Studies on Mahshahr Creeks macrobenthos with emphasis on their importance in fish feeding

To study the macrobenthic community at Mahshahr creek four Creeks namely Bihad, Doragh, Ghazaleh and Ghanam were chosen. Sampling was conducted on bimonthly basis and carried out from August 1996 to June 1997, 216 sediment samples were collected from 12 stations using 0.1 m^2 Van Veen Grab, The stations were located at the mouth, middle and the end of each Creek. In situ measurements of temperature pH, DO and salinity were done using different sensors. The samples for the measurements of TOM, grain size were collected and analysed in vitro. The results indicate spatial and temporal heterogeneity in the structure of macro faunal assemblages of the creeks. A total of 12 macrofaunal groups were identified within the study area. Amphipods were the most dominant group (43%) followed by polychaetes (42%), copepods (3.5%), tanaids (3.1%) and other groups (8.4%). The range for the numerical abundance of macrobenthos was between 12583 to 3648 individual per m2 and the variation was done to different bottom texture the variable environment conditions governing the different parts of each creek as well as within creeks. Application of diversity indices (Shannon H and Simpson indices) on the dominant macrobenthic assemblages (crustaceans & polychaetes) was varied between 1 to 2.5 being higher in Bihad and Ghanarn and much reduced Shannon H index or a higher Simpson in Ghazaleh. Probably brought about activities in this creek. Gut content analysis of four species of fish showed that the main food items consist of Crab, Shrimps and other crustacean species, The secondary production of macrobenthic fauna and hence a fish production were assessed. To do this first the production of most dominant species Apseudes sp. was computed through Cohort analysis. The total macrobenthic production was estimated and from this fish production was computed. The macrobenthic and fish secondary productions were 24300 tons/year) and 24300 (tons/year) respectively. These values were lower than those with similar areas in the Indian Ocean.

Study of feeding competition between invasion ctenophore (M. leidyi) and anchovy (C. engrauliformis) in the Southern Caspian Sea (Mazandran Coast)

Mnemiopsis leidyi one species of phylum Ctenophora, is a native species in America. It has most likely moved across the Atlantic in the ballast water of cargo ships to the Black sea in 1982, and then to the Caspian Sea thought the Volga-Don Channel, in Nov 1999. The population of M. leidyi rows rapidly and by end of 2000, the entire sea was teeming with them. This survey was arranged In order to study the relationship between the invasion of M. leidyi and sharp decline in main stocks pelagic fish such as Kilka. Dietary analysis was conducted on Anchovy Killka (Clupeonella engrauliformis) and M. leidyi from August 2001 to October 2002 in two stations, located at the costal water near Babolsar (52.38° E ,36.42° N ) and Noshahar (51.33° E,36.39° N) in the Caspian Sea province of Mazandaran, Iran. M. leidyi was caught by plankton net, at three vertical strata of both station at surface 5 in, 10m, and 15 m the Kilka was caught by fisheries boat at Babolasar fishery harbour. Samples of M. leidyi were not fixed in its common fixative, we used 96% Ethanol In order to study of M. leidyi digestion system some alive samples, directly, were studied by the fluorescence microscope which was connected to a computer prepared specially for this process. In many cases, the light was directly reflected on the sample and microscopic image was prepared in dark background. We found that there were some common organisms in diet of both species. The Schoener index analysis reflected these similarities, as values more than critical level of overlap (>89 in Babolsar samples and >84 in Noshahar samples) were found. Results from this study suggests that M. leidyi and Anchovy have a similar feeding niche and computation between them is one of the reasons to decline in anchovy stocks. Economical effects of M. leidyi s invasion in research area were studied by data on kilka caught before and after introducing M. leidyi.

Report of the 2005 Workshop on Ocean Ecodynamics Comparison in the Subarctic Pacific

I. Scientific Issues Posed by OECOS II. Participant Contributions to the OECOS Workshop A. ASPECTS OF PHYTOPLANKTON ECOLOGY IN THE SUBARCTIC PACIFIC Microbial community compositions by Karen E. Selph Subarctic Pacific lower trophic interactions: Production-based grazing rates and grazing-corrected production rates by Nicholas Welschmeyer Phytoplankton bloom dynamics and their physiological status in the western subarctic Pacific by Ken Furuya Temporal and spatial variability of phytoplankton biomass and productivity in the northwestern Pacific by Sei-ichi Saitoh, Suguru Okamoto, Hiroki Takemura and Kosei Sasaoka The use of molecular indicators of phytoplankton iron limitation by Deana Erdner B. IRON CONCENTRATION AND CHEMICAL SPECIATION Iron measurements during OECOS by Zanna Chase and Jay Cullen 25 The measurement of iron, nutrients and other chemical components in the northwestern North Pacific Ocean by Kenshi Kuma The measurement of iron, nutrients and other chemical components in the northwestern North Pacific Ocean by Kenshi Kuma C. PHYSICAL OCEANOGRAPHY, FINE-SCALE DISTRIBUTION PATTERNS AND AUTONOMOUS DRIFTERS The use of drifters in Lagrangian experiments: Positives, negatives and what can really be measured by Peter Strutton The interaction between plankton distribution patterns and vertical and horizontal physical processes in the eastern subarctic North Pacific by Timothy J. Cowles D. MICROZOOPLANKTON Microzooplankton processes in oceanic waters of the eastern subarctic Pacific: Project OECOS by Suzanne Strom Functional role of microzooplankton in the pelagic marine ecosystem during phytoplankton blooms in the western subarctic Pacific by Takashi Ota and Akiyoshi Shinada E. MESOZOOPLANKTON Vertical zonation of mesozooplankton, and its variability in response to food availability, density stratification, and turbulence by David L. Mackas and Moira Galbraith Marine ecosystem characteristics and seasonal abundance of dominant calanoid copepods in the Oyashio region by Atsushi Yamaguchi, Tsutomu Ikeda and Naonobu Shiga OECOS: Proposed mesozooplankton research in the Oyashio region, western subarctic Pacific by Tsutomu Ikeda Some background on Neocalanus feeding by Michael Dagg Size and growth of interzonally migrating copepods by Charles B. Miller Growth of large interzonal migrating copepods by Toru Kobari F. MODELING Ecosystem and population dynamics modeling by Harold P. Batchelder III. Reports from Workshop Breakout Groups A. PHYSICAL AND CHEMICAL ASPECTS WITH EMPHASIS ON IRON AND IRON SPECIATION B. PHYTOPLANKTON/MICROZOOPLANKTON STUDIES C. MESOZOOPLANKTON STUDIES IV. Issues arising during the workshop A. PHYTOPLANKTON STOCK VARIATIONS IN HNLC SYSTEMS AND TROPHIC CASCADES IN THE NANO AND MICRO REGIMES B. DIFFERENCES BETWEEN EAST AND WEST IN SITE SELECTION FOR OECOS TIME SERIES C. TIMING OF OECOS EXPEDITIONS D. CHARACTERIZATION OF PHYSICAL OCEANOGRAPHY V. Concluding Remarks VI. References (109 page document)

Food habits as an ecological partitioning mechanism in the nearshore rockfishes (Sebastes) of Carmel Bay, California

In the kelp forests of Carmel Bay there are six common rockfishes (Sebastes). Three are pelagic (S. serranoides, S. mystinus, and S. melanops) and two are demersal (S. chrysomelas and S. carnatus). The sixth (S. atrovirens) is generally found a few meters above the sea floor. The pelagic rockfishes which are spatially overlapping have different feeding habits. All rockfishes except S. mystinus utilize juvenile rockfishes as their primary food source during the upwelling season. Throughout the non-upwelling season, most species consume invertebrate prey. The pelagic rockfishes have shorter maxillary bones and longer gill rakers than their demersal congeners, both specializations for taking smaller prey. They also have longer intestines, enabling them to utilize less digestable foods. S. mystinus, which has the longest intestine, may be able to use algae as a food source. Fat reserves are accumulated from July through October, when prey is most abundant. Fat is depleted throughout the rest of the year as food becomes scarce and development of sexual organs takes place. Gonad development occurs from November through February for all species except S. atrovirens.

Ecology of aquaculture species and enhancement of stocks: proceedings of the thirtieth U.S. - Japan meeting on aquaculture, Sarasota, FL, Dec. 3-4, 2001

CONTENTS: I. U.S.-Japan Cooperation Open Ocean Aquaculture – A Venue for Cooperative Research Between the United States and Japan.............................................................................. 1 C. Helsley II. Growth, Nutrition and Genetic Diversity Daily Ration of Hatchery-Reared Japanese Flounder Paralichthys olivaceus as an Indicator of Release Place, Time and Fry Quality. In situ Direct Estimation and Possibility of New Methods by Stable Isotope............................ 7 O. Tominaga, T. Seikai, T. Tsusaki, Y. Hondo, N. Murakami, K. Nogami, Y. Tanaka and M. Tanaka Nucleic Acids and Protein Content as a Measure to Evaluate the Nutritional Condition of Japanese Flounder Paralichthys olivaceus Larvae and Juveniles........................................................................................................ 25 W. Gwak Genetic Diversity Within and Between Hatchery Strains of Flounder Paralichthys olivaceus Assessed by Means of Microsatellite and Mitochondrial DNA Sequencing Analysis...................................................................... 43 M. Sekino, M. Hara and N. Taniguchi Tracking Released Japanese Flounder Paralichthys olivaceus by Mitochondrial DNA Sequencing................................................................................ 51 T. Fujii Preliminary Aspects of Genetic Management for Pacific Threadfin Polydactylus sexfilis Stock Enhancement Research in Hawaii........................................ 55 M. Tringali, D. Ziemann and K. Stuck Enhancement of Pacific Threadfin Polydactylus sexfilis in Hawaii: Interactions Between Aquaculture and Fisheries............................................................. 75 D. Ziemann Aquaculture and Genetic Structure in the Japanese Eel Anguilla japonica..................... 87 M. Katoh and M. Kobayashi Comparative Diets and Growth of Two Scombrid Species, Chub Mackerel Scomber japonicus and Japanese Spanish Mackerel Scomberomorus niphonius, in the Central Seto Inland Sea, Japan.................................. 93 J. Shoji, M. Tanaka and Tsutomu Maehara iii Evaluating Stock Enhancement Strategies: A Multi-disciplinary Approach................... 105 T. M. Bert, R.H. McMichael, Jr., R.P. Cody, A. B. Forstchen, W. G. Halstead, K. M. Leber, J. O’Hop, C. L. Neidig, J. M. Ransier, M. D. Tringali, B. L. Winner and F. S. Kennedy III. Physiological and Ecological Applications Predation on Juvenile Chum Salmon Oncorhynchus keta by Fishes and Birds in Rivers and Coastal Oceanic Waters of Japan................................... 127 K. Nagasawa and H. Kawamura Interaction Between Cleaner and Host: The Black Porgy Cleaning Behavior of Juvenile Sharpnose Tigerfish Rhyncopelates Oxyrhynchus in the Seto Inland Sea, Western Japan............................................................................. 139 T. Shigeta, H. Usuki and K. Gushima IV. Case Studies Alaska Salmon Enhancement: A Successful Program for Hatchery and Wild Stocks............................................................................................... 149 W. Heard NMFS Involvement with Stock Enhancement as a Management Tool........................... 171 T. McIlwain Stock Enhancement Research with Anadromous and Marine Fishes in South Carolina...................................................................................... 175 T. I. J. Smith, W. E. Jenkins, M. R. Denson and M. R. Collins Comparison of Some Developmental, Nutritional, Behavioral and Health Factors Relevant to Stocking of Striped Mullet, (Mugilidae), Sheepshead (Sparidae), Common Snook (Centropomidae) and Nassau Groupers (Serranidae)........................... 191 J. W. Tucker Jr. and S. B. Kennedy Participants in the Thirtieth U.S.-Japan Meeting on Aquaculture................. Inside Back Cover iv (PDF has 204 pages.)

Interactions between adult migratory striped bass (Morone saxatilis) and their prey during winter off the Virginia and North Carolina Atlantic coast from 1994 through 2007

The migratory population of striped bass (Morone saxatilis) (>400 mm total length[TL]) spends winter in the Atlantic Ocean off the Virginia and North Carolina coasts of the United States. Information on trophic dynamics for these large adults during winter is limited. Feeding habits and prey were described from stomach contents of 1154 striped bass ranging from 373 to 1250 mm TL, collected from trawls during winters of 1994-96, 2000, and 2002-03, and from the recreational fishery during 2005-07. Nineteen prey species were present in the diet. Overall, Atlantic menhaden (Brevoortia tyrannus) and bay anchovy (Anchoa mitchilli) dominated the diet by boimass (67.9%) and numerically (68.6%). The percent biomass of Atlantic menhaden during 1994-2003 to 87.0% during 2005-07. Demersal fish species such as Atlantic croaker (Micropogonias undulatus) and spot (Leiostomus xanthurus) represented <15% of the diet biomass, whereas alosines (Alosa spp.) were rarely observed. Invertebrates were least important, contributing <1.0% by biomass and numerically. Striped bass are capable of feeding on a wide range of prey sizes (2% to 43% of their total length). This study outlines the importance of clupeoid fishes to striped bass winter production and also shows that predation may be exerting pressure on one of their dominant prey, the Atlantic menhaden.

Support for Integrated Ecosystem Assessments of NOAA’s National Estuarine Research Reserves System (NERRS), Volume I: The Impacts of Coastal Development on the Ecology and Human Well-being of Tidal Creek Ecosystems of the US Southeast

A study was conducted, in association with the Sapelo Island and North Carolina National Estuarine Research Reserves (NERRs), to evaluate the impacts of coastal development on sentinel habitats (e.g., tidal creek ecosystems), including potential impacts to human health and well-being. Uplands associated with southeastern tidal creeks and the salt marshes they drain are popular locations for building homes, resorts, and recreational facilities because of the high quality of life and mild climate associated with these environments. Tidal creeks form part of the estuarine ecosystem characterized by high biological productivity, great ecological value, complex environmental gradients, and numerous interconnected processes. This research combined a watershed-level study integrating ecological, public health and human dimension attributes with watershed-level land use data. The approach used for this research was based upon a comparative watershed and ecosystem approach that sampled tidal creek networks draining developed watersheds (e.g., suburban, urban, and industrial) as well as undeveloped sites. The primary objective of this work was to clearly define the relationships between coastal development with its concomitant land use changes and non-point source pollution loading and the ecological and human health and well-being status of tidal creek ecosystems. Nineteen tidal creek systems, located along the southeastern United States coast from southern North Carolina to southern Georgia, were sampled during summer (June-August), 2005 and 2006. Within each system, creeks were divided into two primary segments based upon tidal zoning: intertidal (i.e., shallow, narrow headwater sections) and subtidal (i.e., deeper and wider sections), and watersheds were delineated for each segment. In total, we report findings on 24 intertidal and 19 subtidal creeks. Indicators sampled throughout each creek included water quality (e.g., dissolved oxygen concentration, salinity, nutrients, chlorophyll-a levels), sediment quality (e.g., characteristics, contaminants levels including emerging contaminants), pathogen and viral indicators, and abundance and genetic responses of biological resources (e.g., macrobenthic and nektonic communities, shellfish tissue contaminants, oyster microarray responses). For many indicators, the intertidally-dominated or headwater portions of tidal creeks were found to respond differently than the subtidally-dominated or larger and deeper portions of tidal creeks. Study results indicate that the integrity and productivity of headwater tidal creeks were impaired by land use changes and associated non-point source pollution, suggesting these habitats are valuable early warning sentinels of ensuing ecological impacts and potential public health threats. For these headwater creeks, this research has assisted the validation of a previously developed conceptual model for the southeastern US region. This conceptual model identified adverse changes that generally occurred in the physical and chemical environment (e.g., water quality indicators such as indicator bacteria for sewage pollution or sediment chemical contamination) when impervious cover levels in the watershed reach 10-20%. Ecological characteristics responded and were generally impaired when impervious cover levels exceed 20-30%. Estimates of impervious cover levels defining where human uses are impaired are currently being determined, but it appears that shellfish bed closures and the flooding vulnerability of headwater regions become a concern when impervious cover values exceed 10-30%. This information can be used to forecast the impacts of changing land use patterns on tidal creek environmental quality as well as associated human health and well-being. In addition, this study applied tools and technologies that are adaptable, transferable, and repeatable among the high quality NERRS sites as comparable reference entities to other nearby developed coastal watersheds. The findings herein will be of value in addressing local, regional and national needs for understanding multiple stressor (anthropogenic and human impacts) effects upon estuarine ecosystems and response trends in ecosystem condition with changing coastal impacts (i.e., development, climate change). (PDF contaions 88 pages)

The distribution of ctenophora in the Patuxent estuary during the summer of 1958

Investigation of Ctenophores in the Chesapeake Bay area, includes some aspects of their life history, growth, reproduction, feeding and food habits, abundance and distribution. the purpose of the entire project is to supplement and add to the biological knowledge and understanding of ctenophores as a group and of the several individual species found int he area to be studied. Includes possible factors involved and implications also being looked at. (PDF contains 33 pages)

The Oyster and the Oyster Industry of Maryland

Information n the life-history and management of the Oyster and Oyster Industry. Dr. Truitt has traveled and researched almost every important oyster producing Area in America. Includes semidiagramatic sketches of anatomy, information on food and feeding, respiration and circulation,valves, reproduction. Oyster production - natural beds or rocks, oyster farming, tongs and tonging, dredge. Marketing - canned, raw, shell stock. Includes bibliography. (PDF contains 47 pages)

Noise levels and sources in the Stellwagen Bank National Marine Sanctuary and the St. Lawrence River Estuary

Although ambient (background) noise in the ocean is a topic that has been widely studied since pre-World War II, the effects of noise on marine organisms has only been a focus of concern for the last 25 years. The main point of concern has been the potential of noise to affect the health and behavior of marine mammals. The Stellwagen Bank National Marine Sanctuary (SBNMS) is a site where the degradation of habitat due to increasing noise levels is a concern because it is a feeding ground and summer haven for numerous species of marine mammals. Ambient noise in the ocean is defined as “the part of the total noise background observed with an omnidirectional hydrophone.” It is an inherent characteristic of the medium having no specific point source. Ambient noise is comprised of a number of components that contribute to the “noise level” in varying degrees depending on where the noise is being measured. This report describes the current understanding of ambient noise and existing levels in the Stellwagen Bank National Marine Sanctuary. (PDF contains 32 pages.)

A guide to the Thalassinidea (Crustacea: Malacostraca: Decapoda) of the South Atlantic Bight

Ghost shrimp and mud shrimp in the decapod infraorder Thalassinidea are ecologically important members of many benthic intertidal and shallow subtidal infaunal communities, largely due to the sediment filtration and mixing that result from their burrowing and feeding behavior. These activities considerably modify their immediate environment and have made these cryptic animals extremely interesting to scientists in terms of their behavior, ecology, and classification. Over 20 years ago, seven species of thalassinideans were known from the South Atlantic Bight (Cape Hatteras, NC to Cape Canaveral, FL). During this study, the examination of extensive collections from the National Museum of Natural History (NMNH), the Southeastern Regional Taxonomic Center (SERTC), and regional institutions, resulted in the identification of 14 species of thalassinideans currently known to occur within this region. The family Axiidae is represented by three species: Axius armatus, Calaxius jenneri, and Paraxiopsis gracilimana; the Callianassidae by six: Biffarius biformis, B. cf. fragilis, Callichirus major, Cheramus marginatus, Gilvossius setimanus, and Necallianassa berylae; the Calocarididae by two: Calocaris templemani and Acanthaxius hirsutimanus; and the families Laomediidae, Thomassiniidae, and Upogebiidae are each represented by one: Naushonia crangonoides, Crosniera wennerae, and Upogebia affinis, respectively. An illustrated key is presented for species level identification and supplemental notes on the ecology, distribution, and taxonomy of the species are provided.(PDF file contains 38 pages.)

Sexual Reproduction and Early Development in the Estuarine Sea Anemone, Nematostella vectensis Stephenson, 1935

This dissertation: 1) determines the factor(s) responsible for spawning induction in NematosteJla vectensis; 2) isolates, describes, and documents the source of jelly from egg masses of N. vectensis; and 3) describes N. vectensis' early development. Namatostella vectensis were maintained on a 7-day mussel feeding/water change regime over 159 days. Within 36 hours of mussel feeding/water change. 69.1% of females and 78.5% of males spawned reliably. Through manipulation of feeding, water change, oxygen and nitrogenous waste concentrations, spawning induction was found to be triggered by the oxygen concentration associated with water change, and not by feeding. Ammonia, anemones' major waste product, inhibited this induction in a concentration-dependent manner. Female N. vectensis release eggs in a persistent jellied egg mass which is unique among the Actiniaria. The major component of this egg mass jelly was a positive periodic acid-Schiffs staining, 39.5-40.5 kD glycoprotein. Antibodies developed in rabbits against this glycoprotein bound to jelly of intact egg masses and to granules (~ 2.8 IJm in diameter) present in female anemone mesenteries and their associated filaments. Antibodies did not label male tissues. Nematostella vecfensis embryos underwent first karyokinesis -60 minutes following the addition of sperm to eggs. Second nuclear division took place, followed by first cleavage, 90-120 minutes later. Each of the 4 blastomeres that resulted from first cleavage contained a single nucleus. Arrangement of these blastomeres ranged from radial to pseudospiral. Embryonic development was both asynchronous and holoblastic. Following formation of the 4-cell stage, 71% of embryos proceeded to cleave again to form an 8-cell stage. In each of the remaining 29% of embryos, a fusion of from 2-4 blastomeres resulted in 4 possible patterns which had no affect on either cleavage interval timing or subsequent development. The fusion event was not due to ooplasmic segregation. Blastomeres isolated from 4-celled embryos were regulative and developed into normal planula larvae and juvenile anemones that were 1/4 the size of those that developed from intact 4-celled embryos. Embryos exhibiting the fusion phenomenon were examined at the fine structural level. The fusion phenomenon resulted in formation of a secondary syncytium and was not a mere compaction of blastomeres.

The food and feeding habits of the anchoveta, Cetengraulis mysticetus, in the Gulf of Panama

ENGLISH:The gill rakers of both juvenile and adult anchovetas are long and numerous, with many fine processes which make a very efficient straining apparatus. The stomach is modified into a gizzard. The intestine undergoes heteronomous growth, and attains about eight times the standard length in adults. The stomach contents of 39 samples of juvenile fish and 120 adult fish were examined. Diatoms were the principal food of all the sizes of fish examined, from 29 to 153 millimeters. Silicoflagellates, dinoflagellates, pollen grains, formaniferans, rotifer shells, crustaceans, and eggs, probably of crustaceans, were also found in small amounts. Coscinodiscus, a diatom, was the most important item found in the stomachs of the juvenile fish. No strong differences were observed in the feeding habits of different sizes of juveniles. Even taking into account their smaller size, the juveniles had smaller volumes of material and lesser numbers of organisms in their stomachs than did the adults. The stomachs of the adult fish, unlike those of the juveniles, usually contained considerable quantities of mud. Melosira, Coscinodiscus, and Thalassionema, all diatoms, were the most important organisms found in the stomachs of the adults. The incidence of Melosira was much higher in the stomachs of fish from the areas to the east of the entrance of the Panama Canal than from those to the west. No seasonal differences in the food were observed. The volume of material in the stomachs ranged from almost none to nearly 1.0 milliliter, with an average of a little more than 0.2 milliliter. Twenty-six bottom samples were examined; the organisms found corresponded very closely to those encountered in the stomachs of the adult fish. It is concluded that the juvenile anchovetas are chiefly or entirely filter feeders of the pelagic zone. The adults, however, are mostly iliophagous feeders, but possibly do some feeding upon plankton as well. SPANISH:Las branquispinas de las anchovetas, tanto en las juveniles como en las adultas, son largas y numerosas, can varias protuberancias finas que hacen de ellas un aparato filtrador muy eficiente. El estómago está modificado en una molleja. El intestino está sometido a un crecimiento heterónomo, llega a alcanzar unas oeho veces la longitud estandar en las adultas. Fué examinado el contenido estomacal de 39 ,muestras de peces juveniles y de 120 adultos. Las diatomeas fueron el alimento principal de todos los peces que fueron examinados cuyo tamaño varió entre los 29 y 153 milimetros. Se encontraron también en cantidades silicoflagelados, dinoflagelados, granos de polen, foraminíferos, conchas de rotiferos, crustáceos y huevos, probablemente de crustáceos. Coscinodiscus, una diatomea, fué el alimento más importante encontrado en los estómagos de los peces juveniles. No se observaron mayores diferencias en los hábitos de alimentación en los juveniles de diferentes tamaños. Aún tomando en cuenta su tamaño menor, los juveniles tenian volúmenes más pequeños de material y un número menor de organismos en sus estómagos que los adultos. Los estómagos de los peces adultos, diferentes a los de los juveniles, contenían por lo general considerables cantidades de fango. Melosira, Coscinodiscus, y Thalassionema, todas ellas diatomeas, fueron los organismos más importantes encontrados en los estómagos de los adultos. La contribuciónde Melosira fué mucho más alta en los estómagos de los peces procedentes de las áreas al este de la entrada del Canal de Panamá que la de aquellos provenientes del oeste. No se observaron diferencias estacionales en la alimentacion. El volúmen de material en los estómagos varió de casi cero a cerca de 1.0 mililitros, con un promedio de un poco mas de 0.2 mili1itros. Se examinaron 26 muestras de fonda; los organismos encontrados correspondieron muy cercanamente a los hallados en los estómagos de los peces adultos. Se ha llegado a la conclusión de que las anchovetas juveniles son principalmente ó enteramente filtradoras de alimentos de la zona pelágica. Las adultas, sin embargo, son en su mayoria iliófagas, pero posiblemente se alimentan también de plancton.

The Invertebrate Assemblage Associated with Macrocystis pyrifera and its Utilization as a Food Resource by Kelp Forest Fishes

The present study was designed to examine the following: (1) the taxonomic. spatial, and temporal patterns of availability of all invertebrate species associated with Macrocystis (excluding protozoans and nematodes); (2) the utilization of this invertebrate assemblage as food by kelp forest fishes within the Macrocystis "foliage- searching" feeding guild, as well as proximal mechanisms leading to observed patterns of resource partitioning; and (3) the dynamic relationship between availability and utilization of this food resource. The approach was largely descriptive. with observations collected during a 19-month period from June 1975 to December 1976. Chapter I is an investigation of the resource utilization patterns of four species of kelp forest fishes with respect to food-related resource dimensions. and tests aspects of current theory involving inter- and intraspecific competition. Chapter II is a detailed examination of the invertebrate assemblage associated with Macrocystis and presents life histories of the fishes examined during this study. (PDFs contains 387 pages, chapter 1 is 203 pages, chapter 2 is 184 pages)