MSGID: 1:317/3 63f59a6e   
   PID: hpt/lnx 1.9.0-cur 2019-01-08   
   TID: hpt/lnx 1.9.0-cur 2019-01-08   
    Excess nutrients lead to dramatic ecosystem changes in Cape Cod's   
   Waquoit Bay; the bay is a harbinger for estuaries worldwide, say researchers   
      
      
     Date:   
         February 21, 2023   
     Source:   
         Woods Hole Oceanographic Institution   
     Summary:   
         When the Covid-19 pandemic hit in 2020 with associated travel   
         restrictions, a research group shifted their overseas research   
         projects to instead study the seagrass meadow ecosystem in Waquoit   
         Bay, USA. It's a shallow, micro-tidal estuary on the south side   
         of Cape Cod in Massachusetts.   
      
      
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   FULL STORY   
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   When the Covid-19 pandemic hit in 2020 with associated travel   
   restrictions, Matthew Long thought his students could shift their overseas   
   research projects to instead study the seagrass meadow ecosystem in   
   Waquoit Bay. It's a shallow, micro-tidal estuary on the south side of   
   Cape Cod in Massachusetts, near the Woods Hole Oceanographic Institution   
   (WHOI) where Long is an associate scientist in the Marine Chemistry and   
   Geochemistry Department.   
      
      
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   However, when Long and his students looked for seagrass meadows where he   
   had seen them in previous years, there were only a few shoots of dying   
   Zostera marina eelgrass, a type of seagrass.   
      
   That prompted Long and Jordan Mora, a restoration ecologist with the   
   Association to Preserve Cape Cod, to analyze decades' worth of local   
   environmental monitoring data to find out what has happened to the   
   estuary.   
      
   What they determined is that Waquoit Bay has shifted from a benthic to a   
   pelagically-dominated ecosystem due to human causes, including an excess   
   influx of nutrient pollution along with climate change.   
      
   That disruption to Waquoit Bay's ecosystem presents broad concerns about   
   the fate of coastal estuaries worldwide, according to the researchers.   
      
   In addition, the researchers point to the importance of tapping into and   
   analyzing long-term monitoring data to better understand the changes to   
   Waquoit Bay and potentially to other estuaries as well.   
      
   The water quality and overall health of estuaries continue to degrade due   
   to excess nutrients from leaching septic systems, agricultural runoff,   
   and other anthropogenic sources, the researchers note. In addition,   
   warming water temperatures from climate change, particularly in the   
   northeastern United States, exacerbates the nitrogen loading problem by   
   reducing dissolved oxygen levels and accelerating microbial metabolism   
   which further reduces oxygen levels.   
      
   "This shift toward pelagic dominance in Waquoit Bay may indicate   
   that other eutrophic and warming estuaries may also shift toward   
   pelagic dominance in the future, as the Northeastern US is one of   
   the fastest warming," according to "Deoxygenation, Acidification   
   and Warming in Waquoit Bay, USA, and a Shift to Pelagic Dominance,"   
   a paper co-authored by Long and Mora published in Estuaries and Coasts,   
   the journal of the Coastal and Estuarine Research Federation. "The range   
   of nitrogen loading across the Waquoit Bay sub-watersheds is comparable   
   to the range of nitrogen loading across 90% of the world's estuaries   
   making it an ideal site for investigating eutrophication impacts."   
   The scientists note that their research results in Waquoit Bay "cannot   
   disentangle the contributions of global change or eutrophication to   
   estuary decline. However, they do point to a potential combined effect   
   that may result in other similar estuaries becoming dominated by pelagic   
   metabolism in the future, and the resulting deleterious effects of   
   harmful algal blooms, hypoxia, and the loss of species diversity and   
   ecosystem function."  The researchers' analyses revealed recent and   
   unexpectedly large increases in chlorophyll a concentrations, an indicator   
   of microalgal blooms, in the water column throughout the estuary, which   
   coincided with ongoing decreases in macroalgal density on the bottom of   
   the estuary. In addition, the analyses showed an increase in temperature   
   over the last 20 years and significant declines in oxygen and pH levels,   
   among other changes.   
      
   The analyses relied on long-term monitoring data collected over decades   
   from two monitoring programs coordinated by the Waquoit Bay National   
   Estuarine Research Reserve, including the reserve's System-Wide Monitoring   
   Program and the Waquoit BayWatchers, that latter of which is a citizen   
   science water quality monitoring program.   
      
   One of the main objectives of the current study was to apply time-series   
   analysis techniques and substantial knowledge about the history of   
   the monitoring programs to reveal long-term trends in water quality,   
   according to the paper. "These methods can be applied to other monitoring   
   data to advance the knowledge gained from similar monitoring programs,   
   enhance our understanding of estuarine biogeochemistry, and investigate   
   estuarine responses to long-term change," the paper states.   
      
   Long said eelgrass provides a number of ecosystem benefits including   
   stabilizing sediments and offering habitat for a variety of organisms. In   
   addition, eelgrass is a great indicator of good estuarine water quality   
   and also serves as a carbon sink.   
      
   "Carbon storage is extremely important across the world, and we're   
   actively trying to figure out ways to store and sequester carbon. Seagrass   
   meadows represent a really significant and efficient carbon storage sink,"   
   Long said.   
      
   "Let's not lose the seagrass meadows and the carbon sequestration   
   that we already have in place, and let's actively maintain and restore   
   seagrass meadows. With the loss of seagrass meadows, such as what we've   
   seen in Waquoit Bay, we're actively releasing that carbon back to the   
   atmosphere."  Long added that using environmental monitoring data helped   
   to put together the story of the switch from a seagrass-dominated system   
   to a macroalgal-dominated system from the 1980s to the present in Waquoit   
   Bay. Without the long-term data, gradual changes to the system would be   
   more difficult to detect, he said.   
      
   "This paper isn't just significant because it demonstrates that the   
   estuaries on southern Cape Cod, and more generally the northeastern   
   US, are entering a new level of degradation where not even macroalgae   
   or seaweeds can persist, but also because it provides clear evidence   
   that long-term monitoring programs are extremely important and worth   
   maintaining," said Mora, who worked at the Waquoit Bay National Estuarine   
   Research Reserve for 10 years collecting water quality and submerged   
   vegetation data with visiting scientists, volunteers, and other staff,   
   and witnessed the gradual decline in habitat quality firsthand.   
      
   "My hope is that by showing the impact of increasing temperatures on   
   already degraded systems, this paper will help facilitate local and   
   regional management discussions and accelerate the decision-making needed   
   to mitigate the overload of nutrients in our estuaries," Mora added.   
      
   The paper notes that "there is an urgent need to address wastewater   
   handing to improve the estuary, especially in the face of global changes."   
   Long said, however, that if local stressors including nutrient pollution   
   can be addressed, and if we can reduce carbon emissions and slow down   
   global warming and the amount of carbon that diffuses into the ocean,   
   "we could turn this situation around before it happens to many similar   
   estuarine systems across the world, preserve the valuable ecological   
   functions of seagrass meadows, and enable their carbon storage potential."   
   Funding to support the Marine Biological Laboratory macrophyte data   
   collection was provided by Woods Hole Sea Grant. This research was funded   
   by a WHOI Independent Research and Development grant.?   
       * RELATED_TOPICS   
             o Earth_&_Climate   
                   # Environmental_Issues # Global_Warming # Air_Quality #   
                   Pollution # Climate # Weather # Environmental_Science   
                   # Ecology   
       * RELATED_TERMS   
             o Estuary o North_American_blizzard_of_1978 o Bering_Strait   
             o Bay_mud o Agronomy o Adventure_travel o Tide_pool o Tide   
      
   ==========================================================================   
   Story Source: Materials provided by   
   Woods_Hole_Oceanographic_Institution. Note: Content may be edited for   
   style and length.   
      
      
   ==========================================================================   
   Journal Reference:   
      1. Matthew H. Long, Jordan W. Mora. Deoxygenation, Acidification   
      and Warming   
         in Waquoit Bay, USA, and a Shift to Pelagic Dominance. Estuaries   
         and Coasts, 2023; DOI: 10.1007/s12237-022-01166-7   
   ==========================================================================   
      
   Link to news story:   
   https://www.sciencedaily.com/releases/2023/02/230221180124.htm   
      
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