Meroplankton

Question 1

Meroplankton Basics

Answer 1

Temporary members of plankton
Larvae of most benthic species
Eggs and larvae of nekton
Cnidarian eggs and planula larvae
Cnidarian medusae
In estuaries and coasts meroplankton make a significant seasonal contribution to mesozoop biomass

Question 2

Mero life cycles and larvae

Answer 2

Different life stages and development
Function and development of planktonic larvae
- nutrition, ciliated and non, larval duration
Risk and reward of planktonic larvae

Question 3

Barnacle life cycles

Answer 3

Feeding nauplii stages I-VI
Change into a non-feeding cyrpid stage which will assess factors affecting settlement to the benthos.

Question 4

True jelly life cycles

Answer 4

Planular larva settles into sessile form
Forms ephyra which is planktonic

Question 5

Lecithotrophic larvae

Answer 5

Non-feeding
Possess yolk reserve
Remain in plankton for a few days

Question 6

Planktotrophic larvae

Answer 6

Feeding
Possess well developed feeding and swimming organs
Remain in plankton for several weeks

Question 7

Ciliated downstream larvae

Answer 7

Mouth located behind principal ciliary band, cilia beat towards it.
Locomotory and feeding currents coincide.
Feed as they swim

Question 8

Ciliated upstream larvae

Answer 8

Mouth anterior to main locomotory ciliary bands and beat away from mouth.
Water currents generated during locomotion cannot then be used directly for food capture
Indirect means of concentrating food
Large SAs, swim slow and have bizarre shapes.

Question 9

Teleplanic plankton

Answer 9

period > 2 months, possibly 1 year
Lobster phylosoma larvae

Question 10

Actaeplanic plankton

Answer 10

Coastal plankton 1 week to < 2 months (often 4-6 weeks)
70% of temperatre sublittoral species

Question 11

Anchiplanic plankton

Answer 11

Planktonic for few hours to days
Many sponge and bryozoans

Question 12

plankton duration against dispersal

Answer 12

Linear estimation of how larvae drift and disperse over time based on currents
Low dispersal distance, suggest factors beyond duration
High both, suggests correlation between observed and predicted

Question 13

Benefits of planktonic larvae

Answer 13

Increased gene flow
Dispersal of population
Reduced predation from adults
Reduced competition for space

Question 14

Cons of planktonic larvae

Answer 14

High mortality from:
Surviving critical release and return phases
Predation in the water column
Transport away from suitable site.

Question 15

Larval pool survival and processes over time

Answer 15

At the beginning, the pool is at its largest and the scale of processes influencing the population is much larger
Physical transport processes are v important and a determinant of larval supply.
As population gets smaller, process scale decreases and affect settlement, like microhydrodynamics, behavioral, substrate availability.
Further smaller and processes affect recruitment and population dynamics, like biological interaction, stress and flow rates.

Question 16

Larvae in chemosynthetic ecosystems

Answer 16

Development, behaviour and physiology affect release and time spent in the water column.
Some self recruitment at existing vent.
Bottom, ridge controlled and ocean currents influence movement.
Settlement cues and behaviour around a nearby ridge allow settlement and recruitment.

Question 17

Planula larvae

Answer 17

200-300um
Few range of shapes but mainly pill like

Question 18

Anthozoa larva

Answer 18

Coral spawning contributes to plankton

Question 19

Scyphozoa larvae

Answer 19

Planula larvae to settled polyps
Strobilating polyps release ephyra which grow to adult medusa.

Question 20

Hydrozoa larvae

Answer 20

Move between benthos and plankton
Sexual production of planula larva
Settles on benthos to a polyp which asexually reproduces by budding.
Grows to adult

Question 21

Polychaete development

Answer 21

Trocophore
Metratrocophore larvae
Pre-settlement post-larva stage

Question 22

Mollusc trocophore and veliger larvae

Answer 22

Typically hatch as trocophore then develop into veliger
Veliger has adult organs and enlarged ciliated lobe, velum.
Late veliger stage prior to settlement is a pediveliger, when velum is resorbed.

Question 23

Gastropod larval development

Answer 23

Larval shell develops by torsion and coiling

Question 23

Bivalves

Answer 23

Form small bivalved version of adult
Velichoncha

Question 24

Cyphonaute larva

Answer 24

Bryozoans and branchipods Triangular bivalved, with distinct bilateral symmetry Swims by means of a terminal, circular ciliated band.

Question 25

Pluteus and auricularia larvae

Answer 25

Most echinoderms have a planktonic larval stage Seasonally abundant in coastal zoop Diverse larval stages.

Question 26

Nauplius larvae

Answer 26

Nauplius is 1st larval stage in many crustanceans Median simple naupliar eye N1 is a simple ovoid shape with 3 pairs of appendages, 2 antannae and mandibles. Trunk segments and appendages added during successive moults to N6

Question 27

Copepod or barnacle

Answer 27

Copepod nauplius has no spines Cirripedia (barnacle) nauplius has 2 rostral and 1 caudal spine.

Question 28

Infraclass cirripedia

Answer 28

Planktotrophic naupliar larval stage lasts 2-3 weeks. Cypris is the settlement stage and searches for a suitable substrate to settle and metamorphose Nauplius is cypris larval stage

Question 29

Decapoda

Answer 29

Nauplius to zoea to megalopa larval stages Wide variety of planktotrophic larval forms, often several per species Larvae attain adult form by series of moults and metamorphoses

Question 30

Fish eggs and larvae

Answer 30

Newly hatched larvae feed on yolk Larvae and late larvae feed on plankton Flexion refers to flexion of the notochord during caudal fin dev Fish eggs and larvae known as ichthyoplankton