Marine Biology in Belize

Mangrove forests are important nursery grounds and reduce shoreline erosion. Mangroves tend to dominate in tropical and semitropical areas, whereas salt marsh tend to dominate the same intertidal zone in temperate areas.

Mangoves are woody vascular plants that:

have roots that spread widely or with peculiar prop roots that stem from the trunk Why?.
have adaptations for living in saline waters using various strategies (they are capable of surviving in freshwater, but do not occur there. Why not?).
"seeds" grow rapidly following fertilizaton (development is uninterepted) while still on the parent plant, and float upon release from parent plant.

Based on how seeds take root and the need for fine sediments, where (under what conditions) would mangrove forests likely become established?

Once established, how would sediment dynamics around roots be effected? Why is this "land" of fine sediment relatively stable?

Zonation of mangrove species from shore front to inland is typically strong. In the caribbean, species of mangroves often are distributed into distinct zones (which may reflect seral stages in ecological succession).

In locations with large intertidal variation, the width of mangrove forests is may be 100's of meters.

On small cayes, this zonation may differ (how and why?). In Belize, mangrove cayes lie on limestone platforms that are fossil patch reefs from the late Pleistocene covered within accumulated peat as thick as 10 m.

Food webs and energy flow in mangrove ecosystems
In areas of the forest where mangrove roots extend near or below the lowest tide, the roots are covered with attached organisms including barnacles, oysters, sponges, and sea squirts, and algae. Most of these organisms colonize the roots via planktonic larvae and spores? How might the abundance and distribution of this community change with depth and distance from the shoreward edge, and why? Where might deposit feeding be effective versus suspension feeding?

The above water portion of mangrove are subject to herbivory by terrestrial arthropods with up to 90% of seeds destroy by insects and crabs. However, much mangrove biomass is not consumed directly. Where does this biomass go?

Marine invertebrates have both postive effects (e.g. burrowing crab enhance aeration of the sediment) and negative effect (e.g. a boring isopod can decrease mangrove growth rates by 50%).

Mangroves that are nitrogen limited may benefit from filter feeders that aquire and transform nutrients from the water column. Red mangroves send out roolets into attached sponges, aquiring nitrogen and thereby improving growth. Within the red mangrove zone (Rhizophora mangle), growth of trees along the outer fringes of cayes in Belize tend to be nitrogen limited while those toward the center of cayes are phosphorus limited (Feller, et al. 2004).

Salt marsh systems are extremely productive (both primary and secondary). Why are these systems so productive?

Yet, as with seagrasses and mangroves, there are limited number of animal species consuming living salt marsh grass tissues (blades are toughened with cellulose and silca, and may contain secondary metabolites).

How can secondary production (i.e. consumer production) be high if few species are consuming salt marsh (and mangrove) plant tissue?

Other pathways of energy flow:

Micro-algae (especially diatoms) on stem and mud surfaces

Invertebrate fungus 'farmers'!

marsh periwinkles