Vedi qualcosa da migliorare? Proponi una modifica.
In the summer of 2021, the bays inside Fire Island National Seashore had their best algae readings in over a decade: for the first time since 2009, most of the monitored area was in good condition for chlorophyll. All three water-quality indicators improved slightly. Even so, the verdict of the National Park Service's monitors was unchanged: the estuary is still over-enriched with nutrients.
The estuarine area monitored at Fire Island National Seashore. Credit: National Park Service.
What's being measured
Fire Island National Seashore covers 7,810 hectares on the South Shore of Long Island, New York, and about 46% of that is submerged land in Great South Bay and Moriches Bay. The park owns only a minority of the bays' bottom, but its share is still extensive — and nutrient enrichment, largely from human activity, is a primary management concern.
The Northeast Coastal and Barrier Network monitors three indicators each summer, using thresholds consistent with U.S. Environmental Protection Agency coastal reporting and the National Oceanic and Atmospheric Administration's National Estuarine Eutrophication Assessment:
| Indicator | Why it matters | Good | Fair | Poor |
|---|---|---|---|---|
| Bottom-water dissolved oxygen | Excess nutrients feed algae; decomposing them uses up oxygen near the bottom, which can bring anoxia and toxic sulfides and change which animals live there | 5 mg/L | 2–5 mg/L | < 2 mg/L |
| Surface chlorophyll-a | Measures phytoplankton, which grow with added nutrients | < 5 µg/L | 5–20 µg/L | 20 µg/L |
| Light attenuation (Kd) | How quickly water blocks light; seagrass and other submerged plants need light | < 0.92 m⁻¹ | 0.92–1.61 m⁻¹ | 1.61 m⁻¹ |
The light thresholds come from EPA turbidity criteria for areas with significant submerged aquatic vegetation, and the network tracks light whether or not such vegetation is currently present.
The 2021 results
| Indicator | Share of the sampled estuary | Compared with earlier years |
|---|---|---|
| Dissolved oxygen | Good in 100% | Consistently good; only 2019 saw a slight increase in fair condition |
| Chlorophyll-a | Good in 73.2%, fair in 26.8% | An improvement: since 2009 most of the area had been fair or poor |
| Light attenuation | Good in 24.8%, fair in 66.6%, poor in 2.9%, no data for 5.7% | As usual, mostly fair, with the majority fluctuating between fair and poor |
Park-wide averages rated oxygen and chlorophyll good and light attenuation fair. Taken together, the report concludes, the three indicators show the estuary continues to experience nutrient over-enrichment.
Park staff collect water-quality data in one of the monitored estuaries. Credit: Michaela Compo, National Park Service.
Sources
Based on "2021 Estuarine Nutrient Enrichment Status Report: Fire Island NS," National Park Service Northeast Coastal and Barrier Network, part of the series NCBN Yearly Status Reports | Estuaries, following the network's monitoring protocol (Kopp and Neckles, 2009); a work of the United States government in the public domain. The data are on the NPS DataStore and the network's water quality dashboard.
In queste pubblicazioniFire Island National SeashoreNCBN Yearly Status Reports | Estuaries
Licenza: CC0 1.0 (pubblico dominio) · Tratto da www.nps.gov
1
0
0
0
Commenti
