Fig 1.
Southwest Florida (25.4°-28.4°N, 82.5°-83°N), is shown in relation to the rest of Florida (Inset lower left, red box). Dark Gray shaded polygon containing red marks for cell count sample locations, shows the 5 km (3 mile) extent containing Karenia brevis cell counts from 1953 to 2019 used in this study. The white star in Sarasota County indicates the location for the CMAN (meteorological) station VENF1 at Venice Pier. Blue-filled squares mark the eight beach sites in Manatee and Sarasota Counties where respiratory irritation impact was monitored by the BCRS (Beach Conditions Reporting System, Mote Marine Lab).
Fig 2.
Monthly binned maxima and bloom severity index for K. brevis.
(A) Hovmöller (time-latitude) diagram for the 0.2 degree latitude-binned monthly-maxima of observed K. brevis cell counts within 5 km (3 mile) offshore of the coast during 1953–2019. (B) The bloom severity index (BSI) for southwest Florida [25.4°-28.4° N] for each month determined by adding the bins for each class from the data in (A) and normalizing (more details in Section 2.1). For each bin and stack, the maximal cell count was determined and classified into five categories: <5,000 (light blue gray), >5,000 >50,000 >100,000 and >1,000,000 cells L-1 (salmon color to dark red). In panel (A) white indicates “no sample”, in panel (B) thicker black on the X-axis indicate months without cell count observations in the region; these occurred at intervals between 1953 and 1986. The greater the contribution of the darker colored segments to the overall height of the combined scaled values in any given month, the greater the extent of maximal cell count present.
Fig 3.
Bloom severity index for 25.4° to 28.4° N for each bloom year.
The annual severity index is determined for the bloom year defined as August to the following July and uses the data accumulated from Fig 2B. The annual bloom index was normalized by the largest bloom year so it fell into the scale of 0–10 (0 indicates no bloom; 10 is the largest bloom). Black Xs on the X-axis show bloom years with no available samples.
Fig 4.
Monthly (seasonal) climatology of K. brevis bloom frequency for 1994–2018.
(A) shows the frequency for > 5,000 cells L-1 and (B) shows >100,000 cells L-1. Color coding represents the percentage of years that the latitudinal bin had a concentration above the respective thresholds (5,000 or 100,000 cells L-1). Numbers in each bin are the number of years where the respective threshold was reached in each latitudinal bin (maximum 25). Gray indicates samples collected, but all were below the threshold. White with an X color indicates no samples were ever collected in that latitudinal bin during that month of the year. Axis runs from August to July to correspond to the bloom year. Climatology plots for thresholds of >50,000, and >1,000,000 cells L-1 are provided in S1 Fig.
Fig 5.
Number of days in each month with reports from the Beach Conditions Reporting System.
Each month shows the frequency of days with a report on respiratory irritation condition for the eight sites in Manatee and Sarasota Counties (see Fig 1 for site locations). There was a data gap during September-October of 2015.
Fig 6.
Monthly respiratory irritation impact (RI) index for Manatee and Sarasota Counties, FL from August 2006-January 2019.
The RI index was defined by the number of station days for each respiratory irritation impact condition (present or slight, moderate, and high) and normalized by the highest RI to fall in a range of 0–10 (zero means that no beach experienced respiratory irritation impact, and 10 as the maximum number of beach days). Black Xs on the X-axis show months with no available BCRS data reported.
Fig 7.
Respiratory irritation index for each bloom year for Manatee and Sarasota Counties, 2006 to 2018.
The bloom year starts in August and ends the following July, e.g., 2006 includes August 2006 to July 2007. The respiratory irritation index was defined by the total beach days over the year of each irritation condition (present, moderate, and high), and scaled such that the year with the maximal frequency had a value of 10, and zero indicates no respiratory irritation at any beach during the year.
Fig 8.
Monthly (seasonal) climatology of the frequency of respiratory irritation.
The frequency is the percentage of days with respiratory irritation observed at each beach for each of the twelve months over the data set from 2006–2019. Stations are ordered from north at top to south at bottom (locations in Fig 1). Gray color indicates months when the beach did not have detectable respiratory irritation.
Fig 9.
Comparison of binned monthly maximal bloom concentration and monthly severity with the monthly wind frequency anomalies for 1979–1984.
(A) Hovmöller diagram for the maximal K. brevis cell counts in each 0.2° latitudinal bin for 25.4°-28.4° N for each month (Fig 2). (B) Normalized monthly bloom severity index (BSI) for cell counts in 1979–1994, accumulated from (A). (C) Proportional onshore wind frequency anomaly (OWFA) during each month from the data-assimilative NARR (North American Regional Analysis) product for the location of the VENF1 station (Fig 1). More Positive values are marked in red (more frequent onshore wind) and negative values (less frequent onshore wind) are marked in blue. Markers for the years indicate January 1. In (A), white indicates no samples, light blue gray indicates < 5,000 cells L-1. In (B), Xs on the X-axis indicate no samples were collected (prior to 1987), and the blue stars indicate times when tropical storms had impacts on southwest Florida coastal waters.
Fig 10.
Comparison of binned monthly maximal bloom concentration, bloom severity index, respiratory index, and monthly wind frequency anomalies for 2006 to 2019.
The figure covers the period of the respiratory irritation data set. (A) Hovmöller diagram for the monthly maximal K. brevis cell counts in each 0.2° latitudinal bin. (B) Monthly bloom severity index for the bloom year (August to July). (C) shows the monthly respiratory index for Manatee and Sarasota counties. (D) Monthly onshore wind frequency anomalies (OWFA) for Station VENF1 (Venice Pier, Florida), with positive values (more frequent onshore wind) marked in red and negative values (less frequent onshore wind) marked in blue. Markers for the years are for January 1. Descriptions are the same as Figs 6 and 9. Black Xs on X-axis during 2013 in the OWFA indicate no wind records were available.
Fig 11.
Relationship of monthly respiratory irritation impact (RI) index, monthly bloom severity index (BSI), and winds.
The relationships are shown for cell counts > 50,00 cells L-1 for Manatee and Sarasota Counties, FL. Color-coding represents the onshore wind frequency anomalies (OWFA) for each month, positive (red) indicates onshore, and negative (blue) indicates offshore. Months when bloom were not observed were not shown. Size of the circles represent the wind speed for the month. April-June 2007 were not included because respiratory irritation during those months was caused by the Bugaboo Scrub wildfire. Black dashed line shows the linear regression fit between the monthly RI and BSI (equation shown).