Location and General Description
The ecoregion extends along the coastline as narrow disjunct patches but forms larger habitat blocks in the estuaries of Godavari and Krishna rivers in the states of Orissa and Andhra Pradesh, respectively.
Mangrove ecoregions are not exceptionally rich, but their importance should not be based solely on their species richness. Mangroves play a critical ecological role as a transition habitat from the marine to freshwater and terrestrial systems. They also provide important habitat for numerous species of fishes and crustaceans that are adapted to live and reproduce among the tangled mass of mangrove roots. The juvenile stages of many of these species depend on these mangroves for refuge and survival.
The mangrove vegetation is influenced by tidal fluctuations and salinity patterns. They are not diverse compared with most of the other terrestrial ecosystems (Tomlinson 1986). Undisturbed forests have a dense, unstratified canopy. The undergrowth is made up of seedlings and saplings from the canopy trees. The characteristic flora of these mangroves includes Avicennia marina, Suaeda spp., Rhizophora spp., and Bruguiera spp. Other species such as Avicennia officinalis, Aegiceras corniculatum, Ceriops, Lumnitzera racemosa, and Excoecaria agallocha are less common. Climbers such as Derris trifoliata and Dalbergia spinosa, undershrubs of Suaeda spp. and Acanthus ilicifolius and, very rarely, Sonneratia apetala, Xylocarpus mekongensis, Salicornia brachiata, Arthrocnemum indicum, and Sesuvium portulacastrum provide additional structure to these forests (Puri 1989).
This mangrove ecoregion provides critical habitat for many species of vertebrates and invertebrates, and is an important spawning ground and nursery for fish fry, shrimp, crabs, and other invertebrates. Crocodiles (Crocodylus spp.), monitor lizards (Varanus spp.) (Pandav and Choudhury 1996), and various snake species forage for smaller lizards and other prey. Hermit crabs, fiddler crabs, and mudskippers take refuge in the spaces among the tangle of mangrove roots from egrets and other wading birds that hunt them.
The ecoregion harbors more than 140 bird species, including the globally threatened lesser florican (Eupodotis indica) and a large community of aquatic birds that includes flamingoes (Phoenicoptreus spp.), spot-billed pelicans (Pelecanus philippensis), spoonbills (Platalea spp.), and painted storks (Mycteria leucocephala). In the Krishna River mangroves, Prasad (1989) has reported heron rookeries that are 2-3 ha.
More than 90 percent of this ecoregion's natural habitat has been destroyed. Three small protected areas cover a mere 930 km2 (table 1). Although this represents about 14 percent of the ecoregion's area, most of the protected areas are degraded.
Table 1. WCMC (1997) Protected Areas That Overlap with the Ecoregion.
Protected Area Area (km2) IUCN Category
Point Calimere 250 IV
Pulicat Lake 640 IV
Bhitar Kanika 40 IV
Ecoregion numbers of protected areas that overlap with additional ecoregions are listed in brackets.
Types and Severity of Threats
Because of continuing threats from human activities, the conservation status of this ecoregion was changed from endangered to critical. Most of the threats stem from clearing the forests for shrimp culture, agriculture, plantations, and urban development. Pollution from urban and agricultural runoff exerts great stresses on this delicate ecosystem and on the juvenile stages of many species of fishes and invertebrates that use the mangroves as nurseries and are highly susceptible to changes in environmental quality (Spalding et al. 1997).
Other threats include freshwater diversion for agriculture that prevents or reduces the regular flushing within the system, causing the mangroves to become stagnant. Construction of harbors and channels also reduces freshwater flows, thus increasing the salinity beyond the tolerance levels of the floral and faunal communities.
Justification of Ecoregion Delineation
We used MacKinnon's (1997) digital map of original vegetation and Spalding et al. (1997) to delineate the mangrove habitat along the coast of the Deccan Peninsula. These mangrove habitats were represented by this Godavari-Krishna Mangroves [IM1401].
References for this ecoregion are currently consolidated in one document for the entire Indo-Pacific realm.
Indo-Pacific Reference List
Prepared by: Gopal S. Rawat and Eric D. Wikramanayake