Impacts of Invasive Species on Coastal Environments

Bioinvasions from exotic flora and fauna are a constant threat to the ecological balance that allows coastal ecosystems to maintain homeostasis. Throughout the world, invasive species are responsible for a multitude of impacts upon the coastal zone, some of which include outcompetetion and displacement of native species, biochemical degradation of water resources, destabilization of the soil, overexertion of carrying capacity limits, and the overall collapse of indigenous flora-fauna boundaries. South Florida is a prime example where the successful establishment and dispersal of numerous invasive species has occurred through human disruption and interference of the natural coastal ecosystems. This chapter focuses on five species of invasive vegetation (i.e., Australian pine [Casuarina equisetifolia], Brazilian pepper [Schinus terebinthifolius], broadleaf paperbark tree [Melaleuca quinquenervia], water hyacinth [Eichhornia crassipes], hydrilla [Hydrilla verticillata]) and five species of invasive wildlife (i.e., red lionfish [Pterois volitans], marine cane toad [Bufo marinus], red imported fire ant [Solenopsis invicta], Nile monitor [Varanus niloticus], Burmese python [Python molurus bivittatus]) that have contributed to the profound ecological breakdown of a vulnerable coastal region. By reviewing how different invasive species marginalize the environmental resource base of South Florida, a spotlight is then shone on how invasions can destroy coastal biodiversity worldwide, as well as expose the role of humans, not only as the main introducing factor of alien species, but perhaps as the most invasive of all species on planet Earth.

The Sundarbans mangrove forests, wetlands and their native as well as invasive plant species are lying within the Bangladesh coastal region, which is gifted with vast natural resources, a delta, tidal flat, mangrove forests, marches, lagoons, bars, spilt, estuaries and coastal ecological environment. These habitats, biotopes and ecosystems also serve as habitat for especially four dominant tree species of the Sundarbans, the Sundri (Heritiera fomes), Gewa (Excoecaria agallocha), (Ceriops decandra) and (Sonneratia apetala). But the existence of these and many more native species is endangered. The Sundarbans species are threatened by various natural and anthropogenic pressures including climate change. So the native species are approximately decreasing significantly by the year 2100 due to sea level rise (88 cm) in the Sundarbans area compared to the year 2001.There 23 invasive species, which belong to 18 families and 23 genera. These species are highly invasive, six species are moderately invasive and the remaining are potentially invasive. From the 23 invasive species only four are exotic or alien. The disturbances may arrest succession at any stage and contribute to the biological invasion of invasive plants. The within these biodiversity hotspots and vast natural or coastal water resources lying potential for communities survival and 36.8 million dependent people are some of the strongly pending managing demands next to existing Natural World Heritage Sites’ already existing protective management support to be discussed in this chapter. As with the coastal natural resources drastically reduction due to unplanned use by community and stakeholders, also the Sundarbans mangrove forests, wetlands and their species are vastly affected through these developments and the most important observation for vulnerability aspects and maximum possible amplitudes is coming up, which has been investigated in within this research and chapter. Also the present situation stated that an integrated natural resource management plan is necessary for the protection of the mangrove coastal ecosystem.

The chapter is prepared based on primary and secondary data sources. The objectives of this study are to analyze the present coastal mangrove plant species natural resources management status. The study seeks the deltaic Sundarbans Region with its natural world heritage site and mangrove forests, wetlands plant species development and management strategies for ensuring less vulnerability and a sustainable development of coastal mangrove resources in Ganges-Brahmaputra Rivers deltaic coastal floodplain region in Bangladesh.

Sandy shore vegetation is under threat due to invasions from non-native or invasive species resulting from human interventions. As previous studies have shown, the natural zoning in Sri Lanka is so disturbed that it is possible to record only a few native species. This study was conducted at three representative study sites in the Western Province of Sri Lanka. We recorded twenty one families, 53 genera and 63 species in the sandy shore vegetation. Of these, approximately 14.28% (or 9 species) were found to be native species with Ipomea pes-capre and Spinifex littoreus as the most abundant native species at the study site. About 9.52% (or 6 species), namely, Chromolaena odorata, Cuscuta campestris, Lantana camara, Mikania micrantha, Opuntia stricta and Sphagneticola trilobata were found to be on the national list of invasive species in Sri Lanka. The study shows that a variation in plant diversity is to be found across the gradient of the shore with native species not as abundant and gradually decreasing landward while non-native weeds are more abundant and increasing landward from the sea. The Shannon Diversity Index shows that the diversity of species increases landward due to invasion. The Simpson diversity indices demonstrate that the vegetation is mainly dominated by non-native or invasive species. Thus, the study shows that the typical zoning nature and species composition found in sandy shore vegetation have been disturbed by the spread of invasive species, the main cause of which is ongoing human intervention. Under the existing policy directions, the available legislation therefore has to be enforced in order to restrict the spread of invasive species on sandy shores in Sri Lanka.

This chapter presents the results of a multifaceted approach to determine how sand dune plant communities have been affected by invasion of alien species. We sampled Velika plaža beach in Montenegro (E Adriatic), which is an under-researched part of the Mediterranean. Velika plaža is the largest sandy beach with both still well-developed sand dunes and moist plant communities in this part of Adriatic coast. On the other hand, this beach is also a touristic hot spot and subject to intensive land use change. We gathered maps of past and present land use by using GIS and field mapping from 1950, 1979 and 2015. The species composition of plant communities was randomly sampled and information on phylogeny and plant functional traits was gathered from several databases. Five alien plant species occurred in the sand dune vegetation, with a significant effect of the presence of aliens on native species cover. Invaded plots, when the whole beach is considered, were functionally less diverse than uninvaded ones. Plant species functional traits change along the sea-inland gradient, particularly rosette type, woodiness and nitrogen fixation. Phylogenetic diversity due to the presence of alien species was highest in sand dune slacks, but the results of phylogeny are not consistent and should be used with caution. The results of a multifaceted approach enable further management and monitoring of sand dunes and prevent the conflict between nature conservationists and landscape planners that is foreseen with further development of beaches in this part of the Mediterranean.

As the location of the oldest and busiest international port in the Philippines, Manila Bay is a prime location to study the ecology and dynamics of marine biological invasion in a tropical high marine biodiversity environment. The bay is historically within the center of marine biodiversity in the Philippines. Rapid urbanization in the last 150 years as a result of the expansion of the City of Manila and its suburbs has changed the estuarine watershed and has resulted in environmental change. This is reflected in eutrophication, sedimentation, pollution and land reclamation that has altered fisheries, coastal oceanography and ecology. These problems are exacerbated by the governance system of the National Capital Region resulting in unplanned urban development. In this environment, most of the invertebrate marine non-indigenous species (MNIS) that are invasive in other tropical estuarine ports are not invasive in Manila Bay. It is hypothesized that monsoon driven periodic hypoxia and other pollution related events prevent invasion. While this is true for most of the MNIS, the tropical Atlantic mussel Mytella charruana was introduced in 2014 and is now invasive in the bay. The biological characteristics of this species are likely to displace the pollution tolerant indigenous and non-indigenous malacofauna. The Supreme Court has taken notice of the environmental condition of the bay and through a 2008 Mandamus, ordered the Executive Department of the Philippines Government to restore the environmental quality of the bay. The effects of the Mandamus in rehabilitating the bay still have to be seen and on this any effective management of any marine biological invasion lies.

Numerous ideas have emerged on the definitions, consequences of introduction, causes of damage, population dynamics and mode of propagation, prevention, and adaptibility of invasive species along with their impact on native species directly or indirectly by way of alteration of ecosystem dynamics. An Invasive species is defined as a species having been introduced outside its native range through human activities which are likely to cause economic or ecological harm. Estuaries and Coastal-Estuarine –Mangrove ecosystems being the most productive and sensitive ecosystems in the world, have appeared to be very much susceptible to introductions of non-native species because of lot of possibilities out of different ecological and people oriented activities in and around these eco-regions such as shipping and boating, ecotourism, fisheries, aquaculture etc. Alongside, several ecological perturbations such as eutrophication, global warming, biomagnification and biotransformation of persistent pollutants, etc. along with the negative impacts of introduced species on marine estuarine flora and fauna by outcompeting them for basic life support resources, human health risk associated with transmission of pathogens, and higher bioaccumulation capabilities of invasive species than native species have threatened this ecologically sensitive region considerably.

This book chapter aims at highlighting the prospective consequences of the bioinvasion on the coastal–estuarine networks of West Bengal, India which is unique because of the presence of more than hundred of deltas endowed with world’s largest mangrove chunk and associated flora and fauna giving emphasis on ecosystem processes and functions. In view of the different threats as imposed by invasive species on native ones, even leading to their extinction, proper holistic eco-management strategies are being suggested giving emphasis on the self-sustaining ecosystem functioning of coastal- estuarine -mangrove ecosystem where species do not inevitably spread rapidly and extensively beyond control.

Biofouling on ship hulls is one of the primary vectors of non-indigenous species transport. The most common method to prevent biofouling settlement is through the application of ship hull coatings. However, there is no perfect coating and the ship hull will eventually become colonized by biofouling. Hull husbandry techniques are often employed to remove the biofouling from the ship hull, which adds in restoring the ships functional abilities and prevents the transport of biofouling organism as invasive species. Two such techniques are in-water cleaning and grooming. The cleaning of a ship hull may damage hull coatings, release both biocides and fouling organisms into the local environment, and is regulated or banned in many ports around the world. A more recent mechanical approach to biofouling, is grooming, a frequent and gentle wiping of the hull, which works in synergy with ship hull coatings to prevent the growth of biofouling organisms. By incorporating grooming into the ship maintenance, invasive species recruitment and transport is prevented.

Lionfish consume at least 250 fish and crustaceans prey species in the western Atlantic. Main taxa eaten include grunts (Haemulon aurolineatum), wrasses (Thalassoma bifasciatum and Halichoeres spp.), damselfishes (Stegastes partitus and Chromis cyanea), gobies (Coryphopterus personatus), labrisomids (Malacoctenus triangulatus) and Pterois volitans. Because lionfish prey on such a long list of Caribbean reef fauna it should be considered a generalist invasive species that even threats commercially and ecologically important species such as grunts, groupers, snappers, triggerfishes, parrotfishes, surgeonfishes, gobies, lobsters, and cleaner shrimps. Four richness estimators indicate that lionfish may consume around 300 species. Stable isotopes analysis ratifies that most prey eaten by lionfish are reef dwellers. Lionfish diets from the Colombian Caribbean appear distant from the Bahamas and Cayman Island diets in a cluster analysis. Research and monitoring of this dangerous invading species should be maintained.

Tropical wetlands are commonly used for cattle ranching and have been modified either by draining them or introducing non-native species that are palatable to cattle. Some of these introduced species have become wetland and dune invaders. In Mexico, the introduction of antelope grass (Echinochloa pyramidalis) and its effects are being documented. This grass species is highly appreciated by cattle ranchers and is invading natural wetlands. It has C4 photosynthesis, high biomass production and high vegetative propagation, is tolerant to grazing and able to grow in both flooded and dry conditions. It is reducing plant biodiversity by increasing its own aerial coverage, changing wetland hydrology, reducing faunal habitat and causing soil physicochemical changes (e.g. vertical accretion). Reducing its dominance and increasing the density of native wetland species is difficult, expensive and time-consuming. We began a restoration project in a coastal wetland in central Veracruz, Gulf of Mexico, which included using shade to control the invader. This strategy reduced E. pyramidalis cover and increased the cover of native species, highlighting the importance of understanding the functional differences between native and invasive species when developing strategies for the control and eradication of problematic species.

Undaria pinnatifida (Harvey) Suringar was recorded in Argentina for the first time in December 1992. Since then, it shows an invasive and competitive behavior, spreading quickly from the initial focus and increasing its population density. The first individuals were found attached to the port of Puerto Madryn, suggesting that the vector of introduction was the ballast water of cargo ships arriving to Golfo Nuevo from overseas. Since U. pinnatifida was recorded, it has been spreading along the Argentina coasts, extending its range within and outside Golfo Nuevo, along the coasts of Argentina from Puerto Deseado (Santa Cruz province) to Mar del Plata (Buenos Aires province) far as 1850 km from each other. The invasive condition of this species creates an awareness of the effects inflicted upon the indigenous biodiversity of this region, as well as, on the commercially-important benthic community structure. Moreover, the detachment of subtidal algae, especially during the summer, and its deposition upon the beach, have altered the sedimentary balance along the overall transverse beach profile. This effect, in addition with algal extraction by trucks mainly during tourist seasons, may increase beach erosion processes along Patagonian coasts.

In many countries domesticated dogs occur abundantly on coasts, where they may co-occur with and pose a threat to coastal wildlife such as threatened shorebirds. Dogs on beaches fit the ecological definition of invasive species. The management of dogs on coasts is controversial, with polarised debate surrounding dog access to public open spaces, and questions around the effectiveness of prevailing dog management regulations. We examined the levels of compliance with dog regulations (3516 checks, 69 ocean beaches) under six prevailing management regimes in Victoria, Australia. Compliance was low to moderate across all dog management ‘types’, but varied significantly. The highest compliance rates were associated with ‘no dog’ areas. Despite poor overall compliance, dog regulations appeared to be associated with different rates of occurrence and relative abundances of dogs, suggesting either they effectively displaced dog walkers or that dog area designations reflect usage patterns, or both.

Accompanied, domestic dogs frequently disturb birds on coasts, and meet the ecological definition of invasive species. Dogs occur most commonly singly or in ‘packs’ of two dogs. We examine whether group size (one versus two leashed dogs) influenced Flight-initiation Distance (FID), a measure of wariness towards potential predators, of birds on southern Australian beaches. We report 303 FIDs from 16 species, of which seven species had sufficient data to compare responses between one and two dog approaches. None of the seven focal species varied their FID or escape modality (walk/run versus fly) with one versus two dogs approaching. Birds do not apparently judge risk associated with dogs in relation to ‘pack’ size. Regulations which reduce the number of dogs walked are therefore unlikely to reduce disturbance of coastal birds. Further studies, using unleashed dogs, and dogs which bark, may evoke greater responsiveness than reported here and may reveal indirect effects of dog group size.

Invasive nypa palms (Nypa fruticans) are a major threat to mangroves and coastal systems in the Niger Delta region in Nigeria, apart from oil and gas exploration. The palms were first introduced as foreign species to curb coastal erosion over a century ago (i.e. 1906). They later became invasive and started multiplying in the last 30 years. The palms have acclimatized to the coastal environment by developing superior root system, which they use to tap available nutrients. They also have tough and buoyant seeds, which aid in their wide dispersal. These qualities of the palms had made them to have an edge over the mangroves. Oil and gas exploration, which is responsible for numerous oil spillages, is a major cause of mangrove decimation. The establishment of open waste disposal sites in coastal areas have also contributed to the changes in soil and water qualities, leading to further decline in mangroves, with a resultant increase in invasive nypa palms. The palms change the pedology, hydrology and landscape architecture of the coastal environment once they are established. Therefore, a threat to the mangroves is a threat to the entire coastal system, which benefits from the ecosystem services provided by the mangroves. Mangroves may disappear completely from the Niger Delta in the next 50 years if the encroachment of the palms continue unabated. However, this problem can be resolved by the removal of the palms through mechanical, physical or chemical means. Soils on which the palms grow can be excavated to remove the allelopathic properties, after which the palm soil should be replaced with mangrove soil. To ensure smooth re-colonization of the coast, mangroves propagules with good genetic quality should be selected, nurtured and transplanted from the nursery to the coastal areas. The mangrove propagules should be monitored and protected from further invasion by nypa palm after planting.

This chapter reports the results of a study of Acacia Mangium and Acacia Auricaliformis, which are exotic plantation tree species from Australia that have invaded, and spread within, natural habitats in Brunei Darussalam. There are four types of Acacia trees that are spreading in Brunei, mostly within the coastal areas, the deep forest areas as well as in the urban areas in the country’s capital, Bandar Seri Begawan. This study looks into the presently occupied land areas, vegetation cover, land use and landscape changing patterns in the coastal forest areas in Brunei. By clarifying patterns of variation in demographic parameters and hence population growth it is possible to form a connection between qualitative field data, theoretical ideas about invasiveness and rate of spread. The results show that the present growth and expansion rate of the Acacia plant species is alarming for the primary forest as well as for the forest ecology and ecosystems in the coastal forest areas in Brunei. This study makes use of both primary and secondary data sources. The objective of this chapter is to understand the changing patterns of forest vegetation, such as primary forest to secondary forest, and the forest ecosystem in coastal Brunei. Based on this study’s findings some applied recommendations have been proposed for the better distribution of the Acacia plant species and maintenance of rainforest vegetation in Brunei.