RECOLONIZATION OF AZOIC SEDIMENTS BY MEIOFAUNA IN THE HYDROPSAMMON RECOLONIZATION OF AZOIC SEDIMENTS BY MEIOFAUNA IN THE HYDROPSAMMON OF OTSEGO LAKE, NEW YORKOF OTSEGO LAKE, NEW YORK

Mark D. Cornwell1 & Thomas G. Horvath2

State University New York, Technical College at Cobleskill1 College at Oneonta2

RECOLONIZATION OF AZOIC SEDIMENTS BY MEIOFAUNA IN THE HYDROPSAMMON RECOLONIZATION OF AZOIC SEDIMENTS BY MEIOFAUNA IN THE HYDROPSAMMON OF OTSEGO LAKE, NEW YORKOF OTSEGO LAKE, NEW YORK

Mark D. Cornwell1 & Thomas G. Horvath2

State University New York, Technical College at Cobleskill1 College at Oneonta2

Meiofauna are organisms that pass though a 500m mesh and are retained on a 63m mesh and live between the grains of the littoral and sublittoral sediments. Freshwater psammolittoral zones, sediments and their associated meiofauna communities have been classified as either eupsammon (middle beach), hygropsammon (within 1 m above lake’s edge), and hydropsammon (submerged) by Pennak (1940). These nearshore zones often experience physical disturbances, such as wave actions, ice scouring, and lake-level fluctuations, which can defaunate the sediments. The communities associated with these sediments must recolonize after such disturbances. Little attention has been given to recolonization dynamics involving freshwater meiofauna.

We adapted methods from Palmer & Strayer (1996)for recolonization of hyporheic invertebrates in lakesediments. 1) 50-m-mesh panels, 50 ml tubes2) Sediments defaunated by oven drying at 120C for 4 h3) Azoic sediment packed into treatment tubes with organic

material intact (2% OM by wt)4) Randomized block design (treatments randomly assigned),

blocked by time: 0, 1, 4, and 8 week5) Each time block: 5 replicates for each treatment. 6) Four ambient core samples collected when time block

pulled7) Sediment separated from organisms by elutriation through

63-m-mesh screen

Ambient EndobenthicEpibenthic Control

Colonization complete by week 1: Invertebrate abundance in treatment and ambient samples not significantly differentNo significant difference among treatmentsHarpacticoids and cyclopoids appear to colonize epibenthically: higher abundance in epibenthic tubesOligochaetes and aeolosomatids appear to colonize endobenthically: higher abundance in endobenthic tubesTardigrads, ostracods, and chironomids appear to colonize both epibenthically and endobenthically: no difference in colonization between treatmentsMeiofauna community in the hydropsammon exhibits both stability and resilience

Otsego Lake: Deep (50 m max. depth), 1710 hectares,mesotrophic (12 µg TP/L, 0.8 mg Chl a/L).

Hydropsammon: Permanently inundated with water. Experimental plot under 0.5m water.

Palmer, M. A. & D. L. Strayer. 1996. Meiofauna, in Hauer and Lamberti (eds), Methods in Stream Ecology. Academic Press.Pennak, R. W. 1940. The ecology of the microscopic metazoa. Ecol. Monogr. 10(4):5539-611.

Chironomidae

0 2 4 6 8

0

10

20

30

40

50

60

EPIBENTHICEPIBENTHICEPIBENTHICEPIBENTHIC EPIBENTHIC & ENDOBENTHICEPIBENTHIC & ENDOBENTHICEPIBENTHIC & ENDOBENTHICEPIBENTHIC & ENDOBENTHIC ENDOBENTHICENDOBENTHICENDOBENTHICENDOBENTHIC

Tardigrada

0 2 4 6 8

0

20

40

60

80

100

120

140

160

180

Cyclopoida

0 2 4 6 8

0

2

4

6

8

10

Harpacticoida

0 2 4 6 8

0

1

2

3

4

5

6

Ostracoda

0 2 4 6 8

0

5

10

15

20

25

30

35

Col 1 vs Ambient

Col 1 vs Control

Col 1 vs Side

Aeolosoma sp.

0 2 4 6 8

0

10

20

30

40

Oligochaeta

0 2 4 6 8

0

10

20

30

40

50 0 2 4 6 8

0

50

100

150

200

250

300

Ambient

Control

Endobenthic

Epibenthic

Inve

rteb

rate

s p

er s

amp

le (

50 m

l)

Time in Weeks

SUMMARYSUMMARYSUMMARYSUMMARY

Special thanks to the BiologicalField Station, Cooperstown NY

0 2 4 6 81.0

1.5

2.0

2.5

Time in Weeks

To

tal

inve

rts

per

sam

ple

(50

ml)

Sh

ann

on

-Wei

ner

in

dex

Shannon-Weiner Index based on data accumulated through time.

All error bars ± 1 standard error.

Literature CitedLiterature Cited Literature CitedLiterature Cited

INTRODUCTIONINTRODUCTIONINTRODUCTIONINTRODUCTION

MATERIALS & METHODSMATERIALS & METHODSMATERIALS & METHODSMATERIALS & METHODS CONCLUSIONSCONCLUSIONSCONCLUSIONSCONCLUSIONS

Ambient: Simple core sampleEpibenthic: Open top, closed sidesEndobenthic: Closed top, open sidesControl: Open top, open sides