DOCSLIB.ORG

The Successful and Selective Feeding of Larval Fishes in the Low-Latitude Open Ocean: Is Starvation an Insignificant Source of Mortality?

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The Successful and Selective Feeding of Larval Fishes in the Low-Latitude Open Ocean: Is Starvation an Insignificant Source of Mortality? Not to be cited without prior reference to the authors ICES CM 2009/T:14 The successful and selective feeding of larval fishes in the low-latitude open ocean: Is starvation an insignificant source of mortality? Joel K. Llopiz and Robert K. Cowen University of Miami, Rosenstiel School of Marine and Atmospheric Science, 4600 Rickenbacker Causeway, Miami, FL 33149 USA, [email protected] Abstract Historical interest in understanding the larval stage of high-latitude fishes has provided extensive insight into feeding-related processes that can influence larval fish mortality. However, the feeding dynamics of larvae that occur in lower latitudes, especially those that primarily inhabit oceanic waters, is notably limited. From monthly sampling across the Straits of Florida (SOF) over two years, we acquired data on the feeding ecologies of 21 taxa of fish larvae in order to elucidate levels of feeding success, as well the degree to which this subset of the larval fish community relies upon specific zooplankton prey types. Larval taxa examined included billfishes, tunas, mackerels, and seven families of coral reef fishes. All but one taxon examined for gut contents (total n = 3138) had feeding incidences near 100%. Additionally, gut evacuation was rapid and occurred in ~3 hr, indicating successful and frequent prey consumption. These observations, in conjunction with the fact that larvae withstand a nightly non-feeding period (10- 14 hrs in low-latitudes), point to the possibility that fish larvae in these waters experience low or even negligible levels of starvation mortality, although additional efforts specifically addressing this possibility are needed. Furthermore, diets of larvae were taxon-specific and often extremely narrow, illustrating very selective feeding among a high diversity of available zooplankton prey. Two notable characteristics of the diets of these larvae were high reliance upon appendicularians by several taxa and the prevalence of piscivory, which appears to be exhibited by over 30 species of scombroid larvae that occur in the SOF. Introduction The larval stage of most marine fishes is characterized by a planktonic period during which there is high vulnerability to both starvation and predation. Despite the potential influence of these two processes on total survival to later stages (Houde 1987), our understanding of them is limited, and this is especially so in lower latitudes. The tropical/subtropical ocean is generally oligotrophic and unproductive with fluctuations in productivity that are low in magnitude and temporally inconsistent (Longhurst & Pauly 1987). These conditions, which could represent a nutritionally constraining environment for altricial larvae, differ from those of higher latitudes where there are distinct secondary productivity blooms with which fish spawning periods often coincide (Cushing 1990). Intuitively, low productivity in conjunction with warm temperatures are conditions that should favor high levels of mortality directly due to starvation. However, because of the paucity of data on the feeding success of low-latitude fish larvae, in addition to several other aspects related to their trophic ecologies, there has been little empirical evidence either supporting or refuting this hypothesis. Although there are a few studies on larval fish trophodynamics in lower latitudes, recent work in the Straits of Florida (Llopiz & Cowen 2008, 2009, Sponaugle et al. 2009, Llopiz et al. in review) has taken a large, ecosystem-scale approach in both time and space to better understand the trophic interactions of co-occurring larval fishes in the low-latitude oceanic plankton. This work has thus far examined the trophic ecologies of 21 taxa of larval fishes, highlighting several aspects and behaviors that seem paradoxical when considering the presumed nutritional constraints of this region (i.e. oligotrophic, oceanic, average near-surface temperatures of 28–30°C from late spring to early fall). This contribution brings together many of the interesting results of this work that seem to contradict the potential for high levels of starvation mortality, at least in the Straits of Florida. These results do not show that starvation is not a substantial source of mortality in these waters, but do suggest it is possible—and possibly less so relative to higher latitudes. Future work that directly addresses this possibility is therefore greatly needed. With the recent increased focus on larval fish trophodynamics, we also conducted a meta-analysis to investigate the possibility for any latitudinal differences in several characteristics related to the trophic ecologies of fish larvae. Methods Field sampling The Straits of Florida (SOF) region is a tropical/subtropical oceanic habitat between Florida and both Cuba and the Bahamas (Fig. 1). Within the SOF is the strongly flowing Florida Current that is fed either by the Loop Current of the Gulf of Mexico or, when the Loop Current is occasionally pinched off, directly by the waters exiting the Caribbean Sea through the Yucatan Channel. To the north, the Florida Current becomes a large portion of the Gulf Stream, contributing ca. one-third of the total transport off of Figure 1. Map of the Straits of Florida and upstream regions of the Gulf of Cape Hatteras (Leaman et al. 1989). Mexico and northern Caribbean Sea. In 2003 and 2004, a transect of 17 In 2003 and 2004, a transect stations between the Florida shelf break and Great Bahama Bank was sampled monthly for larval fishes, other zooplankton and several physical of 17 stations (numbered west to parameters. Upstream of the Straits of Florida, the Loop Current in the east) across the SOF between the Gulf of Mexico is most often the source for the Florida Current, but can Florida shelf break south of Miami pinch off resulting in Caribbean waters flowing directly into the Straits of Florida (indicated by gray arrows). and Great Bahama Bank (25.5°N; Fig. 1) was sampled monthly for larval fishes, zooplankton, and several other biological and physical parameters (Llopiz & Cowen 2008). We utilized a coupled, asymmetrical multiple opening closing net and environmental sampling system (MOCNESS; Wiebe et al. 1985, Guigand et al. 2005) consisting of 4 m2 (1 mm mesh) and 1 m2 (150 μm mesh) openings. Discrete-depth sampling occurred in 25 m intervals from a depth of 100 m (50 m at the shallower, westernmost station). A paired neuston net (2x1 m, 1-mm mesh and 0.5x1 m, 150-μm mesh) sampled the sea surface to a depth of ca. 0.5 m. All nets were equipped with flowmeters for calculations of volume filtered, and plankton sampling was conducted during daylight hours except during sampling to estimate gut evacuation rates. Plankton samples were fixed in 95% ethanol and later drained and refilled with 70% ethanol. Larval fishes were sorted from all neuston, all 4-m2 MOCNESS, and the 0 to 25 m 1-m2 MOCNESS samples, and were identified to varying levels of taxonomic resolution (at least family) following Richards (2005). To estimate evacuation rates of billfish and tuna larvae, sampling occurred during two consecutive evenings near the Florida shelf in June 2005, beginning at sunset with a neuston net tow and following with MOCNESS tows (one net, double oblique to 15 m, ~15 min in length) at the approximate times of 0.5, 1.5, 2.5 and 3.5 hours post-sunset. The observation of empty guts in the early morning and the decline of contents after sunset indicated that larval billfishes and tunas, similar to many other taxa, only feed during daylight. Laboratory procedures Larvae were sorted from plankton samples and larval body length (BL; notochord/standard length before/after flexion of the urostyle) and lower jaw length (LJL; mandible) were measured with the ocular micrometer of a stereomicroscope (Leica MZ15). Larvae were dissected with a microscalpel and minutien pins, and the contents of the entire alimentary canal were teased out and identified. At least 5 of the most anterior (least digested) prey items were measured for length (prosome length for copepod copepodite stages except of harpacticoids, carapace length for other relevant crustaceans, and the longest dimension in all other prey, including harpacticoid copepods but excluding the caudal rami). Appendicularians were not measured due to their soft bodies. Appendicularian enumeration became more difficult with the degree of digestion (posteriorly in the intestine), but was estimated by the distinctiveness of the trunk, tail and house regions of the organism and the repeatedly observed anterior to posterior gradient of digestion state. Reference to copepod orders follows Boxshall and Halsey (2004). If identified, only copepod genera are referenced, and no distinction was made between juvenile and adult copepodite stages. Environmental abundances of zooplankton taxa were estimated from the 1 m2 MOCNESS samples. For general temporal and spatial analyses across the SOF, zooplankton samples from the 0-25 m depth interval at even-numbered stations from four months (Apr, Jun, Aug and Oct) in 2003 were examined. Samples were split with a Folsum splitter several times to obtain manageable aliquots from which zooplankton taxa were identified to varying taxonomic levels. Three aliquots were analyzed and individuals for each taxon were enumerated for each aliquot unless at least 50 individuals were counted in previous aliquots. The 150-µm mesh size of the nets precluded accurate abundance estimates of copepod nauplii. To investigate the relationships of individual zooplankton taxa to total zooplankton, we used samples collected off the Florida Keys in 2007. Five pairs of nearshore-to-offshore transects were sampled and the 1 m-2 MOCNESS samples were used. To estimate the abundances of individual taxa, plankton subsamples were from taken with a Hensen-Stempel pipette (typically 5 mL from 1 L of plankton sample) for enumerating the common copepod prey of larval fishes. Subsampling occurred until at least 100 individuals were counted or three subsamples had been analyzed. The displacement volume of the entire plankton sample was used as a measure of total zooplankton.
Load more

Recommended publications
  • A New Type of Plankton Food Web Functioning in Coastal Waters Revealed by Coupling Monte Carlo Markov Chain Linear Inverse Metho
    A new type of plankton food web functioning in coastal waters revealed by coupling Monte Carlo Markov Chain Linear Inverse method and Ecological Network Analysis Marouan Meddeb, Nathalie Niquil, Boutheina Grami, Kaouther Mejri, Matilda Haraldsson, Aurélie Chaalali, Olivier Pringault, Asma Sakka Hlaili To cite this version: Marouan Meddeb, Nathalie Niquil, Boutheina Grami, Kaouther Mejri, Matilda Haraldsson, et al.. A new type of plankton food web functioning in coastal waters revealed by coupling Monte Carlo Markov Chain Linear Inverse method and Ecological Network Analysis. Ecological Indicators, Elsevier, 2019, 104, pp.67-85. 10.1016/j.ecolind.2019.04.077. hal-02146355 HAL Id: hal-02146355 https://hal.archives-ouvertes.fr/hal-02146355 Submitted on 3 Jun 2019 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. 1 A new type of plankton food web functioning in coastal waters revealed by coupling 2 Monte Carlo Markov Chain Linear Inverse method and Ecological Network Analysis 3 4 5 Marouan Meddeba,b*, Nathalie Niquilc, Boutheïna Gramia,d, Kaouther Mejria,b, Matilda 6 Haraldssonc, Aurélie Chaalalic,e,f, Olivier Pringaultg, Asma Sakka Hlailia,b 7 8 aUniversité de Carthage, Faculté des Sciences de Bizerte, Laboratoire de phytoplanctonologie 9 7021 Zarzouna, Bizerte, Tunisie.
    [Show full text]
  • Crustacean Zooplankton in Lake Constance from 1920 to 1995: Response to Eutrophication and Re-Oligotrophication
    Arch. Hydrobiol. Spec. Issues Advanc. Limnol. 53, p. 255-274, December 1998 Lake Constance, Characterization of an ecosystem in transition Crustacean zooplankton in Lake Constance from 1920 to 1995: Response to eutrophication and re-oligotrophication Dietmar Straile and Waiter Geller with 9 figures Abstract: During the first three quarters ofthis century, the trophic state ofLake Constance changed from oligotrophic to meso-/eutrophic conditions. The response ofcrustaceans to the eutrophication process is studied by comparing biomasses ofcrustacean zooplankton from recent years, i.e. from 1979-1995, with data from the early 1920s (AUERBACH et a1. 1924, 1926) and the 1950s (MUCKLE & MUCKLE­ ROTTENGATTER 1976). This comparison revealed a several-fold increase in crustacean biomass. The relative biomass increase was more pronounced from the early 1920s to the 1950s than from the 1950s to the 1980s. Most important changes ofthe species inventory included the invasion of Cyclops vicinus and Daphnia galeata and the extinction of Heterocope borealis and Diaphanosoma brachyurum during the 1950s and early 1960s. All species which did not become extinct increased their biomass during eutrophication. This increase in biomass differed between species and throughout the season which re­ sulted in changes in relative biomass between species. Daphnids were able to enlarge their seasonal window ofrelative dominance from 3 months during the 1920s (June to August) to 7 months during the 1980s (May to November). On an annual average, this resulted in a shift from a copepod dominated lake (biomass ratio cladocerans/copepods = 0.4 during 1920/24) to a cladoceran dominated lake (biomass ratio cladocerans/copepods = 1.5 during 1979/95).
    [Show full text]
  • Fertilizing the Ocean with Iron Is This a Viable Way to Help Reduce Carbon Dioxide Levels in the Atmosphere?
    380 Fertilizing the Ocean with Iron Is this a viable way to help reduce carbon dioxide levels in the atmosphere? 360 ive me half a tanker of iron, and I’ll give you an ice Twenty years on, Martin’s line is still viewed alternately age” may rank as the catchiest line ever uttered by a as a boast or a quip—an opportunity too good to pass up or a biogeochemist.“G The man responsible was the late John Martin, misguided remedy doomed to backfire. Yet over the same pe- former director of the Moss Landing Marine Laboratory, who riod, unrelenting increases in carbon emissions and mount- discovered that sprinkling iron dust in the right ocean waters ing evidence of climate change have taken the debate beyond could trigger plankton blooms the size of a small city. In turn, academic circles and into the free market. the billions of cells produced might absorb enough heat-trap- Today, policymakers, investors, economists, environ- ping carbon dioxide to cool the Earth’s warming atmosphere. mentalists, and lawyers are taking notice of the idea. A few Never mind that Martin companies are planning new, was only half serious when larger experiments. The ab- 340 he made the remark (in his Ocean Iron Fertilization sence of clear regulations for “best Dr. Strangelove accent,” either conducting experiments he later recalled) at an infor- An argument for: Faced with the huge at sea or trading the results mal seminar at Woods Hole consequences of climate change, iron’s in “carbon offset” markets Oceanographic Institution outsized ability to put carbon into the oceans complicates the picture.
    [Show full text]
  • Biological Oceanography - Legendre, Louis and Rassoulzadegan, Fereidoun
    OCEANOGRAPHY – Vol.II - Biological Oceanography - Legendre, Louis and Rassoulzadegan, Fereidoun BIOLOGICAL OCEANOGRAPHY Legendre, Louis and Rassoulzadegan, Fereidoun Laboratoire d'Océanographie de Villefranche, France. Keywords: Algae, allochthonous nutrient, aphotic zone, autochthonous nutrient, Auxotrophs, bacteria, bacterioplankton, benthos, carbon dioxide, carnivory, chelator, chemoautotrophs, ciliates, coastal eutrophication, coccolithophores, convection, crustaceans, cyanobacteria, detritus, diatoms, dinoflagellates, disphotic zone, dissolved organic carbon (DOC), dissolved organic matter (DOM), ecosystem, eukaryotes, euphotic zone, eutrophic, excretion, exoenzymes, exudation, fecal pellet, femtoplankton, fish, fish lavae, flagellates, food web, foraminifers, fungi, harmful algal blooms (HABs), herbivorous food web, herbivory, heterotrophs, holoplankton, ichthyoplankton, irradiance, labile, large planktonic microphages, lysis, macroplankton, marine snow, megaplankton, meroplankton, mesoplankton, metazoan, metazooplankton, microbial food web, microbial loop, microheterotrophs, microplankton, mixotrophs, mollusks, multivorous food web, mutualism, mycoplankton, nanoplankton, nekton, net community production (NCP), neuston, new production, nutrient limitation, nutrient (macro-, micro-, inorganic, organic), oligotrophic, omnivory, osmotrophs, particulate organic carbon (POC), particulate organic matter (POM), pelagic, phagocytosis, phagotrophs, photoautotorphs, photosynthesis, phytoplankton, phytoplankton bloom, picoplankton, plankton,
    [Show full text]
  • Algae and Lakes Algae Are Primitive, Usually Microscopic, Organisms Found in Every Lake
    Algae and Lakes Algae are primitive, usually microscopic, organisms found in every lake. Like green plants, most algae have pigments that allow them to create energy from sunlight through the process of photosynthesis. Algae use this energy and nutrients such as nitrogen and phosphorus to grow and reproduce. Algae form the base of the food web in lakes. Small animals called zooplankton feed on algae. In Drawings from IFAS, Center for Aquatic Plants, turn, zooplankton become food for fish. Algae University of Florida, 1990; and U.S. Soil Conservation Service, Water Quality Indicators Guide: Surface Waters, also produce some of the oxygen found in lake 1989. water and in the atmosphere What types of algae live in my lake? There are thousands of species of freshwater algae living in lakes around the world. Most species of algae in Snohomish County lakes are free-floating, collectively known as phytoplankton. There are also many species of algae that attach to rocks, docks, and aquatic plants, called periphyton. There are three main groups of algae—the green algae (Chlorophyta), the golden brown algae (Chrysophyta) which also includes a large group called diatoms, and A typical microscopic view of algae found in local lakes the blue-green algae (Cyanobacteria)—as well as several smaller groups (euglenoids, cryptomonads, and dinoflagellates). Under the microscope, many algae have beautiful shapes and colors. Algae are important for healthy lakes. Without algae, your lake would likely be devoid of fish and other wildlife. Most algae are inconspicuous and do not cause problems. Unfortunately, a few types of algae can cause water quality problems in lakes.
    [Show full text]
  • Effects of N:P:Si Ratios and Zooplankton Grazing on Phytoplankton Communities in the Northern Adriatic Sea
    AQUATIC MICROBIAL ECOLOGY Vol. 18: 37-54, 1999 Published July 16 Aquat Microb Ecol 1 Effects of N:P:Si ratios and zooplankton grazing on phytoplankton communities in the northern Adriatic Sea. I. Nutrients, phytoplankton biomass, and polysaccharide production Edna Granelil.*, Per ~arlsson',Jefferson T. urne er^, Patricia A. ester^, Christian Bechemin4, Rodger ~awson',Enzo ~unari' 'University of Kalmar, Department of Marine Sciences. POB 905, S-391 29 Kalmar. Sweden 'Biology Department. University of Massachusetts Dartmouth. North Dartmouth, Massachusetts 02747. USA 3National Marine Fisheries Service, NOAA, Southeast Fisheries Science Center. Beaufort Laboratory, Beaufort. North Carolina 28516, USA 4CREMA-L'Houmeau(CNRS-IFREMER), BP5, F-17137 L'Houmeau, France 'Chesapeake Biological Laboratory, University of Maryland, Solomons, Maryland 20688. USA '~aboratoriodi Igiene Ambientale, Istituto di Sanita, Viale R. Elena 299. 1-00161 Rome, Italy ABSTRACT: The northern Adriatic Sea has been historically subjected to phosphorus and nitrogen loading. Recent signs of increasing eutrophication include oxygen def~ciencyin the bottom waters and large-scale formation of gelatinous macroaggregates. The reason for the formation of these macroag- gregates is unclear, but excess production of phytoplankton polysacchandes is suspected. In order to study the effect of different nutrient (nitrogen~phosphorus:silicon)ratios on phytoplankton production, biomass, polysacchandes, and species succession, 4 land-based enclosure experiments were per- formed with northern Adriatic seawater. During 2 of these experiments the importance of zooplankton grazlng as a phytoplankton loss factor was also investigated. Primary productivity in the northern Adri- atic Sea is thought to be phosphorus limited, and our experiments confirmed that even low daily phos- phorus additions Increased phytoplankton biomass.
    [Show full text]
  • Iron Fertilization: a Scientific Review with International Policy Recommendations
    Iron Fertilization: A Scientific Review with International Policy Recommendations By Jennie Dean* TABLE OF CONTENTS INTRODUCTION ................................ ....... .322 I. CLIMATE CHANGE AND THE OCEAN ......................................... 322 A . D escribing the problem ................................................................ 322 B. Identifying a potential solution .................................................... 323 II. IRON FERTILIZATION EXAMINED ............................................... 326 A . Potential benefits .......................................................................... 326 B . Potential problem s ........................................................................ 328 C. Synthesis and suggested action .................................................... 333 III. IRON FERTILIZATION AND INTERNATIONAL LAW ................. 334 A . Introduction .................................................................................. 334 B. Coverage under pollution and dumping regulations ..................... 334 C. Coverage under biological conservation regulations .................... 336 D. Coverage under global climate change mitigation regulations ..... 338 IV. RECOM M ENDATION S ..................................................................... 339 A . Suggested modifications ............................................................. 339 B . F easibility ..................................................................................... 340 C O N C L U SIO N ...............................................................................................
    [Show full text]
  • Ocean Primary Production
    Learning Ocean Science through Ocean Exploration Section 6 Ocean Primary Production Photosynthesis very ecosystem requires an input of energy. The Esource varies with the system. In the majority of ocean ecosystems the source of energy is sunlight that drives photosynthesis done by micro- (phytoplankton) or macro- (seaweeds) algae, green plants, or photosynthetic blue-green or purple bacteria. These organisms produce ecosystem food that supports the food chain, hence they are referred to as primary producers. The balanced equation for photosynthesis that is correct, but seldom used, is 6CO2 + 12H2O = C6H12O6 + 6H2O + 6O2. Water appears on both sides of the equation because the water molecule is split, and new water molecules are made in the process. When the correct equation for photosynthe- sis is used, it is easier to see the similarities with chemo- synthesis in which water is also a product. Systems Lacking There are some ecosystems that depend on primary Primary Producers production from other ecosystems. Many streams have few primary producers and are dependent on the leaves from surrounding forests as a source of food that supports the stream food chain. Snow fields in the high mountains and sand dunes in the desert depend on food blown in from areas that support primary production. The oceans below the photic zone are a vast space, largely dependent on food from photosynthetic primary producers living in the sunlit waters above. Food sinks to the bottom in the form of dead organisms and bacteria. It is as small as marine snow—tiny clumps of bacteria and decomposing microalgae—and as large as an occasional bonanza—a dead whale.
    [Show full text]
  • Ocean Fertilization the Potential of Ocean Fertilization for Climate Change Mitigation
    Report to Congress Ocean Fertilization The potential of ocean fertilization for climate change mitigation Requested on page 636 of House Report 111-366 accompanying the fiscal year 2010 Consolidated Appropriations Act (P.L. 111-117). 1 Executive Summary Page 636 of House Report 111-366 that accompanies the Consolidated Appropriations Act of 2010 (Public Law 111-117) calls for the National Oceanic and Atmospheric Administration (NOAA) to “provide a report on the potential of ocean fertilization for climate change mitigation” to the House and Senate Committees on Appropriation within 60 days of enactment of the Act. Climate change mitigation includes any efforts to reduce climate change including reducing emissions of heat-trapping gases and particles, and increasing removal of heat-trapping gases from the atmosphere. The oceans contain about 50 times as much carbon dioxide (CO2) as the atmosphere, comprising around 38,118 billion metric tons of carbon compared to 762 billion metric tons in the atmosphere. What allows the oceans to store so much CO2 is the fact that when CO2 dissolves in surface seawater, it reacts with a vast reservoir of carbonate ions to form bicarbonate ions. This reaction effectively removes the dissolved gas form of CO2 from the surface water, allowing the water to absorb more gas from the overlying air. This process, in combination with large-scale ocean circulation, has resulted in the transfer of between a quarter and a third of human-induced emissions of CO2 from the atmosphere into the ocean since the beginning of the industrial revolution. Ocean biology enhances the ocean’s ability to absorb CO2 from the atmosphere as follows: plants in the ocean, mostly microscopic floating plants called phytoplankton, absorb CO2 and nutrients when they grow, packaging them into organic material.
    [Show full text]
  • Zooplankton Structure and Potential Food Web Interactions in the Plankton of a Subtropical Chain-Of- Lakes
    Research Article TheScientificWorldJOURNAL (2002) 2, 926–942 ISSN 1537-744X; DOI 10.1100/tsw.2002.171 Zooplankton Structure and Potential Food Web Interactions in the Plankton of a Subtropical Chain-of- Lakes Karl E. Havens Watershed Management Department, South Florida Water Management District, West Palm Beach, FL 33496 E-mail: [email protected] Received January 29, 2002; Accepted February 15, 2002; Published April 8, 2002 This study evaluates the taxonomic and size structure of macro-zooplankton and its potential role in controlling phytoplankton in the Kissimmee Chain-of-Lakes, six shallow interconnected lakes in Florida, U.S. Macro-zooplankton species biomass and standard limnological attributes (temperature, pH, total phosphorus [TP], chlorophyll a [Chl a], and Secchi transparency) were quantified on a bimonthly basisfrom April 1997 to February -1 1999. Concentrations of TP ranged from below 50 to over150 µg l . Peak concentrations of particulate P coincided with maximal Chl a, and in one instance a high concentration of soluble reactive P followed. The cladoceranzooplankton was dominated by small species, including Eubosmina tubicen, Ceriodaphnia rigaudi, and Daphnia ambigua. The exotic daphnid, D. lumholtzii, periodically was abundant. The copepods were strongly dominated by Diaptomus dorsalis, a species previously shown to be highly resistant to fish predation. These results, and findings of controlled experiments on a nearby lake with a nearlyidentical zooplankton species complement, suggest that fish predation may be amajor factor structuring the macro-zooplankton assemblage. Zooplankton biomass,on the other hand, may be affected by resource availability. There was a significantpositive relationship between average biomass of macro-zooplankton and the average concentration of TP among the six lakes.
    [Show full text]
  • Assessment of Water Quality, Eutrophication, and Zooplankton Community in Lake Burullus, Egypt
    diversity Article Assessment of Water Quality, Eutrophication, and Zooplankton Community in Lake Burullus, Egypt Ahmed E. Alprol 1, Ahmed M. M. Heneash 1, Asgad M. Soliman 1, Mohamed Ashour 1,* , Walaa F. Alsanie 2, Ahmed Gaber 3 and Abdallah Tageldein Mansour 4,5 1 National Institute of Oceanography and Fisheries, NIOF, Cairo 11516, Egypt; [email protected] (A.E.A.); [email protected] (A.M.M.H.); [email protected] (A.M.S.) 2 Department of Clinical Laboratories Sciences, The Faculty of Applied Medical Sciences, Taif University, P.O. Box 11099, Taif 21944, Saudi Arabia; [email protected] 3 Department of Biology, College of Science, Taif University, P.O. Box 11099, Taif 21944, Saudi Arabia; [email protected] 4 Animal and Fish Production Department, College of Agricultural and Food Sciences, King Faisal University, P.O. Box 420, Al-Ahsa 31982, Saudi Arabia; [email protected] 5 Fish and Animal Production Department, Faculty of Agriculture (Saba Basha), Alexandria University, Alexandria 21531, Egypt * Correspondence: [email protected] Abstract: Burullus Lake is Egypt’s second most important coastal lagoon. The present study aimed to shed light on the different types of polluted waters entering the lake from various drains, as well as to evaluate the zooplankton community, determine the physical and chemical characteristics of the waters, and study the eutrophication state based on three years of seasonal monitoring from Citation: Alprol, A.E.; Heneash, 2017 to 2019 at 12 stations. The results revealed that Rotifera, Copepoda, Protozoa, and Cladocera A.M.M. ; Soliman, A.M.; Ashour, M.; dominated the zooplankton population across the three-year study period, with a total of 98 taxa from Alsanie, W.F.; Gaber, A.; Mansour, 59 genera and 10 groups detected in the whole-body lake in 2018 and 2019, compared to 93 species A.T.
    [Show full text]
  • Microbial Food Webs & Lake Management
    New Approaches Microbial Food Webs & Lake Management Karl Havens and John Beaver cientists and managers organism’s position in the food web. X magnification under a microscope) dealing with the open water Organisms occurring at lower trophic are prokaryotic cells that represent one (pelagic) region of lakes and levels (e.g., bacteria and flagellates) of the first and simplest forms of life reservoirs often focus on two are near the “bottom” of the food web, on the earth. Most are heterotrophic, componentsS when considering water where energy and nutrients first enter meaning that they require organic quality or fisheries – the suspended the ecosystem. Organisms occurring at sources of carbon, however, some can algae (phytoplankton) and the suspended higher trophic levels (e.g., zooplankton synthesize carbon by photosynthesis or animals (zooplankton). This is for good and fish) are closer to the top of the food chemosynthesis. The blue-green algae reason. Phytoplankton is the component web, i.e., near the biological destination of (cyanobacteria) actually are bacteria, but responsible for noxious algal blooms and the energy and nutrients. We also use the for the purpose of this discussion, are it often is the target of nutrient reduction more familiar term trophic state, however not considered part of the MFW because strategies or other in-lake management only in the context of degree of nutrient they function more like phytoplankton solutions such as the application of enrichment. in the grazing food chain. Flagellates algaecide. Zooplankton is the component (Figure 1c), larger in size (typically 5 that provides the food resource for Who Discovered the to 10 µm) than bacteria but still very most larval fish and for adults of many Microbial Food Web? small compared to zooplankton, are pelagic species.
    [Show full text]