Hurricane Effects on Water Quality and Benthos in the Cape Fear Watershed: Natural and Anthropogenic Impacts

Abstract

In the summer of 1996, southeastern North Carolina, United States, was struck by two hurricanes, with the second (Hurricane Fran) doing considerably more damage than the first (Hurricane Bertha). The Cape Fear watershed, largest in North Carolina, suffered from severe water quality problems for weeks following Fran, including a massive fish kill in the Northeast Cape Fear River. Post-hurricane flooding caused inputs of riparian swamp water to river channels, and sewage treatment plant and pump station power failures caused diversions of millions of liters of raw and partially treated human waste into rivers. Additionally, several swine waste lagoons were breached, overtopped, or inundated, discharging large quantities of concentrated organic waste into the system, particularly into the Northeast Cape Fear River. Dissolved oxygen (DO) decreased to 2 mg/L in the mainstem Cape Fear River, and fell to zero in the Northeast Cape Fear River for Ͼ3 wk. Biochemical oxygen demand in the Northeast Cape Fear River was sixfold greater than in the other tributaries, probably as a result of anthropogenically derived inputs. The Cape Fear Estuary also suffered from hypoxia for several weeks. Following Hurricane Fran, ammonium levels in the Northeast Cape Fear River displayed a distinct increase, and total phosphorus reached its highest concentration in 27 yr. The benthic community, which is dominated by opportunistic species typical of oligohaline to mesohaline estuarine areas, showed a mixed response. There was a significant decline in total benthic abundances immediately after Hurricane Fran at an oligohaline station in the Northeast Cape Fear River, with recovery occurring in ϳ3 mo. An oligohaline station in the mainstem Cape Fear River, which had relatively rapid DO recovery, did not display significant declines. A mesohaline station 5 km below the confluence of these rivers showed broad and long-lasting benthic declines, but benthic declines were less severe in the lowest reaches of the estuary sampled. The natural hurricane effect of swamp water flooding into river basins led to reduced dissolved oxygen levels and increased light attenuation. However, environmental damage was considerably increased by anthropogenic practices, including the lack of backup generating systems for waste treatment systems and subsequent sewage diversions into rivers, as well as accidents occurring at swine waste lagoons sited on river floodplains.

Timescales and Magnitude of Water Quality Change in Three Texas Estuaries Induced by Passage of Hurricane Harvey

“…In addition, it can deliver copious amounts of allochthonous organic matter and nutrients to the estuary (Paerl et al 1998). Respiration of the allochthonous organic matter as well as organic matter from any phytoplankton blooms that develop can cause bottom water hypoxia-anoxia (Paerl et al 1998(Paerl et al , 2001Mallin et al 1999;Peierls et al 2003;Tomasko et al 2006). Despite the potential severe impact of tropical cyclones, most studies have shown that estuarine water quality conditions typically return to pre-storm conditions in 1 month or less (Valiela et al 1998;Hagy et al 2006;Tomasko et al 2006), although longer-term effects have been observed with less frequency (Glibert et al 2009;Briceño and Boyer 2010).…”

Fewer Copepods, Fewer Anchovies, and More Jellyfish: How Does Hypoxia Impact the Chesapeake Bay Zooplankton Community?

“…As a result, salinities measured during the 2011 autumn cruise were much lower than those measured in the previous year. Other studies in estuaries also have observed short-term hypoxia after hurricanes [92,93], and sometimes the recovery to baseline conditions took months [94]. Similarly, early-fall hypoxia was soon reestablished after Hurricane Isabel impacted the Chesapeake Bay, and the resuspension of nutrients into the upper water column led to a large diatom bloom, followed by a dinoflagellate bloom [95].…”

Spatio‐temporal patterns of fish assemblage structure in a coastal plain stream: appropriate scales reveal historic tales

“…Schaefer et al (2006) found fish assemblage structural changes in the neighbouring Pascagoula River, a basin with a nearly identical ichthyofauna to the Pearl, following Hurricane Katrina. Mallin et al (1999) reported the effects of multiple hurricanes in the Cape Fear watershed, NC, including decreased dissolved oxygen levels and massive fish kills. During hurricane events, biological oxygen demand increases because of high woody and leaf debris input.…”

“…River systems of the southeastern United States possess the greatest diversity of temperate freshwater fishes in the world (Warren et al 1997). Many of these systems, however, have been subject to anthropogenic changes including the construction of impoundments, channelisation, in-stream sand and gravel mining (Phillips & Johnston 2004;Hayer & Irwin 2008;Taylor et al 2008), as well as extreme natural environmental perturbations such as hurri-canes, droughts and floods (Freeman et al 1988;Mallin et al 1999;Schaefer et al 2006).…”