Boston University Marine Program (BUMP)
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The Boston University Marine Program is a hands-on, research-oriented curriculum in marine biology, with emphasis on marine ecology, molecular ecology, behavioral ecology, sensory biology, ichthyology, and oceanography. From its inception in 1969 to 2008, BUMP was located at the Marine Biological Laboratory (MBL) in Woods Hole, Massachusetts.
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ArticleMacroalgal responses to experimental nutrient enrichment in shallow coastal waters : growth, internal nutrient pools, and isotopic signatures(Inter-Research, 2008-09-25)Increased nutrient inputs to temperate coastal waters have led to increased occurrences of macroalgal blooms worldwide. To identify nutrients that are limiting to macroalgae and to determine whether different forms of these nutrients and long-term ambient nutrient conditions affect macroalgal response, we used in situ enrichment methods and tested the response of 2 bloom-forming species of macroalgae, Ulva lactuca and Gracilaria tikvahiae, from shallow estuaries of Waquoit Bay, Massachusetts, USA, that receive different land-derived N inputs. We enriched caged macroalgal fronds with nitrate, ammonium, phosphate, and N + P combinations, and measured growth, nutrient content, and δ15N signatures of fronds after 2 wk of incubation. In these estuaries, P did not limit growth, however, the 2 species differed in growth response to N additions. Growth of U. lactuca was greater in Childs River (CR), the estuary with higher nitrate inputs, than in Sage Lot Pond (SLP); growth in SLP increased with nitrate and ammonium enrichment. In contrast, growth of G. tikvahiae was greater in SLP than in CR, but had no growth response to N enrichment in either site. C and N contents differed initially between species and sites, and after nutrient enrichment. Final tissue % N increased and C:N decreased after nitrate and ammonium enrichment. δ15N values of the macroalgae demonstrated uptake of the experimental fertilizers, and a higher affinity and faster turnover of internal N pools with ammonium than nitrate enrichment in both species. We suggest that U. lactuca blooms in areas with both high nitrate and ammonium water column concentrations, and is more N-limited in oligotrophic waters where DIN levels are too low to sustain high growth rates. G. tikvahiae has a greater N storage capacity than U. lactuca, which may allow it to grow in less nutrient-rich waters.
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ArticleChanges in bird abundance in eastern North America : urban sprawl and global footprint?(American Institute of Biological Sciences, 2007-04)The abundance of birds recorded in the North American Breeding Bird Survey decreased by up to 18 percent between 1966 and 2005. The abundance of US and Canadian resident species decreased by 30 percent, and that of migrants within the United States and Canada decreased by 19 percent. By contrast, Neotropical migrants increased by up to 20 percent. Land-cover changes in northern latitudes therefore seem more consequential for bird populations than those occurring in Neotropical habitats. Lower abundances were most marked for resident breeding birds that used open, edge, and wetland habitats, the environments most affected by human disturbances—particularly urban sprawl—in northern latitudes. The abundance of resident and migrant forest-dwelling birds increased (although trends varied from species to species), with the increases seeming to follow the 20th-century expansion of forest area in northern latitudes, rather than the loss of Neotropical forests. The geographic footprint of changes in bird abundance linked to habitat changes in North America may thus be extending southward, with negative effects on birds that use open habitats and positive effects on forest birds.
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ArticleGenetic identity determines risk of post-settlement mortality of a marine fish(Ecological Society of America, 2007-05)Longitudinal sampling of four cohorts of Neopomacentrus filamentosus, a common tropical damselfish from Dampier Archipelago, Western Australia, revealed the evolution of size structure after settlement. Light traps collected premetamorphic individuals from the water column (“settlers”) to establish a baseline for each cohort. Subsequently, divers collected benthic juveniles (“recruits”) at 1–3-month intervals to determine the relative impacts of post-settlement mortality during the first three months. Growth trajectories for individual fish were back-calculated from otolith records and compared with nonlinear mixed-effects models. Size-selective mortality was detected in all cohorts with the loss of smaller, slower growing individuals. Three months after settlement, recruits showed significantly faster growth as juveniles, faster growth as larvae, and larger sizes as hatchlings. The timing and intensity of post-settlement selection differed among cohorts and was correlated with density at settlement. The cohort with the greatest initial abundance experienced the strongest selective mortality, with most of this mortality occurring between one and two months after settlement when juveniles began foraging at higher positions in the water column. Significant genetic structure was found between settlers and three-month-old recruits in this cohort as a result of natural selection that changed the frequency of mtDNA haplotypes measured at the control region. The extent of this genetic difference was enlarged or reduced by artificially manipulating the intensity of size-based selection, thus establishing a link between phenotype and haplotype. Sequence variation in the control region of the mitochondrial genome has been linked to mitochondrial efficiency and weight gain in other studies, which provides a plausible explanation for the patterns observed here.
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ArticleNLOAD : an interactive, web-based modeling tool for nitrogen management in estuaries(Ecological Society of America, 2007-07)Eutrophication of estuaries is an increasing global concern that requires development of new tools to identify causes, quantify conditions, and propose management options that address this environmental problem. Since eutrophication is often associated with increased inputs of land-derived nitrogen to estuaries, we developed NLOAD, a user-friendly, web-based tool that brings together six different published models that predict nitrogen loading to estuaries and two models that estimate nitrogen concentrations in coastal waters. Here we describe each of the models, demonstrate how NLOAD is designed to function, and then use the models in NLOAD to predict nitrogen loads to Barnegat Bay, New Jersey (USA). The four models that we used to estimate nitrogen loads to Barnegat Bay, when adjusted, all had similar results that matched well with measured values and indicated that Barnegat Bay receives roughly 26 kg N·ha−1·yr−1. Atmospheric deposition was the dominant source of nitrogen to Barnegat Bay, followed by fertilizer nitrogen. Wastewater in Barnegat Bay is diverted to an offshore outfall and contributes no nitrogen to the system. The NLOAD tool has an additional feature that allows managers to assess the effectiveness of a variety of management options to reduce nitrogen loads. We demonstrate this feature of NLOAD through simulations in which fertilizer inputs to the Barnegat Bay watershed are reduced. Even modest cutbacks in the use of fertilizers on agricultural fields and lawns can be shown to reduce the amount of N entering Barnegat Bay.
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ArticleCulture-dependent characterization of the microbial community associated with epizootic shell disease lesions in American lobster, Homarus americanus(National Shellfisheries Association, 2005-10-01)Epizootic shell disease in the American lobster is an important factor affecting lobster fisheries in and around the Long Island Sound. It is a strictly dermal disease, because no correlation was observed between occurrence of epizootic shell disease and hemolymph infection. The culturability of bacteria from lesions was variable and averaged around 1.1%. The lesions contained two to four orders of magnitude more bacteria than healthy carapace surfaces of the same animal. Chitinoclastic bacteria comprised a very small fraction of bacteria present in the lesions, suggesting that their role in epizootic shell disease may be limited. Phylogenetic analysis of bacteria isolated from the lesions showed no typical bacterial pathogens of lobsters such as Aerococcus viridans or Vibrio fluvialis. Moreover, bacteria commonly associated with shell disease of other Crustacea or other forms of shell disease of the American lobster were not found. Two common groups of bacteria were isolated from lesions of all lobsters used in this research: one belonging to a species complex affiliated with the Flavobacteriaceae family and the second belonging to a series of closely related if not identical strains of Pseudoalteromonas gracilis. Bacteria isolated from only a few lobsters were related to Shewanella frigidimarina, Alteromonas arctica, Vibrio lentus, Shewanella fidelia, Pseudoalteromonas tunicata and Vibrio spp. Based on the analyses of culturable isolates, overall microbial communities found in lesions of lobsters from eastern Long Island Sound and Buzzards Bay appear to be similar to each other.
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ArticleBaleen whales are not important as prey for killer whales Orcinus orca in high-latitude regions(Inter-Research, 2007-10-25)Certain populations of killer whales Orcinus orca feed primarily or exclusively on marine mammals. However, whether or not baleen whales represent an important prey source for killer whales is debatable. A hypothesis by Springer et al. (2003) suggested that overexploitation of large whales by industrial whaling forced killer whales to prey-switch from baleen whales to pinnipeds and sea otters, resulting in population declines for these smaller marine mammals in the North Pacific and southern Bering Sea. This prey-switching hypothesis is in part contingent upon the idea that killer whales commonly attack mysticetes while they are in these high-latitude areas. In this study, we used photographic and sighting data from long-term studies of baleen whales in 24 regions worldwide to determine the proportion of whales that bear scars (rake marks) from killer whale attacks, and to examine the timing of scar acquisition. The results of this study show that there is considerable geographic variation in the proportion of whales with rake marks, ranging from 0% to >40% in different regions. In every region, the great majority of the scars seen were present on the whales’ bodies when the animals were first sighted. Less than 7% (9 of 132) of scarred humpback whales with multi-year sighting histories acquired new scars after the first sighting. This suggests that most killer whale attacks on baleen whales target young animals, probably calves on their first migration from low-latitude breeding and calving areas to high-latitude feeding grounds. Overall, our results imply that adult baleen whales are not an important prey source for killer whales in high latitudes, and therefore that one of the primary assumptions underlying the Springer et al. (2003) prey-switching hypothesis (and its purported link to industrial whaling) is invalid.
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ArticleEcological importance of passive deposition of organic matter into burrows of the SW Atlantic crab Chasmagnathus granulatus(Inter-Research, 2006-04-24)The burrowing crab Chasmagnathus granulatus is the most abundant bioturbator in estuarine intertidal sediments from southern Brazil to central Argentina. This crab is a deposit feeder that excavates and maintains large semi-permanent open burrows with funnel shaped entrances. In this study we showed that the funnel shaped burrows with low aspect ratio are the most common and, with field experiments, we demonstrated that these burrows are also the most efficient in the capture of organic matter. As shown by C isotopic signatures, the origin of trapped detrital material is Spartina densiflora. Burrows are distributed in the upper part of estuaries and saltmarshes, mostly in areas of low energy, and cover extensive areas between the marsh vegetation and the open estuary. Through sampling of crab densities and use of satellite images, we estimated the number of burrows of different shapes in the Bahia Blanca estuary (38°50’S), one of the largest estuarine intertidals in the SW Atlantic. After combining this information with the trapping efficiency of burrows of different shapes, we estimated that within 100 d, a crab bed could capture the entire annual production from a marsh area of similar size. Therefore, we suggest that these extensive burrow beds may be considered large macrodetritus retention areas, reducing the amount of organic matter exported from marshes but locally increasing the sediment organic matter content.
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ArticleCoupling of estuarine benthic and pelagic food webs to land-derived nitrogen sources in Waquoit Bay, Massachusetts, USA(Inter-Research, 2006-01-24)The fact that land-derived sources of nutrients promote eutrophication in the receiving coastal waters implies coupling between land and marine environments. Increasing nitrogen inputs in the estuaries are followed by major shifts in biota composition and abundances. In the present paper we used N and C isotopic ratios to analyze the coupling of benthic and pelagic components of food webs to estuaries receiving different N loads from their watersheds. We found that primary producers, benthic taxa, and fishes were coupled to the watersheds and estuaries where they were collected. In contrast, zooplankton was uncoupled. Primary consumers and predators feeding on benthic prey within the estuaries were also coupled to the watershed and estuaries, but predators feeding on zooplankton were not. We hypothesized that short water residence time in these estuaries uncoupled plankton from terrestrial influence. Stable isotopic measurements of N in producers, consumers, POM, and sediment in different estuaries of Waquoit Bay, Massachusetts, USA, demonstrate a consistent link between land-use on contributing watersheds and the isotopic ratio in all the benthic components and food webs. The remarkably consistent link suggests that the benthos was tightly coupled to land-derived inputs, and that these components, particularly macrophytes, could be good indicators for monitoring increases in land-derived N inputs. Our results showed that stable isotopes of N and C have the potential for use in basic research and applied monitoring, but need to be applied considering the features of estuaries that might couple or uncouple organisms regarding dependency on land, such as hydrodynamic exchanges.
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ArticleImpact of burrowing crabs on C and N sources, control, and transformations in sediments andfood webs of SW Atlantic estuaries(Inter-Research, 2005-06-02)The intertidal burrowing crab Chasmagnathus granulatus is the dominant species in soft bare sediments and vegetated intertidal areas along the SW Atlantic estuaries (southern Brazil, 28°S, to northern Patagonia, 42°S). C. granulatus creates burrows that can reach densities of 60 burrows m–2, and its burrowing activities increase water and organic matter content of sediments. To evaluate the long-term effect of burrows on the origin and transformation of accumulated organic matter within sediments, we compared C and N stable isotope signatures of sediments, plants, and consumers within areas with and without crabs. 15N signatures of sediments and primary producers were enriched by 3 to 7‰ in areas with crabs. The enrichment was present in 4 different Argentine estuarine environments (Mar Chiquita coastal lagoon, 37°46’S, 57°19’W, Bahia Blanca, 38°50’S, 62°07’W, San Blas, 40°33’S, 62°14’W, San Antonio, 40°48’S, 64°52’W). Enrichment owing to crab activity appeared to overwhelm possible different N loads, anthropogenic influence, and other properties. Crab activity thus uncoupled the nitrogen dynamics in sediments from external controls. Enrichment of the heavier isotope of N could be the result of an increase in denitrification rates in areas with burrows. Crabs therefore forced faster transformation of available to unavailable nitrogen, making less inorganic nitrogen available to deeper waters. Food webs in areas with and without crabs were similar in shape, but less mobile benthic organisms (nematodes, fiddler crabs and the polychaete Laeonereis acuta) showed enriched N isotopic signatures. The benthic food web seemed separate from that of suspension feeders or water column consumers. Benthic microalgae were an important source for infauna, and marsh plants were particularly important for burrowing crabs.
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ArticleResponse of microphytobenthic biomass to experimental nutrient enrichment and grazer exclusion at different land-derived nitrogen loads(Inter-Research, 2005-06-09)Effects of eutrophication on the relative importance of nutrients and macroherbivores as controls of microphytobenthic standing crop were examined in estuaries with different nitrogen loading rates: Sage Lot Pond (14 kg ha–1 yr–1), Green Pond (178 kg ha–1 yr–1), and Childs River (601 kg ha–1 yr–1). We selected 5 sites with similar salinity ranges on shallow-water, sandy substrates per estuary. In year-round experiments, we fertilized sediments with nitrogen + phosphorus to examine nutrient limitation. We conducted exclusion experiments to determine the significance of macroherbivores as controls of microphytobenthic biomass and examined possible interactions between nutrients and grazing in cages fertilized with nitrogen + phosphorus. Cages fertilized with nitrogen only were also included to determine if nitrogen availability was limiting. Nitrogen + phosphorus addition increased sediment chlorophyll a (chl a) content (herein used as a proxy for biomass) by a similar magnitude across estuaries. Grazer exclusion also increased chl a, but to a different extent across estuaries: the magnitude of the response increased with increasing nitrogen loading rates. We found no interactions between nutrients and grazing. Strong chl a increases in response to nitrogen only addition indicated N limitation in Sage Lot Pond and Green Pond. In the highly eutrophic Childs River estuary we found virtually no response to nitrogen-only additions, suggesting the possibility of phosphorus limitation in this estuary.
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ArticleMacrophytes as indicators of land-derived wastewater : application of a δ15N method in aquatic systems(American Geophysical Union, 2005-01-25)We measured δ15N signatures of macrophytes and particulate organic matter (POM) in six estuaries and three freshwater ponds of Massachusetts to assess whether the signatures could be used as indicators of the magnitude of land-derived nitrogen loads, concentration of dissolved inorganic nitrogen in the water column, and percentage of N loads contributed by wastewater disposal. The study focused specifically on sites on Cape Cod and Nantucket Island, in the northeastern United States. There was no evidence of seasonal changes in δ15N values of macrophytes or POM. The δ15N values of macrophytes and POM increased as water column dissolved inorganic nitrogen concentrations increased. We found that δ15N of macrophytes, but not of POM, increased as N load increased. The δ15N values of macrophytes and groundwater NO3 tracked the percent of wastewater contribution linearly. This research confirms that δ15N values of macrophytes and NO3 can be excellent indicators of anthropogenic N in aquatic systems.
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PreprintMacrophyte abundance in Waquoit Bay : effects of land-derived nitrogen loads on seasonal and multi-year biomass patterns( 2008-01)Anthropogenic inputs of nutrients to coastal waters have rapidly restructured coastal ecosystems. To examine the response of macrophyte communities to land-derived nitrogen loading, we measured macrophyte biomass monthly for six years in three estuaries subject to different nitrogen loads owing to different land uses on the watersheds. The set of estuaries sampled had nitrogen loads over the broad range of 12 to 601 kg N ha-1 y-1. Macrophyte biomass increased as nitrogen loads increased, but the response of individual taxa varied. Specifically, biomass of Cladophora vagabunda and Gracilaria tikvahiae increased significantly as nitrogen loads increased. The biomass of other macroalgal taxa tended to decrease with increasing load, and the relative proportion of these taxa to total macrophyte biomass also decreased. The seagrass, Zostera marina, disappeared from the higher loaded estuaries, but remained abundant in the estuary with the lowest load. Seasonal changes in macroalgal standing stock were also affected by nitrogen load, with larger fluctuations in biomass across the year and higher minimum biomass of macroalgae in the higher loaded estuaries. There were no significant changes in macrophyte biomass over the six years of this study, but there was a slight trend of increasing macroalgal biomass in the latter years. Macroalgal biomass was not related to irradiance or temperature, but Z. marina biomass was highest during the summer months when light and temperatures peak. Irradiance might, however, be a secondary limiting factor controlling macroalgal biomass in the higher loaded estuaries by restricting the depth of the macroalgal canopy. The relationship between the bloom-forming macroalgal species, C. vagabunda and G. tikvahiae, and nitrogen loads suggested a strong connection between development on watersheds and macroalgal blooms and loss of seagrasses. The influence of watershed land uses largely overwhelmed seasonal and inter-annual differences in standing stock of macrophytes in these temperate estuaries.
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PreprintEffect of field exposure to 38-year-old residual petroleum hydrocarbons on growth, condition index, and filtration rate of the ribbed mussel, Geukensia demissa( 2007-10-06)In September 1969, the Florida barge spilled 700,000 L of No. 2 fuel oil into the salt marsh sediments of Wild Harbor, MA. Today a substantial amount, approximately 100 kg, of moderately degraded petroleum remains within the sediment and along eroding creek banks. The ribbed mussels, Geukensia demissa, which inhabit the salt marsh creek bank, are exposed to the spilled oil. Examination of short-term exposure was done with transplantation of G. demissa from a control site, Great Sippewissett marsh, into Wild Harbor. We examined the effects of long-term exposure with transplantation of mussels from Wild Harbor into Great Sippewissett. Both the short- and long-term exposure transplants exhibited slower growth rates, shorter mean shell lengths, lower condition indices, and decreased filtration rates. Our results add new knowledge about long-term consequences of spilled oil, a dimension that should be included when assessing oil-impacted areas and developing management plans designed to restore, rehabilitate, or replace impacted areas.
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ArticleKiller whales and marine mammal trends in the North Pacific : a re-examination of evidence for sequential megafauna collapse and the prey-switching hypothesis(Blackwell, 2007-10-26)Springer et al. (2003) contend that sequential declines occurred in North Pacific populations of harbor and fur seals, Steller sea lions, and sea otters. They hypothesize that these were due to increased predation by killer whales, when industrial whaling's removal of large whales as a supposed primary food source precipitated a prey switch. Using a regional approach, we reexamined whale catch data, killer whale predation observations, and the current biomass and trends of potential prey, and found little support for the prey-switching hypothesis. Large whale biomass in the Bering Sea did not decline as much as suggested by Springer et al., and much of the reduction occurred 50–100 yr ago, well before the declines of pinnipeds and sea otters began; thus, the need to switch prey starting in the 1970s is doubtful. With the sole exception that the sea otter decline followed the decline of pinnipeds, the reported declines were not in fact sequential. Given this, it is unlikely that a sequential megafaunal collapse from whales to sea otters occurred. The spatial and temporal patterns of pinniped and sea otter population trends are more complex than Springer et al. suggest, and are often inconsistent with their hypothesis. Populations remained stable or increased in many areas, despite extensive historical whaling and high killer whale abundance. Furthermore, observed killer whale predation has largely involved pinnipeds and small cetaceans; there is little evidence that large whales were ever a major prey item in high latitudes. Small cetaceans (ignored by Springer et al.) were likely abundant throughout the period. Overall, we suggest that the Springer et al. hypothesis represents a misleading and simplistic view of events and trophic relationships within this complex marine ecosystem.
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PreprintBarnegat Bay-Little Egg Harbor Estuary : case study of a highly eutrophic coastal bay system( 2006-09-26)The Barnegat Bay-Little Egg Harbor Estuary is classified here as a highly eutrophic estuary based on application of NOAA’s National Estuarine Eutrophication Assessment model. Because it is shallow, poorly flushed, and bordered by highly developed watershed areas, the estuary is particularly susceptible to the effects of nutrient loading. Most of this load (~50%) is from surface water inflow, but substantial fractions also originate from atmospheric deposition (~39%), and direct groundwater discharges (~11%). No point source inputs of nutrients exist in the Barnegat Bay watershed. Since 1980, all treated wastewater from the Ocean County Utilities Authority's regional wastewater treatment system has been discharged 1.6 km offshore in the Atlantic Ocean. Eutrophy causes problems in this system, including excessive micro- and macroalgal growth, harmful algal blooms (HABs), altered benthic invertebrate communities, impacted harvestable fisheries, and loss of essential habitat (i.e., seagrass and shellfish beds). Similar problems are evident in other shallow lagoonal estuaries of the Mid-Atlantic and South Atlantic regions. To effectively address nutrient enrichment problems in the Barnegat Bay-Little Egg Harbor Estuary, it is important to determine the nutrient loading levels that produce observable impacts in the system. It is also vital to continually monitor and assess priority indicators of water quality change and estuarine health. In addition, the application of a new generation of innovative models using web-based tools (e.g., NLOAD) will enable researchers and decision-makers to more successfully manage nutrient loads from the watershed. Finally, the implementation of stormwater retrofit projects should have beneficial effects on the system.
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PreprintLong-term biological effects of petroleum residues on fiddler crabs in salt marshes( 2007)In September 1969,the Florida barge spilled 700,000 L of No. 2 fuel oil into the salt marsh sediments of Wild Harbor (Buzzards Bay, MA). Today the aboveground environment appears unaffected, but a substantial amount of moderately degraded petroleum still remains 8 to 20 cm below the surface. The salt marsh fiddler crabs, Uca pugnax, which burrow into the sediments at depths of 5 to 25 cm, are chronically exposed to the spilled oil. Behavioral studies conducted with U. pugnax from Wild Harbor and a control site, Great Sippewissett marsh, found that crabs exposed to the oil avoided burrowing into oiled layers, suffered delayed escape responses, lowered feeding rates, and lower densities. The oil residues are therefore biologically active and affect U. pugnax populations. Our results add new knowledge about long-term consequences of spilled oil, a dimension that should be included when assessing oil-impacted areas and developing management plans designed to restore, rehabilitate, or replace impacted areas.
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ArticleConservation biology and traditional ecological knowledge : integrating academic disciplines for better conservation practice(The Resilience Alliance, 2006)Conservation biology and environmental anthropology are disciplines that are both concerned with the identification and preservation of diversity, in one case biological and in the other cultural. Both conservation biology and the study of traditional ecoloigcal knowledge function at the nexus of the social and natural worlds, yet historically there have been major impediments to integrating the two. Here we identify linguistic, cultural, and epistemological barriers between the two disciplines. We argue that the two disciplines are uniquely positioned to inform each other and to provide critical insights and new perspectives on the way these sciences are practiced. We conclude by synthesizing common themes found in conservation success stories, and by making several suggestions on integration. These include cross-disciplinary publication, expanding memberships in professional societies and conducting multidisciplinary research based on similar interests in ecological process, taxonomy, or geography. Finally, we argue that extinction threats, be they biological or cultural/linguistic are imminent, and that by bringing these disciplines together we may be able to forge synergistic conservation programs capable of protecting the vivid splendor of life on Earth.
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PreprintEvolutionary variation in the expression of phenotypically plastic color vision in Caribbean mantis shrimps, genus Neogonodactylus( 2006-03-07)Many animals have color vision systems that are well suited to their local environments. Changes in color vision can occur over long periods (evolutionary time), or over relatively short periods such as during development. A select few animals, including stomatopod crustaceans, are able to adjust their systems of color vision directly in response to varying environmental stimuli. Recently, it has been shown that juveniles of some stomatopod species that inhabit a range of depths can spectrally tune their color vision to local light conditions through spectral changes in filters contained in specialized photoreceptors. The present study quantifies the potential for spectral tuning in adults of three species of Caribbean Neogonodactylus stomatopods that differ in their depth ranges to assess how ecology and evolutionary history influence the expression of phenotypically plastic color vision in adult stomatopods. After 12 weeks in either a full-spectrum “white” or a narrow-spectrum “blue” light treatment, each of the three species evidenced distinctive tuning abilities with respect to the light environment that could be related to its natural depth range. A molecular phylogeny generated using mitochondrial cytochrome oxidase C subunit 1 (CO-1) was used to determine whether tuning abilities were phylogenetically or ecologically constrained. Although the sister taxa N. wennerae and N. bredini both exhibited spectral tuning, their ecology (i.e. preferred depth range) strongly influenced the expression of the phenotypically plastic color vision trait. Our results indicate that adult stomatopods have evolved the ability to undergo habitat-specific spectral tuning, allowing rapid facultative physiological modification to suit ecological constraints.
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ArticleThe relative ineffectiveness of bibliographic search engines(American Institute of Biological Sciences, 2005-08)The increasing number of scientific publications has made bibliographic search engines essential tools in all disciplines. These software-based devices, however, are far from perfect. Comparisons of software-based bibliographic search engines with complete lists of three authors' publications showed that reference citations were not generally available before 1970, and that the effectiveness of recovery was improving but was quite variable, yielding on average 36 percent of the publications. There was marked year-to-year inconsistency in the recovery of titles. The inconsistency could not be explained by differences in indexing due to journal reputation: there was no evident relationship between search effectiveness and journal impact factor, but the percentage of recovered citations was higher for indexed journals. Search engines are widely used in bibliographic searches performed for evaluating researchers, awarding promotions, or assessing journal performance. Given the ineffectiveness of search engines, their use in making such important personal and institutional decisions needs careful consideration.
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PreprintFecundity and spawning of the Atlantic horseshoe crab, Limulus polyphemus, in Pleasant Bay, Cape Cod, Massachusetts, USA( 2005-09-12)This study provided the first comprehensive analysis of Atlantic horseshoe crab (Limulus polyphemus) fecundity. Limulus appear to be determinate spawners, maturing all their eggs for the breeding season before spawning begins. On average, larger females held a larger number of eggs (63,500) than smaller females (14,500). By the end of the breeding season there was an average of 11,600 mature eggs female-1 left undeposited, regardless of female size. Larger females laid a higher percentage of the eggs they contained. Thus they not only contain more eggs, but are more effective at laying them as well. Size of spawning females ranged from about 185-300 mm prosomal width, with by far the highest concentration in the mid-size ranges. Although on an individual basis large females carry and lay the greatest number of eggs, mid-size crabs as a group contributed more to the horseshoe crab population in Pleasant Bay because they were more plentiful (net fecundity was highest for mid-size crabs). These results have implications for the management of this important species, which is harvested for bait, scientific, and biomedical uses. Incorporation of these results into models and other management tools can help predict growth rates, effects of size-selective harvest, reproductive value, and stable stage distribution of populations.