Short Food Chains Research Articles

Amphipod-supported food web: Themisto gaudichaudii, a key food resource for fishes in the southern Patagonian Shelf

The trophic role of the hyperiid amphipod Themisto gaudichaudii in the southern Patagonian shelf food web was assessed from the analysis of stomach contents of the local fish assemblage. A total of 461 trawl samples were collected during seven seasonal cruises. A total of 17 out of 38 fish species were found to ingest T. gaudichaudii. This amphipod was a main prey item in five of these species, showing high values of alimentary index: Seriolella porosa (99.9%), Macruronus magellanicus (68.8%), Micromesistius australis (59.1%), Patagonotothen ramsayi (48.6%), and Merluccius hubbsi (10.9%). The contribution of T. gaudichaudii, in weight, to their summer diet was 60%, on average. This contribution was minimal in winter and maximal in summer. Fisheries studies have indicated that these five species, mainly M. magellanicus, account for almost 85% of the fish biomass in the area. Although the remaining 15% did not feed heavily on T. gaudichaudii, they are known to prey on the main hyperiid predators. Our study shows that T. gaudichaudii contributes greatly, both directly and indirectly, to supporting the fish community. We thus proposed that T. gaudichaudii plays a key role as a “wasp-waist” species in the sub-Antarctic region, similar to that of krill in Antarctic waters, channeling the energy flow and enabling a short and efficient food chain.

Food web dynamics in the Scotia Sea in summer: A stable isotope study

The pelagic food web of the Scotia Sea was studied by analysing natural abundances of nitrogen and carbon stable isotopes of primary producers and pelagic consumers, sampled from the seasonal ice edge in the south to the Antarctic Polar Front in the north. The analysis covered, within a single mid-summer period, particulate organic matter (POM) and 38 taxa, ranging from suspension feeding copepods and salps to omnivorous euphausiids, pelagic fish and higher, land-based predators including fur seals, penguins and flying birds. Spatial variation in δ 15N of POM correlated well with nutrient availability and primary productivity. Latitudinal differences in δ 13C of POM were closely linked to variations in temperature, nutrients and productivity depending on the frontal region sampled. This translated to equivalent (although smaller) regional δ 13C differences among higher trophic levels. The trophic positions of species based on isotope values broadly agreed with previously published dietary data with three important exceptions. First, the carnivorous amphipod Themisto gaudichaudii had anomalously low δ 15N values. Second, Euphausia superba had δ 15N values that were also surprisingly low, considering the abundant literature suggesting its omnivory. Third, the copepod Rhincalanus gigas, considered a suspension feeder, had unexpectedly high δ 15N values rather more in keeping with omnivorous feeding. The consumer δ 15N values ranged from 1.2‰ (min.) measured in Salpa thompsoni (designated here as trophic level (TL) 2 across all regions) to 15.2‰ (max.) measured in white-chinned petrels ( Procellaria aequinoctialis, calculated as TL5 relative to the TL2 of salps). Excluding seabirds, the resulting food chain length of 3.7 TL (above POM at TL1) was lower than in most other Southern Ocean and temperate marine pelagic ecosystems. The majority (60%) of vertebrate predators occupied only 1–1.5 trophic levels above the herbivorous suspension feeders such as krill. This indicates the existence of the classic short food chain of POM–suspension feeder–vertebrate predator. However the presence of trophic levels 4 and above indicates the existence of alternative trophic pathways, for example involving myctophid fish or carrion, and that some wide-ranging predators which breed at South Georgia also feed outside the region. This conclusion is supported first by the continuum of δ 15N values between krill, suspension feeding copepods and myctophid fish, and secondly by higher trophic levels in several of the myctophid species in the low-krill region of the northern Scotia Sea, suggesting latitudinal differences in food web structure and food chain length.

Total mercury in wild fish in Guizhou reservoirs, China

The health hazard of mercury (Hg) compounds is internationally recognized, and the main pathways for methylmercury (MeHg) intake in humans are through consumption of food, especially fish. Given the large releases of Hg to the environment in China, combined with the fast development of hydropower, this issue deserves attention. Provided similar mobilization pathways of Hg in China as seen in reservoirs in North America and Europe one should expect increased Hg contamination in relation to future hydropower reservoir construction in this country. This study presents total Hg (THg) concentrations in wild fish from six Guizhou reservoirs, China. The THg concentrations in fish were generally low despite high background levels in the bedrock and depositions from local point sources. The over all mean ± SD concentration of THg was (0.066 ± 0.078) μg/g ( n = 235). After adjusting for among-reservoir variation in THg, there were significant differences in THg among functional groups of the fish, assumed to reflect trophic levels. Predicted THg-concentration ratios, retrieved from a mixed linear model, between the functional groups were 9:4:4:1 for carnivorous, omnivorous, planktivorous and herbivorous fish. This result indicated that MeHg accumulation may prevail even under circumstances with short food chains as in this Chinese water system. No fish exceeded recommended maximum THg limit for human consumption set by World Health Organization and the Standardization Administration of China (0.5 μg/g fish wet weight (ww)). Only six fish (2.5%) exceeded the maximum THg limit set by US Environmental Protection Agency (0.3 μg/g fish ww).

Foodweb structure in small streams: do we need different models for the tropics?

Prevailing notions of foodweb structure and trophic relations in fresh waters are based on research undertaken in a limited range of latitudes or habitat types. This limitation had led to the general view that stream food webs are detritus-based with short food chains and simple interactions that often are dominated by a few key species. We used gut-content analyses and stable-isotope signatures to characterize feeding relationships and foodweb attributes of benthic communities in riffles in 2 forest streams in Hong Kong. We compared them with existing data on foodweb structure from pools in 1 of the streams and data from the literature. The 2 approaches to dietary analyses yielded complementary results, providing confidence that trophic relations and foodweb structure were adequately characterized. Food webs in both streams were remarkably similar regardless of habitat (riffle vs pool). Consumers in both streams depended primarily on autochthonous resources, as has been reported from some other tropical streams, and food chains were short although connectance was higher than has been recorded previously for stream food webs. Very few omnivores were found, and omnivory was even rarer than is typical of temperate streams, although it is common in other tropical streams and rivers. No evidence was found for dominance by a few common macroconsumer species, as observed elsewhere in the tropics. The apparently high levels of autochthony in tropical running waters imply that models of ecosystem functioning for northern temperate streams are inadequate for describing tropical systems. However, marked differences in the degree of omnivory and dominance of tropical stream food webs by macroconsumers is evidence that characterization of trophic interactions and stream ecosystem functioning cannot be captured by a simple tropical vs temperate dichotomy. Successful management of these systems will depend upon development of conceptual models that reflect the diversity of food webs within and between regions.

Naturally-occurring stable isotopes as direct measures of larval feeding efficiency, nutrient incorporation and turnover

Stable isotopes are non-hazardous markers that have been widely-used in assessing energy flow within aquatic ecosystems. Hatchery systems are also highly amenable to this approach, as they represent controlled mesocosms with a limited number of food sources and short planktonic food chains with rapid and measurable bioaccumulation of the heavier stable isotopes of carbon and nitrogen at each trophic step. Differences in the natural isotopic composition of dietary components may be used to provide direct integrated measures of ingestion, nutrient incorporation and growth through development under normal feeding and environmental conditions, in either the laboratory or the hatchery. Simple isotopic mixing models allow estimation of relative utilisation of inert diets and live feeds, and individual components of compound feeds. Such experiments have investigated the effectiveness of co-feeding regimes, optimal timing of live food transitions (e.g. from rotifers to Artemia), presentation of inert diets, optimal size/age for weaning and incorporation of specific dietary components. Furthermore, time series measurement of changes in tissue isotopic signature ( δ 15N, δ 13C) enables modelling of growth dilution and tissue turnover components of isotopic change driven by nutritional sources. These measures need to take into account the difference in isotope values that is typically observed between the diet and consumer (isotopic discrimination factor, Δ). In marine larvae and early postlarvae, Δ 13C and Δ 15N have been found to range widely, from 0.4–4.1‰ and 0.1–5.3‰ respectively. The observation of such a high level of variation within species and life stages indicates a strong effect of diet quality on isotopic discrimination. Elucidating mechanisms underlying such observations, and much greater resolution in larval nutritional studies, can be achieved by application of rapidly-developing techniques for compound specific stable isotope analysis in tracing the transfer of dietary sources of carbon and nitrogen into tissue components. Fast growing aquatic larvae represent excellent model organisms exhibiting rapid transitions in isotopic composition in response to diet, rapidly-changing feeding behaviour and transitions in trophic level with ready ingestion of modifiable experimental diets in short and controlled food chains. Thus results of studies of the effects of diet composition, developmental stage, growth rates or environmental conditions on stable isotope incorporation will be of broad relevance not only in terms of larval nutrition but can also more broadly inform the design and interpretation of ecological studies.

Effect of plant species loss on aphid–parasitoid communities

1. The consequences of species loss on ecosystem functioning within a single trophic level have been extensively studied. However, the loss of basal species is likely to have profound impacts on the abundance, richness and ecosystem functioning of species at higher trophic levels. 2. Here, we used experimentally established plant communities with a species richness gradient to study the effects of plant species loss on a multi-trophic insect community in the field. We measured densities and species richness of aphids and parasitic wasps (primary, secondary and facultative tertiary parasitoids of aphids) that naturally colonized the grassland plots. 3. Furthermore, we calculated two ecosystem functions: aphid load (the number of aphid individuals per host plant biomass used as a proxy for herbivory) and parasitism rate. We used structural equation models to explore pathways of direct and indirect effects of plant species richness on higher trophic levels. 4. We found that the densities and richness of species at all trophic levels were influenced by changes in plant species richness. The effects were rarely direct, but instead mediated by the abundance and species richness of aphid host plants and subsequent trophic levels. 5. The herbivore and primary parasitoid levels were most directly affected by changes in plant species richness, with highest insect densities and species richness occurring at intermediate plant species richness. The densities and species richness of secondary parasitoids declined linearly with plant species richness owing to sparser resources, resulting in shorter food chains in communities with the highest plant species richness. 6. Aphid load was highest at intermediate plant species richness and negatively affected by both host plant biomass and host plant species richness. Parasitism rate was mostly affected indirectly via aphid density and overall only weakly negatively related to plant species richness. 7. Our results demonstrate that plant species richness can have strong cascading effects up to high trophic levels. However, their direction may differ at the lower and higher ends of the plant species richness spectrum, cautioning against simplifying consequences of plant species loss for specialist food webs that may become limited by sparse resources at high plant richness.

SUSTAINABILITY OF SHORT FOOD SUPPLY CHAINS: ANALYSIS OF RAW MATERIAL SUPPLY IN MILAN PUBLIC SCHOOL CATERING

The demand of short food supply chains is becoming more pressing by consumers, especially in the largest school catering. The implementation of the short chain in a large catering company of Milan, is described in this practical contribution. Several aspects of short food chains sustainability: legal, commercial and economic sustainability, hygienic and gastronomic sustainability, are discussed.

Use of biomarkers to show sub-cellular effects in meadow voles ( Microtus pennsylvanicus) living on an abandoned gold mine site

Run-off from mine tailings ponds constitutes the main anthropogenic release of arsenic in Canada. As a potential consequence, wildlife not normally exposed to arsenic under other circumstances may receive toxicologically relevant concentrations of arsenic compounds in their food and water. To test this hypothesis, and to determine if arsenic is being transported through trophic levels, the arsenic concentrations in members of a short food chain (soil–plant–meadow vole) were measured. Arsenic concentrations were higher in exposed organisms compared with those from a reference location. However, elevated concentrations of arsenic do not necessarily indicate impact, and consequently a biomonitoring study was undertaken to determine if there were sub-cellular effects of exposure in meadow voles ( Microtus pennsylvanicus) as a consequence of arsenic exposure. In this work, adenosine triphosphate (ATP) and liver glutathione (GSH) levels were used as biomarkers of exposure and the frequency of red blood cell micronuclei (mono- and polychromatic) was used as a biomarker of effect. ATP results were not conclusive but there was a statistically significant relationship between a reduction of GSH in vole livers and increased liver arsenic concentrations. A statistically significant relationship was also observed between increased micronucleated monochromatic red blood cells in voles from arsenic contaminated sites compared to a background location. The results of the GSH and monochromatic red blood cell investigations suggest that there are possible sub-cellular effects on these voles as a consequence of dietary arsenic exposure. This is the first field study in which such effects have been observed in voles living near mine tailings.

Differing Forage Fish Assemblages Influence Trophic Structure in Neighboring Urban Lakes

Lakes Sammamish and Washington are two large, urban lakes in close proximity to Seattle, Washington. The two lakes have similar assemblages of apex predators, but differences in lake size, species richness, and forage fish assemblages contribute to contrasting trophic relationships. We used stable isotope and diet analyses to assess lake-specific differences in the trophic structure of fish and invertebrates from these lakes. Estimates of δ15N-based trophic elevation revealed that the food web in Lake Sammamish was truncated by approximately one complete trophic level relative to that of Lake Washington. The shorter food chain in Lake Sammamish reflected the absence of longfin smelt Spirinchus thaleichthys and minimal consumption of threespine stickleback Gasterosteus aculeatus, emphasizing the importance of these species as primary forage fishes and trophic links between invertebrates and piscivores in Lake Washington. As two highly 15N-enriched and 13C-depleted energy sources, longfin smelt and threespine sticklebacks effectively stretched the isotopic endpoints of the Lake Washington food web by contributing to more pronounced ontogenetic shifts in isotope values for piscivores in Lake Washington than for those in Lake Sammamish.

Consumo critico e reti alimentari

- This paper explores the development of alternative practices of production and consumption of food in Italy, pointing out the attention on the potentiality of the short food chains aiming to improve the conditions of small producers as well as on the emerging of critical consumption practices that have encouraged the constitutions of the solidarity purchasing groups (GAS). In particular, this paper presents the results of a national survey about the direct selling practices involving small rural producers as well as the GAS. The networks developed by these actors present specific aspects that are not considered by the analytical approaches just focusing on spatiality, but can be interpreted as "networks of resistance". Key words: critical consumption; agro-food networks; biological production; solidarity purchasing groups; short food chains; direct sale.

Environmental impact assessment for ionising radiation within the Arctic

The Arctic environment is unique in terms of many factors that may influence the behaviour and fate of contaminants including the presence of permafrost, low temperatures, slow breakdown of organic compounds, short food chains and long recovery times for some species. This study introduces the issues surrounding the development of a bespoke environmental impact assessment methodology specifically for the consideration of radiation impacts on Arctic ecosystems. The approach allows for the impact on plants and animals from exposure to radiation to be quantified in a robust manner through integration of our current knowledge concerning transfer in the environment, resultant dose-rates from the presence of radioactivity within biota and their media and information concerning radiobiological effects on endpoints of concern from an environmental protection perspective.

Life in a temperate Polar sea: a unique taphonomic window on the structure of a Late Cretaceous Arctic marine ecosystem

As the earth faces a warming climate, the rock record reminds us that comparable climatic scenarios have occurred before. In the Late Cretaceous, Arctic marine organisms were not subject to frigid temperatures but still contended with seasonal extremes in photoperiod. Here, we describe an unusual fossil assemblage from Devon Island, Arctic Canada, that offers a snapshot of a ca 75 Myr ago marine palaeoecosystem adapted to such conditions. Thick siliceous biogenic sediments and glaucony sands reveal remarkably persistent high primary productivity along a high-latitude Late Cretaceous coastline. Abundant fossil faeces demonstrate that this planktonic bounty supported benthic invertebrates and large, possibly seasonal, vertebrates in short food chains. These ancient organisms filled trophic roles comparable to those of extant Arctic species, but there were fundamental differences in resource dynamics. Whereas most of the modern Arctic is oligotrophic and structured by resources from melting sea ice, we suggest that forested terrestrial landscapes helped support the ancient marine community through high levels of terrigenous organic input.

Cenozoic cooling, Antarctic nutrient pump, and the evolution of whales

Abstract The evolution of large marine mammals and their invasion of the pelagic realm is tied to the availability of sufficient food, which in turn is linked to upwelling areas and other highly productive regions in the ocean, as has been recognized for some time. Here I propose that silicate-supported upwelling (which provides the shorter food chain and hence the higher yield for apex consumers) and deep mixing within the Southern Ocean are the crucial ingredients of the system providing the stage for the evolution of whales. The Circumpolar Current receives silicate from various sources but especially from the North Atlantic Deep Water introduced in the Atlantic sector. The silicate is largely trapped in the Ring, some in the water, and some in the sediment, and is made available to shallower waters by unusually deep mixing. From these shallower depths silica-rich waters can enter the thermocline all through the southern hemisphere, stimulating diatom growth in upwelling systems to the equator and beyond. From the link diatoms–krill–whales and diatoms–krill–small fishes, it is readily apparent that the link between the climate narrative and the narrative of whale evolution (both for mysticetes and odontocetes) is the silica cycle. Studying it will generate hypotheses about whale evolution that can be tested using fossils.

Global patterns of aquatic food chain length

Food chain length is a fundamental ecosystem property, and plays a central role in determining ecosystem functioning. Recent advances in the field of stable isotope ecology allow the estimation of food chain length (FCL) from stable nitrogen isotope (δ15N) data. We conducted a global literature synthesis and estimated FCL for 219 lake, stream, and marine ecosystems. Streams had shorter food chains (∼3.5 trophic levels) than marine and lake ecosystems (∼4.0 trophic levels). In marine systems, inclusion of marine mammals increased FCL by 2/3 of a trophic level. For each ecosystem type, estimates of FCL were normally distributed and spanned two full trophic levels. Comparison with published connectance food webs revealed similar mean FCL values, though stable isotope‐derived FCL estimates were less variable. At the global scale, FCL showed weak or no relationships with ecosystem size, mean annual air temperature, or latitude. Our study highlights the utility of stable isotopes for quantifying among‐system food web variability, and the application of this approach for assessing global‐scale patterns of food chain length.

Global patterns of aquatic food chain length

Food chain length is a fundamental ecosystem property, and plays a central role in determining ecosystem functioning. Recent advances in the field of stable isotope ecology allow the estimation of food chain length (FCL) from stable nitrogen isotope (δ15N) data. We conducted a global literature synthesis and estimated FCL for 219 lake, stream, and marine ecosystems. Streams had shorter food chains (∼3.5 trophic levels) than marine and lake ecosystems (∼4.0 trophic levels). In marine systems, inclusion of marine mammals increased FCL by 2/3 of a trophic level. For each ecosystem type, estimates of FCL were normally distributed and spanned two full trophic levels. Comparison with published connectance food webs revealed similar mean FCL values, though stable isotope-derived FCL estimates were less variable. At the global scale, FCL showed weak or no relationships with ecosystem size, mean annual air temperature, or latitude. Our study highlights the utility of stable isotopes for quantifying among-system food web variability, and the application of this approach for assessing global-scale patterns of food chain length.

Contribution to the feeding ecology of the banded puffer fish Colomesus psittacus (Tetraodontidae) in north Brazilian mangrove creeks

Stomach contents were examined from 102 banded puffer, Colomesus psittacus (Tetraodontidae), caught from intertidal mangrove creeks at diurnal neap tides between June and September, 1997 (early dry season) near Bragança (north Brazil). The study found that C. psittacus were specialized predators of Cirripedia (Balanus spp.) and Brachyuran crabs (Uca spp., Pachygrapsus gracilis) (mean: 58 and 38% by dry weight, respectively), emphasizing a short food chain in the mangrove system. Cirripedia and Brachyura dominated the diet in all size classes, however, the prey spectrum narrowed with fish size. The mean daily consumption of Cirripedia and Brachyura was 6.2% body weight of C. psittacus. On average C. psittacus consumed 100.3 g x ha(-1) x d(-1) of Cirripedia and 178.7 g x ha(-1) x d(-1) of Brachyura (wet weight). The predation on Brachyuran crabs--a significant driver of fluxes of organic matter and energy in the system--provides C. psittacus with an important ecological function in the mangrove food web. A plant-animal interaction is proposed where C. psittacus exerts a mutually beneficial cleaning function on the Aufwuchs (Cirripedia and associated epibiota) of Rhizophora mangle stilt roots. Our results and those of other studies suggest that C. psittacus encounter optimum foraging conditions in the mangrove at high inundations at daylight (spring tide-day) whereas darkness and low inundations are linked to poor foraging conditions (neap tide-night). The C. psittacus resource could be used as an alternative income in the region in terms of i) sustainable catch and filet processing for exports to East Asia, ii) developing certified aquaculture methods for breeding puffers for the aquarium trade.

TROPHIC LEVELS AND TROPHIC TANGLES: THE PREVALENCE OF OMNIVORY IN REAL FOOD WEBS

The concept of trophic levels is one of the oldest in ecology and informs our understanding of energy flow and top-down control within food webs, but it has been criticized for ignoring omnivory. We tested whether trophic levels were apparent in 58 real food webs in four habitat types by examining patterns of trophic position. A large proportion of taxa (64.4%) occupied integer trophic positions, suggesting that discrete trophic levels do exist. Importantly however, the majority of those trophic positions were aggregated around integer values of 0 and 1, representing plants and herbivores. For the majority of the real food webs considered here, secondary consumers were no more likely to occupy an integer trophic position than in randomized food webs. This means that, above the herbivore trophic level, food webs are better characterized as a tangled web of omnivores. Omnivory was most common in marine systems, rarest in streams, and intermediate in lakes and terrestrial food webs. Trophic-level-based concepts such as trophic cascades may apply to systems with short food chains, but they become less valid as food chains lengthen.

ANTHROPOGENIC SUBSIDIES ALTER STREAM CONSUMER–RESOURCE STOICHIOMETRY, BIODIVERSITY, AND FOOD CHAINS

Urbanization is dramatically changing nutrient and organic matter regimes in streams, yet the community and ecosystem implications often remain obscure. We assessed the consequences of sewage-derived particulate organic matter (SDPOM) for invertebrate community structure and function in a headwater stream. Using stable isotope analyses, we found assimilation of organic SDPOM to double community secondary production, and stoichiometric analyses revealed SDPOM enriched in phosphorus (P) to foster putatively fast-growing, P-rich consumers in the subsidized reach. This altered consumer-resource stoichiometry impacted both community structure and nutrient fluxes through the invertebrate community. Community structure shifted toward significantly reduced diversity and evenness in the subsidized reach and consequently toward shorter food chains. Our integration of ecological stoichiometry with stable isotope analyses and food web ecology expands the previous focus of traditional ecotoxicology and ecophysiology to an ecosystem-level appreciation of pollutant ecology.

Role of pelagic crustaceans in the diet of the longnose lancetfish Alepisaurus ferox in the Seychelles waters

The role of pelagic crustaceans in the diet of the longnose lancetfish Alepisaurus ferox was investigated from stomach content analysis of fish collected in the waters surrounding the Seychelles Archipelago in the western Indian Ocean. Crustaceans accounted for 88.4% by prey number and 73.7% by reconstituted mass during the South-West monsoon season. During the North-East monsoon season, crustaceans remained the main prey group and accounted for 63.7% by prey number and 46% by reconstituted mass. There was a clear seasonal pattern with the portunid crab Charybdis smithii predominating during the South-West monsoon season and the pelagic stomatopod Natosquilla investigatoris during the North-East monsoon season. This pattern likely reflects variations in prey availability linked to current movements around the Seychelles Archipelago. Most of the prey consisted of slow-swimming and small individuals, which occur in dense swarms during the pelagic phase of their life history. The dietary trends of lancetfish are consistent with opportunistic feeding on the most abundant prey. They exploit short food chains based on carnivorous crustaceans, and play an important role in the pelagic trophic functioning of the western Indian Ocean.

Ecosystem dynamics of the Pacific-influenced Northern Bering and Chukchi Seas in the Amerasian Arctic

The shallow continental shelves and slope of the Amerasian Arctic are strongly influenced by nutrient-rich Pacific waters advected over the shelves from the northern Bering Sea into the Arctic Ocean. These high-latitude shelf systems are highly productive both as the ice melts and during the open-water period. The duration and extent of seasonal sea ice, seawater temperature and water mass structure are critical controls on water column production, organic carbon cycling and pelagic–benthic coupling. Short food chains and shallow depths are characteristic of high productivity areas in this region, so changes in lower trophic levels can impact higher trophic organisms rapidly, including pelagic- and benthic-feeding marine mammals and seabirds. Subsistence harvesting of many of these animals is locally important for human consumption. The vulnerability of the ecosystem to environmental change is thought to be high, particularly as sea ice extent declines and seawater warms. In this review, we focus on ecosystem dynamics in the northern Bering and Chukchi Seas, with a more limited discussion of the adjoining Pacific-influenced eastern section of the East Siberian Sea and the western section of the Beaufort Sea. Both primary and secondary production are enhanced in specific regions that we discuss here, with the northern Bering and Chukchi Seas sustaining some of the highest water column production and benthic faunal soft-bottom biomass in the world ocean. In addition, these organic carbon-rich Pacific waters are periodically advected into low productivity regions of the nearshore northern Bering, Chukchi and Beaufort Seas off Alaska and sometimes into the East Siberian Sea, all of which have lower productivity on an annual basis. Thus, these near shore areas are intimately tied to nutrients and advected particulate organic carbon from the Pacific influenced Bering Shelf-Anadyr water. Given the short food chains and dependence of many apex predators on sea ice, recent reductions in sea ice in the Pacific-influenced sector of the Arctic have the potential to cause an ecosystem reorganization that may alter this benthic-oriented system to one more dominated by pelagic processes.