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There is a growing body of literature using transcriptomic data to study how tropical cnidarians and their photosynthetic endosymbionts respond to environmental stressors and participate in metabolic exchange. Despite these efforts, our understanding of how essential genes function to facilitate symbiosis establishment and maintenance remains limited. The inclusion of taxonomically and ecologically diverse endosymbionts will enhance our understanding of these interactions. Here we characterize the transcriptomes of two very different symbionts found within the temperate sea anemone Anthopleura elegantissima: the chlorophyte Elliptochloris marina and the dinoflagellate Symbiodinium muscatinei. We use a multi-level approach to assess the diversity of genes found across S. muscatinei and E. marina transcriptomes, and compare their overall protein domains with other dinoflagellates and chlorophytes. Our analysis identified several genes that are potentially involved in mitigating stress response (e.g., heat shock proteins pathways for mediating reactive oxygen species) and metabolic exchange (e.g., ion transporters). Finally, we show that S. muscatinei and other Symbiodinium strains are equipped with a high salt peridinin-chl-protein (HSPCP) gene previously identified only in free-living dinoflagellates. The addition of these transcriptomes to the cnidarian-symbiont molecular toolkit will aid in understanding how these vitally important symbiotic relationships are established and maintained across a variety of environmental conditions.

iv ACKNOWLEDGEMENTS vi TABLE OF CONTENTS vii LIST OF FIGURES viii LIST OF TABLES x INTRODUCTION 1 METHODS 4 Field sampling 4 Preparation of host and symbiont fractions 4 Lipid extraction 5 Lipid analysis 7 Statistical analyses 7 RESULTS 9 Fatty acid profiles of Symbiodinium muscatinei and Elliptochloris marina 9 Fatty acid profiles of zooxanthellate, zoochlorellate, and aposymbiotic hosts 15 Fatty acid profiles of hosts and their algal symbiont 20 DISCUSSION 24 Fatty acid profiles of Symbiodinium muscatinei and Elliptochloris marina 24 Fatty acid profiles of zooxanthellate, zoochlorellate, and aposymbiotic hosts 26 Fatty acid profiles of hosts and their algal symbiont 29 Conclusions and future research directions 30 REFERENCES 32

Accumulations of green macroalgae (green tides) are becoming increasingly common in many coastal habitats and substances released by these blooms may impact other organisms. In the northeastern Pacific, a dominant contributor to green tides is Ulvaria obscura, an alga that produces dopamine which affects a variety of physiological processes and can trigger metamorphosis in marine invertebrates. Eggs, embryos, and larvae of Pacific oysters (Crassostrea gigas) and sand dollars (Dendraster excentricus) were exposed to U. obscura exudates and dopamine to determine how exposure affects fertilization, development, and morphology. Exposing eggs to these compounds had no significant effect on fertilization of C. gigas and limited impact on D. excentricus, relative to unexposed controls. Early embryos exposed to the compounds developed successfully, but the resulting C. gigas veligers had larger shells and the D. excentricus gastrulae had shorter archenterons. When exposed to dopamine, C. gigas veligers had smaller shells, while larval arms of D. excentricus were significantly shorter relative to unexposed controls. Results indicate that compounds released by U. obscura affect development differently between invertebrate species and among developmental stages. The stage-specific responses likely result from changes in structure and metabolic activity at different life history stages, as well as changes in the localization and function of dopamine and dopamine receptors that occur during larval development. The changes in larval morphology and function induced by compounds released by marine macroalgae could ultimately impact the ability of larvae to feed and survive.

For cnidarians that can undergo shifts in algal symbiont relative abundance, the underlying algal physiological changes that accompany these shifts are not well known. The sea anemone Anthopleura elegantissima associates with the dinoflagellate Symbiodinium muscatinei and the chlorophyte Elliptochloris marina, symbionts with very different tolerances to light and temperature. We compared the performance of these symbionts in anemones maintained in an 8-11.5 month outdoor common garden experiment with simulated intertidal conditions and three levels of shading (2, 43, and 85% ambient irradiance). Symbiont densities, mitotic indices, photophysiology and pigments were assessed at three time points during the summer, a period of high irradiance and solar heating during aerial exposure. Whereas S. muscatinei was either neutrally or positively affected by higher irradiance treatments, E. marina responded mostly negatively to high irradiance. E. marina in the 85% irradiance treatment exhibited significantly reduced Pmax and chlorophyll early in the summer, but it was not until nearly 3 months later that a shift in symbiont relative abundance toward S. muscatinei occurred, coincident with bleaching. Symbiont densities and proportions remained largely stable in all other treatments over time, and displacement of S. muscatinei by E. marina was not observed in the 2% irradiance treatment despite the potentially better performance of E. marina. While our results support the view that rapid changes in symbiont relative abundance are typically associated with symbiont physiological dysfunction and bleaching, they also show that significant temporal lags may occur between the onset of symbiont stress and shifts in symbiont relative abundances.

The temperate sea anemone Anthopleura elegantissima is facultatively symbiotic with unicellular algae. Symbiotic A. elegantissima can supplement heterotrophic feeding with excess photosynthate from their algal partners, while asymbiotic individuals must rely solely on heterotrophy. A. elegantissima individuals were collected from Swirl Rocks, Washington (48°25′6″ N, 122°50′58″ W) in July 2010, and prey capture and feeding characteristics were measured to determine whether asymbiotic individuals are more efficient predators. Feeding abilities were then measured again after a 3-week exposure to full sunlight or shaded conditions. Freshly collected asymbiotic anemones had larger nematocysts, but symbiotic individuals showed greater nematocyte sensitivity. Sunlight enhanced digestion and reduced cnida density in all anemones regardless of symbiotic state. Results suggest that the phototropic potential of A. elegantissima, as influenced by symbiotic condition, has little effect on heterotrophic capacity. The anemones appear to maximize heterotrophic energy input independent of the presence or identity of their algal symbionts.

The sea anemone Anthopleura elegantissima is a common member of intertidal communities along the west coast of North America, and can experience extended periods of increased temperature during summertime low tides. Internal body temperatures of emersed individuals of A. elegantissima were monitored in a laboratory wind tunnel and in the field, and factors influencing the anemones’ thermal experience were examined. Larger body size and aggregation with conspecifics slowed body temperature increases in controlled wind tunnel conditions. In the field, anemones in the interior of an aggregation stayed cooler than those on the edges, and microhabitat features related to light exposure and surface orientation overshadowed any direct effects of body size. In the warmest month only (July), aggregations of A. elegantissima were significantly larger at the upper limit of their distribution than they were at the mid and lower limits, suggesting aggregation in high intertidal zones may be a behavioral response to desiccation and temperature stress. As this sea anemone can host multiple species of symbiotic algae with different thermal tolerances, the ability to slow body heating may affect the type of algae hosted and thus the potential contribution of this abundant anemone to primary production in the intertidal zone.

We evaluated the seasonal stability of two algal symbiont populations in the temperate intertidal sea anemone Anthopleura elegantissima on San Juan Island, Washington, where the relatively thermally tolerant dinoflagellate Symbiodinium muscatinei coexists with the less thermally tolerant chlorophyte Elliptochloris marina. Random collection of anemones along repeatedly sampled transects over four seasons and three shore heights revealed S. muscatinei to be the dominant symbiont, with E. marina mostly limited to anemones in the lower intertidal zone. At the lowest shore height sampled (+0.2 m), the proportion of E. marina was between 40% and 50% of the total symbiont population throughout the year. Symbiont distribution patterns persisted despite considerable seasonal variation in aerial exposure, temperature, irradiance, nutrients, and phytoplankton concentration, as well as a high potential for symbiont shuffling, with mixed-symbiont assemblages occurring in 51% of all anemones sampled. Symbiont density in anemones also changed little despite three- to fourfold-higher division frequencies of both symbionts during July and November. Although the intertidal zonation of these symbionts was stable over an annual period, we predict that their spatial distributions will be responsive to longer-term environmental change, and anticipate that this anemone symbiosis will be a useful and highly tractable barometer for future climate change, with this study serving as a baseline. A diverse array of shallow-water cnidarians, including sea anemones, corals, jellyfish, and hydroids, engage in endosymbioses with phototrophic dinoflagellates (Symbiodinium spp.) that translocate photosynthetic products to their host. Many of these symbioses exhibit plasticity with respect to both the population density and genetic identity of the dinoflagellate partner, allowing them to exploit a wide range of conditions that vary spatially and temporally. In tropical systems, where cnidarian symbioses are particularly well studied, many hosts show depth-related differences in symbiont density and physiology, and also undergo predictable seasonal fluctuations in symbiont density and physiology that are correlated with environmental conditions (Fitt et al. 2000; Warner et al. 2002). In

For small tube-building amphipods that live on the algae they consume, food and habitat are tightly linked. This study compared two closely related amphipods to determine whether the species’ algal preferences are based on the food value of the algae or on some other aspect of their algal habitat. Ampithoe lacertosa and Peramphithoe humeralis are both abundant on Shannon Point beach (Anacortes, Washington, USA; 48°30.542′ N, 122°41.070′ W) but specialize on different algae. In observations and laboratory experiments conducted July–September 1997, 2007, and 2008, the two species exhibited markedly different choices of food and habitat when offered six common macroalgae. Ampithoe lacertosa ate all algae offered, but preferentially built tubes on the green alga Ulva lactuca. Survival was relatively low among juveniles maintained on single species diets, except when they were fed Mazzaella splendens. Conversely, P. humeralis consumed primarily the brown kelp Saccharina latissima, Alaria marginata, and Desmarestia ligulata and preferred those species for tube building. Juvenile P. humeralis could not survive on a diet of U. lactuca or M. splendens. While A. lacertosa builds simple, temporary tubes and relocates frequently, P. humeralis is a highly thigmotactic species that builds long-term, complex tubes on the alga it prefers to eat. Feeding and habitat preferences of the two species were not clearly linked to nitrogen content of the algae, C:N ratio, or toughness of the algal tissue. Instead, preferences of the species may be related to their mobility and the permanence of the tubes they build. Ampithoe lacertosa and P. humeralis also use different feeding strategies; the former appears to mix algae to produce a high-quality diet, while the latter is more selective and has a capacity for compensatory feeding. The species are abundant on the same protected rocky shores, but specialize on different algae for habitat and food. Results suggest that the nutritional requirements of these sympatric mesograzers differ considerably and even closely related species can exhibit divergent behavioral strategies.

Because planktonic invertebrate larvae may be food-limited, anything that increases feeding and digestive efficiency should increase the chances of larval survival to metamorphosis. As light directly enhances both feeding and digestion in some planktonic heterotrophic protists, we hypothesize that similar processes might occur in the larvae of marine invertebrates. We studied the direct effects of light on feeding and development in sea urchin larvae (Strongylocentrotus droe- bachiensis, S. franciscanus and sand dollar Dendraster excentricus). Larvae were placed in 12:12 h light:dark cycles or in complete darkness and ingestion rates were measured. We monitored larval morphology during the first 2 to 3 wk of development and tested for light-related differences. Short- term changes in light regime had no effect on feeding rates. However, larvae of all 3 species showed longer-term diel feeding patterns with ingestion rates generally higher during daylight hours. These patterns persisted in S. franciscanus larvae even when larvae were held in complete darkness for 3 d. Larvae of D. excentricus exposed to natural light cycles developed longer arms usually associated with food limitation; those held in darkness had significantly shorter arms. The developing juvenile structures (i.e., rudiments) of S. droebachiensis larvae exposed to light were significantly smaller than those of larvae held in continuous darkness, suggesting that light may have negative effects on larval growth and development. Measuring the effects of light on feeding and growth may clarify the behaviors of invertebrate larvae during their critically important planktonic period.

Nutritional provisioning that passes from a mother to her offspring can produce maternal carryover effects. Though the importance of maternal carryover effects on embryos and early juveniles is well established, it is less clear how long the effects persist and whether they can be detected in subsequent life stages of the offspring. Manipulating the amount of food available to a maternal organism is one way to manipulate maternal investment ability and thereby test maternal carryover. We collected adult brooding Leptasterias aequalis from three beaches with varying prey communities in the northern Puget Sound. When broods were released, we measured size and survival of the juveniles under starvation conditions. The maternal sea stars were then assigned to different feeding treatments and their diets were controlled for a full year until they spawned again. We measured size and growth of juveniles released from these second broods. Juvenile L. aequalis from the initial broods showed surprising resistance to starvation with 80% survival after 6 months and some juveniles living a full year with no food. Juvenile survival over time varied significantly among the mothers from the three study beaches, but we were unable to demonstrate a significant difference in the mean month of juvenile death. Juvenile size also varied significantly among mothers from the three study beaches, even when differences in female size by beach were accounted for. Adult female feeding treatments had no effect on the size of juveniles in the second broods. The patterns of juvenile performance mirrored those seen in the first year regardless of feeding treatment. The beach that a female came from seemed to have a stronger effect than a year of diet treatment. When looking at multiple generations of carryover in L. aequalis , it seems that genetic legacies, and possibly full female feeding history, have a greater effect on juvenile quality than a single year of maternal feeding.

We examined field distributions of the scavenging snail Amphissa columbiana and looked for evidence of fish predation. In the laboratory, we tested for predation by 6 crab and 10 sea star species and measured the ability of A. columbiana to chemically detect and respond to the sea star Leptasterias hexaclis. A. columbiana occurred from the low intertidal zone to depths of at least 92 m. We found no evidence of fish predation, but 4 crab species readily fed on A. columbiana. Only 3 of 10 sea star species fed on A. columbiana and predation rates were low. The inability of many sea stars to prey on A. columbiana was related to an unusual defense in which the snail inserted its proboscis deep into one of the sea star's ambulacral grooves and bit the radial nerve. The injury, which generally repelled the attacking sea star, immobilized the affected arm, rendering it useless for several days. The biting defense appears to be effective against several sea star species and may reduce predation on A. colu...

The sea anemone Anthopleura elegantissima (Brandt) hosts two species of symbiotic dinoflagellates, known as zooxanthellae, which coexist within the host at southern latitudes only. One of these species, Symbiodinium muscatinei LaJeunesse et Trench, has a broad latitudinal distribution, occurring in intertidal anemones from Washington state to Southern California. To investigate whether high thermal tolerance contributes to the ability of S. muscatinei to inhabit anemones from northern and southern regions, the upper thermal tolerance limit for photosynthesis of symbionts in northern (48°24′ N) populations of A. elegantissima was determined by subjecting anemones to a gradual increase in temperature from 12°C to 30°C over a 10-week period. Light-saturated photosynthetic rates of isolated zooxanthellae were the same over the range of 12°C–24°C and declined significantly at 26°C, which is 14°C and 5°C above average summertime seawater temperatures in northern Puget Sound and Southern California, respectively. At 28°C, zooxanthellae isolated from the anemones, and those expelled by their hosts, exhibited extremely low rates of photosynthesis and highly reduced chl content. The photosynthetic rates and chl content of expelled zooxanthellae were lower than those of retained zooxanthellae. The high thermal tolerance of S. muscatinei isolated from northern populations of anemones supports the broad latitudinal distribution of this symbiont, allowing it to coexist with S. californium (#383, Banaszak et al. 1993) in southern populations of anemones.

In recent decades, the world has witnessed an array of harmful invasions by exotic marine organisms. To provide the public and policymakers with better information on the status of exotic species in southern California waters, and to assess differences between port and non-port areas, a Rapid Assessment Survey of selected habitat types in sheltered waters between San Diego and Oxnard was conducted in the summer of 2000. The objectives included comparing the prevalence of exotic species among habitats and regions and between recent and past surveys; obtaining reference data for future assessments of changes in invasion status and the effectiveness of prevention or control efforts; detecting new invasions; and documenting significant range extensions. Twenty-two sites were sampled to include the three major commercial port areas in southern California, non-port-area marinas and lagoon sites. Sampling included dock fouling and adjacent soft-bottom benthos, nearby intertidal sites, and selected subtidal lagoon habitats. Samples were collected by a variety of manual techniques. Sixty-nine of the species collected are exotic, including representatives from two algal divisions and six invertebrate phyla. Ascidians are especially well-represented (14 exotic species) and widely occurring, and some bivalves and bryozoans also occur very widely. The numbers and proportions of exotic taxa were not significantly greater in port areas than in non-port areas. Fil: Cohen, A. N.. San Francisco Estuary Institute; Estados Unidos Fil: Harris, L. H.. National Museum of Natural History; Estados Unidos Fil: Bingham, B. L.. University of Washington; Estados Unidos Fil: Carlton, J. T.. Williams College; Estados Unidos Fil: Chapman, J. W.. State University of Oregon; Estados Unidos Fil: Lambert, C. C.. University of Washington; Estados Unidos Fil: Lambert, G.. University of Washington; Estados Unidos Fil: Ljubenkov, J. C.. Dancing Coyote Ranch Environmental; Estados Unidos Fil: Murray, S. N.. California State University; Estados Unidos Fil: Rao, L. C.. San Francisco Regional Water Quality Control Board; Estados Unidos Fil: Reardon, K.. University of Maine; Estados Unidos Fil: Schwindt, Evangelina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico; Argentina

The solitary ascidian Corella injutu is a com- mon fouling organism in many areas of Puget Sound and the San Juan Archipelago, Washington, USA. Despite its abun- dance, it is conspicuously absent from areas that receive direct sunlight. Previous work suggests that ascidians in unshaded habitats can be overgrown and killed by algal overgrowth. In this study, we tested the hypothesis that UV irradiation contributes to C. inflatu distribution by killing individuals exposed to direct sunlight. To test this, we exposed C. infuta embryos, larvae, juveniles, and adults to UV irradiation and measured the responses. We also tested for UV-absorbing compounds in larvae, juveniles, and adults. In the laboratory, UV significantly damaged all life stages; the earliest stages were most vulnerable. A 3-week UV exposure significantly shortened adult life span. Juve- niles suffered 100% mortality after only 3 days. Tadpole larvae decreased settlement and metamorphosis after I day of UV exposure, and embryos exhibited developmental abnormalities after only 30 minutes of exposure. None of the life-history stages had apparent UV-absorbing com- pounds. Given the vulnerability of this species to UV, we suggest that its unique life-history traits (i.e., time of spawn- ing, brooding behavior, length of larval life) help it persist in its preferred habitat and avoid dispersal into inappropri- ate, UV-exposed areas.

The effect of sponge encrustation on swimming ability of Chlamys hastata was determined by investigating swimming behaviour, scallop morphometry, and energy expended during swimming with and without commensal epibionts. Scallops swam significantly longer after sponge encrustation was removed from their shells, but no significant differences were detected in swimming elevation or distance. Scallops with sponge encrustation showed no adductor muscle hypertrophy or changes in shell morphometry compared to scallops without encrustation. However, C. hastata did exhibit scaling relationships associated with maximizing swimming efficiency. Specifically, shell width and adductor muscle mass were positively allometric with shell height, while shell mass was negatively allometric with shell height. Scallops increased their energy expenditure (both aerobic and anaerobic) during valve-clapping, but no significant difference was detected between unencrusted (43·0 μmol adenosine triphosphate [ATP] consumed during a two min escape swim) and sponge-encrusted (40·0 μmol ATP) scallops. Scallops in both treatments derived 86% of the energy used for swimming from anaerobic sources. The lack of substantial differences between scallops with and without commensal sponges is partially explained by the observation that even heavy sponge encrustation increases the immersed weight of the scallop by only 5%. The presence of a sponge encrustation does not appear to inhibit swimming by this scallop species.

The ascidian Corella inflata (Chordata, Ascidiacea) is common in many areas of Puget Sound, Washington, USA. However, it occurs only in habitats where it is protected from direct sunlight. Previous experiments with artificial lights showed that UV irradiation kills all life stages of this animal. The effects of natural sunlight exposure (measuring survival of adults, juveniles, larvae, and embryos) were compared. We partitioned the light spectrum to separate the effects of UVB, UVA, and visible light (PAR). Natural sunlight severely damaged C. inflata. Adults and juveniles died after 2-5 d. Exposed embryos failed to develop normally and larvae did not settle. As expected, UVB had significant effects, but pronounced effects were also seen when the animals were exposed to longer wavelengths alone (UVA and PAR). Thus, the distribution of C. inflata may be determined largely by exposure to light. Understanding the basic ecology of this species requires consideration of its vulnerability to sunlight damage and the effects of UVB, UVA, and PAR.

Dense populations of the holothurian Cucumaria lubrica (Clark) occur subtidally within the San Juan Archipelago, Washington, USA. These animals occur in a discrete subtidal zone, but the pattern has not been thoroughly studied. The objectives of this study were to document the distribution of C. lubrica, determine if the pattern was stable, and experimentally determine what factors produce it. Ten months of sampling showed that the C. lubrica population exists in a stable band between 7 and 17 m; maximum densities of 400 individuals · m−2 occurred at 12–13 m. The water column at the study site was well mixed, and seawater features (temperature, salinity, turbidity, Chl a, water flow, siltation) were not sufficiently variable to produce the zonation. Light was the only factor that varied significantly with depth. Cucumaria lubrica showed no phototaxis in the laboratory, but did show a strong photokinetic response; the animals were more active at high and low light intensities than they were at intermediate intensities. We propose that photokinetic behavior, particularly of young C. lubrica which are the most active, may contribute to their subtidal zonation. The resulting aggregation is adaptive given the reproductive behaviors of the more sedentary adults.

Submerged roots of red mangroves (Rhizophora mangle) in the Florida Keys were photographed at 1– or 2-month intervals for 38 months to measure population dynamics of the epifaunal invertebrate species. Photographs were analysed for species composition and abundance and information on life spans, persistence, mortality, and seasonality. Larval recruitment to artificial surfaces was used to assess reproductive seasonality. As a measure of stability, populations were tested for narrow stochastic boundedness. In contrast to reports for a tropical mangrove root community, the Florida Keys root community showed enormous variability despite being dominated by long-lived species with low, largely non-seasonal recruitment. Species composition on individual roots changed dramatically on short time scales. Populations of the major species were not narrowly bounded on most roots and there was little evidence for a closely regulated community. Variability of this community related to the frequency and intensity of stochastic perturbations. Physical disturbance due to strong tidal Rows appeared to be the most important structuring process. Species-specific predation and fragmentation of sponges were also important. These features contribute to the instability of the community by producing dramatic fluctuations in species abundances and preventing competitive processes from producing a more stable, equilibrium community. Temporal measurement scale was an additional important consideration in this habitat. Structuring processes occurred on very short time scales (1–2 months) and analysis on longer time scales gave inaccurate impressions of community dynamics.

Larvae of many shallow-water marine invertebrates show phototactic behaviors which may allow them to exercise some control over their positions in the water column. Such behavior should be useful only in regions where light provides a consistent directional cue and might not, therefore, be expected in species found exclusively in deep water where light levels are extremely low. In this paper, we investigated larval phototactic responses in two barnacle and one prosobranch gastropod species that occur epifaunally on tropical, bathyal sea urchins. Newly released larvae of the gastropod Pelseneeria sp. did not respond to light but Stage I nauplii of both barnacle species (Verruca floridana and Paralepas pedunculata) showed strong positive phototaxis at light intensities greater than 2.66 μmol m−2s−1. Larvae are expected to encounter the threshold intensities at depths no greater than 90 m in Caribbean waters. As both barnacle species were collected at much greater depths, phototaxis (at least in the early larvae) should have little effect. The ability to detect and respond to light may foreshadow functional photoresponses in later larvae that move to shallower depths. Alternatively, the presence of photoreceptors and light responses may be interpreted as evidence that these barnacles, which now reside in the deep sea, may have originated in shallow water.

Marine invertebrates growing epifaunally on red mangrove (Rhizophora mangle) prop roots in the Indian River, Florida, USA, were studied in a small mangrove island (Jim Island) through which a number of channels had been cut. Roots hanging down into the water supported diverse epifaunal communities including sponges, oysters, barnacles, bryozoans, and acidians. To determine what factors control species' population dynamics and contribute to the high degree of spatial heterogeneity characteristic of communities in the unique habitat, two hypotheses were tested: (1) Distributions of species on the roots are controlled by differential growth and mortality due to physical features; and (2) Recruitment, as influenced by larval supply, structures the community. Four channels of the island were chosen for comparison and experimentation. Distributions of abundances of epifauna in the channels were determined and physical parameters (i.e., temperature, pH, salinity, flow, turbidity) were measured over a 13—mo perio...

Swimming and nonswimming tadpole larvae of the ascidian Ecteinascidia turbinata Herdman were followed in situ by divers to determine whether swimming affects larval dispersal. Swimming affected neither dispersal direction nor time spent in the water column. However, the dispersal rates and distances of swimming larvae were significantly lower than those of nonswimming larvae. Potential paths of larval dispersal were modeled with subsurface drogues. Movements of both swimming and nonswimming larvae differed consistently from surface flo w direction in these shallow (1.0–1.5 m) waters, indicating that caution should be used in modeling larval dispersal with drogues, particularly when larvae do not consistently remain in surface waters. In our south Florida study site, E. turbinata colonies were present only on unanchored mangrove prop roots and survival of colonies transplanted into surroundings habitats was very low. Drogue paths demonstrated that currents could potentially carry E. turbinata between mangrove islands, but behavior of the larvae suggests that dispersal is generally very localized with larvae settling near colonies from which they were released. This behavior differs dramatically from that reported for E. turbinata larvae in a more homogeneous habitat in the northern Gulf of Mexico. The short-distance dispersal of swimming tadpole larvae inthis study may represnt a local adaptation to favor recruitment near parental habitats and to prevent advection to inappropriate sites. Long-distance exchange between isolated islands probably occurs through rafting of adult colonies on fragmented mangrove roots rather than through larval dispersal.

We manipulated live sponges in Belize, Central America, Big Pine Key, Florida (USA), and Indian River lagoon, Florida (USA) in summer/autumn, 1988. At each location, live sponges of three species were placed within 0.5 cm of ceramic tiles. Tiles with synthetic sponges positioned in the same manner and tiles with no sponges served as controls. Of 26 recruiting species analyzed, only one (Sponge sp. 6 — Indian River) was inhibited by living sponges. Four species (Perophora regina — Belize;Aiptasia pallida — Big Pine Key; andCrassostrea virginica andAscidia nigra — Indian River) recruited in greater numbers in the presence of sponges, suggesting that some larvae may be attracted rather than repelled by sponge allelochemicals. Allelopathic effects were less important than small-scale flow effects and patchy larval supply in determining recruitment patterns on surfaces adjacent to sponges.

Along the North American Pacific coast, the common intertidal sea anemone Anthopleura elegantissima engages in facultative, flexible symbioses with Symbiodinium muscatinei (a dinoflagellate) and Elliptochloris marina (a chlorophyte). Determining how symbiotic state affects host fitness is essential to understanding the ecological significance of engaging in such flexible relationships with diverse symbionts. Fitness consequences of hosting S. muscatinei , E. marina or negligible numbers of either symbiont (aposymbiosis) were investigated by measuring growth, cloning by fission and gonad development after 8.5–11 months of sustained exposure to high, moderate or low irradiance under seasonal environmental conditions. Both symbiotic state and irradiance affected host fitness, leading to divergent life-history strategies. Moderate and high irradiances led to a greater level of gonad development in individuals hosting E. marina , while high irradiance and high summer temperature promoted cloning in individuals hosting S. muscatinei and reduced fitness of aposymbiotic anemones. Associating with S. muscatinei may contribute to the success of A. elegantissima as a spatial competitor on the high shore: (i) by offsetting the costs of living under high temperature and irradiance conditions, and (ii) by promoting a high fission rate and clonal expansion. Our results suggest that basic life-history characteristics of a clonal cnidarian can be affected by the identity of the endosymbionts it hosts.

Mangroves are woody plants that grow at the interface between land and sea in tropical and sub-tropical latitudes where they exist in conditions of high salinity, extreme tides, strong winds, high temperatures and muddy, anaerobic soils. There may be no other group of plants with such highly developed morphological and physiological adaptations to extreme conditions. Because of their environment, mangroves are necessarily tolerant of high salt levels and have mechanisms to take up water despite strong osmotic potentials. Some also take up salts, but excrete them through specialized glands in the leaves. Others transfer salts into senescent leaves or store them in the bark or the wood. Still others simply become increasingly conservative in their water use as water salinity increases Morphological specializations include profuse lateral roots that anchor the trees in the loose sediments, exposed aerial roots for gas exchange and viviparous waterdispersed propagules. Mangroves create unique ecological environments that host rich assemblages of species. The muddy or sandy sediments of the mangal are home to a variety of epibenthic, infaunal, and meiofaunal invertebrates Channels within the mangal support communities of phytoplankton, zooplankton and fish. The mangal may play a special role as nursery habitat for juveniles of fish whose adults occupy other habitats (e.g. coral reefs and seagrass beds). Because they are surrounded by loose sediments, the submerged mangroves' roots, trunks and branches are islands of habitat that may attract rich epifaunal communities including bacteria, fungi, macroalgae and invertebrates. The aerial roots, trunks, leaves and branches host other groups of organisms. A number of crab species live among the roots, on the trunks or even forage in the canopy. Insects, reptiles, amphibians, birds and mammals thrive in the habitat and contribute to its unique character. Living at the interface between land and sea, mangroves are well adapted to deal with natural stressors (e.g. temperature, salinity, anoxia, UV). However, because they live close to their tolerance limits, they may be particularly sensitive to disturbances like those created by human activities. Because of their proximity to population centers, mangals have historically been favored sites for sewage disposal. Industrial effluents have contributed to heavy metal contamination in the sediments. Oil from spills and from petroleum production has flowed into many mangals. These insults have had significant negative effects on the mangroves. Habitat destruction through human encroachment has been the primary cause of mangrove loss. Diversion of freshwater for irrigation and land reclamation has destroyed extensive mangrove forests. In the past several decades, numerous tracts of mangrove have been converted for aquaculture, fundamentally altering the nature of the habitat. Measurements reveal alarming levels of mangrove destruction. Some estimates put global loss rates at one million ha y−1, with mangroves in some regions in danger of complete collapse. Heavy historical exploitation of mangroves has left many remaining habitats severely damaged. These impacts are likely to continue, and worsen, as human populations expand further into the mangals. In regions where mangrove removal has produced significant environmental problems, efforts are underway to launch mangrove agroforestry and agriculture projects. Mangrove systems require intensive care to save threatened areas. So far, conservation and management efforts lag behind the destruction; there is still much to learn about proper management and sustainable harvesting of mangrove forests. Mangroves have enormous ecological value. They protect and stabilize coastlines, enrich coastal waters, yield commercial forest products and support coastal fisheries. Mangrove forests are among the world's most productive ecosystems, producing organic carbon well in excess of the ecosystem requirements and contributing significantly to the global carbon cycle. Extracts from mangroves and mangrove-dependent species have proven activity against human, animal and plant pathogens. Mangroves may be further developed as sources of high-value commercial products and fishery resources and as sites for a burgeoning ecotourism industry. Their unique features also make them ideal sites for experimental studies of biodiversity and ecosystem function. Where degraded areas are being revegetated, continued monitoring and thorough assessment must be done to help understand the recovery process. This knowledge will help develop strategies to promote better rehabilitation of degraded mangrove habitats the world over and ensure that these unique ecosystems survive and flourish.

I would describe my graduate career in ecol ogy as "serendipitous". As a daughter of Latino parents who grew up in challenging environments with limited access to education, I was lucky to graduate from college, let alone pursue a PhD. I was also fortunate to meet a men tor who introduced me to ecology and graduate school. Unfortunately, many students from underrepresented groups lack adequate opportunities and mentorship as they head through the "pipeline" to graduate school. Despite the need for unique perspectives in collaborative scientific research, ethnic minority students continue to "leak" from the system. According to demographic projec tions, over 50% of the US population will be composed of individuals from underrepresented groups by the year 2050 (US Department of Commerce 1996). At present, how ever, these groups constitute only 6.5% of students enrolled in higher degree programs in ecology (NSF 2007). What can we do to remedy this? Exposure, oppor tunity, and access appear to be key. Here, I present some points for consideration for academic professionals (including educators, administrators, and program man agers), based on the first-hand experiences of successful minority scientists I have interviewed or who have pub lished on the subject. Introduce ecology early and supply access to research and career opportunities. It is important to publicize research, internship, and graduate program opportunities and pro vide financial support. The Ecological Society of America's (ESAs) Strategies for Ecology Education, Development, and Sustainability (SEEDS) program has effectively intro duced minority scientists to ecology by providing fellow ships and field trips, as well as travel awards to ESA's annual meetings (www.esa.org/seeds/). Create "bridge" programs that facilitate the transition of minority students from one level of academia to the next. Summer courses, orientation programs, intemships, research experiences, and cultural events all teach stu dents about the academic and social expectations of uni versities. For example, the Meyerhoff Scholars Program at the University of Maryland (UMD) has offered scholar ships, summer bridge programs, and intemships, as well as engaged students' families, and provided faculty and peer mentoring in an effort to recruit and retain minorities in science. As a result, minority participation in the sciences at UMD has increased 18%; in addition, UMD has recently introduced a graduate fellows program (Summers and Hrabowski 2006; WebTables 1 and 2). Build a sense of community through the creation of outreach

Many temperate ascidians reproduce seasonally but the factors controlling their gametogenic cycles have not been experimentally demonstrated. I tested the effects of daylength on gametogenesis in three ascidians (Boltenia villosa, Styela gibbsii, and Chelyosoma productum) by exposing animals to normal or reversed light cycles and measuring gonad and oocyte sizes. Under a normal cycle, all species followed patterns reported for field populations. B. villosa showed evidence of continuous reproduction; S. gibbsii and C. productum spawned primarily in the spring (though a secondary mid-winter spawn may also have occurred in S. gibbsii). Altering the light cycle demonstrated that the gametogenic cues differ in these three species. Gametogenesis in B. villosa and S. gibbsii was largely unaffected by a reversed light treatment but the cycle of C. productum was dramatically changed. Even in C. productum, however, the gametogenic cycle was not completely reset in the 12-month experiment. This suggests that other factors (e.g., temperature, endogenous rhythms) contribute to gametogenic control. Longer-term experiments are needed to establish the relative importance of light cycle in these species. Additional key words: tunicates, reproduction, seasonality, synchrony, daylength Synchronous spawning is critical for marine invertebrates that release gametes into the water column and rely on currents for fertilization. Water temperature, light, phytoplankton abundance, lunar cycle, and presence of conspecifics all may cue populations to synchronize spawning and maximize fertilization (reviewed by Giese & Kanatani 1987; see also Starr et al. 1990, 1991; Tyler et al. 1992). For such cues to be effective, however, some earlier signal must entrain gametogenic cycles so that gonads contain viable sperms and full-grown oocytes or ova when the spawning cue arrives. Laboratory experiments have shown that gonad growth and maturation cycles in some marine invertebrates are affected by temperature or food abundance (reviewed by Giese & Pearse 1974; see also Babcock et al. 1986; Franz 1986; Tyler 1988; Tyler & Young 1992; Tyler et al. 1992; Beauchamp 1993). Some of the clearest evidence for extrinsic control of gametogenesis, however, comes from experimental studies with light. For example, gametogenic cycles of polychaetes (Olive & Pillai 1983; Fong & Pearse 1992a,b), a cephalopod (Richard 1967), seastars (Pearse & Eernisse 1982; Pearse & Beauchamp 1986; Pearse & Walker 1986; Pearse et al. 1986a; Xu & Barker 1990), sea urchins (Pearse et al. 1986b; McClintock & Watts 1990), and a cephalochordate (Fang et al. 1989) have been altered or completely reset by simple modifications of the light cycle. Giese & Kanatani (1987) suggest that daylength may be a fairly general gametogenic cue, but to date, only a few species in a few phyla have been studied. In this paper, I report on the first test for such effects in ascidians (phylum Chordata, subphylum Urochordata). Millar (1952, 1958) and Berrill (1975) suggested that temperature controls gametogenesis in ascidians. At temperate latitudes where annual temperature fluctuations are large and predictable, gametogenic cycles could cue to temperature changes. In tropical waters where temperatures remain quite constant, absence of the temperature cue could lead to non-seasonal reproduction. Consistent with this hypothesis, temperate ascidian species often show highly seasonal reproduction (reviewed by Millar 1971; Berrill 1975) while continuous reproduction has been demonstrated for some tropical species (Goodbody 1961, 1963). However, temperature control of ascidian gametogenesis has never been tested experimentally, and Svane & Young (1989) suggest that daylength should also be considered. The hypothesis that light controls reproductive seasonality can accommodate continuously reproducing tropical species since annual changes in daylength This content downloaded from 207.46.13.129 on Sun, 26 Jun 2016 07:01:17 UTC All use subject to http://about.jstor.org/terms

In the coastal waters of Florida (USA) tadpole larvae of the colonial ascidian Ecteinascidia turbinata contain chemicals which make them unpalatable to planktivorous juvenile pinfish Lagodon rhomboides. Experiments demonstrate that the bright organe color of E. turbinata tadpoles is aposematic. Fish that have recently tasted larvae of E. turbinata will not attack the palatable tadpoles of Clavelina oblonga when the latter are dyed organe to resemble larvae of E. turbinata. Tadpoles of E. turbinata that have been mouthed and rejected by fish generally survive to complete a normal metamorphosis. Individual selection explains the evolution of aposematic coloration in E. turbinata better than kin selection. The identity of the defensive chemical is unknown. The unpalatable substance in larvae of E. turbinata is removed by dialysis, indicating that it has a molecular weight less than 14000 d. Larvae are not acidic, nor is the active substance denatured by doiling.

Many potentially predatory species of gastropods, decapods, asteroids, and fishes were tested to determine their responses to Psolus chitonoides Clark. Asteroids, particularly Dermasterias imbricata (Grube), were found to be the only important predators. Psolus chitonoides was not found in guts of any field-collected fishes, though other sea cucumbers were. Psolus chitonoides had the highest saponin content of four species of Greater Puget Sound holothurians tested. Homogenates of P. chitonoides were highly unpalatable to the tidepool sculpin, Oligocottus maculosus Girard and tissues were toxic when force-fed to O. maculosus. Toxicity of Psolus chitonoides tissue was due to the high saponin content whereas unpalatability appears to be unrelated to the saponins. Toxicity of saponins from Puget Sound holothurians to Oligocottus maculosus depends on whether the toxin is respired or ingested.

Gut analyses of five ascidian species from the San Juan Islands, Washington, Chelyosoma productum Stimpson, Pyura haustor (Stimpson), Ascidia callosa Stimpson, Boltenia villosa (Stimpson) and Styela gibbsii (Stimpson) and five species from the Atlantic coast of Florida, Herdmania momus (Savigny), Ascidia curvata (Traustedt), Ascidia nigra (Savigny), Molgula occidentals Traustedt and Styela plicata (Lesueur), indicate that solitary ascidians consume a variety of invertebrate larvae. Analysis of plankton samples collected near aggregations of live ascidians and near mimic aggregations, however, indicate that the ascidians are not significantly depleting the local supplies of larvae. Temporal and spatial patchiness in larval supply combined with selective feeding by the ascidians and escape responses of larvae are invoked to explain the lack of small scale depletion effects.

The direct developmental mode and sedentary habit of Leptosynapta clarki (Heding), an infaunal, brooding holothuroid, suggest that this species has limited dispersal capabilities. Using starch gel electrophoresis, we estimated allele frequencies at two polymorphic enzyme loci in three populations to look for consequences of limited dispersal on genetic structure of populations. Genetic composition within populations was characterized by linkage equilibrium and heterozygote frequencies which equalled or exceeded Hardy-Weinberg expectations, indicating that inbreeding does not occur and self-fertilization is not a common reproductive mode in this species. Comparisons among populations separated by 11–24 km showed significant differences in allele frequencies at both loci, indicating that populations are genetically differentiated. These differences are probably due to genetic drift or local adaptation occurring in the absence of high levels of gene flow.