**4. Discussion**

The geomorphology of beaches and barrier islands along southwest Florida can be significantly altered by hurricanes and winter storms by means of frontal beach erosion, overwash deposits, migration of foredunes, and the transport of sediments. Persistent transport of beach sediments can cause either erosion or accretion. The landfall of Hurricane Charley on North Captiva Island in 2004 created a cut to the southern end of the island, and since then, both localized sediment erosion and accretion have been observed on the barrier island when surveying the island until 2018 using LiDAR. Sediments were removed from the northern portion of the island after the hurricane in 2004 (R67–R76) and transported to the south to heal the island breach and build back up the width of the southern portion of the island (R76–R82). Most of this sediment redistribution can be attributed to strong southerly long-shore transport during the winter storms and the passage of tropical storms and hurricanes. Another study on barrier island erosional patterns, conducted on the Chandeleur Islands, Louisiana, supports the analysis that shoreline erosion and sediment transport are greatly influenced by changing wind and wave energy as a result of hurricanes and winter storms [15]. Additionally, a study conducted on a Dutch barrier island further backs this analysis that sediment transport on barrier islands is highly impacted by storm frequency [16].

As a low-lying barrier island, North Captiva is a coastal environment that is very susceptible to geomorphological changes. Alterations to the physical outline of the coast, elevation changes of the beach and fordunes, and percentage changes of sediments are all pieces of evidence that support the argument that the northern portion of North Captiva Island has experienced greater erosion of sediments since 2004, sediments which were naturally transported down the longshore current and used to heal the cut inflicted on the southern part of the island when Hurricane Charley made landfall.

Recovery of North Captiva is most evident in the southern portion of the island where Hurricane Charley inflicted the most damage in 2004. LiDAR mapping immediately after the hurricane shows that at the southern breach, a section of the island is underwater. Only three years after Hurricane Charley, at the area of the southern breach, the island sat above sea level once again, and by 2018, it had gained over 2 m of height. The sediment loads that likely supplied renourishment to the southern end of the island likely came from the northern part of North Captiva Island, the coastline of which has been eroding consistently for almost two decades. Winter storms likely played a significant role in the redistribution of these eroded sediments along the study area. Overall, the damage inflicted to the island in Hurricane Charley was significant, but the subsequent erosion of the northern beaches and longshore transport of sediments to the damaged area was able to naturally heal the cut.

Similar patterns in erosion and accretion as a result of tropical cyclones and winter storms have been frequently observed and documented across the Caribbean Sea also [17,18]. In several small islands across the Eastern Caribbean, significant erosion of accretionary features such as spits and tombolas has been reported over the past several decades, especially on islands impacted by recent hurricanes [5]. A study conducted on Colombian Caribbean beaches found that storms with cold front characteristics were equally, and in most cases, more damaging than hurricanes. The erosional effect of these winter storms was found to have greater magnitude and additionally, remain for longer periods of time. As a result, coastal environments were often unable to fully recover from sediment loss before the next storm season [19]. Another study was conducted to compare the damage inflicted by Hurricane Wilma in 2005 to an exposed beach in Cancun and a beach fronted by a fringing reef in Puerto Morelos. Widespread erosion was observed at Cancun after the hurricane, whereas Puerto Morelos experienced substantial accretion of about 30 m on this beach [17,20]. Similar to the accretion of sand in the southern portion of North Captiva Island, accretion at Puerto Morelos is thought to be the contribution of sand from the northern beaches transported during storms [17].

Chronic erosion occurred to majority of the coastal environments mentioned can also be attributed to other anthropogenic factors such as coastal development, sand mining, coastal construction, and land clearing. Beach erosion in those cases were further exacerbated by increased wave energy from storms [5,16,18,21]. However, practices such as those mentioned above could prove to be detrimental to coastal environments that are most impacted by winter storms and hurricanes because of the way that they can potentially degrade natural barriers. Additional studies bring to light the importance of preserving natural protective barriers in coastal regions, such as coral reefs, mangroves, sand dunes and spits. All of these natural structures provide coastal environments with the valuable ecosystem service of coastal buffering and protection. In many cases, these structures may disperse wave energy and prevent sediment erosion. In Puerto Morelos, the presence of fringing coral reefs not only protected the beach from Hurricane Wilma, but also contributed to inducing coastal growth [20].
