DOCSLIB.ORG

Krill in the Arctic and the Atlantic – Climatic Variability and Adaptive Capacity –

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Krill in the Arctic and the Atlantic – Climatic Variability and Adaptive Capacity – Krill in the Arctic and the Atlantic – Climatic Variability and Adaptive Capacity – Dissertation with the Aim of Achieving a Doctoral Degree in Natural Science – Dr. rer. nat. – at the Faculty of Mathematics, Informatics and Natural Sciences Department of Biology of the University of Hamburg submitted by Lara Kim Hünerlage M.Sc. Marine Biology B.Sc. Environmental Science Hamburg 2015 This cumulative dissertation corresponds to the exam copy (submitted November 11th, 2014). The detailed content of the single publications may have changed during the review processes. Please contact the author for citation purposes. Day of oral defence: 20th of February, 2015 The following evaluators recommend the acceptance of the dissertation: 1. Evaluator Prof. Dr. Friedrich Buchholz Institut für Hydrobiologie und Fischereiwissenschaft, Fakultät für Mathematik, Informatik und Naturwissenschaften, Universität Hamburg; Alfred-Wegner-Institut Helmholtz Zentrum für Polar- und Meeresforschung, Funktionelle Ökologie, Bremerhaven 2. Evaluator Prof. Dr. Myron Peck Institut für Hydrobiologie und Fischereiwissenschaft, Fakultät für Mathematik, Informatik und Naturwissenschaften, Universität Hamburg 3. Evaluator Prof. Dr. Ulrich Bathmann Leibniz-Institut für Ostseeforschung Warnemünde; Interdisziplinäre Fakultät für Maritime Systeme, Universität Rostock IN MEMORY OF MY FATHER, GERD HÜNERLAGE DEDICATED TO MY FAMILY PREFACE This cumulative dissertation summarizes the research findings of my PhD project which was conducted from September 2011 to October 2014. Primarily, it was part of the French-German AWIPEV project KOP 124 (RIS ID 3451) but was also supported by the African-German GENUS-I project (BMBF 03F0497F) and benefitted from the French KREVET project (J.Y. Toullec and K. Cascella; Station Biologique de Roscoff). The main focus of the work was to compare the metabolic performance, biochemical composition and adaptive capacity of six krill species, from the Atlantic (the Benguela Current system and the Northern Atlantic) and the Arctic (the high Arctic Kongsfjord), in order to estimate these species’ regional persistence under aspects of climate variability. The thesis includes a general introduction (Chapter 1) and a synoptic discussion (Chapter 7) and is composed of five publications (Chapters 2 – 6) presented as manuscripts as listed below. The general concept of the PhD project was developed by myself with advice from my supervisor Prof. Dr. Friedrich Buchholz. CHAPTER 2 Huenerlage K and Buchholz F Krill of the northern Benguela Current and the Angola-Benguela frontal zone compared: physiological performance and short-term starvation in Euphausia hanseni The study concept was developed by myself and Dr. F. Buchholz. The samples were collected by both authors during a research cruise on-board the German R/V Maria S. Merian in late austral summer 2011. The experiments, analytical work and data evaluation was conducted by me, partly in the frame work of my Master’s thesis. I wrote the manuscript with contributions from Dr. F. Buchholz. The paper was published in the Journal of Plankton Research (2013) 35(2): 337-351. i Preface CHAPTER 3 Huenerlage K, Graeve M, Buchholz C and Buchholz F The other krill: overwintering physiology of adult Thysanoessa inermis (Euphausiacea) from the high Arctic Kongsfjord The scientific concept of the study was developed by myself with advice from Dr. F. Buchholz. T. inermis specimens were sampled by us on-board the Kings Bay AS workboat MS Teisten in summer 2012. I developed the experimental set-up. The experiments were conducted by myself with help from Dr. F. Buchholz. All analyses and data evaluation were performed by me. I wrote the manuscript with contributions from all authors. This paper is in the review process in Aquatic Biology (27.10.2014; manuscript number: AB201408030). CHAPTER 4 Huenerlage K, Graeve M, Buchholz F Lipid composition and trophic relationships of krill species in a high Arctic fjord The concept of this paper was developed by myself and discussed with Dr. M. Graeve. The samples from the Benguela Current system and the Kongsfjord were collected by myself and Dr. F. Buchholz. Krill samples from the Iceland Basin were taken by Dr. F. Buchholz. All analytical analyses and data evaluation were performed by me. The fatty acid and lipid class analyses were advised by Dr. M. Graeve. I wrote the manuscript with scientific contributions of both authors. This paper was published online in Polar Biology S.I. Kongsfjord (30.10.2014; DOI: 10.1007/s00300-014-1607-6). CHAPTER 5 Huenerlage K and Buchholz F Thermal metabolic limits of krill species from the high Arctic Kongsfjord (Spitsbergen) may help explain euphausiid biogeographic variability The scientific concept was developed together with Dr. F. Buchholz. The krill samples were collected by us on-board the Kings Bay AS workboat MS Teisten. I performed the experiments, analytical work and data analyses and wrote the manuscript with contributions from Dr. F. Buchholz. This paper was submitted to Marine Ecology Progress Series (29.10.2014 submission number: 17132). ii Preface CHAPTER 6 Huenerlage K, Cascella K, Toullec JY and Buchholz F Towards finding the upper thermal limit of the arcto-boreal krill Thysanoessa inermis: Linking physiology to transcriptomics – first results The scientific concept was developed by all authors. The specimens were sampled by myself and Dr. F. Buchholz in August 2012. I performed the respiration experiments and related data analyses. The heat shock experiments were conducted by Dr. K. Cascella and Dr. J.Y. Toullec. Related data (gene expression of heat shock protein 70) were collected and analysed by Dr. K. Cascella. I wrote the manuscript with contributions from all authors. This paper is in preparation for publication. LARA KIM HÜNERLAGE iii iv TABLE OF CONTENTS Preface i Thesis Summary vii Abbreviations xi 1 General Introduction 1 2 Publication I 15 Huenerlage & Buchholz (2013) Krill of the northern Benguela Current and the Angola-Benguela frontal zone compared: physiological performance and short- term starvation in Euphausia hanseni 3 Publication II 49 Huenerlage et al. (in rev.) The other krill: overwintering physiology of adult Thysanoessa inermis (Euphausiacea) from the high Arctic Kongsfjord 4 Publication III 75 Huenerlage et al. (2014) Lipid composition and trophic relationships of krill species in a high Arctic fjord 5 Publication IV 109 Huenerlage & Buchholz (submitted) Explaining biogeographic distribution: thermal limits of krill species from the high Arctic Kongsfjord (Svalbard) 6 Publication V 133 Huenerlage et al. (in prep.) Towards finding the upper thermal limit of the arcto-boreal krill Thysanoessa inermis: Linking physiology to transcriptomics – first results 7 Synoptic Discussion and Conclusions 149 Acknowledgements 173 Appendix I v vi THESIS SUMMARY Krill are key species in marine food-webs and are distributed in all oceans with 86 species worldwide. They occupy a central role as consumers and as secondary producers forming an important food source for higher trophic levels from fish, squid and sea birds to marine mammals such as seals and whales. A change in regional krill populations would thus have a dramatic impact on the ecosystems of many climate zones. However, scientific knowledge on the ecophysiology of krill is scarce. The state of science is rather patchy (mainly focused on the charismatic Antarctic krill Euphausia superba) and there is no or little data available for an understanding of these key species’ ecology with a view to predict ecosystem changes in the oceans. The present PhD thesis aimed to contribute a broad range of ecophysiological data of abundant and ecologically important krill species from the Atlantic and the Arctic to assess these species’ metabolic performance and elucidate their overall adaptation to their respective environments under the constraints of ecosystem variability. The thesis is composed of five scientific publications (Chapters 2 – 6), which address in detail a) the temperature-induced metabolic performance and starvation capacity of the dominant krill species (Euphausia hanseni) from the highly productive northern Benguela Current system; b) the overwintering physiology, i.e. starvation capacity, of the dominant krill species (Thysanoessa inermis) from the high Arctic Kongsfjord; c) the energetic condition and trophic relationships of five different euphausiid species recently forming the krill community of the high Arctic Kongsfjord (T. inermis, T. raschii, T. longicaudata, Meganyctiphanes norvegica and Nematoscelis megalops) including an extended regional comparison to N. megalops specimens, which were sampled from the north Atlantic (i.e. the Iceland Basin) and the south Atlantic Benguela Current system; d) the temperature- induced metabolic performance of four krill species (T. inermis, T. raschii, M. norvegica and vii Thesis Summary N. megalops) from the high Arctic Kongsfjord and e) the metabolic and transcriptomic response to temperature increase in the dominant krill species (T. inermis) from the high Arctic Kongsfjord. In order to achieve an appropriate approximation of the single species’ physiological condition and adaptive capacity within their respective environments, the particular scientific questions of this thesis were tackled by investigating a variety of key physiological parameters: individual life parameters (stomach fullness, hepatopancreas colour, sex, size and body weight; Publications I – V), species-specific moulting rates
Load more

Recommended publications
  • Settlement-Driven, Multiscale Demographic Patterns of Large Benthic Decapods in the Gulf of Maine
    Journal of Experimental Marine Biology and Ecology, L 241 (1999) 107±136 Settlement-driven, multiscale demographic patterns of large benthic decapods in the Gulf of Maine Alvaro T. Palmaa,* , Robert S. Steneck b , Carl J. Wilson b aDepartamento EcologõaÂÂ, Ponti®cia Universidad Catolica de Chile, Alameda 340, Casilla 114-D, Santiago, Chile bIra C. Darling Marine Center, School of Marine Sciences, University of Maine, Walpole, ME 04573, USA Received 3 November 1998; received in revised form 30 April 1999; accepted 5 May 1999 Abstract Three decapod species in the Gulf of Maine (American lobster Homarus americanus Milne Edwards, 1837, rock crab Cancer irroratus Say, 1817, and Jonah crab Cancer borealis Stimpson, 1859) were investigated to determine how their patterns of settlement and post-settlement abundance varied at different spatial and temporal scales. Spatial scales ranged from centimeters to hundreds of kilometers. Abundances of newly settled and older (sum of several cohorts) individuals were measured at different substrata, depths, sites within and among widely spaced regions, and along estuarine gradients. Temporal scales ranged from weekly censuses of new settlers within a season to inter-annual comparisons of settlement strengths. Over the scales considered here, only lobsters and rock crabs were consistently abundant in their early post- settlement stages. Compared to rock crabs, lobsters settled at lower densities but in speci®c habitats and over a narrower range of conditions. The abundance and distribution of older individuals of both species were, however, similar at all scales. This is consistent with previous observations that, by virtue of high fecundity, rock crabs have high rates of settlement, but do not discriminate among habitats, and suffer high levels of post-settlement mortality relative to lobsters.
    [Show full text]
  • Retail Stores Policies for Marketing of Lobsters in Sardinia (Italy) As Influenced by Different Practices Related to Animal Welf
    foods Article Retail Stores Policies for Marketing of Lobsters in Sardinia (Italy) as Influenced by Different Practices Related to Animal Welfare and Product Quality Giuseppe Esposito 1, Daniele Nucera 2 and Domenico Meloni 1,* ID 1 Department of Veterinary Medicine, University of Sassari, Via Vienna 2, 07100 Sassari, Italy; [email protected] 2 Department of Agriculture, Forest and Food Science, University of Turin, Via Verdi 8, 10124 Turin, Italy; [email protected] * Correspondence: [email protected]; Tel.: +39-079-229-570; Fax: +39-079-229-458 Received: 12 June 2018; Accepted: 29 June 2018; Published: 2 July 2018 Abstract: The aim of the present study was to evaluate the marketing policies of lobsters as influenced by different practices related to product quality in seven supermarkets located in Italy. Retailers were divided in two categories: large scale and medium scale. The two groups were compared to screen for differences and to assess differences in score distribution attributed to different practices related to product quality. Our results showed no statistical differences (p > 0.05) between the two categories. Lobsters were often marketed alive on ice and/or stocked for long periods in supermarket aquariums, highlighting the need to improve the specific European regulations on health, welfare, and quality at the market stage. Retail shop managers should be encouraged to develop better practices and policies in terms of marketing of lobsters. This will help in keeping the animals in good health and improve product quality at the marketing stages. Keywords: crustaceans; supermarkets; aquarium; ice 1. Introduction In the last decades, the global total consumption of seafood products has increased: this has resulted in a rapidly growing demand for these products, especially in emerging markets [1].
    [Show full text]
  • Modelling Growth of Northern Krill (Meganyctiphanes Norvegica) Using an Energy-Budget Approach?
    Modelling growth of northern krill (Meganyctiphanes norvegica) using an energy-budget approach? Tjalling Jagera,, Elisa Ravagnanb aDEBtox Research, De Bilt, the Netherlands bIRIS Environment, International Research Institute of Stavanger, Postboks 8046, N-4068 Stavanger, Norway Abstract Northern krill (Meganyctiphanes norvegica) is an important species in the North Atlantic and the Mediterranean Sea, but very little life-history infor- mation is available under controlled (laboratory) conditions. Here, we use the DEBkiss model to piece together the available data into a quantitative energy budget. We use this model to analyse larval growth curves, and to re- construct the feeding history for field populations from their (reconstructed) multi-year growth patterns. The resulting model parameters are also used to provide estimates for respiration, feeding and reproduction rates that are consistent with measured values. Many uncertainties remain, but this anal- ysis demonstrates how simple and generic energy-budget models have the potential to integrate observations on different traits, to interpret growth as a function of food and temperature, and to compare different species in a meaningful manner. Keywords: Dynamic Energy Budget, DEBkiss, Meganyctiphanes norvegica, life-history traits, growth modeling, krill ?©2016. This manuscript version is made available under the CC-BY-NC-ND 4.0 license https://creativecommons.org/licenses/by-nc-nd/4.0/. The paper was pub- lished as: Jager T, Ravagnan E. 2016. Modelling growth of northern krill (Meganyc- tiphanes norvegica) using an energy-budget approach. Ecological Modelling 325:28-34.. http://dx.doi.org/10.1016/j.ecolmodel.2015.12.020. Email address: [email protected] (Tjalling Jager) URL: http://www.debtox.nl/ (Tjalling Jager) Preprint submitted to Ecological Modelling March 14, 2021 1.
    [Show full text]
  • Fronts in the World Ocean's Large Marine Ecosystems. ICES CM 2007
    - 1 - This paper can be freely cited without prior reference to the authors International Council ICES CM 2007/D:21 for the Exploration Theme Session D: Comparative Marine Ecosystem of the Sea (ICES) Structure and Function: Descriptors and Characteristics Fronts in the World Ocean’s Large Marine Ecosystems Igor M. Belkin and Peter C. Cornillon Abstract. Oceanic fronts shape marine ecosystems; therefore front mapping and characterization is one of the most important aspects of physical oceanography. Here we report on the first effort to map and describe all major fronts in the World Ocean’s Large Marine Ecosystems (LMEs). Apart from a geographical review, these fronts are classified according to their origin and physical mechanisms that maintain them. This first-ever zero-order pattern of the LME fronts is based on a unique global frontal data base assembled at the University of Rhode Island. Thermal fronts were automatically derived from 12 years (1985-1996) of twice-daily satellite 9-km resolution global AVHRR SST fields with the Cayula-Cornillon front detection algorithm. These frontal maps serve as guidance in using hydrographic data to explore subsurface thermohaline fronts, whose surface thermal signatures have been mapped from space. Our most recent study of chlorophyll fronts in the Northwest Atlantic from high-resolution 1-km data (Belkin and O’Reilly, 2007) revealed a close spatial association between chlorophyll fronts and SST fronts, suggesting causative links between these two types of fronts. Keywords: Fronts; Large Marine Ecosystems; World Ocean; sea surface temperature. Igor M. Belkin: Graduate School of Oceanography, University of Rhode Island, 215 South Ferry Road, Narragansett, Rhode Island 02882, USA [tel.: +1 401 874 6533, fax: +1 874 6728, email: [email protected]].
    [Show full text]
  • <I>Cancer Irroratus</I>
    BULLETIN OF MARINE SCIENCE, 36(3): 454-466,1985 RHYTHMICITY UNDER CONSTANT CONDITIONS IN THE ROCK CRAB, CANCER IRRORATUS Steve Rebach ABSTRACT The existence of activity rhythms in migratory populations of the rock crab, Cancer ir- roratus, which spend most of the year in deep water, was investigated. Mature individuals from the Mid-Atlantic Bight were tested under laboratory conditions of constant light (LL) and constant dark (DD) after an initial ambient photoperiod was presented. Activity levels were simultaneously monitored for 20 crabs maintained in separate compartments, using an infrared beam-break system. Activity was analyzed using an Enright periodogram. Activity under LL was at a relatively low level and with no rhythmic periodicity exhibited. In DD, activity was concentrated at approximately 25-h intervals, approximating a tidal period. Under ambient (natural photoperiod) conditions, a 24-h rhythm was present with activity greatest during the scotophase and with peaks at dawn and dusk. Possible advantages to the presence of a tidal rhythmicity in a deep water species are discussed and include temporal partitioning of the environment, a timekeeping mechanism for the initiation of migration, and an evolutionary or ecological remnant from shallow water populations. The common rock crab, Cancer irroratus, is found from Labrador to South Carolina (Haefner, 1976) and is most abundant from Maine to North Carolina. Rock crabs inhabit cold water (50-15°C, Haefner, 1976) and in the mid-Atlantic region they live at depths of 10-700 m (depending on age and season), with highest densities between 40 and 60 m (15-30 km offshore) (Musick and McEachran, 1972; Haefner, 1976).
    [Show full text]
  • Diversity and Life-Cycle Analysis of Pacific Ocean Zooplankton by Video Microscopy and DNA Barcoding: Crustacea
    Journal of Aquaculture & Marine Biology Research Article Open Access Diversity and life-cycle analysis of Pacific Ocean zooplankton by video microscopy and DNA barcoding: Crustacea Abstract Volume 10 Issue 3 - 2021 Determining the DNA sequencing of a small element in the mitochondrial DNA (DNA Peter Bryant,1 Timothy Arehart2 barcoding) makes it possible to easily identify individuals of different larval stages of 1Department of Developmental and Cell Biology, University of marine crustaceans without the need for laboratory rearing. It can also be used to construct California, USA taxonomic trees, although it is not yet clear to what extent this barcode-based taxonomy 2Crystal Cove Conservancy, Newport Coast, CA, USA reflects more traditional morphological or molecular taxonomy. Collections of zooplankton were made using conventional plankton nets in Newport Bay and the Pacific Ocean near Correspondence: Peter Bryant, Department of Newport Beach, California (Lat. 33.628342, Long. -117.927933) between May 2013 and Developmental and Cell Biology, University of California, USA, January 2020, and individual crustacean specimens were documented by video microscopy. Email Adult crustaceans were collected from solid substrates in the same areas. Specimens were preserved in ethanol and sent to the Canadian Centre for DNA Barcoding at the Received: June 03, 2021 | Published: July 26, 2021 University of Guelph, Ontario, Canada for sequencing of the COI DNA barcode. From 1042 specimens, 544 COI sequences were obtained falling into 199 Barcode Identification Numbers (BINs), of which 76 correspond to recognized species. For 15 species of decapods (Loxorhynchus grandis, Pelia tumida, Pugettia dalli, Metacarcinus anthonyi, Metacarcinus gracilis, Pachygrapsus crassipes, Pleuroncodes planipes, Lophopanopeus sp., Pinnixa franciscana, Pinnixa tubicola, Pagurus longicarpus, Petrolisthes cabrilloi, Portunus xantusii, Hemigrapsus oregonensis, Heptacarpus brevirostris), DNA barcoding allowed the matching of different life-cycle stages (zoea, megalops, adult).
    [Show full text]
  • The Secret Lives of JELLYFISH Long Regarded As Minor Players in Ocean Ecology, Jellyfish Are Actually Important Parts of the Marine Food Web
    The secret lives of JELLYFISH Long regarded as minor players in ocean ecology, jellyfish are actually important parts of the marine food web. BY GARRY HAMILTON ennifer Purcell watches intently as the boom of the research ship Moon jellyfish (Aurelia Skookum slowly eases a 3-metre-long plankton net out of Puget Sound aurita) contain more Jnear Olympia, Washington. The marine biologist sports a rain suit, calories than some which seems odd for a sunny day in August until the bottom of the net other jellyfish. is manoeuvred in her direction, its mesh straining from a load of moon jellyfish (Aurelia aurita). Slime drips from the bulging net, and long ten- tacles dangle like a scene from an alien horror film. But it does not bother Purcell, a researcher at Western Washington University’s marine centre in Anacortes. Pushing up her sleeves, she plunges in her hands and begins to count and measure the messy haul with an assuredness borne from nearly 40 years studying these animals. 432 | NATURE | VOL 531 | 24 MARCH 2016 © 2016 Macmillan Publishers Limited. All rights reserved FEATURE NEWS Most marine scientists do not share her enthusiasm for the creatures. also inaccessible, living far out at sea or deep below the light zone. They Purcell has spent much of her career locked in a battle to find funding often live in scattered aggregations that are prone to dramatic popula- and to convince ocean researchers that jellyfish deserve attention. But tion swings, making them difficult to census. Lacking hard parts, they’re she hasn’t had much luck.
    [Show full text]
  • Enormous Carnivores, Microscopic Food, and a Restaurant That's Hard to Find
    Enormous Carnivores, Microscopic Food, and a Restaurant That's Hard to Find MARK F. BAUMGARTNER, CHARLES A. MAYO, AND ROBERT D. KENNEY April 1986 Cape Cod Bay We'd known for a long time that there were places east of Cape Cod where pow+l tidal impulses meet the sluggiih southward-moving coastal cur- rent, places where right whales lined up along the rips where plankton con- centrate. On a windless day in early April 1986, we decided to see ifright whales hadfoundsuch an area. The winter season, when right whales come to Cape Cod, had been a hard one, and calm hys like this were few, so we could at last get to the more distant convergence and, as localjshermen do, see what we could catch. It was gloomy and nearly dzrk when we lefi the port. For those of us who study whales, expectations are usually tempered by realip; we were lookingfor one of the rarest of all mammals in the shroud of the ocean. To- day, however, spirits were high as the hybreak was filed with springtime promise. Along the great outer beach of the Cape, so close to shore that we couldsmell the land nearb, thefist right whale was spotted working along one of those current rips. And as the sun climbed out of the haze, the whale rose and opened that great and odd mouth and skimmed the su$ace in a silence broken only ly the sizzle of water passing through its huge filtering Enormous Carnivores, Microscopic Food 139 apparatus. Our earlier optimism was warranted, andfor several hours we drzFedjust clear of the linear rip that the whale was working, recording the complex pattern of its movements.
    [Show full text]
  • Trophic Diversity of Plankton in the Epipelagic and Mesopelagic Layers of the Tropical and Equatorial Atlantic Determined with Stable Isotopes
    diversity Article Trophic Diversity of Plankton in the Epipelagic and Mesopelagic Layers of the Tropical and Equatorial Atlantic Determined with Stable Isotopes Antonio Bode 1,* ID and Santiago Hernández-León 2 1 Instituto Español de Oceanografía, Centro Oceanográfico de A Coruña, Apdo 130, 15080 A Coruña, Spain 2 Instituto de Oceanografía y Cambio Global (IOCAG), Universidad de las Palmas de Gran Canaria, Campus de Taliarte, Telde, Gran Canaria, 35214 Islas Canarias, Spain; [email protected] * Correspondence: [email protected]; Tel.: +34-981205362 Received: 30 April 2018; Accepted: 12 June 2018; Published: 13 June 2018 Abstract: Plankton living in the deep ocean either migrate to the surface to feed or feed in situ on other organisms and detritus. Planktonic communities in the upper 800 m of the tropical and equatorial Atlantic were studied using the natural abundance of stable carbon and nitrogen isotopes to identify their food sources and trophic diversity. Seston and zooplankton (>200 µm) samples were collected with Niskin bottles and MOCNESS nets, respectively, in the epipelagic (0–200 m), upper mesopelagic (200–500 m), and lower mesopelagic layers (500–800 m) at 11 stations. Food sources for plankton in the productive zone influenced by the NW African upwelling and the Canary Current were different from those in the oligotrophic tropical and equatorial zones. In the latter, zooplankton collected during the night in the mesopelagic layers was enriched in heavy nitrogen isotopes relative to day samples, supporting the active migration of organisms from deep layers. Isotopic niches showed also zonal differences in size (largest in the north), mean trophic diversity (largest in the tropical zone), food sources, and the number of trophic levels (largest in the equatorial zone).
    [Show full text]
  • The Canary Current Temperatures from Portugal to Cape Most Reliable Indicators
    V. Sediments and benthos Rapp. P.-v. Réun. Cons. int. Explor. Mer, 180: 315-322. 1982. Sediments in up welling areas, particularly off Northwest Africa Eugen Seibold Geologisch-Paläontologisches Institut der Universität Kiel Olshausenstrasse 40/60, 2300 Kiel 1, Bundesrepublik Deutschland Introduction Oceanic upwelling supplies water from subsurface lay­ with sediments, however, most of these variations, ers to the surface layer and may occur as a persistent together with biological production cycles, are aver­ process anywhere, although it is a particularly con­ aged out, as even the uppermost centimetre of sedi­ spicuous phenomenon along western coasts of conti­ ment normally includes events spanning a century or nents where prevailing winds drive the surface water more. Most of the indicators employed are of organic from the coast (Smith, 1973). origin. It is well established that typical upwelling This paper discusses indicators of coastal upwelling water masses are several degrees cooler than nearby revealed in the underlying sediments off Northwest waters, are less saline, show a relatively low oxygen Africa and makes some comparisons with upwelling content, and have higher nutrient concentrations, effects in sediments from the coastal area off Southwest increasing primary production in the photic zone. At Africa. From these results it will be attempted to present only lowered temperatures as preserved in reconstruct periods of upwelling during the last 20 mil­ planktonic organisms tests can be used as clear indi­ lion years off Northwest Africa. Some of these prob­ cators for upwelling, although higher productivity may lems have been treated generally in the classic paper of provide additional hints.
    [Show full text]
  • Ecological Effects of Predator Information Mediated by Prey Behavior
    ECOLOGICAL EFFECTS OF PREDATOR INFORMATION MEDIATED BY PREY BEHAVIOR Tyler C. Wood A Dissertation Submitted to the Graduate College of Bowling Green State University in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY May 2020 Committee: Paul Moore, Advisor Robert Green Graduate Faculty Representative Shannon Pelini Andrew Turner Daniel Wiegmann ii ABSTRACT Paul Moore, Advisor The interactions between predators and their prey are complex and drive much of what we know about the dynamics of ecological communities. When prey animals are exposed to threatening stimuli from a predator, they respond by altering their morphology, physiology, or behavior to defend themselves or avoid encountering the predator. The non-consumptive effects of predators (NCEs) are costly for prey in terms of energy use and lost opportunities to access resources. Often, the antipredator behaviors of prey impact their foraging behavior which can influence other species in the community; a process known as a behaviorally mediated trophic cascade (BMTC). In this dissertation, predator odor cues were manipulated to explore how prey use predator information to assess threats in their environment and make decisions about resource use. The three studies were based on a tri-trophic interaction involving predatory fish, crayfish as prey, and aquatic plants as the prey’s food. Predator odors were manipulated while the foraging behavior, shelter use, and activity of prey were monitored. The abundances of aquatic plants were also measured to quantify the influence of altered crayfish foraging behavior on plant communities. The first experiment tested the influence of predator odor presence or absence on crayfish behavior.
    [Show full text]
  • EUPHAUSIIDS in the GULF of CALIFORNIA-THE 1957 CRUISES Calcofi Rep., Vol
    BRINTON AND TOWNSEND: EUPHAUSIIDS IN THE GULF OF CALIFORNIA-THE 1957 CRUISES CalCOFI Rep., Vol. XXI, 1980 EUPHAUSIIDS IN THE GULF OF CALIFORNIA-THE 1957 CRUISES E. BRINTON AND A.W. TOWNSEND Marine Life Research Group Scripps institution of Oceanography La Jolla. CA 92093 ABSTRACT las especies y de sus etapas de vida, en particular las de Euphasiid crustaceans in the Gulf of California were las larvas mas juveniles, se describen en relacion con las examined from four bimonthly CalCOFI grid cruises variaciones estacionales en el flujo y las temperaturas de during February through August of 1957. Of the nine las aguas del Golfo. species found to regularly inhabit the Gulf, Nematoscelis dificilis and Nyctiphanes simplex are common to the INTRODUCTION warm-temperate California Current. These have the The Gulf of California is inhabited by dense stocks of broadest ranges in the Gulf, peaking in abundance and plankton (Osario-Tafall 1946; Zeitzschel 1969). This reproducing maximally during February-April and Feb- appendix of the North Pacific Ocean communicates. ruary-June respectively, before intense August heating with the 'eastern boundary circulation at the northern limit takes place in the Gulf. Euphausia eximia, a species of the eastern tropical Pacific, which is characterized by having high densities at zones considered marginal to the its distinctive oxygen-deficient layer. The 1 000-km axis eastern tropical Pacific, also varies little in range during of the Gulf extends from the mouth at the tropic, 23"27'N, the year, consistently occupying the southern half of the to latitude 32"N, which is within the belt of the warm- Gulf.
    [Show full text]