Sea Otters: Their Role in Structuring Nearshore Communities

Estes, James A.; Palmisano, John F.

doi:10.1126/science.185.4156.1058

Cited by 977 publications

(767 citation statements)

References 18 publications

(8 reference statements)

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“…We found that emigration, rather than predation, accounted for about 50% of the reduction in minnow numbers following bass addition to a Campostoma pool (Power et al, 1985). This clear flowing river with its replicated pool habitats facilitated experiments that supported predictions from the trophic cascade model (Estes and Palmisano, 1974;Estes et al, 1978) and theory predicting the stabilizing effects of the differential mobility of predators versus prey through patchy environments (Huffaker, 1958;Hastings, 1977).…”

Section: When Is a Pool A Pool?supporting

confidence: 53%

Environmental controls on food web regimes: A fluvial perspective

Power

2006

Progress in Oceanography

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Because food web regimes control the biomass of primary producers (e.g., plants or algae), intermediate consumers (e.g., invertebrates), and large top predators (tuna, killer whales), they are of societal as well as academic interest. Some controls over food web regimes may be internal, but many are mediated by conditions or fluxes over large spatial scales. To understand locally observed changes in food webs, we must learn more about how environmental gradients and boundaries affect the fluxes of energy, materials, or organisms through landscapes or seascapes that influence local species interactions. Marine biologists and oceanographers have overcome formidable challenges of fieldwork on the high seas to make remarkable progress towards this goal. In river drainage networks, we have opportunities to address similar questions at smaller spatial scales, in ecosystems with clear physical structure and organization. Despite these advantages, we still have much to learn about linkages between fluxes from watershed landscapes and local food webs in river networks. Longitudinal (downstream) gradients in productivity, disturbance regimes, and habitat structure exert strong effects on the organisms and energy sources of river food webs, but their effects on species interactions are just beginning to be explored. In fluid ecosystems with less obvious physical structure, like the open ocean, discerning features that control the movement of organisms and affect food web dynamics is even more challenging. In both habitats, new sensing, tracing and mapping technologies have revealed how landscape or seascape features (e.g., watershed divides, ocean fronts or circulation cells) channel, contain or concentrate organisms, energy and materials. Field experiments and direct in situ observations of basic natural history, however, remain as vital as ever in interpreting the responses of biota to these features. We need field data that quantify the many spatial and temporal scales of functional relationships that link environments, fluxes and food web interactions to understand how they will respond to intensifying anthropogenic forcing over the coming decades.

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Section: When Is a Pool A Pool?supporting

confidence: 53%

Environmental controls on food web regimes: A fluvial perspective

Power

2006

Progress in Oceanography

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“…Predation is a process that may have changed through time to change the selection pressures on mussel shell construction. Sea otter (Enhydra lutris) abundance in the Pacific Northwest is known to have decreased markedly over time [55], and there is evidence that they were used and hunted by Native Americans in this region, although their remains are nearly absent in the Sand Point midden [56]. Shell thickness may offer little protection against predation by sea otters, which prey on an entire patch of mussels at once [57].…”

Section: Discussionmentioning

confidence: 99%

Historical baselines and the future of shell calcification for a foundation species in a changing ocean

et al. 2016

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Seawater pH and the availability of carbonate ions are decreasing due to anthropogenic carbon dioxide emissions, posing challenges for calcifying marine species. Marine mussels are of particular concern given their role as foundation species worldwide. Here, we document shell growth and calcification patterns in Mytilus californianus, the California mussel, over millennial and decadal scales. By comparing shell thickness across the largest modern shells, the largest mussels collected in the 1960s-1970s and shells from two Native American midden sites ( 1000-2420 years BP), we found that modern shells are thinner overall, thinner per age category and thinner per unit length. Thus, the largest individuals of this species are calcifying less now than in the past. Comparisons of shell thickness in smaller individuals over the past 10-40 years, however, do not show significant shell thinning. Given our sampling strategy, these results are unlikely to simply reflect within-site variability or preservation effects. Review of environmental and biotic drivers known to affect shell calcification suggests declining ocean pH as a likely explanation for the observed shell thinning. Further future decreases in shell thickness could have significant negative impacts on M. californianus survival and, in turn, negatively impact the species-rich complex that occupies mussel beds.

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“…Some detail of this ecosystem is available in Estes and Palmisano (1974) and Estes et al (1998), only a broad and aggregated picture is used in the simulations. The ecosystem is a food web with four trophic levels illustrated in Figure 2.…”

Section: Numerical Simulationsmentioning

confidence: 99%