Marine Creatures of the Northern Gulf – Red Algae

Members of the seaweed group Rhodophyta – the red algae – prefer warmer marine waters.  Though the diversity and abundance of seaweeds in the northern Gulf is low due to unsuitable substrate for them to attach to, the red algae may be the most diverse group we have.

One publication produced by Florida Gulf Coast University¹ lists 20 different species of seaweeds in our state; 13 (65%) are red algae.  Most of them a thin bladed.  Some are smooth and others have “hooks” along their blades.  Some species are drift algae – drifting in the water and settling on seagrasses similar to how Spanish moss settles on oak trees.  Most are found in south Florida, due to the hard limestone bottom found there, but there are species in our area attached to rock jetties and seawalls.

We also have drift algae here.  Large clumps of red algae known as Gracilaria are found atop seagrasses.  Though they provide suitable habitat for fish and invertebrates, but they are not so good for the seagrass.  These drift algae cover the grass not allowing the much needed sunlight.  They also compete with our seagrasses for available nutrients in the water column.  Volunteers in our local seagrass citizen science monitoring project – Eyes on Seagrass – record whether drift algae are present when they are monitoring as well as noting whether it was abundant or not.  We have noticed that it may be abundant in one season and not another.  We have also noticed that when it is abundant in Santa Rosa Sound it may not be present in Big Lagoon – and vice versa.

Though there is no commercial use for the red algae in our area, there are many species popular in the seafood industry.  Nori is a popular seaweed used in Sushi dishes and Dulce is said to help with sea sickness.

In the last three posts we have introduced you to the seaweeds of the northern Gulf.  Though neither diverse nor abundant, they are present and do play an important role in the ecology of our area.  I recently witnessed mallard ducks feeding off of red algae on a rock jetty on Pensacola Beach.  In our next article we will turn our attention to the only group of true submerged marine plants in our area – the seagrasses.

References

¹ Algae Identification Guide. Florida Gulf Coast University. https://hillsborough.wateratlas.usf.edu/upload/documents/FGCU_Algae_Identification_Guide.pdf