Ctenophores, jellyfish, anchovies, zooplankton and menhaden - OH MY!

1. Ctenophores, jellyfish, anchovies, zooplankton and menhaden -OH MY! Jim Uphoff MD DNR, Fisheries Service

2. Ctenophores, jellyfish, anchovies, zooplankton and menhaden represent important middle links in Chesapeake Bay trophic and nutrient dynamics

3. Zooplankton Phytoplankton

4. Don’t forget microbes!

5. What fisheries fear!Too many nutrientsToo many removals What fisheries want!Balanced nutrients and fishing

6. A look at the middle of the food chain and a couple of mediators (summer data) It’s a Maryland-centric look for now

7. Chesapeake Bay Menhaden Indices

8. Menhaden in the Bay – indices of relative demand by bass (fc of regulations and year-class) and relative exploitation by fishery have risen.

9. Mean 4 week peak sea nettle count (approximated from Breitburg and Fulford 2006) and MD bay anchovy seine index (geometric mean).

10. Bay Program Zooplankton Monitoring – trends in sea nettle and ctenophore biovolume geometric mean.Note monitoring ends in 2002

11. Ctenophores go up, anchovies go down.

12. Anchovies are also subject to striped bass predatory demand. Demand index a function of regulations and year-class success.

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

14. Exploratory linear regressions of community dynamics. All variables loge-transformed. Yellow indicates P < 0.05. C=count & B=biovolume.

15. So far, things are acting logically; anchovies (high predation) & menhaden (high predation & exploitation) replaced by ctenophores as sea nettles drop. Comforting, ain’t it?

16. 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!

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

18. Now we have this? We had this. This might mean something! What’s happening to the food chain? We should look into this!

19. OOPS! No more Baywide monitoring!

23. Feedback from memo • Mike Lane – ODU • U-shaped trend in primary production • Primary production correlated with DIN or DIN:DIP • Increasing cyanobacteria abundance

24. 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

25. Feedback 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

26. 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

27. 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

28. 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

29. What’s Next? This is my obligatory Three Stooges slide