Seagrass Meadows Vital for Marine Conservation
Unsworth, Richard K. F., Cullen-Unsworth, Leanne C., Pacific Ecologist
Seagrass meadows are often neglected in marine conservation with its high focus on coral reef protection, report RICHARD K F UNSWORTH & LEANNE C CULLEN-UNSWORTH. Yet seagrass perform many vital ecological functions and are very important fishing areas in the Indo-Pacific region. Their over-exploitation has serious consequences for coral reef conservation, due to inter-connected processes, fish migrations and nursery functions. Recent research highlights the value of seagrasses in mitigating climate change in a future Blue Carbon project. New marine conservation strategies must place seagrass meadows securely on the conservation programme.
Extensive evidence is documenting the sad and disastrous decline of the world's biodiverse and productive coral reefs. (1,2) To halt this decline, conservationists often fight a losing battle with the combined forces of global economics, climate change, corruption and limited education as they try to determine best practice methods to save these wonderful environments. Threats to seagrass meadows are less well acknowledged, yet they are key components of coastal and marine environments, (16) providing some of the most economically important ecosystem services of any marine habitat. (4) Important fisheries in their own right, they also play a significant role in the productivity of coral reefs and other fisheries. Seagrass meadows additionally support numerous charismatic faunal species, including turtle, dugong and seahorse. (15)
Over-exploited food source
Seagrass meadows are marine or estuarine habitats comprised of flowering plants, more closely related to terrestrial lilies than to true grasses. (3) They live in inter-tidal and sub-tidal areas, creating habitats that can be hundreds of kilometres in length and support a plethora of rich and diverse fauna. (3) Despite the recognised importance of seagrass meadows in supplying ecosystem services such as nutrient and carbon cycling, critical fish nursery habitats, coastal defence and food supply, there is growing evidence they are experiencing unprecedented levels of damage and deterioration. (4) This destruction can almost entirely be attributed to human activities. Degradation of seagrass meadows has been commonly associated with increased nutrient run-off, sedimentation, damage from boats, other physical impacts, and pesticide leaching. (4) However, in many areas of the world seagrass meadows are increasingly threatened by overexploitation of their productive fish and invertebrate assemblages. (5-7) Over-exploitation is of particular concern within the Indo-Pacific bioregion where seagrass meadows offer an easily exploitable and abundant food source for local people.
Across the Indo-Pacific as full moon approaches, the exposed inter-tidal zone at sunset becomes a significant fishing area, with numerous fishers and families collecting invertebrates, trapping fish stranded in tide pools, or bringing in their nets laden with fish after the tide gone out. Much of this fishing is subsistence and community-based activity, but it also includes small family fishing collectives earning a basic living selling excess catch. In many locations it involves the whole family, including small children, and as a result exists as a social and recreational activity. This type of exploitation remains largely unquantified, but it can be assumed to be increasing in areas of rapid human population growth. The over-exploitation of seagrass meadows combined with other anthropogenic impacts is threatening this vastly under-appreciated resource in many regions across the Indo-Pacific.
With tropical marine conservation firmly focussed on protecting coral reef biodiversity, sadly, governments, scientists and NGOs often appear oblivious to the consequences of seagrass decline. Coral reefs are important conservation targets as iconic habitats supporting high biodiversity and productivity and providing essential ecosystem services. …