Florida LAKEWATCH
 

The Phlips Side

Dr. Ed Phlips is a professor at UF's Fisheries and Aquatic Sciences program. For almost 20 years his research has been focused on the biology, ecology, and management of algae and aquatic micro-organisms in Florida waters. 
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The Toxic Algae Threat in Florida -
A More Tempered View

The past year has seen an abundance of media accounts concerning toxic algae in the state of Florida. Many of these accounts have involved inflammatory rhetoric, including the recent special report by the Orlando Sentinel entitled 'Health Menace Lurks in Lakes' (Aug. 26, 2001). I was asked to contribute information to this article as it relates to 23 lakes sampled by the Sentinel staff. My own laboratory examined these samples for algal composition and the results were provided to their reporters along with an extensive discussion about the meaning of the results. Unfortunately, the article generated by the Sentinel does not fully reflect my interpretation of the data. The following report provides a more thorough review of my results and their meaning, particularly as it pertains to our current state of understanding about the threat of algal toxins to Florida residents.

Over the past few decades, research on water quality in the state of Florida has revealed numerous lakes that contain high concentrations of blue-green algae (also known as cyanobacteria). These algae are important components of aquatic food webs throughout the world and in Florida, they are often the most abundant form of algae in lakes. This is not surprising considering the sub-tropical climate in Florida and the high concentrations of nutrients present in many of Florida's waterbodies. As the oldest algal group on earth (dating back 3.2 billion years), they have long played a critical role in photosynthetic production in aquatic ecosystems.

Results

In August of this year the Sentinel staff collected water from 23 lakes in the Orlando area and delivered the samples to my laboratory for analysis. August is prime time for algal blooms in Florida lakes. We were asked to perform rudimentary counts of the major blue-green algae species in the samples, with emphasis on two taxonomic groups, Microcystis and Cylindrospermopsis- which contain species shown to be toxic in other regions around the world.

The results obtained by our laboratory, shown in Table1 (below), were provided to the Sentinel in August. It should be noted that these numbers do not match those reported by the Sentinel in their August 26 article because their staff converted our counts to cell numbers.

The results of the analysis are as follows:

• Five of the lakes tested (Beresford, Griffin, Jessup, Harris and Howell) had   high concentrations of Cylindrospermopsis.
• Another four lakes (Harney, Maitland, Apopka and Triplet) contained moderate   levels of Cylindrospermopsis.
• Three of the lakes (Jessup, Beresford and Griffin) had high concentrations   of Microcystis aeruginosa.
• Another seven lakes (Toho, Apopka, Harney, Holden, Harris, Howell and Clear    Lake) had moderate concentrations of Microcystis aeruginosa.

As might be expected, samples with high concentrations of these key algal groups all came from lakes that are known to be eutrophic (i.e. a term used to describe lakes that are rich in nutrients, after the Greek term meaning 'well-fed').

To provide additional information for the Sentinel we included two other groups of blue-green algae, Oscillatoria and Microcystis incerta, that also proved to be major elements of the algal community within the 23 lakes studied. Within the group Oscillatoria, only a few species have been confirmed as producers of potent toxins. Microcystis incerta has not been associated with toxin production.

What the results mean

The results showed that 11 of the 23 lakes tested had moderate to high concentrations of the two algal groups of greatest concern at the time of sampling. Cell counts for these groups are shown in Table 2 (below). It remains to be seen whether these levels of Cylindrospermopsis and Microcystis aeruginosa are typical of these lakes. It is also uncertain whether the specific strains of Cylindrospermopsis and Microcystis aeruginosa observed in these lakes are toxin producers. If they prove to be toxin producers, the question of how much toxin is actually produced by these strains under the environmental conditions found in each lake system will have to be determined. Therefore, at this point these counts can only be labeled as potential toxin producers. It is clear that these systems would be definite candidates for toxin and plankton monitoring research in the future.

It is important to note that even in Australia, where extensive toxic algal research has been done for over a decade, the achievement of certain cell counts does not necessarily allow for a determination of risk. As stated in the current Australian Water Association government web site: "If the water quality exceeds a trigger value (e.g., for cell counts), it is advisable to investigate further to determine the level of risk."

Current Knowledge on the Toxic Algae Threat In Florida

As a matter of perspective, it is important to realize that prior to the 1990s, research on toxin-producing forms of blue-green algae was primarily limited to a relatively small group of scum-loving scientists like me. This changed with the occurrence of several well-publicized incidents involving toxic algae, primarily in Australia. Such incidents demonstrated that the problem of toxic algae warrants serious attention. The past decade has seen a rapid growth in toxic algae research efforts throughout the world. Major efforts to study toxin production by blue-green algae in freshwater ecosystems in Florida began several years ago, even though research on toxic marine algae has been going on for several decades. The first preliminary results of this research are just now being reported. I use the word 'preliminary' for several reasons:

1. The number of lakes and rivers that have been tested for toxins is relatively small and the time period over which the sampling has been carried out is relatively short. This means that we are in the early stages of understanding the scope of this phenomenon in Florida.

2. Although detectable levels of several blue-green algal toxins have been observed in some of these initial samples, there remains controversy over differences in the concentrations of the toxins reported by different independent labs (as described in a recent report by Burns et al. 2001). With time, these methodological issues will undoubtedly be resolved.

3. Most of the information obtained in the Florida research effort has yet to pass the test of peer-review in respected scientific journals. This means that the current interpretations of the preliminary results have yet to be fully examined by the scientific community.

Among the thousands of species of blue-green algae that have been identified, some groups are known to produce toxins under certain conditions. These include several taxonomic groups commonly found in Florida, including Microcystis aeruginos,Anabaena flos-aquae, Cylindrospermopsis and Aphanizomena flos-aquae.

Many media accounts of toxic algae have left the impression that these species are recent arrivals to Florida's lakes and rivers. Our research shows that they have been important members of phytoplankton communities within Florida lakes since at least the 1980s when our testing began. It is also likely that they have been part of Florida's aquatic environments for a long time, although the paucity and often primitive quality of data available before the 1970s makes it difficult to establish a definite date. Establishing the presence of these groups in Florida is, however, only the first step in identifying the toxic risk they represent. This is true for several reasons:

1. It is well known that a group of algae that has been shown to produce toxins in certain ecosystems may not produce toxins in other ecosystems. For example, while Microcystis aeruginosa have been shown to produce toxins within certain lakes around the world, algae identified as the same species in other lakes have been shown not to produce toxins. For this reason the scientific community commonly uses the terms 'toxic and non-toxic strains' to define these differences. In addition, even strains of algae species known to produce toxins vary in the amount of toxin they produce, depending on genetic differences and differences in environmental conditions. These nuances are sometimes lost in the translation when communicating with tthe media or the public. This can be attributed to the fact that the public is more familiar with straight-forward toxic phenomena, such as rattlesnake bites.

2. Identification of algae species is a complex and sometimes controversial process. For example, the taxonomy of the genus Cylindrospermopsis has been an issue of discussion between the experts for several decades. The species that has been associated with toxic events in Australia has been identified as Cylindrospermopsis raciborski. There is still considerable disagreement about whether the form of Cylindrospermopsis found in Florida belong to the same species. This issue has a direct bearing on the toxic threat that Cylindrospermopsis may pose in Florida.

If the species or strains of Cylindrospermopsis found in Florida are not the same as those associated with severe toxin production in other areas of the world , it will take researchers even longer to establish the toxic threat to Floridians. Research is currently underway at several labs around the world to develop genetic markers for toxic strains that will ultimately make this task much easier and more precise.

In summary, the presence of blue-green algae in Florida lakes that are similar to those that have been associated with toxic events in other locations around the world clearly requires serious investigation. The fact that preliminary research has revealed the presence of detectable levels of blue-green algal toxins in certain Florida ecosystems places further weight on the need for this research. However, it will take considerable time and effort to determine the real risk that these potentially toxic species of blue-green pose to the health of ecosystems and people.

What should people do?

1. Don't Panic

The newspaper and television media have focused public attention on the issue of toxic algae. However, the public must realize that many uncertainties remain about the actual threat that algal toxins represent to human health in Florida. Research dealing with these issues is underway and in time there will be a clearer picture of this threat. Meanwhile it is important to keep in mind that people have been using a wide range of lakes and rivers in Florida for recreation for over a hundred years without reports of any overwhelming human health catastrophe involving toxic algae. After the research community has arrived at a definitive picture of the toxic algae threat it should be possible to establish reasonable guidelines to help prevent such catastrophes in the future.

2. Use Common Sense

Until reasonable and justifiable guidelines for exposure to algal populations in Florida's lakes are established the public will need to apply common sense in their recreational activities.

• If you encounter a lake with a nasty surface scum of algae you might choose not to swim in it, as   it probably would not be a pleasant experience, anyway.

• Don't drink large quantities of pond scum. Trust me, it tastes and smells awful and may not be   good for your health.

• If you become ill while recreating in a lake or river, go home. Seek medical attention if it is serious. If possible, report the incident to your local health authority so that data can be accumulated to serve the public good. Remember, however, that the illness may or may not be linked to toxic algae. Such reactions can be associated with a wide range of issues, including bacterial contamination, chemical contamination, allergic reactions, pre-existing medical conditions and in some rare cases the over- consumption of intoxicating substances.

3. Stay Well-Informed

While "a little knowledge can be a dangerous thing," ignorance is much worse. Although newspapers, radio and television media play an essential and powerful role in informing people about important issues, they should not be the soul source of information that concerned citizens rely on. Take the extra effort to seek out information from local and state agencies (i.e., Water Management District, Florida Fish and Wildlife Conservation Commission, Department of Environmental Protection, etc.), public health organizations and university research and public education programs like the Florida LAKEWATCH program.


 
Table 1. Selected cyanobacterial counts for samples collected by the Orlando Sentinel staff

Lake
Cylindro-
spermopsis
trichomes/ml
Microcystis
aeruginosa
(# colonies
<100 cells/colony)
Microcystis
aeruginosa
(# colonies
>100 cells/colony)

Anabaena
trichomes/ml

Oscillatoria (>25m length) trichomes/ml Oscillatoria (<25m length) trichomes/ml Microcystis incerta
(# colonies
<100 cells/colony)
Microcystis incerta
(# colonies
>100 cells/colony)
Anabaen-
opsis
trichomes/ml
Lake Beresford
25083
5821
76
0
72997
20096
32872
3780
454
Lake Griffin
17981
4536
0
0
24484
33778
58942
3704
0
Lake Jessup
7258

8089

0
0
126499
6728
2117
529
76
Lake Harris
7182
3024
0
0
43753
4990
40353
3704
0
Lake Howell
6653
2344
0
302
5216
832
13381
832
0
Lake Harney
3100
3402
0
454
11794
4990
30151
4990
832
Lake Maitland
2873
151
0
76
73451
11247
3931
76
0
Lake Apopka
1964
3476
151
0
2418
756
10577
907
0
Lake Triplet
1058
0
0
227
4234
983
8618
1210
0
Lake Toho
680
3629
0
0
983
0
16772
1814
0
Lake Fairview
453
76
0
60
1991
136
1148
76
0
Lake Underhill
227
605
0
0
37406
11567
5972
0
0
Lake Holden
151
3402
0
0
59849
62569
1663
0
0
Clear Lake
76
983
0
0
47380
15261
2570
227
0
Lake Mineola
49
0
0
0
205
8
57
0
0
Lake Downey
38
0
0
0
114
30
1254
114
0
Lake Butler
6
0
3
0
42
3
273
15
0
East Lake Toho
0
6
0
0
48
21
786
54
3
Lake Eola
0
0
0
0
3141
1208
393
181
0
Lake Dorr
0
0
0
0
2745
78
0
0
0
Crane's Roost
0
0
0
0
15
15
136
76
0
Lake Ashby
0
0
0
0
0
15
23
0
0
Lake Conway
0
0
0
137
99
8
1254
53
0

Table 2. My estimated cell counts of potentially toxic blue green algae (including Cylindrospermopsis,Microcystis aeruginosa and Anabaena).
Lake
My estimates cells/ml
Lake Beresford
386,397
Lake Griffin
275,228
Lake Jessup
267,548
Lake Harris
140,238
Lake Apopka
134,789
Lake Howell
121,489
Lake Harney
117,482
Lake Tohopekaliga
96,844
Lake Holden
86,411
Lake Maitland
30,391
Clear Lake
25,250
Lake Underhill
17,161
Lake Triplet
11,794
Lake Fairview
6,569
Lake Conway
1,368
Lake Butler
654
Lake Minneola
443
Lake Downey
342
East Lake Tohopekaliga
150
Lake Eola
0
Lake Dorr
0
Crane's Roost
0
Lake Ashby
0
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