2. Sandy beaches are loose deposits of sand,
including some gravel or shells, that cover the
shoreline in many places.
Beaches serve as buffer zones or shock absorbers
that protect the coastline, dunes from direct wave
attack.
It is an extremely dynamic environment where sand,
water and air are always in motion. Fine-grained
sand beaches tend to be gently sloping and quite
flat.
3. Sandy beaches are soft shores formed by deposition
of particles that have been carried by currents and
waves. The transported material derived from:
• shore erosion
• land and transported by rivers to the sea
The two main types of beach material are:
• quartz
• carbonate sands
Other material includes heavy minerals, basalt and
feldspar.
4. The grain size of sand varies from very fine to very
coarse. Quartz sands have a slightly lower density
than carbonate sands.
The quartz particles are generally more rounded.
Calcium carbonate particles sink more slowly in
water due to their more irregular shapes, even if
their density is higher.
Most sands have a porosity of about 30 to 40 % of
the total volume. The finer a sand the greater its
porosity.
5. Fine sands have lower permeabilities due to their
smaller pore sizes.
Penetrability is related to particle size and porosity.
It can be important to the macrofauna.
All species must be able to burrow into the
substratum. To determine the penetrability, the
proportion of clay and silt and the water content are
very important.
6. The two basic beach
types are :
1. Dissipative
2. Reflective
7. Sr no. Reflective Dissipative
1 Narrow and steep wide and flat
2 coarse grained finer sediments
3 no surf zones extensive surf zone
4 Filtration volumes are
higher
Lower
8. Sandy beaches are not just piles of sand, they are home to
numerous species, they have important linkages with
adjacent ecosystem.
There is a full array of living organisms from bacteria, fungi,
microphythobenthos, and protozoa to extremely specialized
metazoan on the beach.
Hundreds of species inhabit sandy beaches but most of
them are small and buried. They occupy interstitial spaces
between sand grains.
These sandy beach dwellers exhibit remarkable physiological
and behavioural adaptation to changing environmental
conditions.
9. Sandy beaches are dynamic and sensitive place.
Biodiversity provides many ecosystem services
that are often not readily visible.
10.
11.
12.
13. Macrofauna of sandy beaches are often abundant and, in
some cases, attain exceptionally high densities. Their
main feature is the high degree of mobility displayed by
all species.
These animals may vary from a few mm to 20 cm in
length. The macrofauna community consists of organisms
too large to move between the sand grains.
The macrofauna of sandy beaches includes most major
invertebrate taxa although it has been recognised that
molluscs, crustaceans and polychaetes are the most
important.
14. There is a tendency for crustaceans to be more abundant
on tropical sandy beaches and molluscs to be more
abundant on less exposed and on temperate beaches
although there are many exceptions of this and
polychaetes are sometimes more abundant than either of
these taxa.
Generally crustaceans dominate the sands towards the
upper tidal level and molluscs the lower down level.
Physical factors, primary wave action and particle size of
the sand largely determine distribution and diversity of the
invertebrate macrofauna of sandy beaches. Food input and
surf-zone productivity may determinate the population
abundance.
15. The porous system averages about 40% of the total
sediment volume. Its inhabitants include small metazoans
forming the meiofauna, protozoans, bacteria and diatoms.
The meiofauna is defined as those metazoan animals
passing undamaged though 0.5 to 1.0 mm sieves and
trapped on 30 mm screens. On most beaches the
interstitial fauna is rich and diverse .
The dominant taxa of sandy beach meiofauna are
nematodes and harpacticoid copepod with other
important groups including turbellarians, oligochaetes,
ostracods .
16. The intertidal beach zone is covered part of the day by
water and is part of the day exposed to air. Swash and
tides supply nutrients and food.
Intertidal filter-feeders cannot feed while the tide has
retreated. Many species of the meiofauna use vertical
tidal migrations through the sand column. Other species
move up and down the beach with the tides.
There is a difference between directional stimuli (such as
light, slope of the beach, water currents) and
nondirectional stimuli (such as disturbance of the sand,
changes in temperature, hydrostatic pressure).
17. Some adaptations are an increased ventilation rate, an
increased ventilation efficiency, reduced metabolic rate or
other ways of energy economy.
Many sheltered-shore animals are facultative anaerobes
as an adaptation to ebb tides.
Other animals in oxygenated surf-swept beaches are
essentially aerobic.
Some species bury themselves to escape high
temperatures; others cool by evaporation, by entering the
sea or by absorbing water from the substratum.
18. Some species adapt by reproducing frequently or by
reproducing just once in a year. There are also species
that follow the lunar cycle to reproduce at the right time.
To avoid predation, several behaviors have developed.
The first one is deep burrowing.
Another one is migration with the tide to escape
predation.
According to circumstances, animals can modify their
behavior. This is called phenotypic plasticity.
Several groups of vertebrates make use of sandy beaches
for foraging, nesting and breeding.
19. Turtles nest on the backshore of sandy beaches.
Birds use the beach for foraging, nesting and
roosting.
Seals use several areas of the beach for nesting,
molting, breeding and raising pups.
Other terrestrial animals such as otters, baboons,
raccoons,may descend onto the beach to forage.
20. sediment storage and transport
dynamic response to sea level rise
breakdown of organic materials and pollutant
water filtration
nutrient mineralization and recycling
maintenance of biodiversity and genetic resources
21. providing a nursery area for juvenile fish
nesting sites or rookeries for turtles, shorebirds,
and pinnipeds
prey for birds and other terrestrial wildlife
recreational opportunities
functional links between terrestrial and marine
environments (Defeo et al., 2009).
22. Today almost every beach on every coastline is
threatened by human activities.
Sea-level rise and other effects of global warming
are expected to intensify other anthropogenic
pressures, and could cause unprecedented
ecological impacts.
23. Impacts caused directly by recreational activities are emerging as
significant environmental issues (Schlacher et al., 2008).
camping and driving activities, which severely impact dune vegetation,
both continue unabated in many parts of the world (Luckenbach and
Bury, 1983, Hockings and Twyford, 1997, Groom et al., 2007).
24. Human activities disturb shorebirds, modifying key
behavioural traits that are crucial to their survival and
reproduction (Burger, 1991, Burger, 1994, Lord et al.,
2001, Verhulst et al., 2001), including:
(1) changes to foraging behaviour resulting in less feeding
time, shifts in feeding times and decreased food intake
(2) decreased parental care when disturbed birds spend less
time attending the nest, thus increasing exposure and
vulnerability of eggs and chicks to predators
(3) decreased nesting densities in disturbed areas and
population shifts to less impacted sites.
25. Cleaning or grooming, a common practice on beaches heavily used
for tourism (Poinar, 1977, Llewellyn and Shackley, 1996, Engelhard and
Withers, 1997, Dugan et al., 2003, Davenport and Davenport, 2006)
The heavy equipment used in beach grooming can also cause direct
mortality of the eggs and young of beach-nesting shorebirds, turtles
and fish (Martin et al., 2006)
26. Pollution is a sensitive issue on beaches given their immense value for
recreation and tourism.
Pollutants include a variety of anthropogenic materials, ranging in size
from molecules to large debris, and can impair the physiology, survival,
reproduction and behaviour of species in all habitats of the beach from
interstitial environments (McLachlan, 1977) .
27. Artisanal invertebrate fisheries are the most common form of
exploitation on sandy beaches (McLachlan et al., 1996, Kyle et al.,
1997).
Harvesting not only affects the targeted species directly through
fishing mortality, but it also has collateral impacts that can alter
ecosystem structure and functioning,
28. Beach sands have been mined in many places, including Sri Lanka for
building lime from coral sand (Clark, 1996), Tanzania, Korea, Argentina,
Italy and many other countries for building sand (Masalu, 2002, Cho,
2006, Pousa et al., 2007), the Namibian coast for diamonds (McLachlan,
1996, Theron et al., 2003), and several areas for heavy minerals such as
titanium and zirconium (Mulaba-Bafubiandi et al., 2002, Panigrahi, 2005,
Pirkle et al., 2005, Ghosh et al., 2006).
