2001 Progress Report: Nutrient Cycling and Algal Productivity in the Florida Keys

EPA Grant Number: R828020C002
Subproject: this is subproject number 002 , established and managed by the Center Director under grant R828020
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).

Center: National Center for Caribbean Coral Reef Research (NCORE)
Center Director: McManus, John W.
Title: Nutrient Cycling and Algal Productivity in the Florida Keys
Investigators: Szmant, Alina
Institution: University of North Carolina - Wilmington
EPA Project Officer: Packard, Benjamin H
Project Period: December 15, 1999 through December 14, 2003
Project Period Covered by this Report: December 15, 2000 through December 14, 2001
RFA: National Center for Caribbean Coral Reef Research (1999) RFA Text |  Recipients Lists
Research Category: Congressionally Mandated Center , Targeted Research

Progress Summary:

The aims of the Year 1 and 2 work remain the same as in the proposal. We have been able to complete three 2-week field sessions (May and Aug 2000, February 2001) in the Florida Keys, with support from the National Undersea Research Center of UNCW, during which we have measured algal percent cover, biomass and algal productivity at 11 stations representing three habitat types (patch reef, relic reef, and high-relief reef). We found after the first trip that the 2-week duration for the productivity/caging studies was not long enough, and so we modified our method slightly for the August period (we did not clip back the algal biomass to such low levels as the first time), and for the February trip (the cages were put out three weeks before the field trip so that more algal biomass could accrete). We also worked at being more consistent in which reef zone we sampled. Initially were followed behind the fish survey team, but because of differences in sampling scale and logistics, we were not able to sample all of the same transects they sampled. We were concerned that the way we were sampling we would not be able to connect the fish and algal community data sets, and this is a primary goal of the project. During the February 2001 trip, a more concerted effort was made to integrate better the two sampling protocols.

We had to reduce the number of transects and biomass samples we collected at each station because of time constraints. We spent 8 or more hours per day in the field and then had 8-10 hours of samples to process each night. This proved to be too much work for our team of 3-4. We have since been successful at recruiting volunteers from The Nature Conservancy's community volunteer program to help with the algal sorting in Key Largo. This has made it feasible to get the algal samples processed in a timely fashion. Altogether ca. 180 algal samples were collected each trip that had to be sorted to algal species or functional group, dried, weighed and packaged for return to UNCW. Each sample had 5 or more types of algae in it, and so we have processed close to 2000 samples to date.

Sample and data analysis: Dried algal samples from the various biomass quadrats were pooled for each station for determination of ash-free dry weight, N and P analysis. All of the AFDWs, N and P contents were measured for the May samples by the temporary interns. We are re-analyzing some of these to make sure that the results are consistent. The August samples have been pooled and ground but their chemical analysis has not been started. No work has been done on the February 2001 samples since they just returned from the field.

The visual estimates of % cover for the May and August dates have been entered into the computer and statistical analysis and graphing is proceeding. We have not had the personnel to work on the photographs until Shauna Slingsby arrived, and she has just started analyzing the photographs for % cover. We have confirmed that the photographs underestimate algal turf and crustose coralline algae, two important components of coral reef algal communities, because of the sediments that more often than not blanket the reef substrate. This layer of sediment, often more than 1 cm thick, is fanned away before doing the visual estimates of percent cover, but not before doing the photographs (because doing so makes the water turbid and thus unsuitable for photography). While it is important to continue to take the photographs since they provide a permanent record of the sites, they may not be the best tool for actually estimating percent cover of those algal groups, or of algal species found in trace quantities. Thus the visual estimates appears to provide the more complete estimate of algal community structure even when there are concerns about variability in producing the estimates. The photographs produce higher estimates for the more abundance macroalgal groups that are distributed in small patches over the plots, indicating that visual estimates underestimate those types of algal distributions. Therefore, it appears that to both methods are necessary to provide best estimates of algal community structure.

For our task of collaborating of the nutrient sources task, Dr. Dafner has participated on one water sampling cruise (October 2000), and water samples were collected for us for nutrient analysis on two additional cruises (December 2000, and February 2001). The samples from the first 2 cruises have all been processed and the data sent to Dr. Peter Swart for his use with his N-15 data.

The sediment enrichment experiment has been delayed until Year 2 because my new nutrient lab at UNCW was not operational in time to support the work, and because I had not yet been able to recruit the student who will be working on the experiment.

Changes in Key Personnel

Project funding did not arrive at UNCW until April 1, 2000, and so the initial parts of the work was accomplished with student interns that were recruited to work during the late spring and early summer of 2000. These have been replaced with a graduate student (Andy Martin) who began working on the project July 15, 2000, and a second graduate student (Shauna Slingsby) began on December 6, 2000. A RSMAS graduate student was hired to help with the August field work. One UNCW and one RSMAS graduate student each were hired for the February field trip. I anticipate that I will need to continue to hire temporary help for the field work since optimally we need a team of 4 people for each trip to work on the algal sampling and processing.

Mr. Scott Kaczynski who helped prepare our initial QA/QC plan left the employ of UNCW in June of 2000. He has been replaced by Dr. Evgeny Dafner who is the now the nutrient chemist in charge of nutrient analysis and QA/QC. Dr. Dafner is not paid off of NCORE funds; he is a permanent employee of the State of NC.


About 2/3 of the work planned for Year 1 has been completed and about 70 % of the Year 1 funds have been expended. Re-budgeting was done to allow for the purchase of a digital camera for taking the photoquadrats. The algal vacuum systems which were to be purchased were instead manufactured by CMS's machine shop and electronic technicians (our original vendor apparently has gone out of business). Personnel costs have been higher because we needed more help in the field and so I've used temporary help for the field work. Travel expenses have also been higher than originally budgeted mostly because of vehicle expenses for travel to and from the Florida Keys. I anticipate being able to complete the Year 1 work with Year 1 funds.

Quality Assurance

Among the significant improvements during the August trip were a redesign of the photographic tripod, modifications of components in the underwater suction devices devised to collect algae for the biomass and productivity measurements, and an improved data sheet for the visual % cover estimates. Statistical analysis shows that the variance within station is acceptable as long as we confine our sampling to a given reef zone. We have worked on assuring good reproducibility of the nutrient analyses on the dried algal samples. The autoanalyzer used for the nutrient analysis of the water samples is now working well and yielding reproducible results. Fresh standards are run each day.

It is still too soon to really examine the data for "results", since a major objective of the work is to document seasonal patterns of algal community structure and biomass. We found that the photographic method misses group with very low cover while the visual method underestimates % cover of groups with patchy low cover. Therefore we need to continue using both methods of measuring % algal cover in order to do a complete characterization of algal communities.

With regard to the % cover data, on patch reefs 4 to 5 groups of algae account for most of the % cover, and there were more algal groups present later in the summer. On the low-relief relic reefs, there were fewer groups/spp of algae than on patch reefs, and there was also an increased cover by other groups later in the summer. The high-relief offshore reefs had a higher diversity of algal groups/spp than on relic reefs, and again, there was increased cover by other groups later in the summer. Reefs we characterize as belonging to a certain type of reef category are not similar in their algal cover. The seasonal patterns of change were not consistent among stations, nor within groups of stations classified according to reef type. Furthermore, for the most part: stations classified according to reef type are significantly different in their algal community structure. Therefore we should not consider reefs as 'replicates' in terms of 'type'.

With regard to biomass, on patch reefs Halimeda spp. had the highest biomass even though it did not have the highest % cover. It's biomass was generally lower in August. On low-relief reefs, there lower biomass of algae than on patch reefs but there was increased biomass of Dictyota and other algal groups later in the summer. On the high relief offshore reefs, there were fewer groups/spp of algae contributing to the biomass than on the patch and relic reefs, but the high relief reefs had the highest areal algal biomass.

It was noted that there was less algal cover and biomass during the February 2001 sampling trip, as was expected.

Representative figures for the % cover and biomass for each of the stations for the May and August sampling dates are appended.

Future Activities:

Sample and data analysis is continuing and it will take us until the May sampling trip to complete the analysis of the August and new algal samples. Two additional NURC missions have been scheduled for May and August of 2001, which will complete the planned seasonal sampling. We plan to rent a house in Key Largo to serve as a base of operations for our research group this summer to conduct the sediment enrichment experiment, as well as to conduct more detailed sampling work to document zonation of the algal communities and to better characterize the microhabitats occupied by the major species.

Journal Articles on this Report : 2 Displayed | Download in RIS Format

Other subproject views: All 3 publications 2 publications in selected types All 2 journal articles
Other center views: All 9 publications 2 publications in selected types All 2 journal articles
Type Citation Sub Project Document Sources
Journal Article Szmant AM. Introduction to the special issue of Coral Reefs on "Coral Reef Algal Community Dynamics"—Why are coral reefs world-wide becoming overgrown by algae? 'Algae, algae everywhere, and nowhere a bite to eat!' Coral Reefs 2001;19(4):299-302. R828020 (2006)
R828020C002 (2001)
  • Abstract: SpringerLink
  • Journal Article Szmant AM. Nutrient enrichment on coral reefs: is it a major cause of coral reef decline? Estuaries and Coasts 2002;25(4):743-766. R828020 (2006)
    R828020C002 (2001)
  • Abstract: Springer
  • Other: Springer
  • Supplemental Keywords:

    RFA, Scientific Discipline, Geographic Area, Water, ECOSYSTEMS, Ecosystem Protection/Environmental Exposure & Risk, estuarine research, Nutrients, Ecology, Aquatic Ecosystems & Estuarine Research, Water & Watershed, State, Aquatic Ecosystem, Aquatic Ecosystems, algal blooms, Terrestrial Ecosystems, Ecological Monitoring, Ecological Risk Assessment, Ecology and Ecosystems, Watersheds, marine ecosystem, marine food web, nutrient supply, wetlands, coastal ecosystem, nutrient transport, nutrient dynamics, bloom dynamics, coastal resources, coastal watershed, coral reefs, estuaries, nutrient loading, nutrient sensitive ecosystems, nutrient concentrations, estuarine integrity, Florida Keys, marine biology, watershed sustainablity, nutrient flux, algal growth, coastal environments, nutrient kinetics, esturarine eutrophication, coral-algal symbiosis, nutrient stress, coral reef ecosystem integrity, environmental indicators, environmental stress, water quality, coastal ecosystems, nutrient cycling, watershed sustainablility, coral reef communities, ecological indicators, Florida, ecosystem stress, watershed assessment, ecological research, watershed restoration, FLA

    Progress and Final Reports:

    Original Abstract
  • 2000
  • 2002
  • Final

  • Main Center Abstract and Reports:

    R828020    National Center for Caribbean Coral Reef Research (NCORE)

    Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
    R828020C002 Nutrient Cycling and Algal Productivity in the Florida Keys
    R828020C003 Top-Down Trophodynamics
    R828020C004 Physical Oceanographic Studies
    R828020C005 Impacts of Nutrients on Reefs in the Florida Keys