Graduate research examines changes in Galveston beaches
A zoology doctoral student in the department of biology at Texas A&M University, Witmer is combing the beaches at Sabine Pass, High Island, Jamaica Beach and Surfside Beach along the Galveston coast. She's collecting as much data as possible while examining the composition of the beaches and identifying changes due to seasonality and storm events.
She's also gathered information for a research paper depicting immediate observations after Hurricane Ike. She saw immediate changes in grain size and the effects on living organisms.
The hurricane took great quantities of the sand that had been on the beach and pulled it back into the ocean, she said. Now, nine months after Ike, she continued, "the beach is slowly coming back from the erosion that occurred. There was definitely a huge loss of sand and sediment on the slopes (of the beaches), making them become steeper."
Witmer has also documented changes in animal life after Hurricane Ike as a result of the negative impacts on the beaches.
Dr. Rusty Feagin, a Texas AgriLife Research ecosystems management scientist, is on her doctoral committee and is researching different aspects of ecosystems along Galveston Island.
Witmer’s research emphasis is seasonal variations from summer to winter. The initial findings indicate changing composition of beaches even before Hurricane Ike ravaged the Texas coastline, she said. Her data collection began in 2007 examining seasonal changes, including northers and tropical storms.
“Then when Hurricane Ike came through, I started looking at changes when such big storms hit beaches and the changes in the future,” she said. “I started looking at the beaches to create a baseline of data.”
Her first observations were that the beaches are already eroding and had been eroding for some time. She’s noticed more living organisms during the summer months than winter.
“I’m basically looking for any animal that shows up, such as crabs, little shrimps.”
Those include the amphipod, “a little bug, as I tell people, but it’s actually a crustacean,” Witmer said.
“The plans are for it to be a two-year study and to go out once every four weeks and see how organisms change," she said.
In early July 2007, Witmer started the first month of data collection. Hurricane Ike hit at the 15-month mark in September 2008.
“I had a full year's worth of data to compare against. Now I’ve been in the process of gathering recovery data sets.”
Of the sites observed prior to hurricanes Rita and Ike, she had sites that “range from those known to be actively eroding with larger coarse sand to those more stable beaches with sands that were very fine. “
“Organisms were greater in abundance in summer and fewer in winter,” she said. “I was looking specifically to see if animals changed consistently or if there was a trend we could actually be watching. I have currently identified around 34 different species, but only about six occurred consistently. The two most dominant species were an amphipod crustacean species 'little bug', and a fuzzy polychaete worm. Those show up consistently at every beach, with fewer numbers at the eroding beach.”
To gather samples, Witmer sets up several stations between the high-tide mark and the low-tide mark on the beach.
“I take core samples at each of those stations,” she said. “I have a 10-centimeter by 10-centimeter cylindrical core. I take a plug of sand and run it through a sieve, then anything that's larger than one millimeter is counted. Every now and then something that lives in the water will be found, but I am specifically interested in what lives in the sand. I take extra plugs of sand to run grain-size analysis.”
Witmer said she has seen lots of change post-Hurricane Ike.
“The storm displaced much of the light-weight beach sand, silt and clays, anything that could be stirred up easily, and deposited it on land and in nearshore sandbars. I’ve also been looking at changes in elevation, slope and shell composition–what’s going on, birds on beach this month, etc.”
Her research is in the completion phase, and she’s seen noticeable results.
“If you look at seasonal data, it shows expected changes with the exception of the eroding beach – species that live there are very, very few. Definitely what you would expect. These organisms I’m looking at as sort of a primary consumer group that are eaten by larger fish, crabs in the area and even birds. Usually where you have few organisms you have fewer birds. This is great information and I hope it will help someone else’s research down the road.”
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