Spatial-Temporal Patchiness. Patchiness Defined

Transcription

1 Spatial-Temporal Patchiness Steady State vs. Non-Steady State Box Models Chaos, Non-linearity Spectral Analysis Small-Scale Variability Medium-Scale Variability Large-Scale Variability The Paradox of the Plankton Patchiness Defined Patchiness: variance about the mean distribution of some measurement that is controlled by spatial and/or temporal processes In environmental science, variance of 10-30% (or more) is not uncommon 1

2 Mathematical Description Patchiness is defined statistically, such that if there s no patchiness, we d expect a random distribution: Patchiness = variance / mean < 1 = random distribution > 1 = non-uniform Steady-State Over some appropriate time-space scale, everything balances Inflow No change Outflow 2

3 Biological Pump Box Model CO 2 Inflow POC Flux CO 2 Outflow Decomposition Chaos Theory Chaotic Processes: the dynamical evolution that is aperiodic and sensitively dependent on initial conditions. Can t explain future behavior (more than a few steps in time) based on the existing state You CAN, however, put boundaries on it 3

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5 Monterey Bay Time-Series Mooring M1 Fluorescence

6 Spatial Variability Large-Scale Variability Blooms Domes Upwelling Gyres Island Effect Iron Fertilization 6

7 Definitions Eutrophic: High Productivity HNLC Oligotrophic Mesotrophic: Moderate Oligotrophic: Low Prod. HNLC: High Nutrient, Low Chl Small Scale Variability Dominated by cellscale processes Shear, Viscosity, Diffusion Sinking, Swimming, Aggregation 7

8 Physical Fronts Langmuir Cells caused by winds Upwelling Downwelling River Fronts caused by changes in density (salinity) Medium Scale Variability Medium-Scale patterns of phytoplankton are dominated by physical processes the physical forcing is at a scale that is larger than the growth-dynamics of the phytoplankton cells 8

9 A Line in the Sea Under the right conditions, a medium-scale event (such as the formation of a front) can become a large-scale phenomenon 9

10 Island Mass Effect Downstream from islands, you get enhanced nutrients due to turbulent mixing. Eddies and Gyres rings are formed when water breaks away from a current. Warm rings spin clockwise, cold rings spin counterclockwise. Gyres are basin-scale warm rings (spinning clockwise). 10

11 Hurricanes and HABs Hurricanes, similar to other large-scale events, can promote plankton blooms (including HABs) by opening and closing niches. 11

12 Fig. 6. Distribution of Pfiesteria spp. in the NRE water column and sediments after the 1999 hurricanes, based on PCR data (25) and standardized fish bioassays (10) (n = 36 sites positive for Pfiesteria spp., shown in red; n = 82 sites where Pfiesteria spp. were not found, shown in black) Burkholder, JoAnn et al. (2004) Proc. Natl. Acad. Sci. USA 101, Copyright 2004 by the National Academy of Sciences Physical-Biological Interactions Thin Layers are prevalent in upwelling systems, and frequently concentrate harmful species. McManus et al., in prep. 12

13 Physical-Biological Interactions: Assemblages Encystment/ excystment in dinos might be paralleled by resting stages/spores and heterotrophy in diatoms. Mesoscale Interactions bloom species are often selected as a result of being in the right place at the right time at suitable inoculum levels Smayda and Reynolds, 2001 Pelagic Seed Banks and upwelling centers Larval recruitment in upwelling centers 13

14 Pelagic Seed Banks Donaghay & Osborne, 1997 Population dynamics of Alexandrium spp. 14

15 A cross-isobath transport mechanism for initiation of Alexandrium blooms River plume 15

16 Upwelling relaxation Upwelling relaxation: the wrong (common) view 2D upwelling relaxation: what really happens 16

17 So how does water get back to the coast? Some possibilities: It s not relaxation, but downwelling Baroclinic instability 17

18 Monterey Bay During Autumn 2002, a meander in the California Current flushed the Monterey Bay, effectively replacing the water column to a depth of 200 m with offshore waters 18

19 Monterey Bay Sequential images of SeaWiFS chlorophyll showing the replacement of a diatom community by a red tide. 19

20 Monterey Bay Typical life cycle of marine organisms Planktonic dispersal Pelagic larvae Roughly 80% of all marine organisms (> 90,000 currently described species of vertebrates, invertebrates & algae) have a biphasic life cycle and produce planktonic propagules Thorson (1964) Cue detection & metamorphosis Sedentary Benthic adults 20

21 Coral P. damicornis Zoanthid Palythoa sp. Sea Star Mediaster Chiton Tonicella Tunicate Botryllus Hairy Triton Cymatium Polychaete Spirobranchus Bryozoan Membranipora Barnacle Lepas Sea star Pisaster Brittle star Ophiopholis Three basic modes of larval development Direct -- essentially no larval stage Larval stage encapsulated, internally brooded or bypassed entirely Lecithotrophic -- yolk feeding Nonfeeding larval stage Larvae do not require food to complete development Planktonic lifespan is typically short (minutes to days) Planktotrophic -- plankton feeding Feeding larval stage Larvae are incapable of completing development without feeding Planktonic lifespan typically long (days to months) 21

22 Planktonic larval duration (PLD) among modes Direct -- no time in the plankton Capacity for dispersal is highly limited Few offspring produced per parent ( ) Large parental investment in each egg produced Lecithotrophic -- typically short PLD Larval capacity for dispersal is intermediate Intermediate number of offspring per parent ( ) Intermediate parental investment in each egg produced Planktotrophic -- typically long PLD Larval capacity for dispersal is high Large number of offspring per parent ( ) Small parental investment in each egg produced Larval mortality by developmental mode Direct -- protected eggs often have chemical and/or physical defenses relatively high survival rate Lecithotrophic -- large obvious larvae may have chemical and/or physical defenses shorter time in plankton (minutes to days) survival rate probably intermediate Planktotrophic -- small transparent larvae relatively few species have obvious defenses long time in the plankton (days to months) survival rate probably relatively low 22

23 Typical life cycle of marine organisms Planktonic dispersal Pelagic larvae Problem with swimming larvae: water motion often carries them away from appropriate habitat Water flow in the ocean is complex -- internal waves, longshore drift, wind-driven currents and eddies can all affect where larvae end up Cue detection & metamorphosis Sedentary Benthic adults Sea Star Zoanthid Polychaete Hairy Triton Flounder Crab Sea Bream Kelp Zoospore Sea Urchin Starfish Larvae are motile and capable of directional swimming Behavior can alter passive dispersal larvae may be retained despite currents 23

24 Larval behavior can allow for retention Tidal Flow Flood tide Tidal Flow Ebb tide Vertical migration can result in retention of larvae within estuary: larvae rise on flood tide, and sink on ebb Typical life cycle of marine organisms Planktonic dispersal Pelagic larvae Cues used to assess habitats can be chemical or physical, and larvae often respond to some combination of multiple cues Cue detection & metamorphosis Cues can be positive or negative Sedentary Benthic adults 24