The Benthic Ecology of Molluscs in the Death Assemblage at Pigeon Creek, San Salvador, Bahamas

The Molluscs of Pigeon Creek, San Salvador, Bahamas

Miami has 100s of acres of beautiful Natural Areas which lend themselves to research projects! (Quicktime movie~4 mb). On the same walk, I spotted my first garter snake of the spring! In another 1 mb quicktime movie, a pair of mallard ducks lands in Harkers Run in Bachelor Woods

R. Hays Cummins, Western Program

It is 6:20:01 PM on Saturday, November 7, 2009. This page has served 35549 mollusc lovers and was last updated on Wednesday, December 10, 2008.

Paper:

Cummins, R.H., M.R. Boardman and A.I. Miller. 1995. The recognition of environmental transitions using species composition, biomass estimates, and taphonomic signatures in a Holocene carbonate lagoon, Pigeon Creek, San Salvador, Bahamas. Proceedings of the 7th Symposium on the Geology of the Bahamas. 10 pages

Rationale:

One goal of our study was to use dead molluscs to better recognize environmental transitions as preserved in the sediment record. There are a surprising variety of molluscs found in the death assemblage of Pigeon Creek. The types of dead molluscs seems to be at least partially determined by the amount of living seagrass present on the seafloor. For a glimpse of some of the results of a recent study, look at the relative abundances of the overall molluscan death assemblage at Pigeon Creek as shown in the table below. Compare the overall molluscan abundance in Pigeon Creek with the Relative Abundances and Biomass Dominants from the different environments within this diverse ecosystem. For a more complete overview of the objectives, methods, and results of our study, please see the paper referenced above.

We examined the molluscan death assemblage from 34 core samples from a variety of environments in the southern arm of Pigeon Creek located at the SE corner of San Salvador island. I have included a Detailed Map of San Salvador.

This detailed map illustrates our specific study area in Pigeon Creek.The solid black circles refer to sampling locations. The Seagrass Coefficient is delineated by color.

Some Representative Molluscs from the Tropical Lagoons of San Salvador

Caecum sp.

Cerithium variable

Unknown Lucinid

Chione cancellata

Tricolia affinis

Lucina penslyvanica

**Some Representative Molluscs from the Tropical Lagoons of San Salvador**
Caecum sp.	Cerithium variable	Unknown Lucinid
Chione cancellata	Tricolia affinis	Lucina penslyvanica

Total Molluscan Relative Abundance in the Southern Branch of Pigeon Creek

Species Numerical Abundance Relative Abundance (%)

Cerithium eburneum 2525 25.60

Codakia orbiculata 1029 10.40

Cerithium variable 785 7.94

Tellina sp. 662 6.70

Divaricella quadrisulcata 505 5.10

Cerithium literatum 465 4.71

Trigoniocardia antillarum 441 4.60

Lucina pensylvanica 405 4.10

Modulus carchedonius 395 4.00

Bulla striata 356 3.60

Acmaea pustulata 281 2.84

Tegula fasciata 167 1.69

Semele nuculoides 151 1.53

Tricolia affinis 147 1.49

Chione cancellata 131 1.33

Cerithidea scalariformis 115 1.16

Anomalocardia brasiliana 112 1.13

Rissoina cancellata 103 1.04

Nassarius albus 91 0.92

Smaragdia viridis viridemaris 86 0.87

Turbo castaneus 86 0.87

Polinices lacteus 86 0.87

Anachis sparsa 75 0.76

Brachidontes exustus 58 0.59

Bailya parva 57 0.58

Codakia costata 56 0.56

Olivella floralia 44 0.45

Vermicularia spirata 35 0.35

Barbatia cancellaria 33 0.33

Crenella divaricata 31 0.31

Retusa sulcata 29 0.29

Haminoea succinea 20 0.21

Pinctada radiata 21 0.21

Dentalium sp. 18 0.18

Arcopsis adamsi 18 0.18

Columbella mercatoria 17 0.17

Total Molluscan Relative Abundance in the Southern Branch of Pigeon Creek
Species	Numerical Abundance	Relative Abundance (%)
Cerithium eburneum	2525	25.60
Codakia orbiculata	1029	10.40
Cerithium variable	785	7.94
Tellina sp.	662	6.70
Divaricella quadrisulcata	505	5.10
Cerithium literatum	465	4.71
Trigoniocardia antillarum	441	4.60
Lucina pensylvanica	405	4.10
Modulus carchedonius	395	4.00
Bulla striata	356	3.60
Acmaea pustulata	281	2.84
Tegula fasciata	167	1.69
Semele nuculoides	151	1.53
Tricolia affinis	147	1.49
Chione cancellata	131	1.33
Cerithidea scalariformis	115	1.16
Anomalocardia brasiliana	112	1.13
Rissoina cancellata	103	1.04
Nassarius albus	91	0.92
Smaragdia viridis viridemaris	86	0.87
Turbo castaneus	86	0.87
Polinices lacteus	86	0.87
Anachis sparsa	75	0.76
Brachidontes exustus	58	0.59
Bailya parva	57	0.58
Codakia costata	56	0.56
Olivella floralia	44	0.45
Vermicularia spirata	35	0.35
Barbatia cancellaria	33	0.33
Crenella divaricata	31	0.31
Retusa sulcata	29	0.29
Haminoea succinea	20	0.21
Pinctada radiata	21	0.21
Dentalium sp.	18	0.18
Arcopsis adamsi	18	0.18
Columbella mercatoria	17	0.17

Relative Abundance of Molluscs as a Function of Seagrass Cover & Bottom Type

(Click on the Image to download a Crisper, Larger View)

Molluscan Biomass Dominants as a Function of Seagrass Cover & Bottom Type

(Click on the Image to download a Crisper, Larger View)

A look at the tidal Range & Current Velocity in the "Blow-Out" area near the mouth of Pigeon Creek.

Some typical molluscs found in the seagrass beds of San Salvador.

Bivalve and Gastropod Morphology

These figures are from Jean Andrews 1971 publication Seashells of the Texas Coast, # 5, The Elma Dill Russel Spencer Foundation Series, University of Texas Press, Austin.

Click on an Image for a Larger View!

Bivalve Geography!

Typical Gastropod Shapes

Typical Bivalve Shapes

Typical Molluscan Benthic Epi- and In-fauna
Molluscs are Cool!

Gastropod Geography

**Click on an Image for a Larger View!**
Bivalve Geography!	Typical Gastropod Shapes	Typical Bivalve Shapes
Typical Molluscan Benthic Epi- and In-fauna	Molluscs are Cool!	Gastropod Geography

Pigeon Creek Mangrove Quicktime Movies

You'll need Apple's quicktime to view these movies.

Mangroves are wonderful ecosystems found throughout the worlds tropical coastlines. The plants themselves are not closely related to one another. Rather, they have evolved to inhabit the same stressful environments--they are incredibly important estaurine nursery grounds. Hosts to incredible biomass, they are where I take my students for their first snorkel.

Pigeon Creek, a tidal estuary on San Salvador, Bahamas, has extensive seagrass and mangroves. (TME 99)

Near the mouth of the SW arm of Pigeon Creek, tidal velocities on a daily basis reach an amazing 1 meter/sec. I wonder what the velocities are during storms? Blow-outs dominate the central channel. Note the extent the seagrass roots extend into the sediment! (TME 99)
Mangrove Roots (Rhizophora mangle)serve as a haven for many vertebrate and invertebrate species. These movies were taken near the mouth of Pigeon Creek in the SW arm. (TME 99)
Another "Mangrove Root Perspective." Note the juvenile fish navigating thru the roots. (TME 99)
And one last time. Mangrove systems hold a special mystery for me. (TME 99)
This polychaete worm was feeding with mucous laden tentacles hoping to entrap organic rich sediments. (TME 99)

Pigeon Creek Mangrove Quicktime Movies

You'll need Apple's quicktime to view these movies.
Mangroves are wonderful ecosystems found throughout the worlds tropical coastlines. The plants themselves are not closely related to one another. Rather, they have evolved to inhabit the same stressful environments--they are incredibly important estaurine nursery grounds. Hosts to incredible biomass, they are where I take my students for their first snorkel. Pigeon Creek, a tidal estuary on San Salvador, Bahamas, has extensive seagrass and mangroves. (TME 99) Near the mouth of the SW arm of Pigeon Creek, tidal velocities on a daily basis reach an amazing 1 meter/sec. I wonder what the velocities are during storms? Blow-outs dominate the central channel. Note the extent the seagrass roots extend into the sediment! (TME 99) Mangrove Roots (Rhizophora mangle)serve as a haven for many vertebrate and invertebrate species. These movies were taken near the mouth of Pigeon Creek in the SW arm. (TME 99) Another "Mangrove Root Perspective." Note the juvenile fish navigating thru the roots. (TME 99) And one last time. Mangrove systems hold a special mystery for me. (TME 99) This polychaete worm was feeding with mucous laden tentacles hoping to entrap organic rich sediments. (TME 99)