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: Examples from the literature are summarized that may serve as a means to critically analyze postulated ideas and offer new questions for future study.
68 citations
"Marine chemical ecology: chemical s..." refers background in this paper
...…mates, to stimulating or deterring copulation once mates are in contact, to sperm-egg chemical signaling that promotes or prevents fertilization when egg and sperm are nearby or in contact (Lonsdale et al. 1998, Kamio et al. 2002, Stebbing et al. 2003, Raffell et al. 2004, Sato & Goshima 2007)....
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...Several studies with crustaceans have documented the presence of pheromones that stimulate mate searching from a distance (Lonsdale et al. 1998, Breithaupt & Thiel 2008)....
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TL;DR: This study documents an example of an invertebrate that cannot defend itself chemically increasing its chances of survival by capturing and carrying a species that can (a pteropod) and has benefits and costs for the carrier, but only costs to the captive.
Abstract: THIS study documents an example of an invertebrate that cannot defend itself chemically (an amphipod) increasing its chances of survival by capturing and carrying a species that can (a pteropod). Although chemical defences are found in a wide variety of marine invertebrates1–4, few studies have established the extent to which these chemicals will deter predators5–7, and even fewer have investigated how one organism might exploit another's chemical defence to protect itself8–10. These chemicals are usually ingested or sequestered in the host's tissue8,9. Several species indiscriminately decorate themselves with potentially toxic organisms or are passively fouled with chemically defended organisms11,12. These seem to be commensalisms or sometimes mutualisms. Our example has benefits and costs for the carrier, but only costs to the captive. The antarctic marine food web not only has a variety of chemically defended organisms13–16, contrary to earlier predictions17–19, but has at least one unusual symbiosis that makes use of noxiousness.
67 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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TL;DR: How infochemicals may affect the dynamics and structure of planktonic food webs is discussed in this chapter.
67 citations
"Marine chemical ecology: chemical s..." refers background in this paper
...Van Donk (2007) reviews several instances in planktonic systems where chemical cues from consumers reduced zooplankton activity, feeding, gut fullness, and thus visibility to visual consumers....
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TL;DR: The data suggest that the preference of N. norrisi for kelps over other potentially edible and palatable seaweeds may not be related to nutritional content, but instead may have evolved in response to factors such as availability, habitat provision, or refuge from predation.
Abstract: Through two-choice gustatory experiments, a␣preference hierarchy was established␣for␣the␣herbivorous gastropod Norrisianorrisi Sowerby, with laminarialean kelps preferred over all other seaweeds. Among the kelps, laminae of Macrocystispyrifera were slightly preferred over Egregiamenziesii, and both were strongly preferred over sporophylls of Eiseniaarborea. E.arborea, the least preferred kelp, was consistently chosen over other algae common in the snail's habitat (Halidrysdioica, Dictyotaflabellata, and Pterocladiacapillacea) and over seaweeds believed to be edible and palatable based on their morphology, structure, and secondary chemistry (Endarachnebinghamiae, Mazzaellaflaccida, and Ulvalobata). The morphologies and structural toughness of tested seaweeds varied significantly as did their nutritional (% carbon, % nitrogen, C:N ratio, and % ash) contents and phlorotannin concentrations; however, snails preferred to feed on kelps regardless of nutritional content, toughness or phlorotannin concentration; and among kelps preferred to feed on the least tough species (based on penetrometer measurements), which also were those containing the lowest phlorotannin concentrations. Preference for kelp was not upheld in experiments using agarose thalli to which freeze-dried powder, of either the kelp Eiseniaarborea or non-kelp Endarachnebinghamiae was added, suggesting the destruction of attractant chemicals during the making of the artificial foods. Our data suggest that the preference of N. norrisi for kelps over other potentially edible and palatable seaweeds may not be related to nutritional content, but instead may have evolved in response to factors such as availability, habitat provision, or refuge from predation.
66 citations
"Marine chemical ecology: chemical s..." refers background in this paper
...…time on primary substrate instead of in the plant canopy is associated with increased predation risk (Schmitt et al. 1983; see also discussion in Wakefiled & Murry 1998), this chemically mediated emigration is likely to be of both direct (less grazing) and indirect (increased predation on…...
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66 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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