21 hours ago
Alappuzha coast home to 417 macrofaunal species, finds study
A comprehensive study undertaken along the Alappuzha coast has recorded 417 species of macrofauna.
The research documented four species of cnidaria (jellyfish), 44 species of crustacea (brachyuran crabs, hermit crabs, shrimps, mantis shrimps and lobsters), 185 species of mollusca, seven species of echinodermata, 135 species of fishes, five species of reptiles (turtles and sea snakes), 30 species of birds (shore and sea birds), and seven species of mammals (whales and dolphins).
The findings of the study, conducted by Arun C. R., research scholar at Department of Aquatic Biology and Fisheries, University of Kerala, and A. Biju Kumar, Vice-Chancellor of Kerala University of Fisheries and Ocean Studies, have been published in the Zoological Survey of India journal Records of the Zoological Survey of India.
Seahorse species
The macrofaunal diversity of Alappuzha is dominated by mollusca (44%), fishes (32%) and crustacea (11%). The study has identified three species of seahorses- Hippocampus spinosissimus, Hippocampus trimaculatus and Hippocampus kuda- which are included in Schedule I of the Wildlife (Protection) Act of India. The vulnerable Olive Ridley sea turtles nest on the beaches of the district, especially at Thottappally. Onboard surveys observed the critically endangered hawksbill sea turtle (Eretmochelys imbricata). The shell of a vulnerable leatherback turtle (Dermochelys coriacea) was found washed ashore during the survey.
Among the mammals, the blue whale (Balaenoptera musculus), an endangered species, was identified from video footage provided by fishers, while a Bryde's whale (Balaenoptera brydei) was identified from a specimen washed ashore on the Azheekkal beach.
The research also documented the traditional environmental knowledge (TEK) of the region's marine biodiversity. This knowledge highlights the insights of Alappuzha's coastal fishers regarding marine resources, ecosystems, and the impacts of climate change on biodiversity.
The study notes that fishers observe peak fish populations, particularly among pelagic species, during the monsoon season (June to September). However, the abundance of shellfish (shrimps and crabs) and squids is notably higher from September to February.
By fishers
It also sheds light on fish identification practices used by fishers at sea. According to the study, small fish move in shoals, colloquially called 'Polappu' or 'Paadam' by fishermen.
'They identify shoal fish by their colour and behaviour. Shoals can be discerned by observing the water's surface. The size of the bubbles provides clues about the fish species present. For instance, a shoal with small bubbles typically indicates 'mathi' (oil sardines). Red colouration in the sea may suggest the presence of sardines, anchovies, or shrimps. If it is shrimp, they may leap over the water's surface. Black patches on the water may also indicate sardines. Species differentiation based on this knowledge may be scientifically explored in collaboration with fishers,' reads the study.
The study titled Documentation of Macrofaunal Biodiversity of the Coastal Waters of Alappuzha District, Kerala, and Traditional Environmental Knowledge of Marine Fishers was conducted with the financial assistance of the University of Kerala. The study will soon be published as a coffee table book and a documentary on the marine life of Alappuzha is also in the making.
