Fig 1 - uploaded by Peter Barile
Content may be subject to copyright.
Map of the Indian River lagoon system. Included are labels for the 5 subsections of the IRL system: Mosquito Lagoon, Banana River Lagoon, Northern, Central and Southern Indian River Lagoon. Sample site locations denoted as (+). 

Map of the Indian River lagoon system. Included are labels for the 5 subsections of the IRL system: Mosquito Lagoon, Banana River Lagoon, Northern, Central and Southern Indian River Lagoon. Sample site locations denoted as (+). 

Source publication
Article
Full-text available
Abstract The Indian River Lagoon (IRL) system, a poorly flushed 240km long estuary in east-central Florida (USA), previously received 200 MLD of point source municipal wastewater that was largely mitigated by the mid-1990’s. Since then, non-point source loads, including septic tank effluent, have become more important. Seventy sites were sampled fo...

Citations

... These factors, combined with sufficient light and warm water temperatures, create the ideal environment for harmful algal blooms in the IRL system [11]. In 2011, a "super bloom" occurred in the northern IRL, and the excessive growth of phytoplankton led to the loss of seagrasses, simultaneously resulting in an MME that saw the large-scale deaths of a variety of animals, including manatees, dolphins, seabirds, and fish [13][14][15]. ...
Article
Full-text available
Globally, the health of coastal water bodies continues to be threatened by climate change and mounting anthropogenic pressures related to population increase and associated development. Land use changes have increased the direct runoff of freshwater, nutrients, and other contaminants from watersheds into coastal systems. Exacerbated by increased temperatures, these changes have contributed to a worldwide decline in seagrass coverage and losses of critical habitat and ecosystem functions. For restricted estuaries and lagoons, the influx of nutrients is particularly damaging due to high water residence times and impaired flushing. The result is eutrophication and associated declines in water quality and ecosystem function. To mitigate degraded water quality, engineered ocean–estuary exchanges have been carried out and studied with examples in Australia, New Zealand, India, Denmark, the Netherlands, Portugal, and the United States of America. Based on successes including decreased nutrient concentrations, turbidity, and chlorophyll and increased faunal abundance in some past studies, this option is considered as a management tool for combatting worsening water quality in other estuaries including the Indian River Lagoon, a subtropical, lagoon-type estuary on the central east coast of Florida, USA. Decreased residence times, lower nutrients, higher dissolved oxygen (DO), higher salinity, lower temperature, and lower turbidity all combine for improved ecosystem health. In this review, the successes and failures of past projects intended to increase ocean–estuary exchanges, including biological and geochemical processes that contributed to observed outcomes, are evaluated. The primary indicators of water quality considered in this review include nutrient contents (e.g., nitrogen and phosphorus) and dissolved oxygen levels. Secondary indicators include changes in temperature and salinity pre- and post- engineering as well as turbidity, which can also impact seagrass growth and overall ecosystem health. Each of the sites investigated recorded improvements in water quality, though some were more pronounced and occurred over shorter time scales. Overall, enhanced ocean exchange in restricted, impaired water bodies resulted in system-specific response trajectories, with many experiencing a net positive outcome with respect to water quality and ecosystem health.
... Wastewater discharges into water bodies subject aquatic biota to chronic exposure to complex mixtures of pollutants, eutrophication, oxygen depletion, thermal pollution and general habitat deterioration (Wear et al., 2021). Similarly, parameters such as turbidity, odor or color are also directly influenced (Barile, 2018). ...
... It has been suggested that the post-regime shift blooms in the IRL have in part been driven by shifts in the distribution of internal nutrient pools from the benthos to water column phytoplankton (Phlips et al., 2015;Phlips et al., 2021), and N-enrichment from sewage and septic tank pollution (LaPointe et al., 2015;Barile, 2018). Both of these sources heighten the potential role of ammonium and organic forms of nitrogen and phosphorus as nutrient sources for phytoplankton production. ...
Article
Full-text available
Introduction Successful management and mitigation of harmful algal blooms (HABs) requires an in-depth understanding of the physiology and nutrient utilization of the organisms responsible. We explored the preference of various nitrogen (N) and phosphorus (P) substrates by two novel groups of HAB-forming phytoplankton originating from the Indian River Lagoon (IRL), Florida: 1) a consortium of picocyanobacteria (Crocosphaera sp. and ‘Synechococcus’ sp.) and 2) ananochlorophyte (Picochlorum sp.). Methods Short-term kinetic uptake experiments tested algal use and affinity for inorganic and organic N substrates (ammonium (NH4 ⁺), nitrate (NO3 ⁻), urea, and an amino acid (AA) mixture) through ¹⁵N and ¹³C isotope tracing into biomass. Results Picocyanobacteria exhibited Michaelis-Menten type uptake for the AA mixture only, while nanochlorophytes reached saturation for NH4 ⁺, the AA mixture, and urea at or below 25 µM-N. Both picocyanobacteria and nanochlorophyte cultures had highest affinity (Vmax/Ks) for NH4 ⁺ followed by the AA mixture and urea. Neither culture showed significant uptake of isotopically-labeled nitrate. Disappearance of glucose-6-phosphate (G6P) added to culture medium suggesting use of organic P by both cultures was confirmed by detection of alkaline phosphatase activity and the tracing of ¹³C-G6P into biomass. Discussion Together, our results suggest that these HAB-forming phytoplankton groups are able to use a variety of N and P sources including organic forms, and prefer reduced forms of N. These traits are likely favorable under conditions found in the IRL during periods of significant competition for low concentrations of inorganic nutrients. Bloom-forming phytoplankton are therefore able to subsist on organic or recycled forms of N and P that typically dominate the IRL nutrient pools.
... potential indicator of water pollution (Jona-Lasinio et al., 2015;Barile, 2018). Primary producers, such as phytoplankton, with their rapid N absorption directly from the water column and growth rates, can reflect nutrient incorporation in days (short-term biomonitoring), whereas algae may take weeks or months to show changes (mid-term biomonitoring) (Ochoa-Izaguirre and Soto-Jiménez, 2015). ...
... Ratios of stable isotopes of carbon ( 13 C/ 12 C) and nitrogen ( 15 N/ 14 N) have been used to identify and trace sources and transport pathways for organic matter in the environment (Cloern et al., 2002;Onodera et al., 2015). For example, N isotopes in benthic macroalgae have been used to infer that failing septic systems and sewage spills are an important external source of N to the IRL (Lapointe et al., 2015;Barile, 2018). Other external sources of N to the IRL include fertilizer, reclaimed water, rainwater and upland vegetation. ...
... However, NIRL sediments had d 13 C values that were consistent with a mix of terrestrial and marine OM and not in the range of values typically found for sewage (Supplementary Figure 2). This observation complicates assessments of the relative importance of wastewater to d 15 N values in benthic algae (Lapointe et al., 2015;Barile, 2018) because interstitial ammonium carries essentially the same isotope signature as benthic macroalgae and sewage (Supplementary Figure 2). Variability in stable isotope ratios for C and/or N in a source chemical (e.g., ammonium) or composite material (e.g., sewage), as well as a plant or animal that may take up a certain chemical, can confound use of an isotope pair and require a complementary tool, such as a molecular biomarker to confirm sources and pathways (Cloern et al., 2002). ...
Article
Full-text available
Nutrient fluxes from fine-grained, organic-rich sediments in estuaries can hasten the onset and progression of eutrophication and harmful algal blooms. Targeted efforts to manage degraded sediments and improve estuarine water quality require a better understanding of physicochemical controls and the relative importance of benthic fluxes. Toward that end, we determined fluxes from organic-rich, high porosity sediments deposited during the past 5-6 decades along 60 km of the Indian River Lagoon, a barrier island lagoon in Florida, USA. Highly bioavailable ammonium and phosphate were the predominant chemical forms of interstitial nitrogen and phosphorus in these highly-reducing sediments. Median fluxes of ammonium and phosphate were 320 µmol m⁻² h⁻¹ and 11 µmol m⁻² h⁻¹, respectively. Fluxes were 3-10 times greater when sediment temperatures were >28°C and interstitial sulfide concentrations were >1 mM. Temperature-compensated fluxes of ammonium and phosphate were significantly correlated with sediment organic matter content; total organic carbon averaged 5.3 ± 2.4% and the maximum was 12.4% for the sediments studied. Fine-scale physical probing, plus lidar data, showed that these organic-rich sediments covered <10% of our study area; however, fluxes from these sediments were estimated to supply 20-40% of internal + external annual loads of nitrogen and phosphorus. Furthermore, 60% of nitrogen and phosphorus fluxes from sediments in the northern Indian River Lagoon came from just 22% of the total surface area. Lagoon segments with high benthic fluxes overlapped in part with areas prone to harmful algal blooms. Effective strategies to manage degraded sediments in the Indian River Lagoon depend on knowing the relative magnitude of internal loading of nutrients as well as appropriate techniques to mitigate sediment fluxes.
... In the 1970s, the IRL was considered one of the last "unpolluted coastal lagoons in Florida" (Briel et al., 1974). However, as the citrus industry declined over the last fifty years, local populations and urban development increased, and water quality diminished in many areas along the IRL (Lapointe et al., 2015;Lapointe et al., 2017;Barile, 2018;Lapointe et al., 2020;Herren et al., 2021;Lapointe et al., 2023). For example, in the IRL chlorophyll-a concentrations have increased dramatically over the last 25 years alongside local populations (Phlips et al., 1986;Lapointe et al., 2015;Phlips et al., 2015;Lapointe et al., 2017;Phlips et al., 2021;Lapointe et al., 2023). ...
... Major sources of nitrogen (N) and phosphorus (P) to the IRL have been estimated to be over 70 % agricultural/urban runoff, followed by groundwater, and wastewater treatment plants (Sigua & Tweedale, 2003). Following rainfall events, dissolved inorganic N (DIN) loading from agricultural lands (Dierberg, 1991), stormwater runoff (Trefry & Fox, 2021), and septic systems (Lapointe et al., 2015;Lapointe et al., 2017;Barile, 2018;Herren et al., 2021;Lapointe et al., 2023) can be especially high. Stable isotope values of macroalgae are effective bioindicators for identifying N sources in estuarine environments (Costanzo et al., 2001). ...
... Stable isotope values of macroalgae are effective bioindicators for identifying N sources in estuarine environments (Costanzo et al., 2001). In the IRL, enriched stable N isotope (δ 15 N) values (> +5 ‰) of macroalgae collected during 2011-2017 suggested that human waste is a major source of N in areas that are adjacent to urbanized municipalities with high concentrations of septic systems or insufficient wastewater infrastructure (Lapointe et al., 2015;Lapointe et al., 2017;Barile, 2018;Herren et al., 2021;Lapointe et al., 2023). In 2013-2014, the southernmost Mosquito Lagoon, which is surrounded by protected natural areas (Canaveral National Seashore and Merritt Island National Wildlife Refuge) had macroalgae with more depleted δ 15 N values (+1 to < +3‰), suggestive of atmospheric deposition or N fixation as a primary N source (Barile, 2018). ...
... N stable isotopes (ẟ 15 N) of primary producers can be used to assess sources of N fueling eutrophication with higher values (>+3 ‰) indicating human waste sources, lower values (<+2 ‰) indicating synthetic fertilizers, and values ~0 ‰ indicating Nfixation (Peterson and Fry, 1987;Cabana and Rasmussen, 1994;McClelland et al., 1997;McClelland and Valiela, 1998b;Costanzo et al., 2001;Glibert et al., 2019Sánchez et al., 2023. Through assessment of ẟ 15 N values of macrophytes, anthropogenic N inputs to the IRL, particularly human waste, have been identified as major N sources contributing to the initiation and proliferation of both phytoplankton and macroalgal HABs (Lapointe et al., 2015(Lapointe et al., , 2017Barile, 2018;Freeman et al., 2018;Herren et al., 2021;Lapointe et al., 2023;Brewton, 2023) and seagrass losses (Lapointe et al., 2020). Despite this enrichment and the observed primary producer shifts at the base of the food web, little is known about how this cultural eutrophication is affecting the trophic pathways within the IRL. ...
... Higher concentrations (~2×) of NH 4 + may indicate that in the BR and NIRL, human waste N is more prevalent or has longer residence times than in the CIRL. Widespread contamination of the CIRL by human waste has been previously confirmed (Lapointe et al., 2015;Barile, 2018;Herren et al., 2021;Lapointe et al., 2023), and this study reaffirms the findings of Brewton (2023) that this issue is worse in the NIRL and BR. To further investigate this issue, analysis of the δ 15 N for both NH 4 + and NO x would enhance discrimination of N sources and provide better understanding of IRL N dynamics. ...
... Brown tide has persisted in the NIRL and BR since 2012, which may relate to the high NH 4 + , TON, and TDN concentrations observed in these segments (Lopez et al., 2021). These nutrients may come from external sources, like stormwater runoff, septic system effluent, or wastewater treatment plant overflows (Lapointe et al., 2015;Barile, 2018;Applied Ecology, 2020;Lapointe et al., 2023), as well as from internal sources available due to muck dredging or regime shifts, such as decaying biomass of seagrasses, macroalgae, and phytoplankton Hall et al., 2022;Lapointe et al., 2023). The high nutrient loads are compounded by the lack of flushing in these segments compared to the CIRL, which exchanges seawater with the Atlantic Ocean via two inlets. ...
Article
Full-text available
Nitrogen (N) loading can affect estuarine food webs through alteration of primary producers. In the Indian River Lagoon (IRL), Florida there has been long-term N enrichment, worsening phytoplankton blooms, large-scale macroalgal blooms, and catastrophic seagrass losses. To investigate how N enrichment affects higher trophic levels and food webs in the IRL, nutrient availability was compared to primary producer and faunal stable N (δ15N) isotope values. Seawater samples were collected in the IRL for dissolved nutrient, chlorophyll-a, and particulate organic matter δ15N analyses. Macrophytes and fauna were also collected for δ15N analyses. Throughout the IRL, N was elevated but was highest in the northern IRL and Banana River Lagoon. δ15N was enriched in these segments for most samples to levels characteristic of human-waste impacted estuaries. Variability in δ15N among lagoon segments suggests a low level of trophic connectivity. Decreasing N loading to the IRL and other eutrophic estuaries may help improve resiliency.
... The Indian River Lagoon (IRL) is a large sub-tropical estuary located on the east coast of Florida. Like many estuaries worldwide, it has seen a decline in water quality due to anthropogenic stressors, a consequence of which has led to the presence of harmful bacteria, large-scale algal blooms, fish kills, and seagrass die-off (Indian River Lagoon 2011; Barile, 2018;Indian River Lagoon, 2016). ...
Article
Full-text available
The Living Docks restoration program was implemented in the Indian River Lagoon (IRL), Florida, with the goal of affixing oyster restoration mats to dock pilings to promote the growth of filter feeding benthic organisms which can help improve local water quality. However, the relationship between IRL water quality parameters and the presence of filter feeders on the mats is not entirely clear. This study investigates the presence of benthic organisms on eight Living Docks which were deployed throughout the central part of the IRL. Environmental factors (e.g., water salinity, turbidity, pH, and temperature) were collected from the closest available water station to each dock. The main goal was to identify the presence and overall change in percent cover of specific benthic organism(s), those which are known filter feeders, in relationship to environmental parameters. Among functional groups which were identified, barnacles, biofilms, encrusting bryozoans (EBs), oysters, and sponges demonstrated significantly higher cover than the others. Barnacles were higher in abundance at specific dock locations and an increased water pH (up to 8.1), turbidity, and temperature. EB presence was positively impacted by salinity but did not respond to changes in turbidity or temperature within the measured ranges. Oysters were not observed to be impacted by any of the factors within measured ranges. Sponges had sustained abundance in half of the docks in this study. However, they did not respond to any of the environmental factors within measured ranges in different seasons. Results from this study can help target future Living Dock locations which will provide the best environment for the recruitment of filter feeding organisms.
... Therefore, the differences in δ 15 N values in T. testudinum leaves cannot be explained by the flushing between these sites influenced by anthropogenic activity. The low δ 15 N values in the Indian River Lagoon and the Texan coastal lagoons may be associated with the mixture of various anthropogenic nitrogen sources (Barile, 2018). ...
... The positive correlation of δ 15 N and ammonium concentration in these two coastal lagoons suggests wastewater in some sites close to urban areas (Lapointe et al., 2020;Delgado et al., 2017;Congdon and Dunton, 2019). Although other external nitrogen sources depleted in 15 N, such as fertilizers used in agriculture and river water runoff, have been detected in these coastal lagoons (Barile, 2018;Lapointe et al., 2020), they may be the cause of low T. testudinum δ 15 N values. ...
Article
The conservation of Mexican Caribbean Ecosystems (MCE) involves ensuring their capacity to provide resources and ecosystem services to society. Monitoring programs are necessary to establish their management and ensure their sustainability. Thalassia testudinum is the community used to determine anthropogenic influence, in which wastewater is the primary anthropogenic nitrogen source. The extensive amount of pelagic sargassum that enters the area and its decomposition may be additional nitrogen sources in MCE. In the present study, the δ15N in T. testudinum was examined from 2009 to 2019 to infer the nitrogen contribution from pelagic sargassum to MCE. T. testudinum δ15N values showed significant depletion from June/October 2014 to 2019 concerning previous periods. Pelagic sargassum was an alternative nitrogen source, and its leaching reduced T. testudinum δ15N values in MCE.
... The Indian River Lagoon (IRL) on Florida's east-central Atlantic coast (Fig. 1) is a biologically diverse and ecologically important estuary (Tremain and Adams, 1995) that is experiencing eutrophication due to excess nutrient loading (Lapointe et al., 2015;Barile, 2018). As such, some segments of the IRL are classified as impaired under Section 303(d) of the United States Clean Water Act of 1972 for total nitrogen (TN) and total phosphorus (TP). ...
... These findings suggest that the increasing concentrations of dissolved inorganic N and P observed in some segments of the IRL following ~five years of fertilizer bans would support the worsening trend of algal blooms. For example, dramatic spikes in NH 4 + and NO 3 − occurred during the post-ban wet season (Fig. 3 a,b) in the BR and NIRL where severe brown tides occurred in -2013, 2015-2018(Phlips et al., 2021. This is important as northeastern brown tides (Aureococcus anophagefferens) from Long Island Sound are favored in environments with moderate concentrations of NH 4 + (Taylor et al., 2006), such as the BR and NIRL during the post-ban sampling. ...
... The highest δ 15 N values (+8.62 ‰) occurred in the BR during the 2016 brown tide and closely matched values for partially treated wastewater (+8 ‰) (Costanzo et al., 2001;Lapointe et al., 2005;Savage, 2005), which would be expected in this highly urbanized area with aging wastewater collection systems and secondary treatment without N removal. Slightly lower, but still enriched, POM δ 15 N values for the overall mean brown tide (+4.87 ‰) and the NIRL brown tide (+4.41 ‰) are similar to values for septic system effluent (+4.9 ‰) (Hinkle et al., 2008), which has been widely observed in macroalgae throughout the IRL (Lapointe et al., 2015;Barile, 2018). The volatilization and microbial processing (nitrification) of ammonium from septic effluent would enrich the DIN δ 15 N value to levels observed in the POM during this study (Lapointe et al., 2017). ...
Article
In Florida's Indian River Lagoon (IRL), anthropogenic eutrophication has resulted in harmful algal blooms and catastrophic seagrass losses. Hoping to improve water quality, policy makers enacted fertilizer bans, assuming that this would reduce the nitrogen (N) load. To assess the effectiveness of these bans, seawater and macroalgal samples were collected at 20 sites "pre" and ~ five-years "post" bans and analyzed to determine concentrations of dissolved nutrients and stable nitrogen isotope values (δ15N). Higher concentrations of ammonium and nitrate were observed post-ban and macroalgal δ15N values increased. A comparison of nutrient concentrations and δ15N between brown tide (Aureoumbra lagunensis) blooms indicated that the post-ban bloom was more strongly N-enriched with higher δ15N values than the pre-ban bloom, which had depleted values in the range of fertilizers. These data indicate a primary role of human waste influence in the IRL, suggesting that current management actions have been insufficient at mitigating eutrophication.