Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Panulirus argus (Latreille, 1804) é uma das principais espécies de lagosta no Atlântico, sendo um dos maiores recursos pesqueiros do Atlântico Ocidental, onde apresenta um alto valor comercial. A forte explotação da espécie resulta em uma grande pressão sobre suas populações. Recentemente, foi descoberto que sob o binômio P. argus estão contidas duas espécies crípticas que ocorrem em alopatria, uma na região do Caribe e outra na costa brasileira. Esta tese tem como objetivo estudar como se estruturam geneticamente as populações dessas duas espécies, com o propósito de fornecer mais informações para a determinação de estoques e um correto manejo das espécies, e analisar os processos históricos evolutivos que moldaram suas histórias demográficas. Para tal, foram estudados dois marcadores mitocondriais (região controle e o gene da Citocromo Oxidase I) e loci de microssatélites de indivíduos de 7 regiões do Caribe (Florida, Bahamas, Turks e Caicos, Porto Rico, Cuba, Colômbia e Venezuela) e 11 estados do Brasil (Pará, Maranhão, Piauí, Ceará, Rio Grande do Norte, Pernambuco, Alagoas, Bahia, Espírito Santo, Rio de Janeiro e São Paulo). Dentro de cada espécie foram observadas duas linhagens mitocondriais diferentes, que co-ocorriam, de maneira homogênea, ao longo de suas distribuições. Hipotetiso que essas linhagens foram formadas a partir de um evento de vicariância com contato secundário ou como consequência de um efeito gargalo seguido de expansão. As duas linhagens são evidentes nas sequências da região controle mitocondrial, mas no gene da COI foram evidentes apenas em P. cf. argus do Caribe. As linhagens do Brasil se separaram há aproximadamente 233 - 288 mil anos e cada uma sofreu expansão em tempos diferentes, a primeira se expandiu há 100 mil anos e a segunda linhagem há 50 mil anos. As linhagens do Caribe se separaram cerca de 1 milhão de anos atrás e possuem o mesmo tempo de expansão, 50 mil anos. Os microssatélites não revelaram subdivisão populacional para nenhuma das duas espécies, porém os marcadores, juntos, sugeriram um fluxo gênico diferenciado entre localidades expostas a diferentes correntes marítimas. Considerando que essas lagostas são intensamente explotadas, é importante ser cuidadoso no momento de definir estoques pesqueiros. Para a espécie do Brasil, dois estoques pesqueiros foram sugeridos, o primeiro do Pará à Bahia e o segundo do sul da Bahia a São Paulo. Para a espécie do Caribe, foi mantida e reforçada a hipótese de quatro estoques sugerida pela FAO (Norte, Sul, Centro-Norte e Centro-Sul). / Panulirus argus (Latreille, 1804) is one of the main lobster species in the Atlantic, and one of the largest fisheries in the western Atlantic, with a high commercial value. The heavy exploitation of the species results in much pressure on its populations. Recently, it was discovered that under the name P. argus there are two cryptic species that occur in allopatry, one in the Caribbean and the other on the coast of Brazil. This thesis studies the population genetic structure of those two species with the purpose of providing more information to delimitate stocks for fisheries management, and for understanding the historical processes that have shaped their evolutionary demographic histories. For this, we analysed two mitochondrial markers (control region and the Cytochrome Oxidase I gene) and microsatellite markers of individuals from 7 localities in the Caribbean (Florida, Bahamas, Turks and Caicos, Puerto Rico, Cuba, Colombia, and Venezuela) and 11 States of Brazil (Pará, Maranhão, Piauí, Ceará, Rio Grande do Norte, Pernambuco, Alagoas, Bahia, Espírito Santo, Rio de Janeiro, and São Paulo). Within each species two different mitochondrial lineages were observed. They occurred throughout their distributions, and it is hypothesized that they were formed from a vicariance event with secondary contact or are the result of a genetic bottleneck followed by expansion. The lineages of P. cf. argus from Brazil were only observed in the mitochondrial control region and were separated approximately 233-288 thousand years ago, and each lineage underwent expansion at different times: the first expanded 100,000 years ago and the second 50,000 years ago. The lineages of the Caribbean species were found for the two mitochondrial markers. They were separated about 1 million years ago and have had the same expansion time, 50,000 years. Microsatellites revealed no population subdivision for either species, but the molecular markers together suggest a differential gene flow between localities exposed to different currents. Since these lobsters are heavily exploited, it is important to be conservative when defining their fishing stocks. For the species from Brazil, two fishing stocks are suggested, the first from Pará to Bahia States and the second from Southern Bahia to São Paulo State. For the species of the Caribbean, our data give support to the four stocks suggested by FAO (North, South, North Central and South Central).

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Panulirus argus (Latreille, 1804) é uma das principais espécies de lagosta no Atlântico, sendo um dos maiores recursos pesqueiros do Atlântico Ocidental, onde apresenta um alto valor comercial. A forte explotação da espécie resulta em uma grande pressão sobre suas populações. Recentemente, foi descoberto que sob o binômio P. argus estão contidas duas espécies crípticas que ocorrem em alopatria, uma na região do Caribe e outra na costa brasileira. Esta tese tem como objetivo estudar como se estruturam geneticamente as populações dessas duas espécies, com o propósito de fornecer mais informações para a determinação de estoques e um correto manejo das espécies, e analisar os processos históricos evolutivos que moldaram suas histórias demográficas. Para tal, foram estudados dois marcadores mitocondriais (região controle e o gene da Citocromo Oxidase I) e loci de microssatélites de indivíduos de 7 regiões do Caribe (Florida, Bahamas, Turks e Caicos, Porto Rico, Cuba, Colômbia e Venezuela) e 11 estados do Brasil (Pará, Maranhão, Piauí, Ceará, Rio Grande do Norte, Pernambuco, Alagoas, Bahia, Espírito Santo, Rio de Janeiro e São Paulo). Dentro de cada espécie foram observadas duas linhagens mitocondriais diferentes, que co-ocorriam, de maneira homogênea, ao longo de suas distribuições. Hipotetiso que essas linhagens foram formadas a partir de um evento de vicariância com contato secundário ou como consequência de um efeito gargalo seguido de expansão. As duas linhagens são evidentes nas sequências da região controle mitocondrial, mas no gene da COI foram evidentes apenas em P. cf. argus do Caribe. As linhagens do Brasil se separaram há aproximadamente 233 - 288 mil anos e cada uma sofreu expansão em tempos diferentes, a primeira se expandiu há 100 mil anos e a segunda linhagem há 50 mil anos. As linhagens do Caribe se separaram cerca de 1 milhão de anos atrás e possuem o mesmo tempo de expansão, 50 mil anos. Os microssatélites não revelaram subdivisão populacional para nenhuma das duas espécies, porém os marcadores, juntos, sugeriram um fluxo gênico diferenciado entre localidades expostas a diferentes correntes marítimas. Considerando que essas lagostas são intensamente explotadas, é importante ser cuidadoso no momento de definir estoques pesqueiros. Para a espécie do Brasil, dois estoques pesqueiros foram sugeridos, o primeiro do Pará à Bahia e o segundo do sul da Bahia a São Paulo. Para a espécie do Caribe, foi mantida e reforçada a hipótese de quatro estoques sugerida pela FAO (Norte, Sul, Centro-Norte e Centro-Sul). / Panulirus argus (Latreille, 1804) is one of the main lobster species in the Atlantic, and one of the largest fisheries in the western Atlantic, with a high commercial value. The heavy exploitation of the species results in much pressure on its populations. Recently, it was discovered that under the name P. argus there are two cryptic species that occur in allopatry, one in the Caribbean and the other on the coast of Brazil. This thesis studies the population genetic structure of those two species with the purpose of providing more information to delimitate stocks for fisheries management, and for understanding the historical processes that have shaped their evolutionary demographic histories. For this, we analysed two mitochondrial markers (control region and the Cytochrome Oxidase I gene) and microsatellite markers of individuals from 7 localities in the Caribbean (Florida, Bahamas, Turks and Caicos, Puerto Rico, Cuba, Colombia, and Venezuela) and 11 States of Brazil (Pará, Maranhão, Piauí, Ceará, Rio Grande do Norte, Pernambuco, Alagoas, Bahia, Espírito Santo, Rio de Janeiro, and São Paulo). Within each species two different mitochondrial lineages were observed. They occurred throughout their distributions, and it is hypothesized that they were formed from a vicariance event with secondary contact or are the result of a genetic bottleneck followed by expansion. The lineages of P. cf. argus from Brazil were only observed in the mitochondrial control region and were separated approximately 233-288 thousand years ago, and each lineage underwent expansion at different times: the first expanded 100,000 years ago and the second 50,000 years ago. The lineages of the Caribbean species were found for the two mitochondrial markers. They were separated about 1 million years ago and have had the same expansion time, 50,000 years. Microsatellites revealed no population subdivision for either species, but the molecular markers together suggest a differential gene flow between localities exposed to different currents. Since these lobsters are heavily exploited, it is important to be conservative when defining their fishing stocks. For the species from Brazil, two fishing stocks are suggested, the first from Pará to Bahia States and the second from Southern Bahia to São Paulo State. For the species of the Caribbean, our data give support to the four stocks suggested by FAO (North, South, North Central and South Central).

Syftet med denna uppsats har varit att göra en närläsning och undersöka Yorgos Lanthimos sex långfilmer; Kinetta, Dogtooth, Alps, The Lobster, The Killing of a Sacred Deer och The Favourite. Jag har analyserat dessa filmer utifrån auteurteorin där jag utgått från Jason M. Silvermans (2011) begreppsapparat. Det jag fann var att Lanthimos gillar att skildra verkligheten, i linje med representational view, men på ett annorlunda och nytt sätt, som i linje med creative or imaginative view. Han sätter sina rollfigurer i absurda omständigheter där våld och genant intimitet står ut, vilket har en stark koppling till provocative view. Lanthimos samarbetar gärna med personer flertalet gånger, både bakom och framför kameran. Detta återfinns i idealtypen collborative view. Angående idealtypen pastische view kan man hitta inspiration från tidigare verk, bland annat i grekiska mytologier och i användandet av klassisk musik. Färgpaletten som används i varje film är relativt ljus och kall, vilket tillsammans med de ofta sterila miljöerna kan skapa en känsla av obehag. Detta tillsammans med hur han frekvent använder sig av vidvinklar och avståndsbilder bidrar till en känsla av hopplöshet. Han använder många långa tagningar där kameran antingen är statisk och fungerar som en fluga på väggen, eller har en långsam zoom för att ge intrycket om voyeurism.

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In this thesis I assessed the causes of long-term changes in two large, commercially important decapod crustacean populations, American lobster (Homarus americanus) and snow crab (Chionoecetes opilio), in the northwest (NW) Atlantic Ocean. By combining available time-series data, including commercial landings, research surveys, and local ecological knowledge (LEK), I explored the causes of an observed ecosystem shift in the NW Atlantic (~1950–2009) which entailed a region-wide decline of groundfish and an increase in benthic invertebrates, including these decapods. Three hypotheses were examined to explain the increase in decapod abundance: (1) the predation hypothesis, whereby a decrease in predatory groundfish led to an increase in their decapod prey (top-down effects); (2) the climate hypothesis, whereby changes in temperature or other climatic variables helped to increase decapod numbers (bottom-up effects); and (3) the anthropogenic hypothesis, whereby changes in fishing pressure drove decapod population dynamics. I explored these hypotheses separately for lobster and snow crab, which may experience different ecological and commercial pressures. First, I investigated the interactions between predatory groundfish and lobster in the inshore region of southwest Nova Scotia. Long-term fisheries-independent abundance indices for lobsters and their predators are available for Gulf of Maine (GOM) waters in the USA, but not in Canada. To address research gaps I designed and executed a survey to collect the LEK of lobster fishermen fishing in the Canadian GOM. Forty-two fishermen were interviewed. Corresponding survey results from the USA were compared to the LEK results. Both sources provided evidence for a top-down effect (predation release), contributing to observed increases in GOM lobster abundance and landings. Second, I explored relationships between lobster abundance and landings in the NW Atlantic as they may relate to temporal changes in predators, temperature, climate (North Atlantic Oscillation Index, NAOI), and fishing. Available landings data and fisheries-independent abundance estimates were collated to investigate trends in lobster abundance and catch. Links between lobster, groundfish, temperature and climate indices were explored using mixed effects models. Results offered partial support for the predation hypothesis, namely in the waters off Newfoundland, Nova Scotia, and southern New England as well as broad support for a climate effect on early life stages. This effect appeared related to a region-wide climate signal, the NAOI, but was independent of changes in water temperature. Fishing effort appeared to be following lobster abundance, rather than regulating abundance in a consistent way. Third, variation in snow crab abundance was examined through meta-analysis of time-series data of cod and crab abundance and temperature. Temperature had opposing effects on the two species: snow crab abundance was negatively correlated with temperature whereas cod and temperature were positively related. Controlling for the effect of temperature, the analysis revealed significant negative interactions between snow crab and cod abundance, with cod leading snow crab up to a five-year lag. Results indicate that snow crab is largely influenced by temperature during early post-settlement years and becomes increasingly regulated by top-down mechanisms as they approach fishery recruitment. Overall, I conclude that both climate and predation can act as population controls on large decapod populations, but these variables affect decapods at different life stages.

Dissertation (PhD)--University of Stellenbosch, 2001. / ENGLISH ABSTRACT: The efficient management of renewable resources may ensure sustainable income to communities and countries. In the past the mathematical modelling used in the management decisions, in South Africa, was based on biological considerations only. In this thesis we include economic factors in the models and aim to determine steady state harvesting levels such that a maximum present value of all future revenues may be reached. A bio-economical approach is followed throughout the study and applied to the South African Cape Rock Lobster (Jasus lalandii) resource. We first address the problem using the simplest surplus production models. The model is applied to the Cape Rock Lobster, finding that the economical factors do indeed influence the steady state results, emphasising that they should be incorporated in the modelling process. A more descriptive two-sex-delay-difference model is then applied, which includes delay times for juveniles to reach sexual maturity and distinguishes between sexes. Yet further involved stage-class models are also studied and we propose a solution to the non-linear programming problem reached. These models may assist decision makers in future as knowledge on, for example, the growth of the two sexes, proper size limits and the influence of price differences are gained. Finally, we propose a harvesting strategy where catch is taken from alternative spatial lanes and apply here results from reaction diffusion theory. This theoretical approach might provide guidelines to new and underdeveloped fisheries in future, but also influence current inshore fisheries towards new management strategies. / AFRIKAANSE OPSOMMING: Die doeltreffende bestuur van hernubare hulpbronne kan 'n volhoubare ekonomiese opbrengs aan gemeenskappe en lande verseker. In die verlede is die wiskundige modelle wat in die besluitnemingsproses gebruik is, in Suid Afrika, gebaseer op biologiese oorwegings alleen. In hierdie studie word ook ekonomiese faktore in die modelle ingesluit en word ewewigstoestande bepaal vir vangste, sodanig dat 'n maksimum huidige waarde van toekomstige inkomste uit 'n vissery bereik word. 'n Bio-ekonomiese benadering word deurgaans gevolg en modelle word toegepas op die Suid-Afrikaanse Weskus Kreefbron (Jasus lalandii). Die studie begin deur basiese surplus produksie modelle te gebruik. Die resultate van die toepassing op die Weskus Kreefbron toon dat die ekonomiese faktore 'n groot invloed op die voorgestelde ewewigstoestand van die populasie het. Dit benadruk dus die feit dat hierdie faktore in die modelleringsproses ingesluit behoort te word. Meer beskrywende twee-geslag-vertragings-verskil modelle word daarna toegepas, en sluit in 'n vertragings periode vir vis om 'n volwasse stadium te bereik. Hierdie tydfaktor verskil dikwels vir mannetjies en wyfies en daarom word hier 'n twee-geslag model gebruik. Meer gevorderde klasse modelle word ook bespreek. Ons stel 'n oplossing vir hierdie nie-lineêre programmeringsprobleem voor. Hierdie gevorderde modelle mag in die toekoms handige hulpmiddels wees wanneer inligting rakende 'n spesie gesoek word. Sulke inligting mag insluit die groeitempos van mannetjies en wyfies, geskikte grootte beperkings vir vangste en die invloed van prysverskille vir verskillende groottes vis. 'n Nuwe vangste strategie word ook voorgestel waar vangste slegs geneem word uit alternatiewe ruimtelike bane en pas ons hier resultate uit die reaksie-diffusie teorie toe. Hierdie teoretiese oplossings mag riglyne bied wanneer nuwe visserye in die toekoms ontgin word, maar ook huidige visserye beïnvloed in die rigting van 'n nuwe bestuur strategie.

[Truncated abstract] Removal of consumers through fishing has been shown to influence ecosystem structure and function by changing the biomass and composition of organisms occupying lower trophic levels. The western rock lobster (Panurilus cygnus), an abundant consumer along the temperate west coast of Australia, forms the basis of Australia's largest single species fishery, with catches frequently exceeding 11000 tonnes annually. Despite their high abundance and commercial importance, the diet and trophic role of adult lobster populations in deep-coastal-ecosystems (35-60 m) remains unknown. An understanding of the diet and trophic role of lobsters in these ecosystems is a key component of the assessment of ecosystem effects of the western rock lobster fishery. This study uses gut content and stable isotope analyses to determine the diet and trophic role of lobsters in deep-coastal ecosystems. Dietary analysis indicated adult lobsters in deep-coastal ecosystems were primarily carnivorous with diet reflecting food available on the benthos. Gut content analyses indicate crabs (62 %) and amphipods/isopods (~10 %) are the most important lobster dietary sources. Stable isotope analysis indicates natural diet of lobsters in deep coastal ecosystems is dominated by amphipods/isopods (contributing up to ~50 %) and crabs (to ~75 %), with bivalves/gastropods, red algae and sponges of lesser importance (<10 % of diet each). Diet of lobsters in deep-coastal ecosystems differed from that reported for lobsters inhabiting shallow water ecosystems in this region, reflecting differences in food availability and food choice between these ecosystems. Bait from the fishery was also determined (by stable isotope analyses) to be a significant dietary component of lobsters in deep-coastal ecosystems, contributing between 10 and 80 % of lobster food requirements at some study locations. '...' Given observed effects of organic matter addition in trawl fisheries, and also associated with aquaculture, bait addition is likely to have implications for processes occurring within deep-coastal ecosystems in this region, particularly given its oligotrophic status, most likely by increasing the food available to scavenging species. Removal of lobsters from deep-coastal ecosystems may affect the composition and abundance of lobster prey communities through a reduction in predation pressure. Such effects have been demonstrated for other spiny lobster species. These effects are typically most observable amongst common prey taxa which in other studies have been commonly herbivores. In deep-coastal ecosystems, crabs and amphipods/isopods are the most common prey taxa and most likely to be effected. The ecosystem-impacts of top-down control of non-herbivorous prey species is unknown and constrains the inferences possible from this study. However, the establishment of 'no-take' areas in deep-coastal ecosystems would allow the ecosystem effects of lobster removal to be further assessed in these deep-coastal ecosystems. While data from the current study did not allow the ecosystem effects of lobster removal to be properly assessed, this study provided information regarding the ecology of western rock lobsters in previously unstudied ecosystems.

Knowledge of the interactions among species and communities is vital for their management and protection. Increasingly, the role of marine protected areas in this regard is being recognised, primarily because of the potential for previously-harvested species to increase in density and biomass, and the linkages among species to be restored. Monitoring and research was conducted within and surrounding two marine reserves on the east coast of the North Island of New Zealand – Te Tapuwae o Rongokako, near Gisborne, and Te Angiangi, south of Napier. The aim was to describe the biological characteristics of spiny lobsters (Jasus edwardsii) in the absence of fishing, and to describe the effects of fishing and protection on lobster populations and the communities of which they are a component. Diver and pot surveys showed that lobsters were significantly more abundant within the reserves than in the surrounding fisheries and that the populations were comprised of a larger proportion of legal-sized individuals. Higher female fecundity within Te Tapuwae o Rongokako Marine Reserve compared with the surrounding fishery was proposed to be primarily a result of increased availability of large males within the reserve. The impact of the fishery on lobsters was also evidenced in the lower tail width to carapace length ratio of the fished population compared to the population within Te Tapuwae o Rongokako Marine Reserve, due to the minimum legal size for Jasus edwardsii in New Zealand being based on tail width. The largest tagging study ever to be conducted in a New Zealand marine reserve showed that sublegal male lobsters within Te Tapuwae o Rongokako Marine Reserve were growing on average faster than the same sized individuals outside the reserve, potentially as a result of the effects of handling and / or size-selective fishing. A decrease in growth rate over time was recorded in male lobsters within the reserve, which coincided with an increase in catch per unit effort and may indicate that density-dependent effects are operating. Distinct seasonal movements of tagged lobsters were recorded, with the vast majority of movements taking place within reefs. Where the boundaries of the reserve crossed reef habitat, significant movement of lobsters across the boundaries occurred. Lobsters within Te Tapuwae o Rongokako Marine Reserve not only exhibited cannibalistic behaviour but foraged during the day, including on intertidal reef platforms at high tide, potentially as a behavioural response to increased competition for food – behaviour not previously reported for this species. Outside the reserve, lobster bait apparently provided an alternative protein source but despite this supplementation of diet, these lobsters were in poorer nutritional condition, as evidenced by their lower body weights relative to carapace length and tail width for both sexes. Lobsters outside the reserve were also significantly more affected by a bacterial infection associated with handling, than lobsters within the reserve. These findings have significant implications for fisheries management and for the design and management of marine protected areas (MPAs). This study demonstrates that many of the biological parameters used in evaluating harvest strategies in the New Zealand lobster fishery may be biased unless collected from populations with a natural size structure, such as may occur within marine protected areas.

In an attempt to address the seeming imbalance within studies of rural communities in Australia linked to primary industries, this study examines the broader aspects of policy changes and bio-economic imperatives in the Western Rock Lobster Fishery and the effects of the restructuring of the fishery on communities that host the rock lobster fleet. It is an innovative study in that it is one of the first comprehensive studies of industry restructuring in the fisheries sector; a study of the linkages and implications of restructuring on the social, economic and cultural facets of coastal communities in Western Australia. Globalisation in the fishery sector, aided by technological advances, has resulted in a greater exploitation of high-value fisheries for export. Intensified globalisation has also brought about environmental and social standards that ensure the survival of by-catch species and promote responsible codes of fishing practice. In Australia, the active support of the government for globalisation, led to the adoption of export-oriented policies emphasising competitiveness and efficiency. Consideration of market principles thus govern fisheries regulators when deciding on the management arrangements to adopt for a particular fishery. In considering a number of policy instruments and management measures, government regulators also consider the conservation of marine resources alongside the production of significant economic and social benefits. The Western Rock Lobster Fishery is the most valuable single species fishery in Western Australia with a sizeable financial and employment contribution to coastal communities along the Western Australian coast. Any management scheme adopted for this fishery, as such, not only has to take into account biological and environmental imperatives but also economic and social objectives. The analysis of the fishery undertaken in this thesis underlines the need for a holistic view of fishery management that takes into consideration not only biological sustainability, but also promotes an understanding of fishers' behaviours and fishing patterns and the consequent effects on specific communities. The demographic and social changes that affect rural communities further complicate the economic restructuring at the fishery level, with fishers' responses differing based on their circumstances and preferences. This thesis presents a snapshot of a fishery deliberating changes in management arrangements and its effects on coastal communities whose socio-demographic and economic development historically has depended, and to a great extent is still dependent, upon rock lobster fishing. It provides empirical evidence that lends support to the view that the pro-market policies promoting competition and entrepreneurialism have resulted in a spatially uneven development in regional Australia. Specific localities can deal with the changes brought about by globalisation and policy change. However, the manner in which these communities deal and cope with these changes depends on a number of factors, among others, the level of diversification of the local economy, demographic and social structures, and other factors such as the level of resilience and the social capital base within the community.

Chemical senses play a critical role in predator-prey and social interactions of many animals. Predators often evoke adaptive escape responses by prey, one of which is the release of chemicals that induce adaptive avoidance behaviors from both predators and conspecifics. I explore the use of chemicals in predator-prey and social interactions, using a crustacean model system, the spiny lobster. As predators, spiny lobsters are opportunistic, polyphagous feeders, and they rely heavily on their chemical senses during feeding. Some of their potential prey deter attacks through chemical defenses that act through the spiny lobsters’ chemical senses. An example of this is sea hares, Aplysia californica, which secrete an ink when vigorously attacked by sympatric spiny lobsters, Panulirus interruptus. I show that that this ink defends sea hares from spiny lobsters through several mechanisms that include phagomimicry, sensory disruption, and deterrence, and that the ink’s efficacy is enhanced by its naturally high acidity. As prey, spiny lobsters rely heavily on their chemical senses to assess risk from predators. One way to assess risk of predation is through ‘alarm cues’, which are injury-related chemicals. I show that injured Caribbean spiny lobsters, Panulirus argus, release alarm cues in their hemolymph, and that nearby conspecifics detect these cues using olfaction. Hemolymph from conspecifics induces primarily alarm behavior in the form of retreat, sheltering, and suppression of appetitive responses. In contrast, hemolymph from heterospecifics, depending on phylogenetic relatedness, induces either mixed alarm and appetitive behaviors or primarily appetitive behaviors. Spiny lobsters also use chemical cues to assess risk during social interactions with conspecific. I show that spiny lobsters use urine-borne chemical signals and agonistic behaviors to communicate social status and that these chemical signals are detected exclusively by the olfactory pathway. Dominant animals increase urine release during social interactions, whereas subordinates do not. Experimental prevention of urine release during interactions causes an increase in agonism, but this increase is abolished when urine of dominants is reintroduced. My findings lay the foundation for neuroethological studies of risk-assessment systems mediated by intraspecific chemical cues.