Authors: Amanda, Anne & Hannah
According to Beyonce, girls run the world, but from Bishop O’Dowd’s sandy beach monitoring data, it’s female sand crabs with eggs the run Ocean Beach. Sand crabs are important animals on California beaches because they can indicate the health of the area of the beach in which they live. Also, they are an important species in the food chain. They are the primary consumers on the beach and many other species rely on their existence.
Over the past ten years, the amount of female crabs with eggs has fluctuated greatly. The crabs had fruitful mating seasons in 2009 and 2011, as shown by the graph below. Following the pinnacle of pregnant crab abundance in 2009, Ocean Beach’s sand crab population boomed (see year 2010 in the graph). Most of these crabs were juveniles and possibly offspring of the pregnant females from the year before. This population boom may be due to climate change; recent studies have shown our planet faces challenges that may be devastating for the species that make their home, reproduce, and live in sandy beaches.
While there were a great number of female crabs with eggs in 2009 and 2011, there were some limiting factors which may have affected our data. A possible limitation that may have prohibited us from gathering more accurate data is that we did not collect sand crabs from lower in the swash zone, where research shows most of the females with eggs are often found. The data might have been a lot different if we had gathered data deeper into the swash zone. Other factors may include the weather, the season, and level of human impact on the days we monitored. Furthermore, a recent article in Global Change Biology reveals that climate change impacts (rising sea levels, habitat destruction, and ocean acidification) may threaten the survival of many marine organisms on sandy beaches. Human activity, including climate change, may cause a population decline in future generations of sand crabs as well.
Our data demonstrated no specific pattern regarding female sand crabs with eggs over the duration of the past 10 years. However we observed an event in which the high amount of pregnant crabs one year were followed by a year that contained a drastic increase in total sand crabs, particularly recruits. We observed this scenario in 2009-2010, but it may have happened many times throughout the years at Ocean Beach. Only time will tell.
Beyonce rules the music industry just like sand crabs dominate the ecosystem of beaches. Based on our data, female sand crabs with eggs display at least one major comeback within the ten year duration; similar to Beyonce’s big comeback with her song, “Girls Run the World.”