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: Compensatory feeding allowed this amphipod to maintain high fitness when cultured on most, but not all, algae, and may reduce the need to move among host algae in order to mix diets, thus decreasing the risk of movement-associated detection by predators.
Abstract: Selective feeding, compensatory feeding, and diet mixing have all been proposed as adap- tive strategies allowing herbivores to enhance nutrient intake from low quality plant and algal foods. However, little is known about the relative importance of these alternative feeding strategies for con- sumer fitness or about how these strategies are affected by prey nutritional traits. To address this, we studied the effects of algal nutritional value and toughness on feeding choices, feeding rates, and sur- vival, growth and fecundity of the amphipod Ampithoe longimana. To assess the value of diet mixing, we compared fitness of amphipods cultured on each of 15 algal species or on 4 different mixtures of algae. We also quantified how sequentially switching between algae that supported higher and lower fitness affected fitness compared to monospecific diets of these algae and to a constant mixture of the algae. Protein, nitrogen, organic content, or toughness of algae did not correlate with food choice by A. longimana. In contrast, we found a strong inverse correlation between feeding rates and algal organic content (ash free dry mass/wet mass (AFDM:WM) and total organic carbon (TOC)), and, to a lesser extent, protein (but not nitrogen). Thus, when confined with algae having lower nutritional value, A. longimana used quantity to compensate for quality. This compensatory feeding was confirmed by feed- ing amphipods on artificial diets that varied only in their amount of AFDM:WM. Despite broad differ- ences in algal nutrient content or other traits, compensatory feeding allowed this amphipod to maintain high fitness when cultured on most, but not all, algae. Access to algal mixtures did not enhance fitness compared to feeding on several algae offered alone, suggesting that A. longimana need not rely on a mixed diet. Even when significant differences in survivorship or growth occurred between a mono- specific diet and a mixed diet, fecundity or size of eggs produced by egg-bearing survivors were gen- erally unaffected. Furthermore, when amphipods were switched sequentially (every 24 h) between 2 different quality algae, only growth (but not survivorship, fecundity, or egg size) was affected, with growth determined primarily by the higher quality alga offered. Amphipods confined with the green alga Codium fragile ovulated significantly later than conspecifics on one mixed diet, but this effect was observed only in 1 of 2 long-term assays. Thus, dietary mixing offered only a moderate benefit to this am- phipod under very restrictive conditions. For A. longimana, food selection is relatively unresponsive to algal nutritional quality, apparently because compensatory feeding allows this amphipod to successfully exploit a variety of algal foods. Compensatory feeding also may reduce the need to move among host algae in order to mix diets, thus decreasing the risk of movement-associated detection by predators.
148 citations
"Marine chemical ecology: chemical s..." refers background in this paper
...F or p er so na l u se o nl y. rather than its value as a food; when cultured in the lab on numerous different seaweeds, Dictyota does not enhance the survivorship, growth, or fecundity of A. longimana relative to numerous other local seaweeds (Cruz-Rivera & Hay 2001)....
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Book•
01 Jan 2007
TL;DR: This book synthesizes the state of the field in crustacean behavior and sociobiology and places it in a conceptually based, comparative framework that will be valuable to active researchers and students in animal behavior, ecology, and evolutionary biology.
Abstract: Understanding of animal social and sexual evolution has seen a renaissance in recent years with discoveries of frequent infidelity in apparently monogamous species, the importance of sperm competition, active female mate choice, and eusocial behavior in animals outside the traditional social insect groups Each of these findings has raised new questions, and suggested new answers, about the evolution of behavioral interactions among animals This volume synthesizes recent research on the sexual and social biology of the Crustacea, one of the dominant invertebrate groups on earth Its staggering diversity includes ecologically important inhabitants of nearly every environment from deep-sea trenches, through headwater streams, to desert soils The wide range of crustacean phenotypes and environments is accompanied by a comparable diversity of behavioral and social systems, including the elaborate courtship and wildly exaggerated morphologies of fiddler crabs, the mysterious queuing behavior of migrating spiny lobsters, and even eusociality in coral-reef shrimps This diversity makes crustaceans particularly valuable for exploring the comparative evolution of sexual and social systems Despite exciting recent advances, however, general recognition of the value of Crustacea as models has lagged behind that of the better studied insects and vertebrates This book synthesizes the state of the field in crustacean behavior and sociobiology and places it in a conceptually based, comparative framework that will be valuable to active researchers and students in animal behavior, ecology, and evolutionary biology It brings together a group of internationally recognized and rising experts in fields related to crustacean behavioral ecology, ranging from physiology and functional morphology, through mating and social behavior, to ecology and phylogeny Each chapter makes connections to other, non-crustacean taxa, and the volume closes with a summary section that synthesizes the contributions, discusses anthropogenic impacts, highlights unanswered questions, and provides a vision for profitable future research
145 citations
"Marine chemical ecology: chemical s..." refers background in this paper
...Lobsters, stomatopods, and crayfish, for example, can chemically recognize individuals that they have previously encountered and behave appropriately given their relative dominance (Atema 1995, Duffy & Thiel 2007)....
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...Although crayfish live in fresh water, their chemically mediated behaviors appear to parallel marine crustaceans, such as lobster and stomatopods; they have been well studied and offer potential insights to marine species (Duffy & Thiel 2007)....
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TL;DR: It is shown that water-borne cues from actively feeding herbivorous gastropods, flat periwinkles (Littorina obtusata), can serve as external signals to induce production of defense chemicals (phlorotannins) in unharmed individuals of seaweeds, knotted wrack, and that the increased levels ofDefense chemicals deter further feeding by periwinkle attacks.
Abstract: It is well known that herbivores can induce chemical defenses in terrestrial vascular plants, but few examples of inducible production of defense chemicals have been reported for aquatic macrophytes. Furthermore, it is well established that water-borne chemical cues from predators or predator-wounded conspecifics can induce defensive changes of aquatic prey animals, but no such communication between aquatic herbivores and seaweeds has been reported. Here we show that water-borne cues from actively feeding herbivorous gastropods, flat periwinkles (Littorina obtusata), can serve as external signals to induce production of defense chemicals (phlorotannins) in unharmed individuals of seaweeds, knotted wrack (Ascophyllum nodosum), and that the increased levels of defense chemicals deter further feeding by periwinkles. Because seaweeds have poorly developed internal-transport systems and may not be able to elicit systemic-induced chemical defenses through conveyance of internal signals, this mechanism ensures that seaweeds can anticipate future periwinkle attacks without receiving direct damage by herbivores.
141 citations
TL;DR: It is demonstrated that chemical cues associated with each of these grazers induce consumer-specific, but opposing, morphological transformations in the bloom-forming species Phaeocystis globosa, which may redirect energy and nutrients from food webs supporting fisheries to those fueling detrital pathways, thus potentially altering ecosystem-level processes such as productivity, carbon storage, and nutrient release.
Abstract: Blooms of the phytoplankton Phaeocystis can comprise 85% of total production and generate major biogeochemical signals across broad oceanic regions. The success of Phaeocystis may result from its ability to change size by many orders of magnitude when it shifts from small cells of 4–6 μm to large colonies of up to 30,000 μm in diameter. Single cells are consumed by ciliates but not copepods, whereas colonies are consumed by copepods but not ciliates. We demonstrate that chemical cues associated with each of these grazers induce consumer-specific, but opposing, morphological transformations in the bloom-forming species Phaeocystis globosa. Chemical cues from grazing copepods suppress colony formation by a significant 60–90%, a response that should be adaptive because copepods feed four times more on colonies versus solitary cells. In contrast, chemical cues from grazing ciliates enhance colony formation by >25%, a response that should be adaptive because ciliates grow three times faster when fed solitary cells versus colonies. Because size-selective predation fundamentally alters community structure and ecosystem function, this chemically cued shift may redirect energy and nutrients from food webs supporting fisheries to those fueling detrital pathways, thus potentially altering ecosystem-level processes such as productivity, carbon storage, and nutrient release.
139 citations
"Marine chemical ecology: chemical s..." refers background in this paper
...…from ones where most production is consumed by ciliates and recycled in the upper water column to ones where much of the production is consumed by copepods, packaged into larger feces, and transported to the deeper ocean, potentially affecting rates of carbon sequestration (Long et al. 2007)....
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...…instances of subtle chemical signaling that are being discovered in marine systems (e.g., Toth & Pavia 2000, Stachowicz 2001, Selander et al. 2006, Long et al. 2007), multitrophic level signaling could be common and important, but underinvestigated, in marine systems (Byrnes et al. 2006)....
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...…attacked conspecifics, congeners, or ecologically similar prey occur in many systems and the trophic cascades produced by the indirect effects of this “ecology of fear” often equals or exceeds the direct effects of predators on prey (Peacor & Werner 2001, Trussell et al. 2004, Long et al. 2007)....
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...F or p er so na l u se o nl y. (ciliates); the prey respond by suppressing colony formation and growing as individual cells that are too small for copepods to attack (Long et al. 2007)....
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...These shifts could alter energy flow, nutrient cycling, and patterns of carbon sequestration (Long et al. 2007)....
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TL;DR: Results indicate that allelopathy occurs widely but with species-specific consequences in bloom dynamics, and that brevetoxins at ecologically reasonable waterborne concentrations accounted for the modest inhibition by K. brevis.
Abstract: Monospecific blooms of phytoplankton can disrupt pelagic communities and negatively affect human health and economies. Interspecific competition may play an important role in promoting blooms, and so we tested (1) whether the outcome of competition between the red tide dinoflagellate Karenia brevis (ex Gymnodinium breve) and 12 cooccurring phytoplankters could be explained by allelopathic effects of compounds released by K. brevis and (2) whether waterborne, lipophilic molecules, including brevetoxins, are involved. Nine of 12 phytoplankton species were suppressed when grown with live K. brevis at bloom concentrations. K. brevis extracellular filtrates or lipophilic extracts of filtrates inhibited six of these nine species, indicating allelopathy. However, these inhibitory effects were weaker than those experienced by competitors exposed to live K. brevis. Brevetoxins at ecologically reasonable waterborne concentrations accounted for the modest inhibition by K. brevis of only one competitor, Skeletonema costatum. The addition of brevetoxins also caused significant autoinhibition, reducing the maximum concentration of K. brevis. Allelopathy is one mechanism by which K. brevis appears to exhibit competitive advantage over some sympatric phytoplankters, although unidentified compounds other than brevetoxins must be involved, in most cases. K. brevis was also susceptible to competitive exclusion by several species, including Odontella aurita and Prorocentrum minimum, known to thrive during K. brevis blooms. Although field experiments are required to assess whether allelopathy plays a fundamental role in bloom dynamics, our results indicate that allelopathy occurs widely but with species-specific consequences.
138 citations
"Marine chemical ecology: chemical s..." refers background in this paper
...As an example, cell-free filtrates from cultures of the red tide dinoflagellate Karenia brevis chemically suppressed 6 of the 12 co-occurring phytoplankton they were tested against (Kubanek et al. 2005)....
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