine, metolachlor, malathion, chlorpyrifos and endosulfan in south Biscayne Bay
and found that atrazine was the most frequently detected pesticide but only at low
levels. Harman-Fetcho et al. (2005) studied pesticides associated with agricultural
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runoff to the canal network and found that there were seasonal variations and that
harvest season when endosulfan is commonly used had a higher hazard potential.
Seba (1969) reported pesticides associated with surface microlayers in Biscayne Bay
were related to atmospheric transport and deposition.
Past and present use pesticides and herbicides have been consistently detected
in canals and near-shore locations along the southern portions of the bay. For example,
atrazine and some of its metabolites are present in almost all water samples collected in
the freshwater environments at concentrations up to approximately 100 ng/L and also in
coastal areas at lower levels 5-10 ng/L. A similar trend is also evident for the herbicide
metolachlor. However, the water quality guidelines for these herbicides are several
orders of magnitude above the environmental concentrations thus unlikely to produce
detrimental effects. Legacy pesticides, mainly p,p’-DDE (metabolite of DDT) is often
found in canal sediments and occasionally in areas immediately adjacent to canal
discharge points (Princeton, Military, Mowry, North and Florida City canals and at Black
Point Marina). Gardinali et al. (2008c) examined the levels of endosulfan in fish tissues
from BNP and Everglades National Parks and reported that endosulfan sulfate is
generally present in areas of Everglades National Park near the Homestead Agricultural
Area but seldom detected in coastal areas of Biscayne Bay.
Metals
Judge and Curtiss (1977) examined sediment samples from the middle of
Biscayne Bay (just north of the park) for heavy metal contamination and found little
difference between most areas sampled except for lower values near Fisher Island and
a sink for metals in sediments near the mouth of the Miami River. They expressed the
concern that south Biscayne Bay may have been polluted by waters from Miami River
flowing south under Rickenbacker Causeway. Schroeder and Thorhaug (1980)
examined uptake of trace metals into seagrass blades finding higher levels in tissues
than in the surrounding water. Miller (1984) analyzed the runoff from several different
basins types in South Florida and found the highest lead runoff was from a commercial
(shopping center) type basin. Cantillo and Lauenstein (2004) analyzed samples from
South Biscayne Bay and Manatee Bay for contaminated marine sediment. The total
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trace metals (Cu, Zn, Ni, Pb, Cd, Hg, Ag) found in sediments at the mouths of five
canals studied indicated toxic conditions were likely. Lidz (2002) reported initial results
of surface sediment samples analyzed for heavy metals and concluded that Cu, Pb, and
Zn were highest near marinas in the northern parts of the bay, that metal contamination
decreased southward and seaward. Among the trace metals, Copper, Arsenic, and
Lead have been reported in sediments of the bay at concentrations that are above the
national median for the NOAA NS&T Mussel watch program and in some cases above
the 85th percentile. However, all the values reported for south Biscayne Bay away from
the influences of marinas are below the ―probable effects level‖ (PEL) or the sediment
quality assessment guidelines (SQAGs) for coastal sediments used in Florida to assess
sediment contamination. With regards to mercury levels in biota, Evans et al. (2008)
reported mercury levels in fish samples from Florida Bay and Biscayne Bay with highest
values in Crevalle jacks found in south Florida and in other species associated with
areas of restricted circulation.
Anti-fouling agents
In the past decade, some non-traditional contaminants have also been reported
in the vicinity of BNP. Organotin (TBTs) related antifouling compounds were reported in
sediments at the North Canal at Homestead Bayfront Marina and Irgarol 1051, an
antifouling booster biocide, has also been reported in many marinas in the bay. All
these pollutants are related only to boating activity and transport beyond their localized
usage area is not expected. Since TBTs have been banned, Irgarol 1051, in conjunction
with copper are contaminants that need to be further monitored with respect to marinas
and boatyards. Maxey (2006) analyzed surface water, seagrass, and sediment for the
antifouling biocide Irgarol 1051 and its metabolites. Concentrations of Irgarol in surface
water and seagrass ranged from N.D. to 1239 ng/L and 2.35 ng/g to 225 ng/g,
respectively. Concentrations of Irgarol in sediments were negligible (< 10 ng/g).
Bioconcentration factors (BCF) are measurement of the ratio of the chemical
concentration in a marine organism compared to that of the surrounding water. BCFs
greater than 1000 are considered to be accumulative, while BCFs greater than 5000 are
considered highly accumulative. BCF values for Irgarol uptake into seagrass ranged
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from 60 to 31588. While Irgarol was found at the majority of the marinas sampled, no
Irgarol was found at any coral reef, the specie reported to be the most sensitive to
Irgarol.
PCBs and PAHs
Lang and coworkers (Lang et al., 2002) reported the abundance and atmospheric
deposition of a variety of organic contaminants, including polychlorinated biphenyls
(PCBs) and polycyclic aromatic hydrocarbons (PAHs), in the Miami metropolitan area.
PAHs are commonly present in many sediment samples but their concentrations are
relatively low and consistent with background levels in urbanized areas. Marinas,
however, represent a deviation of this observation and is common to see sediments in
canals and access areas to major marinas to have elevated concentrations of Total
PAHs. Litz et al. (2007) reported total PCBs (sigma 73PCBs) present in the highest
concentrations and 5 times higher in males dolphins with sighting histories in the
northern, metropolitan area of Biscayne Bay than males with sighting histories in the
southern, more rural area. All compound classes had higher concentrations in northern