Dead Fish on Texas Beach: Unraveling the Mystery

Authorities in Texas are urging people to stay away from a beach where many dead fish have washed up. The fish, mostly Gulf menhaden, were found in large numbers on the shore. Videos showed thousands of fish carcasses floating on the water's surface at Bryan Beach.

Officials at Quintana Beach County Park have warned swimmers to avoid the coastline due to high levels of bacteria and sharp fins on the dead fish. They strongly discourage anyone from going into the water.

So, what caused the fish to die? According to experts from Texas Parks & Wildlife, there was very little oxygen dissolved in the water. Fish deaths like this are common during the summer when temperatures rise because warm water holds less oxygen. If fish are swimming in shallow water when the temperature goes above 70 degrees Fahrenheit, it can lead to problems.

The calm conditions in the nearshore waters of the Gulf of Mexico in Brazoria County for the past few weeks have also contributed to the low oxygen levels. Additionally, the presence of clouds from recent overcast days has reduced the amount of oxygen produced through photosynthesis by phytoplankton and macroalgae. At the same time, other plants and animals in the water continue to consume oxygen, causing overall oxygen levels to decrease.

Before a mass fish death occurs, fish can be seen trying to get oxygen by gulping at the water's surface in the early morning. Bryan Frazier, the director of Brazoria County Parks Department, believes that oxygen levels will return to normal soon as nature finds a balance.

In the summer, warm water holds less dissolved oxygen, making it challenging for fish to get enough oxygen. Algae and bacteria also consume oxygen, even at night when photosynthesis stops. During warm summer nights and algal blooms, dissolved oxygen levels can drop to levels that are insufficient for fish survival. Human activities that introduce nutrients like nitrogen and phosphorus into water systems can exacerbate this problem. Factors like poor water circulation, dredging, and sudden rainfall after a dry period can also contribute to low oxygen levels.

Toxic compounds released into the water can also cause fish kills, but the concentration of the toxic compound must be high. In this case, there is no evidence of a chemical spill causing the fish deaths.

The cleanup of the beach started on Friday and was completed on Sunday, with only degraded fish remains left on the shore. Local authorities advise waiting a few days before visiting the beach. Water samples from nearby sources revealed extremely low levels of dissolved oxygen, and there is no indication of a chemical spill causing the event.