Marine chemical ecology: chemical signals and cues structure marine populations, communities, and ecosystems.
TL;DR: How chemical cues regulate critical aspects of the behavior of marine organisms from bacteria to phytoplankton to benthic invertebrates and water column fishes is reviewed.
Abstract: Chemical cues constitute much of the language of life in the sea. Our understanding of biotic interactions and their effects on marine ecosystems will advance more rapidly if this language is studied and understood. Here, I review how chemical cues regulate critical aspects of the behavior of marine organisms from bacteria to phytoplankton to benthic invertebrates and water column fishes. These chemically mediated interactions strongly affect population structure, community organization, and ecosystem function. Chemical cues determine foraging strategies, feeding choices, commensal associations, selection of mates and habitats, competitive interactions, and transfer of energy and nutrients within and among ecosystems. In numerous cases, the indirect effects of chemical signals on behavior have as much or more effect on community structure and function as the direct effects of consumers and pathogens. Chemical cues are critical for understanding marine systems, but their omnipresence and impact are inadequ...
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TL;DR: The potential for marine organisms to adapt to increasing CO2 and broader implications for ocean ecosystems are not well known; both are high priorities for future research as mentioned in this paper, and both are only imperfect analogs to current conditions.
Abstract: Rising atmospheric carbon dioxide (CO2), primarily from human fossil fuel combustion, reduces ocean pH and causes wholesale shifts in seawater carbonate chemistry. The process of ocean acidification is well documented in field data, and the rate will accelerate over this century unless future CO2 emissions are curbed dramatically. Acidification alters seawater chemical speciation and biogeochemical cycles of many elements and compounds. One well-known effect is the lowering of calcium carbonate saturation states, which impacts shell-forming marine organisms from plankton to benthic molluscs, echinoderms, and corals. Many calcifying species exhibit reduced calcification and growth rates in laboratory experiments under high-CO2 conditions. Ocean acidification also causes an increase in carbon fixation rates in some photosynthetic organisms (both calcifying and noncalcifying). The potential for marine organisms to adapt to increasing CO2 and broader implications for ocean ecosystems are not well known; both are high priorities for future research. Although ocean pH has varied in the geological past, paleo-events may be only imperfect analogs to current conditions.
2,995 citations
TL;DR: Evidence from direct and indirect approaches using geochemical and genetic techniques suggests that populations range from fully open to fully closed and a full understanding of population connectivity has important applications for management and conservation.
Abstract: Connectivity, or the exchange of individuals among marine populations, is a central topic in marine ecology. For most benthic marine species with complex life cycles, this exchange occurs primarily during the pelagic larval stage. The small size of larvae coupled with the vast and complex fluid environment they occupy hamper our ability to quantify dispersal and connectivity. Evidence from direct and indirect approaches using geochemical and genetic techniques suggests that populations range from fully open to fully closed. Understanding the biophysical processes that contribute to observed dispersal patterns requires integrated interdisciplinary approaches that incorporate high-resolution biophysical modeling and empirical data. Further, differential postsettlement survival of larvae may add complexity to measurements of connectivity. The degree to which populations self recruit or receive subsidy from other populations has consequences for a number of fundamental ecological processes that affect population regulation and persistence. Finally, a full understanding of population connectivity has important applications for management and conservation.
1,640 citations
TL;DR: It is concluded that the best way to protect salt marshes and the services they provide is through the integrated approach of ecosystem-based management.
Abstract: Salt marshes are among the most abundant, fertile, and accessible coastal habitats on earth, and they provide more ecosystem services to coastal populations than any other environment. Since the Middle Ages, humans have manipulated salt marshes at a grand scale, altering species composition, distribution, and ecosystem function. Here, we review historic and contemporary human activities in marsh ecosystems—exploitation of plant products; conversion to farmland, salt works, and urban land; introduction of non-native species; alteration of coastal hydrology; and metal and nutrient pollution. Unexpectedly, diverse types of impacts can have a similar consequence, turning salt marsh food webs upside down, dramatically increasing top down control. Of the various impacts, invasive species, runaway consumer effects, and sea level rise represent the greatest threats to salt marsh ecosystems. We conclude that the best way to protect salt marshes and the services they provide is through the integrated approach of ecosystem-based management.
770 citations
TL;DR: It is shown how the use of global variables of environmental forcing that have recently become available and gas exchange relationships that incorporate the main forcing factors will lead to improved estimates of global and regional air-sea gas fluxes based on better fundamental physical, chemical, and biological foundations.
Abstract: The past decade has seen a substantial amount of research on air-sea gas exchange and its environmental controls. These studies have significantly advanced the understanding of processes that control gas transfer, led to higher quality field measurements, and improved estimates of the flux of climate-relevant gases between the ocean and atmosphere. This review discusses the fundamental principles of air-sea gas transfer and recent developments in gas transfer theory, parameterizations, and measurement techniques in the context of the exchange of carbon dioxide. However, much of this discussion is applicable to any sparingly soluble, non-reactive gas. We show how the use of global variables of environmental forcing that have recently become available and gas exchange relationships that incorporate the main forcing factors will lead to improved estimates of global and regional air-sea gas fluxes based on better fundamental physical, chemical, and biological foundations.
626 citations
TL;DR: The results imply that humans could be substantially impacting iron and bioavailable iron deposition to ocean regions, but there are large uncertainties in the authors' understanding.
562 citations
References
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TL;DR: This work investigates the feeding relationship between the specialist sea hare Stylocheilus longicauda and its food, the filamentous cyanobacterium Microcoleus lyngbyaceus (Kutz.) Crouan, and finds that it is adpated to feed on chemically defended foods, and it uses sequestered secondary metabolites for its own antipredator defenses.
94 citations
"Marine chemical ecology: chemical s..." refers background in this paper
...Numerous sea hares also sequester defenses from chemically rich algae that they consume (Paul & Pennings 1991), but they have also evolved a second counterdefense based on chemically distracting consumers via phagomimicry and sensory disruption (Kicklighter et al. 2005)....
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TL;DR: This review compares and contrasts the use of odors by fish and birds over a range of spatial scales that span from thousands of kilometers to less than a meter, and identifies behavioral similarities and new questions that need to be addressed regarding the olfactory ecology of these diverse groups of organisms.
Abstract: Salmon travel hundreds of kilometers of open ocean and meandering rivers to return to their natal stream to spawn; procellariiform seabirds soar over thousands of kilometers of the ocean’s surface searching for foraging opportunities and accurately return to their nesting islands. These large-scale olfactory-guided behaviors are among the most dramatic examples of animal navigation ever described. At much closer ranges, the sense of smell can be used for behaviors as diverse as tracking prey, nest location, and mate selection. Both fish and birds face similar problems interpreting olfactory information in fluid mediums where odors are dispersed as filamentous patches. Similar to insects, which have served as model organisms for investigating olfactory related behaviors, the few fish and bird species that have been studied tend to use olfactory information in conjunction with other sensory modalities. Similar to insects, fish and birds also employ oscillatory or cross-stream movement as sampling mechanisms. This review compares and contrasts the use of odors by fish and birds over a range of spatial scales that span from thousands of kilometers to less than a meter. In so doing, we identify behavioral similarities and new questions that need to be addressed regarding the olfactory ecology of these diverse groups of organisms.
94 citations
"Marine chemical ecology: chemical s..." refers background in this paper
...These DMS signals for feeding are not restricted only to seabirds, but also seem to be used by reef fishes (DeBose & Nevitt 2008), harbor seals (Kowalewsky et al. 2006), and whale sharks (Martin 2007). www.annualreviews.org • Marine Chemical Ecology 195 A nn u....
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94 citations
"Marine chemical ecology: chemical s..." refers background in this paper
...These birds are noted for their wide-ranging, pelagic lifestyle and for having among the largest olfactory bulbs of birds (Bang 1966)....
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TL;DR: By forming temporary cysts, S. trochoidea may be able to overcome the effect of allelochemicals, and thereby have an adaptive advantage over other organisms unable to do so, especially when the allelopathic effect is moderate.
Abstract: Competition among phytoplankton for limiting resources may involve direct or indirect interactions. A direct interaction of competitors is the release of chemicals that inhibit other species, a process known as allelopathy. Here, we investigated the allelopathic effect of three toxic microalgae species (Alexandrium tamarense, Karenia mikimotoi and Chrysochromulina polylepis) on a natural population of the dinoflagellate Scrippsiella trochoidea. Our major findings were that in addition to causing death of S. trochoidea cells, the allelopathic species also induced the formation of temporary cysts in S. trochoidea. Because cysts were not lysed, encystment may act as a defence mechanism for S. trochoidea to resist allelochemicals, especially when the allelopathic effect is moderate. By forming temporary cysts, S. trochoidea may be able to overcome the effect of allelochemicals, and thereby have an adaptive advantage over other organisms unable to do so.
93 citations
"Marine chemical ecology: chemical s..." refers background in this paper
...When in its normal growth form, the dinoflagellate Scrippsiella trochoidea is lysed and killed by allelopathic agents from some competing microalgae; however, these conditions induce S. trochoidea to form temporary cysts that do not lyse, allowing the alga to persist (Fistarol et al. 2004)....
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TL;DR: A greater complexity in the significance of odors to the foraging ecology of different tube-nosed species than has commonly been assumed is suggested.
Abstract: Antarctic procellariiform seabirds are known for their well-developed sense of smell, yet few behavioral experiments have addressed how these birds use olfactory cues to forage at sea. I describe results from controlled, shipboard experiments performed in Antarctic waters near Elephant Island. Birds were presented with plain or krill-scented (Euphausia superba) vegetable oil slicks, and their behavioral responses were compared. Krill-scented vegetable oil slicks were highly attractive to some but not all procellariiform species foraging in this area (p < 0.001, G-test). Cape petrels Daption capense and southern giant petrels Macronectes giganteus appeared at krill-scented slicks within 1 min, whereas black-browed albatrosses Diomedea melanophris appeared within 3 min. Cape petrels D. capense showed the strongest attraction: these birds were observed as much as 5 times as frequently at krill-scented slicks as compared to unscented control slicks (p < 0.001, G-test), while storm-petrels (Oceanites oceanicus and Fregetta tropica) and Antarctic Fulmars Fulmarus glacialoides responded in equal numbers to krill-scented and unscented slicks. When considered with respect to previously published findings, these results suggest a greater complexity in the significance of odors to the foraging ecology of different tube-nosed species than has commonly been assumed.
91 citations
"Marine chemical ecology: chemical s..." refers background in this paper
...Those not significantly attracted to DMS tend to be larger, more aggressive, and seem better adapted to exploit multimodal cues that include scents of crushed prey and visual cues associated with feeding by other birds and marine predators (Nevitt 1999, Nevitt & Bonadonna 2005, Nevitt et al. 2004)....
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