Background. The dramatic decline of California’s abalone populations, including those found in the waters surrounding the northern Channel Islands, is a striking example of how human impacts and other factors can dramatically affect marine wildlife and biodiversity. The serial depletion of abalone species through overharvesting – beginning first with red and pink abalone, then green, white, and black abalone – led to a near-total collapse of abalone populations in California. Despite bans on abalone fishing, already weakened populations continued to decline due to the combined effects of disease and changing oceanographic conditions.
Recovery of depleted abalone populations is critically dependent on the interplay of human activities and important ecological issues associated with resiliency, reproduction, and recruitment. These issues, which are central to the preservation of all marine species, have guided the design of a network of marine protected areas surrounding California’s northern Channel Islands, which include Anacapa, Santa Cruz, Santa Rosa, San Miguel, and Santa Barbara Islands.
Field Work. During the field component of this program session, students will receive an in-depth introduction to abalone species diversity, reproduction, development, and growth. As in the Biomes to Genomes program, students will also explore: 1) the biogeographic factors influencing kelp forest biodiversity; 2) the fundamental scientific issues guiding the design of the Channel Islands marine protected areas (MPAs); 3) the parameters used to assess MPA efficacy; and 4) the biology/ecology of locally relevant marine indicator species. Issues associated with abalone mariculture practices, their role in supplying commercial markets for food and jewelry, and their potential for replenishing wild abalone stock populations will also be discussed.
In the field, students will conduct basic underwater marine surveys modeled after those used by biologists to monitor the abundance of fish and invertebrate indicator species that provide vital signs of ecosystem health. Underwater survey data will be organized and submitted to an online database managed by REEF, a marine biodiversity monitoring project that was founded in 1990 in response to growing concerns over the health of the world’s oceans.
Background. Many marine invertebrates, including abalone, produce large numbers of larvae that swim in the water column in an arrested state of development. Release from developmental arrest occurs only after larvae encounter a microhabitat that is particularly suitable for their growth and survival. Specific biomolecules present in these microhabitats appear to instruct larvae to settle from the plankton, undergo metamorphosis, and assume a benthic existence.
For the larvae of red abalone (Haliotis rufescens), settlement and metamorphosis is controlled by inducer peptides displayed by encrusting red algae. Structurally similar to GABA (gamma-aminobutyric acid), an inhibitory neurotransmitter used for nerve cell communication, these peptides are recognized by receptors or sensors present on the cilia of abalone. Once bound to the receptors, the peptides trigger a cascade of biological events that result in the metamorphosis of abalone larvae into the adult form.
Interestingly, the receptors and inducer molecules, as well as the biochemical pathways that mediate this metamorphic response, share many similarities to those that control neuronal activity, cell proliferation, and cell specialization (differentiation) in mammalian cells. These cellular events are the primary focus of study for many biomedical scientists. Understanding the biomolecular pathways that regulate cell proliferation, cell differentiation, cell death, and cell migration has important implications for treating certain human diseases, including various types of cancer.
Laboratory Work. The laboratory component of this program session will trace the scientific work that led to the identification and characterization of the biomolecular pathways controlling abalone settlement and metamorphosis. This information will be used as a conceptual basis for students to explore broader concepts associated with neuronal excitability and signal transduction in mammalian systems. In CMB’s marine lab, students will employ a simple method currently used in mariculture facilities to induce the spawning of farm-reared abalone stocks. They will then monitor the development of fertilized oocytes and use standard microscopic techniques and image analysis procedures to document the major morphological changes that occur during the initial stages of abalone embryogenesis and larval development. In a separate series of experiments, students will establish standard bioassays to evaluate and document the effects of natural and synthetic compounds (including GABA-mimetic peptides) on the metamorphosis of abalone larvae.
In CMB’s cell biology laboratory, students will extend their studies to the cellular level by investigating the role of different factors on the differentiation of non-human pluripotent cell lines, including neuronal and glial precursors. Differentiation and morphological changes will be monitored and documented using a suite of fluorescent molecular probes and markers in combination with epifluorescence microscopy.