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
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TL;DR: The quantified pleopod pumping activity upon exposure to a range of synthetic peptides to identify compounds that will induce larval release behaviors support the conceptual model that larvalRelease in subtidal crustaceans is controlled by small peptides that act as pheromones.
Abstract: Larval release in the Caribbean spiny lobster Panulirus argus is highly synchronous and is controlled by a “pumping pheromone” released from the hatching eggs. The pheromone induces a parent female to undergo stereotypical larval release behaviors, including rapid abdominal extensions and pleopod pumping. These behaviors help to break open the egg membranes and result in the synchronous release of larvae. Based on previous studies on larval release in brachyuran crabs, we hypothesized that larval release behaviors are induced by pheromones composed of small peptides. We quantified pleopod pumping activity upon exposure to a range of synthetic peptides to identify compounds that will induce larval release behaviors. Chemically cued pumping behavior was described in terms of the threshold concentration for response, maximum percentage response, and effective concentration range. Pleopod pumping behavior was evoked by di- and tripeptides with a neutral amino acid at the amino terminus and a basic amino acid at the carboxy terminus and also by the basic–basic dipeptide Lys–Arg. All carboxy-terminal arginine peptides tested produced a significant pumping response, with the exception of Trp–Ile–Arg. Response concentration thresholds ranged from 10−9 M for the most potent peptide (Gly–Arg) to 10−4 M for the least potent (Gly–His–Lys). The maximum percentage of lobsters responding was largely independent of the threshold concentration and ranged from 24.3 to 58.3%. Effective concentration ranges for the peptides were variable from 1 to 4 orders of magnitude. Pumping response usually declined with increasing concentration beyond the concentration that evoked the maximum response of the peptides. Our results support the conceptual model that larval release in subtidal crustaceans is controlled by small peptides that act as pheromones.
11 citations
"Marine chemical ecology: chemical s..." refers background in this paper
...This pattern suggests that mesograzer use of chemically noxious seaweeds has been selected owing to the values of these seaweeds for predator escape or deterrence rather than their direct value as a food....
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...This behavior is cued by chemical signals from the developing embryos that elicit this behavior in the crustacean mother (Tankersley et al. 2002, Ziegler & Forward 2007)....
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TL;DR: It is demonstrated that at least two-thirds of the ingested DMSP ends up in tissues or feces or in solution in the ambient water in the first 24 h after feeding, and virtually none is converted to ambient DMS during that time period.
Abstract: Dimethylsulfoniopropionate (DMSP) synthesized by marine phytoplankton is the princi- pal source of dimethylsulfide (DMS), an important climate-affecting gas. Prior research has demon- strated that grazing by invertebrate phytoplanktivores often affects the dynamics of DMS production from algal DMSP, but the effects of grazing by phytoplanktivorous fish have not previously been investigated. We studied the fate of algal DMSP following grazing by juvenile Atlantic menhaden Brevoortia tyrannus (13 cm fork length), which are generally viewed as the most specialized for phy- toplanktivory of all postlarval fish. The menhaden were fed the dinoflagellate Prorocentrum micans, containing 1 to 2 pmol DMSP cell -1 . During the first 24 h following ingestion of algal DMSP, almost none of the DMSP (ca. 1%) appeared as DMS. About 21% of ingested DMSP appeared in the water column as dissolved DMSP, peaking in concentration 9 to 11 h after feeding; in natural settings, this fraction would be poised for microbial metabolism, including potential conversion to DMS in surface waters from which outgassing to the atmosphere could occur. About 10% of ingested DMSP appeared in fecal pellets that tended to sink rapidly toward the bottom of the tanks. About 33% of ingested DMSP was deposited in the tissues of the menhaden, in particular in the red and white swimming muscles, in which we observed concentrations exceeding 0.7 µmol g -1 . This final fraction could ultimately be metabolized to DMS, or it could be passed up food chains and possibly act as a taste factor in commercially important piscivores such as striped bass and bluefish. In total, our research demonstrated that at least two-thirds of the ingested DMSP ends up in tissues or feces or in solution in the ambient water in the first 24 h after feeding, and virtually none is converted to ambient DMS during that time period.
10 citations
"Marine chemical ecology: chemical s..." refers background in this paper
...When zooplankton attack blooms of phytoplankton, dimethyl sulfide (DMS) is commonly released owing to the attack and through excretion by zooplankton and other predators (Dacey & Wakeham 1986, Hill & Dacey 2006)....
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8 citations
"Marine chemical ecology: chemical s..." refers background in this paper
...In a compelling example from an Antartic pelagic system (McClintock & Janssen 1990, Yoshida et al. 1995), the amphipod Hyperiella dilatata grasps the chemically defended pteropod Clione antarctica, holds it on its dorsal surface, and by doing so becomes protected from fish predation....
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