Maria Pia Miglietta
Current research: Life cycle evolution, morphological traits an decological correlates in Hydrozoa (phylum Cnidaria)
I study the group Hydrozoa (Cnidaria), which in terms of life cycle have one of the widest arrays of mode of reproductions within the Metazoa. Their life cycle comprises two morphs: the benthic polyp (feeding and asexual) and medusa (feeding and sexual). I am investigating the life cycle evolution, morphological characters and ecological correlates in the benthic and planktonic stage of sister species of Hydrozoa across the Isthmus of Panama and in Florida. The rise of the Isthmus about 3.5 my ago induced dramatic environmental changes that resulted in strong alteration of ocean productivity and temperature. Today the Pacific side has high productivity and seasonal temperature changes, while the Atlantic side has low productivity and quite constant temperature through out the year; the Atlantic Coast of Florida has a very high productivity. My project aims to:
- Investigate whether the medusa stage of closely related species responds with heterochronic events (change in time of development) to the different regimes of water productivity on the two sides of the Isthmus of Panama and in Florida.
- Investigate through common garden experiment, if the heterochronic events are the outcome of hereditary divergence or plastic response to the environment.
- Investigate the nature of environmental cues that trigger medusa production from the benthic polyp. The Hydrozoa, with their occurrence in both, benthic and planktonic habitats, their high variability, and complex life cycles, represent a single group that can account for responses at different ecological levels. It can therefore be used as a paradigm for the understanding of general mechanisms that act on a great number of other phyla.
David I. Kline
Smithsonian Marine Science Network Fellow
The main focus of my research has been to explore the relationship between water quality, environmental change, and symbiont diversity (both bacterial and algal) on coral health and reef decline in Bocas del Toro, Panama.
My primary research focuses on how different components of pollution change the relationship between corals and their associated symbiotic microbial communities. A major finding of my research is that dissolved organic carbon (DOC, e.g. simple sugars), a pollutant rarely measured on reefs but released from agriculture, sewage, and macroalgae, causes significant coral mortality. DOC causes coral mortality by disrupting the balance between the coral and its associated bacterial community. This research was highlighted in the February 2006 issue of Science and is published in Marine Ecology Progress Series (Vol. 314: 119-125, 2006 and Vol. 294: 173-180, 2005) and Limnology and Oceanography: Methods (In Press).
My second research focus is on the dynamics of White Band Disease (WBD) transmission, focusing on the environmental and genetic influences on disease susceptibility. This study involves conducting disease transmission experiments on genotyped corals colonies from both impacted and isolated Acropora cervicornis reefs within the Bocas archipelago. This research suggests that there may be a large environmental influence on disease transmission and a role of host genetics in disease resistance. This research is being done in collaboration with Steve Vollmer, a fellow Smithsonian postdoctoral researcher.
My third major research focus has been studying the massive Caribbean bleaching event of 2005 in collaboration with Mary Alice Coffroth of the State University of New York at Buffalo. We are using over four hundred permanently tagged corals in Bocas del Toro to determine how zooxanthellae clades change through the bleaching process and into recovery.
The final major component of my research involves developing computer vision applications for assessing coral reef health. This is a multidisciplinary, collaborative project in which I have been working with computer scientists, engineers, and optical specialists to try to develop tools for rapid, automated surveying of coral reefs. With Greg Mitchell of the Scripps Institution of Oceanography and computer vision scientists from the University of California, San Diego we are developing coral reef image training sets to train computers to distinguish healthy, diseased, and bleached corals.
I love to study how social animals are organized and how they deal with internal and external problems. Eusocial (or truly social) animals include the familiar ants, honeybees and termites. They live often in large colonies that have overlapping generations, where most of the colony-members forego reproduction and instead help to rear the progeny of one or a few individuals. Because sociality would appear to contradict Darwin 's emphasis on behavior benefiting oneself, explaining the origin and maintenance of sociality has presented a challenge. However, even if individuals do not disperse they can still benefit relatives, thereby favoring genes they themselves possess.
Although in the past I worked with tropical bees, after my PhD. I switched study objects and currently I study eusocial snapping shrimp. Because social shrimp have been discovered fairly recently and because they live under water, which makes them hard to access, shrimp are one of the least studied taxa of social animals. Social shrimp societies live in the internal canals of sponges and feed probably on host tissues and/or detritus. Colonies vary in size from a few tens to a few hundred individuals, according to the species. The animals are tiny, varying from a few to 15 mm. These snapping shrimp posses two claws that are very asymmetrical in size, they use the powerful major claw to communicate or fight, eliciting a snapping sound familiar to tropical divers worldwide. As in the other social animal societies, shrimp colonies contain one or a few queens that are larger than the rest of the group and produce the offspring. Once the eggs are fertilized queens carry them in their abdominal pouch and take care of them until they hatch. The rest of the colony consists of juveniles of different sizes and larger animals without developed gonads, most of these are the offspring of the queen. Queens usually do not show much activity, it is especially the larger animals that territorially defend the sponge and thus the colony from intruders.
Since there is limited amount of data on social shrimp, they represent an exciting frontier in social biology and animal behavior. Moreover, this work gives me the chance to compare terrestrial eusocial societies with marine ones and to explore the roles of their divergent ecologies. The study of social shrimp offers a rigorous testing of general theories of animal social evolution.
At the moment I am involved in several projects, some of these are: 1) determining the genetic structure within shrimp colonies, 2) determining sexes of helpers and their sex ratio's in colonies, 3) comparing the morphology of social shrimps and non-social shrimp, 4) comparing colonization rate and success of sponge hosts of social compared to pair-forming shrimp, and 5) comparing and observing behavioral interactions between colony members in shrimp colonies.