Biomonitors are commonly used to assess levels of bioavailable contaminants in the environment, however the relationships between biomonitor tissue concentrations and ecological effects are rarely ...assessed. The present study investigated metal contamination within a highly industrialised harbour and ecological effects on sessile invertebrates. The native oyster Saccostrea glomerata was deployed as a biomonitor across twenty-six sites to test for correlations between metal levels in their tissues and the recruitment of hard-substrate invertebrates. Concentrations of lead and copper in oyster tissues were negatively correlated with densities of the dominant barnacle, Amphibalanus variegatus, and positively correlated with densities of the dominant polychaete, Hydroides elegans, and the two native encrusting bryozoans Celloporaria nodulosa and Arachnopusia unicornis. Results suggest that highly localised events drive contaminant availability and that these events pose a significant risk to fauna. Biomonitoring studies may be enhanced by running concurrent ecological surveys.
Within our lakes, streams, estuaries, and oceans, there is an astounding chemodiversity of secondary metabolites produced by microbes, algae, and invertebrates. Nearly 30 years of study have yielded ...hundreds of examples in which secondary metabolites alter the foraging behavior or fitness of aquatic consumers, or both. However, our understanding of the mechanisms that mediate the fate and consequences of these metabolites in aquatic consumers remains in its infancy. Interactions between metabolites and consumers at the molecular and biochemical level are the purview of modern pharmacology, which is rooted in the long history of human-drug interactions and can be adopted for ecological studies. Here, we argue that a pharmacological approach to consumer-prey interactions will be as productive within aquatic systems as it has been for understanding terrestrial systems. We review the diversity of secondary metabolites in aquatic organisms, their known effects on the feeding behaviors and performance of aquatic consumers, and the few studies that have attempted to describe their biochemical manipulation within consumer tissues, i. e., their absorption, distribution, metabolism (including detoxification), and excretion. We then highlight vexing issues in the ecology and evolution of aquatic consumer-prey interactions that would benefit from a pharmacological approach, including specialist-versus-generalist feeding strategies, dietary mixing, nutrient-toxin interactions, and taste. Finally, we argue that a pharmacological approach could help to predict how consumer-prey interactions are altered by global changes in pH, water temperature and ultraviolet radiation, or by pollution. Arguably, the state of knowledge of aquatic consumer-prey interactions is equivalent to that faced by ecologists studying terrestrial herbivores in the 1970s; the literature documents profound variation among consumers in their feeding tolerances for secondary metabolites without a thorough understanding of the mechanisms that underlie that variation. The subsequent advancement in our understanding of terrestrial herbivores in the intervening decades provides confidence that applying a pharmacological approach to aquatic consumers will prove equally productive.
Modular organisms are composed of iterated units of construction that vary in their spatial arrangement. This variation is expected to affect the fitness of modular organisms due to interactions ...among neighboring modules and the potential for such organisms to be genetically heterogeneous. We devise a spatially explicit model to investigate how spatial interactions among neighboring modules affect organism fitness. We show that fitness is strongly dependent on the spatial arrangement of modules in both genetically homogeneous and heterogeneous organisms, and that the magnitude of the variation is dependent on the strength of interactions among modules. Organism fitness is more variable with interactions among modules that are symmetrical (each affects each other in the same directions) than with asymmetrical interactions (neighbors affect each other in different directions). We conclude by discussing potential extension of the present framework to a general dynamic model of spatially structured organism development.
The feeding preferences of small, invertebrate herbivores inhabiting the brown alga Zonaria angustata were examined. The 2 most common herbivores, the amphipods Tethygeneia sp. and Hyale rubra, ...consumed Z. angustata, strongly preferring the meristematic region at the apex of each branch. Amphipod preference for new growth and the extent of damage to plants in the field suggest that they may cause considerable damage to Z. angustata. In contrast to the common preconceptions about the diets of such herbivores, amphipods did not consistently prefer to consume the most abundant epiphytes of Z. angustata ahead of the host macroalga itself. Z. angustata was not a homogeneous food source for amphipods. Amphipod feeding was negatively correlated with the density of phlorotannin-containing physodes in, but not with toughness of, the tissues at the apex of each branch. This correlation indicated that the pattern of damage to Z. angustata was most likely a result of within-plant variation in the amount of secondary chemicals. This variation occurred over only a few millimetres but influenced amphipod feeding due to their ability to select between algal tissues at a very small scale.
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