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Highly abundant and widespread populations of the introduced eastern Pacific ophiuroid brittle star Ophiothela mirabilis occur in southeast Florida, extending the range of this new non-native species from southern Brazil northward to the Caribbean Sea and Florida, now spanning about 6000 km of latitude along western Atlantic tropical/subtropical shores. This brittle star species, representing two lineages, is an epizoite on shallow-occurring (3–15 m depth) plexaurid octocorals (e.g., Eunicea spp., Muricea elongata, and Plexaurella dichotoma). Overall body color (disk and arms) is commonly beige or orange; a few individuals display combinations of both colors: orange disk/beige arms or beige disk/orange arms. Population densities in situ commonly ranged between 5 and 12 individuals of O. mirabilis per 10-cm-long octocoral branch with up to six arms generally curled around their octocoral host’s branches. In a 33-day experiment, M. elongata colony surface areas with reduced (contracted) polyps and reduced polyp extension lengths were not statistically different between octocorals with brittle stars versus octocorals without brittle stars. At the end of 33 days, brittle star densities demonstrated an overall decline. In a 66-day experiment, increasing brittle star densities resulted in reduced extended polyp areas in M. elongata, but no changes in Eunicea flexuosa. Polyp extension lengths decreased in both octocoral hosts with increasing densities of O. mirabilis. Overall, experimental brittle star densities did not change, with several octocoral hosts revealing increases in O. mirabilis by means of fissiparity. The presence and increasing densities of O. mirabilis causing a reduction in octocoral polyp extension were greatest in M. elongata but did not result in visible adverse effects to host condition. Black spotting on octocoral stems, a sign of tissue deterioration, was not observed during or after the two experiments. Nearly all experimental octocorals demonstrated tissue growth in the 66-day experiment, expanding over relatively large areas of the supporting pedestals.

The invasive brittle star Ophiothela mirabilis (family Ophiotrichidae), a tropical Indo-Pacific endemic species, first reported in Atlantic waters off southern Brazil in 2000, has extended its range northward to the Caribbean Sea, to the Lesser Antilles in 2011, and was first reported in south Florida in January 2019. Its occurrence in southeast Florida extends along nearly 70km of coastline, from near the Port of Miami, Miami-Dade County, northward to Deerfield Beach, Broward County. It occurs abundantly as an epizoite on octocorals, attaining population densities of 25 individuals and more per 10-cm long octocoral stem. The surface texture of octocoral hosts (rough, smooth) did not affect the densities of the ophiuroid epizoites, and there were significantly greater abundances on octocorals during two winter sampling periods than in the summer. Beige and orange-coloured morphs are sometimes present on the same octocoral stem. Gut content analysis supported a suspension feeding mode, revealing essentially identical ingested items in both colour morphs with a preponderance of amorphous detritus and filamentous algae. Molecular genetic evidence (COI16s) has established the identity of O. mirabilis and its relationship to invasive Brazilian populations. The orange and beige morphs form two distinct, but closely related lineages that may represent two separate introductions. The orange morph shares haplotypes with Brazilian and Caribbean specimens suggesting a further range expansion of the 'original' invasion. The beige morph, however, shares haplotypes with specimens from the Mexican Pacific and Peru and potentially represents a secondary introduction. Traits promoting dispersal and establishment of this species in new habitats are manifold: vagility and ability to cling tightly to diverse host taxa (e.g. sponges, cnidarians, bryozoans, and echinoderms), frequent asexual reproduction (fissiparity), suspension feeding, including a wide range of dietary items, possession of integument-covered ossicles and arm spines offering protection from predators, and an effective competitive edge over associated microbiota for substrate space.

Comparative analysis of the expanding genomic resources for scleractinian corals may provide insights into the evolution of these organisms, with implications for their continued persistence under global climate change. Here, we sequenced and annotated the genome of Pocillopora damicornis, one of the most abundant and widespread corals in the world. We compared this genome, based on protein-coding gene orthology, with other publicly available coral genomes (Cnidaria, Anthozoa, Scleractinia), as well as genomes from other anthozoan groups (Actiniaria, Corallimorpharia), and two basal metazoan outgroup phlya (Porifera, Ctenophora). We found that 46.6% of P. damicornis genes had orthologs in all other scleractinians, defining a coral ‘core’ genome enriched in basic housekeeping functions. Of these core genes, 3.7% were unique to scleractinians and were enriched in immune functionality, suggesting an important role of the immune system in coral evolution. Genes occurring only in P. damicornis were enriched in cellular signaling and stress response pathways, and we found similar immune-related gene family expansions in each coral species, indicating that immune system diversification may be a prominent feature of scleractinian coral evolution at multiple taxonomic levels. Diversification of the immune gene repertoire may underlie scleractinian adaptations to symbiosis, pathogen interactions, and environmental stress.

With the expansion of marine aquaculture throughout the world comes a need for solutions to improve the economic viability and environmental sustainability of farming operations. Integrated multi-trophic aquaculture (IMTA) has been identified as a promising method of farming that typically combines multiple cultured species in connected systems in an effort to decrease the concentration of nutrients expelled as waste products from intensive finfish culture while also increasing commercial profits via subsequent extractive biomass production. This study examined the effectiveness of South Florida native red macroalgal species Agardhiella subulata for use as a productive, nutrient-extracting species for IMTA in the Atlantic, Gulf of Mexico, and Caribbean regions. When cultured in a pilot-scale, land-based IMTA system for replicated 15 day trials with American red snapper, Lutjanus campechanus, A. subulata grew up to 14.4% d−1 and significantly decreased the concentration of all measured dissolved inorganic nutrients in the effluent water. The average percent (% ± SE) removal of nutrients were: 68.8 ± 4.8 ammonia, 94.5 ± 1.3 nitrate, 96.6 ± 2.0 nitrite, and 93.2 ± 3.1 phosphate from primary culture effluents. Further evidence of A. subulata fitness for commercial IMTA practices is shown through significantly high bulk nitrogen tissue concentration of experimental (nutrient-enriched) compared to control (un-enriched) groups. Results of this study demonstrate the efficient growth and nutrient removal capabilities of A. subulata when used in IMTA applications with marine finfish production in warm water environments, as may be encountered in marine aquaculture projects in the Atlantic, Gulf of Mexico and Caribbean regions.

The invasive brittle star Ophiothela mirabilis (family Ophiotrichidae), a tropical Indo-Pacific endemic species, first reported in Atlantic waters off southern Brazil in 2000, has extended its range northward to the Caribbean Sea, to the Lesser Antilles in 2011, and was first reported in south Florida in January 2019. Its occurrence in southeast Florida extends along nearly 70 km of coastline, from near the Port of Miami, Miami-Dade County, northward to Deerfield Beach, Broward County. It occurs abundantly as an epizoite on octocorals, attaining population densities of 25 individuals and more per 10-cm long octocoral stem. The surface texture of octocoral hosts (rough, smooth) did not affect the densities of the ophiuroid epizoites, and there were significantly greater abundances on octocorals during two winter sampling periods than in the summer. Beige and orange-coloured morphs are sometimes present on the same octocoral stem. Gut content analysis supported a suspension feeding mode, revealing essentially identical ingested items in both colour morphs with a preponderance of amorphous detritus and filamentous algae. Molecular genetic evidence (COI & 16s) has established the identity of O. mirabilis and its relationship to invasive Brazilian populations. The orange and beige morphs form two distinct, but closely related lineages that may represent two separate introductions. The orange morph shares haplotypes with Brazilian and Caribbean specimens suggesting a further range expansion of the ‘original’ invasion. The beige morph, however, shares haplotypes with specimens from the Mexican Pacific and Peru and potentially represents a secondary introduction. Traits promoting dispersal and establishment of this species in new habitats are manifold: vagility and ability to cling tightly to diverse host taxa (e.g. sponges, cnidarians, bryozoans, and echinoderms), frequent asexual reproduction (fissiparity), suspension feeding, including a wide range of dietary items, possession of integument-covered ossicles and arm spines offering protection from predators, and an effective competitive edge over associated microbiota for substrate space.

Regulating partner abunclance may allow symmotic organisms to mediate interaction outcomes, facilitating adaptive responses to environmental change. To explore the capacity for-adaptive regulation in an ecologically important endosymbiosis, we studied the population dynamics of symbiotic algae in reef-building corals under different abiotic contexts. We found high natural variability in symbiont abundance in corals across reefs, but this variability converged to different symbiont-specific abundances when colonies were maintained under constant conditions. When conditions changed seasonally, symbiont abundance readjusted to new equilibria. We explain these patterns using an a priori model of symbiotic costs and benefits to the coral host, which shows that the observed changes in symbiont abundance are consistent with the maximization of interaction benefit under different environmental conditions. These results indicate that, while regulating symbiont abundance helps hosts sustain maximum benefit in a dynamic environment, spatiotemporal variation in abiotic factors creates a broad range of symbiont abundances (and interaction outcomes) among corals that may account for observed natural variability in performance (e.g., growth rate) and stress tolerance (e.g., bleaching susceptibility). This cost or benefit framework provides a new perspective on the dynamic regulation of reef coral symbioses and illustrates that the dependence of interaction outcomes on biotic and abiotic contexts may be important in understanding how diverse mutualisms respond to environmental change.

Aplysia californica was hatchery-reared in two turbulence protocols intended to imitate the intermittent turbulence of the native habitat and to promote development of the foot muscle from the exercise of adhering to the substrate. Hatchery-reared animals in turbulence regimes were compared to siblings reared in quiet water, and to wild animals, using noninvasive assessments of the development of the foot muscle. The objective was to learn if the turbulence-reared phenotype mimicked laboratory-targeted aspects of the wild phenotype, that is, reflex behavior, swim tunnel performance, and resting oxygen consumption (MO(2)). No group exhibited different MO(2). MO(2) values for all of the compared groups of animals followed the power law, with an exponent of 0.69, consistent with this relationship throughout the animal kingdom. Turbulence-induced exercise did not affect the righting reflex or the tail withdrawal reflex, standard behavioral tests that involve the foot muscle, compared to quiet water-reared siblings. Wild individuals had significantly shorter time-to-right than all hatchery reared animals, however, wild animals did not perform better in flume tests. That turbulence-reared hatchery- or wild animals lacked superior in flume performance suggests that this species may shelter from intertidal wave energy to remain near its optimal feeding areas.

The growth and survival of reef corals are influenced by their symbiotic algal partners (Symbiodinium spp.), which may be flexible in space and time. Tradeoffs among partnerships exist such that corals with thermotol- erant symbionts (e.g., clade D) resist bleaching but grow more slowly, making the long-term ecosystem-level impacts of different host-symbiont associations uncertain. However, much of this uncertainty is due to limited data regarding these tradeoffs and particularly how they are mediated by the environment. To address this knowledge gap, we measured growth and survival of Pocillopora damicornis with thermally sensitive (clade C) or tolerant (clade D) symbionts at three temperatures over 18-55 weeks. Warming reduced coral growth overall, but altered the tradeoffs associated with symbiont type. While clade D corals grew 35-40 % slower than clade C corals at cooler temperatures (26 C), warming of 1.5-3 C reduced and eliminated this growth disadvantage. These results suggest that although warmer oceans will negatively impact corals, clade D may enhance survival at no cost to growth relative to clade C. Understanding these genotype- environment interactions can help improve modeling efforts and conservation strategies for reefs under global climate change.

For many coral species, the obligate association with phylogenetically diverse algal endosymbiont species is dynamic in time and space. Here, we used controlled laboratory inoculations of newly settled, aposymbiotic corals (Orbicella faveolata) with two cultured species of algal symbiont (Symbiodinium microadriaticum and S. minutum) to examine the role of symbiont identity on growth, survivorship, and thermal tolerance of the coral holobiont. We evaluated these data in the context of Symbiodinium photophysiology for 9 months post-settlement and also during a 5-d period of elevated temperatures Our data show that recruits that were inoculated with S. minutum grew significantly slower than those inoculated with S. microadriaticum (occasionally co-occurring with S. minutum), but that there was no difference in survivorship of O. faveolata polyps infected with Symbiodinium. However, photophysiological metrics (∆Fv/F'm, the efficiency with which available light is used to drive photosynthesis and α, the maximum light utilization coefficient) were higher in those slower growing recruits containing S. minutum. These findings suggest that light use (i.e., photophysiology) and carbon acquisition by the coral host (i.e., host growth) are decoupled, but did not distinguish the source of this difference. Neither Symbiodinium treatment demonstrated a significant negative effect of a 5-d exposure to temperatures as high as 32°C under low light conditions similar to those measured at settlement habitats.

Previous studies have demonstrated that the euryhaline copepod Acartia tonsa is extremely sensitive to dietborne silver (Ag) exposure, with a 20 % inhibition (EC(20)) of survival occurring when copepods are fed algae with 1.6 μg g(-1) dry weight (dw) Ag, corresponding to a waterborne Ag concentration of 0.46 μg l(-1) Ag. In contrast, 43 μg l(-1) Ag is required to elicit similar effects in copepods exposed to Ag by way of water. In the current study, we investigated whether another planktonic marine organism might also be sensitive to dietary Ag. Specifically, we tested larvae of the echinoderm, Lytechinus variegatus in an 18-day study in which larvae were continuously exposed to Ag-laden algae (Isochrysis galbana). After 7 days of exposure, no significant effects were observed on larval growth up to the highest concentration tested (10.68 μg g(-1) dw Ag in algae after exposure to 3.88 μg l(-1) waterborne Ag). After 18 days, significant effects were observed in all Ag treatments resulting in a lowest-observable effect concentration of 0.68 μg g(-1) dw Ag in algae and corresponding waterborne Ag concentration of 0.05-0.07 μg l(-1) Ag (depending on background Ag [see Results]). However, the dose-response relationship was quite flat with a similar level of growth inhibition (approximately 15 %) in all Ag treatments, resulting in an EC(20) of10.68 μg g(-1) dw Ag in algae (3.88 μg l(-1) Ag in water). This flat dose-response relationship is characteristic of dietary metal (silver, copper, cadmium, nickel, and zinc) toxicity to copepods as well, although the effect is slightly more robust (approximately 20-30 % inhibition of survival or reproduction). We conclude that echinoderm larvae may be similar to copepods in their sensitivity to dietary Ag, although a better understanding of the mechanisms underlying the apparent flat dose-response relationships is clearly needed.

Land-based sources of pollution have been identified as significant stressors linked to the widespread declines of coral cover in coastal reef ecosystems over the last 30 years. Metal contaminants, although noted as a concern, have not been closely monitored in these sensitive ecosystems, nor have their potential impacts on coral-algal symbioses been characterized. In this study, three species of laboratory-reared scleractinian corals, Acropora cervicornis, Pocillopora damicornis, and Montastraea faveolata each containing different algal symbionts (Symbiodinium A3, C1 and D1a, respectively) were exposed to copper (ranging from 2 to 20g/L) for 5 weeks. At the end of the exposure period, copper had accumulated in the endosymbiotic dinoflagellate (“zooxanthellae”) and animal tissue of A. cervicornis and the animal tissue of M. faveolata; however, no copper accumulation was detected in the zooxanthellae or animal tissue of P. damicornis. The three coral species exhibited significantly different sensitivities to copper, with effects occurring in A. cervicornis and P. damicornis at copper concentrations as low as 4g/L. Copper exposure affected zooxanthellae photosynthesis in A. cervicornis and P. damicornis, and carbonic anhydrase was significantly decreased in A. cervicornis and M. faveolata. Likewise, significant decreases in skeletal growth were observed in A. cervicornis and P. damicornis after copper exposure. Based on preliminary results, no changes in Symbiodinium communities were apparent in response to increasing copper concentration. These results indicate that the relationships between physiological/toxicological endpoints and copper accumulation between coral species differ, suggesting different mechanisms of toxicity and/or susceptibility. This may be driven, in part, by differences in the algal symbiont communities of the coral species in question. Published by Elsevier B.V.

Over the last three decades, the California sea hare, Aplysia californica, has played an increasingly important role as a model organism in the neurosciences. Since 1995, the National Resource for Aplysia has supported a growing research community by providing a consistent supply of laboratory-reared individuals of known age, reproductive status, and environmental history. The purpose of the present study was to resolve the key biological factors necessary for successful culture of large numbers of high quality larval Aplysia. Data from a sequence of five experiments demonstrated that algal diet, food concentration, and veliger density significantly affected growth, attainment of metamorphic competency, and survival of Aplysia larvae. The highest growth and survival were achieved with a mixed algal diet of 1:1 Isochrysis sp (TISO) and Chaetoceros muelleri (CHGRA) at a total concentration of 250 x 10(3) cells/mL and a larval density of 0.5-1.0 per mL. Rapid growth was always correlated with faster attainment of developmental milestones and increased survival, indicating that the more rapidly growing larvae were healthier. Trials conducted with our improved protocol resulted in larval growth rates of >14 microm/day, which yielded metamorphically competent animals within 21 days with survival rates in excess of 90%. These data indicate the important effects of biotic factors on the critical larval growth period in the laboratory and show the advantages of developing optimized protocols for culture of such marine invertebrates.

To evaluate the effect of elevated pCO(2) exposure on the juvenile growth of the sea urchin Lytechinus variegatus, we reared individuals for three months in one of three target pCO(2) levels: ambient seawater (380 µatm) and two scenarios that are projected to occur by the middle (560 µatm) and end (800 µatm) of this century. At the end of 89 days, urchins reared at ambient pCO(2) weighed 12% more than those reared at 560 µatm and 28% more than those reared at 800 µatm. Skeletons were analyzed using scanning electron miscroscopy, revealing degradation of spines in urchins reared at elevated pCO(2) (800 µatm). Our results indicate that elevated pCO(2) levels projected to occur this century may adversely affect the development of juvenile sea urchins. Acidification-induced changes to juvenile urchin development would likely impair performance and functioning of juvenile stages with implications for adult populations.