Zooplankton: sampling, diversity and biogeography

Continous plankton recorder (CPR)

Is towed behind ships at roughly 10 m depth and takes samples of plankton

Factors to influence the selectiveness of a plankton net

• Towing speed

• Depth

• Mouth opneing size

• Camouflage of net (color)

• Mesh size

• Duration

• Type and size of net

Ringnet

Gentle, relatively short, shallow tows with clsoed cod end to collect undamgaged animals for use in experiments, 200 m wire paid out

Bong net

1 hour quantitative oblique tows (max 300 m depth) with a flowmeter and time depth recorder attached to the net. Gives two replicates, 550 m wire paid out

RMTI net

2.5 oblique tows (1000m max depth) to catch larger, rare taxa living at depth. 1800m wire paid out

Multinet

Has multiple nets that can be electronically opened and closed, allows for sampling at different depth strata

Different mesh sizes for zooplankton sampling net

50, 200, 1000 micrometers

Sample preservation techniques

• Buffer formalin

• Ethanol

• RNAlater

• Flash Freezing

Buffer formaline (2%-5%)

Doesnt perserve DNA very well

Ethanol (70%-100%)

Doesnt work for gelatineous plankton

RNAlater

Salty solution, works well for RNA extraction

Flash freezing

Uses liquid nitrogen

Oceanic distribution

Throughout the oceans

Neritic distribution

More focused in upper water column in more shallow waters like coasts

Latitudinal diversy gradient

There is a clear decrease of species diversity from equator to pole, however not that clear in oceanic organisms

Longhursts biogeochemical provinces

Based on chlorophyll and temperature images from spaces

Marine biogeographical realms

Based on species diversity

Mesopleagic ecoregions

Based on fossils

DNA barcoding

Use of short specific DNA sequences for species recognition and discrimination. Based on sanger sequencing of individual organisms

Metabarcoding

Large-scale taxonomic identification of complex samples via one or more homologous DNA regions (barcodes)

Positives of metabarcoding

• Rapid detection of climate change

• Monitoring ecosystem health

• Detection of introduced species

• Study trophic interactions

Negatives of metabarcoding

• Methadological artefacts (PCR)

• Standardization of target barcodes

• Lack of taxonomic resolution

• Paucity of reference databases

DVM

Dial Vertical Migration