Balanus eburneus

Salinity in coastal rivers and tributary creeks may be an indicator of the rise in sea levels.  In Florida this can happen with hurricanes, but these are occasional.  Rising sea levels, however, are not intermittent, and, therefore, will have an impact on plants and animal life on a fresh water creek or river.

Certain plants are more tolerant of salt than others, but all terrestrial plants are affected by the composition of soil infused by salt water.  Excessive salts in the soil can inhibit absorption of water, causing plant dehydration.  Salts carried into the capillary system of plants can cause chlorosis which affects leaves (which turn pale and yellowish).   The inability of sufficient leaves to produce chlorophyll needed by the plant affects the growth of the plant.

Barnacles require salt water to live.  In the absence of saline testing equipment, we have been checking on barnacle growth in Womack Creek.

Barnacles are closely related to lobsters and crabs.  They have shells of connected overlapping plates along with jointed legs and slender and wispy feet.

Twenty five percent of barnacles live in the inter-tidal zone, but are protected against water loss in low tide.  They require water to feed and when not feeding have two calcite plates which can close.  This also protects them from predators.  There are species of barnacles which attach themselves to crabs.

When feeding on phytoplanton and zooplanton in the water, barnacles have feathery legs which beat in the water drawing food into the shell.

Barnacles ready to mate are sessile (fixed in one place) so in some species the male reproductive organ has had to adapt by increasing its length in a ratio to its size considerably greater than that found in other animals.   Other adaptive methods of fertilization have been noted, such as sperm casting which the female barnacles intercept to fertilize their eggs.   Single barnacles may be  able to produce both sperm and egg.

Fertilized eggs hatch into the nauplius larva which is brooded by the parent for about 6 months before being released as  free-swimming cyprids.  The cyprid is a non-feeding stage when the creature seeks a permanent site to attach itself.  Using its antennules, it seeks a site and then fastens itself head first with a secreted substance.  Finally able to reach its final stage, sessile barnacles begin to build their shells which fix them to a location for their life span of about 5-10 years.

Worms, whelks, mussels, shorebirds, snails and sea stars are common predators of barnacles.   Oil spills are also detrimental to the species.

We have only been able to identify colonies when the tide is low, the most recent on March 13, close to a full moon day.  Although resembling a colony, the barnacles do not see to be alive, rather just the exterior shells remain.  Last year, there were a few living barnacles.  Also observed last year were small fiddler crabs in the first branch after the Womack Creek put-in.  These crabs have not been seen this year.  Both require saline water.