Barnacles Associated with Marine Vertebrates in Puerto Rico and Florida
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Barnacles Associated with Marine Vertebrates in Puerto Rico and Florida by Jamilette Cintrón-De Jesús A thesis submitted in partial fulfillment of the requirements for the degree of Master of Marine Science In Biological Oceanography University of Puerto Rico Mayagüez Campus 2001 Approved by: Ernest H. Williams, PhD Date President, Graduate Committee Antonio A. Mignucci- Giannoni, PhD Date Member, Graduate Committee Juan G. González Lagoa, PhD Date Member, Graduate Committee Dallas E. Alston, PhD Date Director of the Department of Marine Science Angel Berrios, PhD Date Representative of Graduate School Jaime Seguel, PhD Date 1 2 Introduction Most studies about cirripeds or barnacles are directed toward finding methods for their removal from marine structures and vessels. Other studies focus on biodiversity, phylogeny, zoogeography and life history parameters of species. Barnacles (balano, ballocas or caracolillos, in Spanish) are crustacean arthropods belonging to the subclass Cirripedia and to the order Thoracica (true barnacles). They can be divided in two groups by their types and morphological differences (Fig. 1): The acorn barnacle and stalk or “goose” barnacles. Some species are edible and commercially managed (percebes, in Spanish). They are mostly marine but some species are resistant to fresh water, i.e., Balanus improvisus (Zullo, 1979). Many species are located in the intertidal zone and can usually be observed in piers, seawalls, marinas and boats. For that reason most of the studies have been directed to finding ways or eradicate them. In boats and ships, they increase fuel consumption. This research mostly looks at the adhering mechanics and morphology of the cirripeds. Barnacles are mostly hermaphrodites, but they need another individual to fertilize them. They are usually gathered in clusters to assure their reproduction. A single barnacle can produce thousands of eggs (Poor and Taylor, 1998). Eggs hatch into microscopic nauplii larvae that pass through six metamorphic changes each increased complexity until the cyprid crawls over a surface with the help of its 3 antennae and attaches from the head with a special cement or glue excreted by the antennae. At that point, the cyprid stage changes to the juvenile, begins to develop and turns in to a sessile crustacean. If larvae do not find a place to settle in a limited amount of time, they cannot complete their cycle and will die. Some species from the order of Rhizocephala are parasitic. The rest have a symbiotic relationship known as commensalism. Barnacles feed by sweeping the water with their cirri, or feathery legs. The mechanics of this movement depends on the species. Some maintain their operculum (the opening from where the cirri protrude) closed tightly and others partially closed. They can extend their cirri two or three times per day or only in high tides or only during the nights, depending on the species. The species, and sometimes the environment, determines essentially the feeding mechanisms of the barnacle. The literature concerning the taxonomy of barnacles in the Caribbean, and thus Puerto Rico, is scarce. Mignucci-Giannoni (1996) reported these crustaceans to be epibionts of marine vertebrates, specifically cetaceans, sirenians and chelonids, confirming their existence, but not establishing a detailed list of their taxonomy identification, characteristics or description. It has been presumed that some barnacle species are specific to a certain substrate or host. This research examines the correctness of these assumptions, providing a description of each species and a key of the 4 cirripeds found associated with the West Indian manatee (Trichechus manatus), the humpback whale (Megaptera novaeangliae), the green sea turtle (Chelonia mydas), and the hawksbill sea turtle (Eretmochelys imbricata). Additionally the samples were examined to verify occurrence, geographic range and morphometric comparisons of the shell diameter and height and operculum measurements of each barnacle. Literature review Naturalist Sir Robert Morey (1678) from Great Britain referred to the cirripeds as “little birds perfectly shaped” believing that barnacles were eggs of barnacle geese. When Linnaeus (1758) began to classify the animal kingdom, he considered barnacles to be mollusks. Later, Vaughn Thompson, a British army surgeon, demonstrated that barnacles were crustaceans. Charles Darwin studied in his two monographs, cirripeds and wrote a monograph on these, divided in two parts, Lepadidae or pendunculate cirripeds (Darwin 1851), and Monograph of the Balanidae, the Verrucidae (Darwin 1854). These are still the most important reports on barnacles. Many cirripedologists still use these references for the classification and description of the species. Many others studies have been conducted concerning the biology of barnacles, but only in the last decade the physiology and the ecology of barnacles has begun to be studied. Most works are about removal of 5 barnacles from ships due to economics limitations that these cause on fuel efficiency. Others contribute with geographic location and classification. Pilsbry (1916) classified the barnacles in the U.S. National Museum collections, while Nilsson-Cantell (1927) classified barnacles in the British Museum. Parker (1960) studied the ecology of cirripeds, and detailed characteristics of some barnacles. Crisp (1967) studied how substrate influenced barnacle morphological development, as well as details on phylogeny of the group. Newman (1976) revised the taxonomy of balanomorph barnacles, including a catalog of the species. Zullo (1979) reported on the marine flora and fauna of the northeastern United States, including the characteristics of barnacles in New England. The same year, Monroe and Limpus (1979) provided the systematics and the characteristics of all barnacle species found on turtles in Queensland, Australia. Anderson (1994) provided an extensive list of references and excellent information of the biology and phylogeny of the cirripeds. In the Gulf of Mexico, Pilsbry (1953) detailed Florida barnacles, while it was not until the 1980s that Gittings (1986) studied barnacles in its northern part. In the Caribbean, especially in Puerto Rico, the knowledge about barnacles associated with marine vertebrates is minimal. While poorly, Bigelow (1899) detailed the cirripedia collected by the Fishhawk Expedition in 1898-1899. Williams (1978) and Williams et al. (1986) reported on the 6 associations of pendunculate barnacles with fishes, one from the Japan area and the other in the Caribbean area off St. Thomas. Rodríguez-Fourquet (1992) studied the barnacles present in the estuarine ecosystems of Joyuda Bay. In the 1990s, the Caribbean Stranding Network began their operations, and as a consequence, major studies concerning marine mammals and sea turtles increased. As part of their mortality assessment research, barnacles were collected from stranded animals and stored for future analysis. Mignucci-Giannoni (1996), Mignucci-Giannoni et al. (1998), Mignucci-Giannoni et al. (1999), Rodriguez-López and Mignucci-Giannoni (1999), and Rosario-Delestre et al. (1999) reported the presence of barnacles on marine mammals from Puerto Rico and the Virgin Islands. Conchoderma auritum, Coronula sp. and Chelonibia manati were identified from the samples. Materials and Methods Barnacles were collected and removed from stranded whales (humpback whale, Megaptera novaeangliae), manatees (Trichechus manatus) and sea turtles (hawksbill sea turtle, Eretmochelys imbricata, and green sea turtle, Chelonia mydas) in Puerto Rico and Florida. They were collected during necropsy or salvage procedure following the protocols of Mignucci-Giannoni et al. (1998) and Ortíz-Rivera (2000). Most samples were preserved in 70% ethanol, except for those found in humpback whales, which were fixed first in 10% formalin and later preserved in ethanol. Barnacles examined for size and strength of the shell were cut with a geologic saw. Remaining samples from manatees and sea turtles were dissected using pliers. A small brush was used to clean the barnacles from inorganic and organic material. Identification and classification of the barnacles was done using Darwin (1854), Pilsbry (1916), Newman and Ross (1976), Gittings et al. (1986) and Anderson (1997) as reference. Each barnacle specimen was identified based on morphological differences, primarily external characters. Some were dissected and observed internally with a stereoscope. Specimens were measured with calipers to determine their shell diameter, shell height and diameter of the operculum. Operculum/shell diameter and 7 8 shell height/shell diameter were used for statistical analysis and to provide a better morphological description. All data were analyzed using t-test (two populations) independently. The comparison was done between locations with same host and different host's species in the same location. Box chart graphs were used, where each Y column of data is represented as a separate box. The column names or labels supply the X-axis tick labels. The horizontal lines in the boxes denote the 25th, 50th and 75th percentile values. The error bars denote the 5th and 95th percentiles values. The two symbols below the 95th percentile error bar denote the 0 and 1st percentile values. The two symbols above the 95th percentile error bar denote the 99th and 100th percentiles. The square symbol in the boxes denote the mean of the column of data. Results A total of three barnacles from humpback whales, (Megaptera