An estuary is a coastal area where freshwater from rivers mixes with saltwater from the sea, creating a unique and productive habitat for many plants and animals.
Characteristics of an estuarine habitat:
-
Mix of fresh and salt water – Known as brackish water.
-
Tidal influence – Water levels and salinity change with tides.
-
High nutrient levels – Supports rich plant and animal life.
-
Muddy or sandy bottoms – Good for burrowing organisms.
-
Sheltered environment – Provides safe breeding grounds.
-
Variable salinity – Ranges from freshwater to seawater depending on tides and rainfall.
4 types of estuarine habitats found in Africa:
-
Mangrove Forests – Found along West African coasts, especially in Nigeria, Senegal, and Mozambique.
-
Salt Marshes – Common in southern African estuaries like those in South Africa’s Eastern Cape.
-
Mudflats – Found in estuaries like the Rufiji Delta in Tanzania and parts of the Niger Delta.
-
Seagrass Beds – Located in shallow estuarine waters along the coasts of Kenya, Tanzania, and Madagascar.
DISTRIBUTION OF PLANTS AND ANIMALS IN AN ESTUARY AND THEIR ADAPTIVE FEATURES.
A. Plants Species and Adaptive Features
PLANKTON
i. Presence of air spaces in their tissues for buoyancy
ii. Possession of rhizoids for attachment to rocky shores
WHITE MANGROVE
i. Possession of Pneumatophores or breathing roots for gaseous exchange
ii. Possession of stilt roots for anchorage
B. Animal Species And Their Adaptive Features.
MOSQUITO LARVAE AND PUPAE
i. Possession of breathing trumpet for gaseous exchange
a MUDSKIPPERS
i. Possession of fins adapted for crawling on land and swimming in water
FOOD CHAIN IN ESTUARINE HABITAT
i. Detritus→Worms → Snails → Birds
ii. Phytoplanktons → Barnacles → Fish → Birds
FACTORS AFFECTING ESTUARINE HABITAT
1. Temperature
2. Wind
3. Relative humidity
4. Light
5. pH
FRESHWATER
Freshwater habitats are bodies of water formed mainly from inland waters and contain very low levels of salinity. Examples are Rivers, Ponds, Streams, Springs and Lakes.
CHARACTERISTICS OF FRESHWATER HABITAT
1. Low Salinity
2. Small in size
3. Variation in temperature
4. High Oxygen Concentration
5. Shallowness of water
6. Seasonal variation
7. Current
TYPES OF FRESHWATER HABITAT:
1. Lotic Freshwaters , e.g , Rivers, Springs, and Streams
2. Lentic Freshwaters, e.g, Lakes, Ponds, Swamps, and Dams.
MAJORLY ECOLOGICAL ZONES OF FRESHWATER HABITAT
-
Littoral Zone – The shallow, near-shore area with sunlight penetration and rooted aquatic plants.
-
Limnetic Zone – The open water zone away from the shore, where sunlight supports plankton and fish.
-
Profundal Zone – The deep, dark part of the water body where little or no sunlight reaches; low oxygen levels.
-
Benthic Zone – The bottom of the water body, consisting of sediment where decomposers and some bottom-dwelling organisms live.
ADAPTIVE FEATURES OF SOME ORGANISMS IN FRESHWATER HABITAT
A. PLANT SPECIES
I. Water weed (Elodia)
i. possess a long and flexible submerged petiole, which enables it to swing with the water current
II. Spirogyra
i Possession of mucilaginous cover for protection
B. ANIMAL SPECIES
1. Tilapia species
I. Presence of swim bladder for buoyancy
II . Possession of gills for gaseous exchange
2. LungFish ( Protopterus)
I Possession of gills adapted for obtaining oxygen in water and breathing in atmospheric oxygen when the water dries out during dry season.
FOOD CHAIN IN FRESHWATER HABITAT
Spirogyra → Tadpoles → Carps → Kingfishers
Diatoms → Fish Fry → Tilapia
FACTORS AFFECTING FRESHWATER HABITAT
-
Water Pollution – From chemicals, waste, and runoff that harm aquatic life.
-
Temperature Changes – Affects oxygen levels and survival of aquatic organisms.
-
Water Flow and Level – Dams or droughts can disrupt natural flow and habitat structure.
-
Invasive Species – Non-native plants or animals can outcompete or harm native species.
ASSESSMENT
1. Define Freshwater Habitat
2. State abiotic factors affecting freshwater habitat.
3. Mention the characteristics of Freshwater Habitat
Comments