Ctenophores, jellyfish, anchovies, zooplankton and

menhaden -OH MY!

Jim UphoffMD DNR, Fisheries Service

Ctenophores, jellyfish, anchovies, zooplankton and

menhaden

Ctenophores, jellyfish, anchovies, zooplankton and

menhaden

represent important middle links in Chesapeake Bay

trophic and nutrient dynamics

represent important middle links in Chesapeake Bay

trophic and nutrient dynamics

Phytoplankton

Zooplankton

Don’t forget microbes!

What fisheries want!

Balanced nutrients and fishing

What fisheries fear!

Too many nutrientsToo many removals

A look at the middle of the food chain and a couple of mediators

(summer data)

It’s a Maryland-centric

look for now

Chesapeake Bay Menhaden Indices

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nd

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ized

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MD Juvenile

MD Age 1+

PRFC Age 1+

Menhaden in the Bay – indices of relative demand by bass (fc of regulations and year-class) and relative

exploitation by fishery have risen.

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Relative Exploitaion

Mean 4 week peak sea nettle count (approximated from Breitburg and Fulford 2006) and MD bay anchovy seine

index (geometric mean).

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fish

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Mean jellyfishcount

MD Anchovy GM

Bay Program Zooplankton Monitoring – trends in sea nettle and ctenophore biovolume geometric mean.

Note monitoring ends in 2002

00.2

0.40.6

0.81

1.21.4

1.61.8

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Jell

yfis

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jelly GM

Cteno GM

Ctenophores go up, anchovies go down.

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GM

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Cteno GM

MD anchovy index

Anchovies are also subject to striped bass predatory demand. Demand index a function of

regulations and year-class success.

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Relative bassdemand

Sea nettle abundance index follows MD oyster biomass index (skipjack CPUE)

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ettl

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eanPounds/Skipjack

Nettle count

Exploratory linear regressions of community dynamics. All variables loge-transformed. Yellow indicates P < 0.05.

C=count & B=biovolume.

Comparison r2 N

Oyster & nettle C + 0.32 20

Nettle B & ctenophore B 0.06 18

Nettle B & ctenophore B

Category (threshold?)

0.53

(- ?)

18

Nettle C & ctenophore B -0.35 12

Ctenophore B & anchovy -0.48 18

Nettle C & anchovy +0.22 38

Anchovy & striped bass -0.24 46

So far, things are acting logically; anchovies (high predation) & menhaden (high predation &

exploitation) replaced by ctenophores as sea nettles drop.

Comforting, ain’t it?

Based on my fishing observations, impervious surface sampling over the past 2 years,

and 34 years of experience

it looks to me like ctenophores have also dropped to a low level and others don’t appear to be

increasing!

Presence-absence of ctenophores has fallen in our impervious surface study. Brackish tributaries, same 2003-2005. Corsica only one continuously sampled.

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P/N cteno

Corsica P/N

Systems

We had this. Now we have this

?

This might mean something!What’s happening to the food chain?

We should look into this!

OOPS!No more Baywide monitoring!

MEAN SUMMER BAY ACARTIA DENSITYCB3.3C-CB4.3C-CB5.2 1985-2002

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#/L

ITE

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CB3.3C CB4.3C CB5.2

MEAN SUMMER ACARTIA, CTENOPHORE & ANCHOVY MD MESOHALINE BAY 1985-2002 (6)

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TIA

#/L

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ACARTIA CTENOPHORE ANCHOVYSeries4 Series5

MEAN SUMMER ACARTIA DENSITY & FILAMENTOUS CYANO CARBON 1985-2002 (6)

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ug

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ACARTIA CYANO C

Feedback from memo

• Mike Lane – ODU

• U-shaped trend in primary production

• Primary production correlated with DIN or DIN:DIP

• Increasing cyanobacteria abundance

Feedback from memo

• Claire Buchanan – ICPRB

• Prototype mesozooplankton IBI declining 1976-2003

• Calvert cliffs mesozooplankton (Marcia Olson) 1976-1980

N/L: min=2.2, max=65.1, median=14.3

• CB 4.3 1998-2002

N/L: min=0.2, max=16.0, median=6.7

• Claire Buchanan – ICPRB

• Prototype mesozooplankton IBI declining 1976-2003

• Calvert cliffs mesozooplankton (Marcia Olson) 1976-1980

N/L: min=2.2, max=65.1, median=14.3

• CB 4.3 1998-2002

N/L: min=0.2, max=16.0, median=6.7

Feedback from memoFeedback from memo

• Denise Breitburg – SI• Denise Breitburg and Richard Fulford

did a very nice exploration of much of this (Estuaries and Coasts 2006 29:776-784)

• Late ctenophores and jellies not unprecented

• 2003 & 2007 were late

• Denise Breitburg – SI• Denise Breitburg and Richard Fulford

did a very nice exploration of much of this (Estuaries and Coasts 2006 29:776-784)

• Late ctenophores and jellies not unprecented

• 2003 & 2007 were late

Feedback from memo

• Thoughts from Peter Tango – CBP• Mesozooplankton low numbers could reflect:

– Decline in reproductive success– High powered microzooplankton grazing– High abundance of low nutrition

phytoplankton

• Ed Houde – CBL

• Regime shift thinking in vogue – be cautious

• Serves as preliminary hypothesis

• MD anchovy index may not be best

• MD Index accumulates fish of all sizes

• Most spawning in lower 1/3 Bay, most ctenophores too

• Hypoxia may be factor in interactions

• He’s wary anchovy abundance has shifted in last 2-4 years

• Ed Houde – CBL

• Regime shift thinking in vogue – be cautious

• Serves as preliminary hypothesis

• MD anchovy index may not be best

• MD Index accumulates fish of all sizes

• Most spawning in lower 1/3 Bay, most ctenophores too

• Hypoxia may be factor in interactions

• He’s wary anchovy abundance has shifted in last 2-4 years

In the last years of my career I think I will

begin to work on the microbial loop where

most of the energy and action is concentrated

Ed Houde

What’s Next?What’s Next?

This is my obligatory Three Stooges slide

This is my obligatory Three Stooges slide