Bio 260 midterm 2

importance of cholorphyll a

used to measure primary productivity (measured by satellites)

normally higher concentrations near the coast (specifically west coast), mid-latitudes

primary productivity

the rate at which biomass is produced by photosynthesis 

bioassay experiment

study done to test the effects of a substrate on a living organism

bioassay for nitrates and phosphates

found that adding nitrates increased productivity, adding phosphates alone did not increase productivity, but adding both created more productivity than the sum of both nitrate and phosphate

nitrogen

usable form for phytoplankton is NO₃^- (nitrate). nitrogen is essential for making amino acids and proteins. a large part of it comes from runoff

phosphorus

phosphates come from eroding land and poo (guano — good fertilizer because it’s full of phosphorus)

chlorophyll a concentration in tropics

sunlight year-round, so the nutrients are used as fast as they are deposited, and then the water is nutrient-limited

chlorophyll a concentration in polar regions

no light in winter → no photosynthesis. nutrients build up and then during the summer all the nutrients get used up

chlorophyll a concentration in temperate regions

light limited in winter → less photosynthesis, low production. then there is a huge bloom in spring but then nutrients are depleted by the summer. in the fall there is a secondary bloom because the dead plankton from the spring bloom begin to be recycled and the nutrient concentration increases

upwelling: northern hemisphere

wind from the north pushes the water to the west (coriolis) so then cold water upwells near the coast

Ekman transport

bulk of the water goes right while the surface current follows the wind south

downwelling: northern hemisphere

wind comes from the south and the bulk of the water is pushed east by ekman transport. thermocline drops, warm water near coast

why is there high primary productivity on the west coast?

because of the circulation of the currents, in the mid latitudes, the winds tend to go towards the equator on the west coast, which creates strong upwelling in those areas due to ekman transport

somalia is the one exception that occurs because the strong winds from the indian summer monsoon create seasonal upwelling

why is there high productivity in the south pole but low productivity in the north pole?

both have cold water, but there is no landmass in the north pole. in the south pole, antarctica creates a landmass to upwell against, and a source of nutrients from runoff

how is primary productivity related to fish?

higher productivity generally is associated with higher fisheries yield. the exception is coral reefs because coral reef fishes are not usually fished commercially. → fisheries data isn’t always all-encompassing

trophic relationships: socal bays and estuaries

multiple types of primary producers (eelgrass, benthic microalgae (diatoms), macroalgae, phytoplankton)

rich food web

ex: diatoms → copepods → topsmelt

transfer efficiency

percent of biomass consumed that results in newly created biomass in then next trophic level

typically 10 percent

fisheries efficiency

depends on how much energy the predator spends to eat the prey

anchovies spend little energy catching their prey so their transfer efficiency is about 20 percent

tuna are high in the trophic level so they have a low efficiency

productivity in estuaries

shallow, lots of sunlight, lots of runoff → multiple kinds of primary producers and high primary productivity

fish biomass over the year

after the spring bloom there is a slight delay before the uptick in fish biomass. so there is more fish production in the summer (and dont really see fall bloom reflected in fish biomass)

Bolsa Chica Ecological Reserve

became paved over by oil fields and roads but was then restored successfully in 2006

shovelnose guitarfish

• uses bays and estuaries for mating, pupping, and feeding in summer

• high level predator - eats benthic inverts and fishes

• use the full tidal basin of bolsa chica

acousitc fish tracking

transmitters last months to years, picked up by recievers that are put in the estuary called synch transmitters

used to track shovelnose guitarfish

proportional habitat use

a value above 1 means significant correlation - in this case it means selection for that habitat as opposed to random use

findings on the guitarfish using acoustic tracking

they stayed in the basin for about 2.5 months

they use subtidal mud

were more active during incoming and high tide (because more habitat is available during high tide)

more active at night

most recorded in bolsa chica were juveniles (born offshore and migrate in)

fisheries independent data

no effort made to catch one specific thing or to catch more or less. more random

CPUE

catch per unit effort (can be fisheries dependent)

fisheries dependent data

can be biased because fisheries target one thing or will try to catch more so they go to certain areas or at certain times

Anaheim Bay Estuary

restored in late 1980s

restored tidal basins tend to be warmer in the summer because of their location farther up the estuary (farther from tidal fluctuations)

round stingray

• internal fertilization

• matrotrophic (mother provides additional nutrition via uterine secretions)

• viviparous

findings on round stingrays in anaheim bay estuary using beach seines 

in restored areas: majority caught were females, and a majority of those were pregnant 

over time: the temp decreased (august -october) and the pregnant females were moving out of the estuary 

caught no newborns/juveniles 

what were the round stingrays using the warm areas of anaheim bay estuary for?

elasmobranch maternity ward!

warm water shortens gestation period and the young turn out larger

they dont absorb food as well in this warm water but they tolerate it so they can be pregnant for a shorter amount of time

takeaway from round stingrays in anaheim bay estuary

if you know when/where individuals of a species are captured in an estuary, you can classify them

for example: round stingrays are marine migrants

community definition

a group of populations that coexist/interact in space and time

species richness

number of species

species evenness

proportion of individuals of each species

species diversity

richness and evenness (ex: shannon index)

Shannon Diversity Index

H’ = - sum(p_iln(p_i))

p_i is the proportional representation of each species 

higher number means higher diversity

generally get a more accurate value with a larger sample size 

diversity value only matters in comparison to other examples of the same habitat

predation

animals eating animals, animals eating plants (herbivory)

ecology of fear

prey animals who are more fearful survive better, so the behavior is selected for by natural selection

sub-lethal effect of predation

presence of predators causes prey to grow more slowly because they hide more and therefore eat less and reproduce less

competition

two or more individuals attempt to use an essential limited resource

intraspecific competition

generally thought to be more intense than interspecific because the animals are competing for the exact same thing

interspecific competition

animals on the same trophic level and same habitat are more likely to compete with each other

resource partitioning

when animals avoid competing with each other by living in different areas (even though they technically dont have to live only in those specific areas)

eelgrass traits

• vascular

• have rhizome

• blades are basically just solar panels

• sequesters carbon (b/c they have belowground biomass because of rhizome)

• angiosperm

• more like an orchid or lily

• not directly fed on by other animals

function of the rhizome for eelgrass

• gets nutrients from sediment

• allows the plant to be more resilient 

• belowground so it sequesters carbon when it dies

distribution of eelgrass

• soft bottom substrate (sand, silt)

• light is the major limiting resource (depth)

• pretty wide distribution across globe

• 2 species in CA

2 species of eelgrass in ca

zostera marina: narrow bladed, bays and harbors, low energy environment

zostera pacifica: wider blade, open ocean habitat, harbors different species than z. marina

surf grass

not eelgrass

grows on rocks

fine blades

is still a type of sea grass

ecosystem services of eelgrass

• dampens energy of storms and waves — reduces erosion

• sequesters carbon

• structural habitat for fishes

• cycles nutrients

• valuable for recreation (human)

• algae grows on it (epiphyte) that the fish feed on

ontogenetic shift paradigm 

change in an organism's ecological niche, behavior, or habitat use over its lifetime

many larvae settle in seagrass to grow 

not well understood outside the tropics