TABLE OF CONTENT
CONTENT PAGES
Title Page – – – – – – – – – i
Declaration – – – – – – – – – ii
Certification – – – – – – – – – iii
Dedication – – – – – – – – – iv
Acknowledgement – – – – – – – – – v
Table of Contents – – – – – – – – – vi
List of tables – – – – – – – – viii
List of figures – – – – – – – – ix
Abstract – – – – – – – – – x
CHAPTER ONE: Introduction
1.1 Background of the study- – – – – – – – 1
1.2Significance of the Study – – – – – – – – 12
1.3Aims and Objectives of the Study – – – – – – 12
CHAPTER TWO: Literature Review
2.1 Occurrence of macroinvertebrates along sandy beaches- – – 13
2.2 Distribution of macroinvertebrates along sandy beaches- – – 19
CHAPTER THREE: Materials and Method
3.1 Description of study Area – – – – – – 22
3.2 Sample design and collection – – – – – – 24
3.3 Analysis of sample – – – – – – – – 25
3.4 Species composition – – – – – – – 25
3.5 Data (statistical) analysis – – – – – – – 25
3.5.1 Species Richness Indices (Diversity) – – – – – 25
3.5.2 Relative Percentage Abundance (%Ra) – – – – 26
CHAPTER FOUR: Result
4.0 Macroinvertebrate Community Structure – – – – 27
4.1 Discussion – – – – – – – – – 34
CHAPTER FIVE: Summary
5.1 Conclusion – – – – – – – 37
5.2 Recommendation – – – – – – – – 37
References – – – – – – – – – – 38
Appendix – – – – – – – – 44
List of Tables
Table 1: The Overall Composition, Distribution and
Abundance of Macroinvertebrates along Ibeno Beach
Table 2: Diversity of benthic macroinvertebrates along the sites of Ibeno
beach
List of Figures
Figure 1: Map of the Study Area Showing Ibeno Beach
Figure 2: Variations of the Major Taxonomy Groups along the
stations at the Beach
Figure 3: Variations of Percentage Abundance and Occurrence
of the Taxonomy groups along the stations at the Beach
ABSTRACT
Macroinvertebrates play significant roles in marine benthic food chain, energy link and pollution metabolism and dispersion. This study was conducted for a period of three (3) months from July to September 2017 at Ibeno beach aimed to evaluate and determine the benthic macroinvertebrate occurrence, abundance, distribution along the shores of Ibeno beach. The factors affecting them were also evaluated. The species were distributed and collected at three stations and were sampled monthly. A total of 652 macroinvertebrates comprising of 45 taxa, 13 groups, 25 families were recorded. Dominant taxonomic taxa varied relatively; Diptera 151no.m-2 (23%), Hemiptera 122no.m-2 (9%), Coleoptera101no.m-2 (15%), Mollusca 63no.m-2 (10%), Oligochaeta 64nom-2 (10%), Nematoda 17no.m-2 (3% ), Odonata 30nom-2 (5% ). The variations in taxa and number of individuals between stations were not significantly different (P>0.05). Sorenson’s quotient (Q/S) indicated similarities in the species composition between the sites. The presence of marginal vegetation, pollutants also influence the composition and diversity of macroinvertebrate community.The study area is organically enriched. Higher abundance can be attributed to loose texture of sediment due to high sand with higher interstitial space for the macroinvertebrates to harbor. Less abundance is attributed to avoidance of these organisms to high organic carbon area being a possible indication that o organic matter affects the abundance and distribution of macroinvertebrates adversely.
CHAPTER ONE
INTRODUCTION
1.1 BACKGROUND OF THE STUDY
Beaches are dynamic environments where elements such as wind, water and sand interact, resulting in complex hydrodynamic and depositional processes. (Brown and Mclachlan, 1990). Beach organisms are usually buried in sand during the period when the intertidal zone is most accessible to researchers.
Sandy beaches are a common ocean dominated ecosystem. They are loose deposits of sand gravel or shells that cover the shoreline in many places. They serve as buffer zones or shock absorbers that protect the coastline, sea cliffs or dunes from direct wave attack. It is an extremely dynamic environment where sand water and air are always in motion (Achutankutty, 1996) Several groups of vertebrates make use of sandy beaches for foraging nesting and breeding. Turtles nest on the back shore of sandy beaches. Birds use the beach for roosting, seals use several areas of the beach for nesting molting breeding and raising pups. They are coastal recreational areas for people (Pearse, et a.,1942). The occurrence of molluscs was best explained by the concentration of chlorophyll and wave exposure whereas those of crust oceans and polychaetes were best explained by an ensemble of variables including beach slope, sea surface temperature and grain size. Occurrence of suspension feeders was best explained by chlorophyll-a, occurrence of deposit feeders was best explained beach slope, sea surface and chlorophyll-a.The distribution and abundance of the sediment in fauna is mostly controlled by complex interactions between the physicochemical and biological properties of the sediment (grain size, water content, flushing rate of water through the sediment oxidation-reduction state, dissolved oxygen, temperature, light, organic content. (Anderson,etal.,1979). Biological properties are food availability and feeding activity reproductive effects on dispersal and settlement behaviour that induces movement and aggregation, intraspecific competition, interspecific competition, competitive exclusion and predation effects. The macrofauna of sandy beaches incudes most major invertebrates taxa although it has been recognised that molluscs, crustaceans and polychaetes. There is a tendency for crustaceans to be more abundant on tropical sandy beaches or more exposed beaches and molluscs to be abundant on less exposed and on temperate beaches. The dominant taxa of sandy beach meiofauna are nematodes and copepod including turbellarians, oligochaetes, gastrotrichs, ostracods. Occurrence of predators and scavengers was best explained by sea surface temperature and beach slope (Rodil,et al., 2012).
Beaches are homes to crabs, clams, fish, tiny invertebrates. These habitats are experiencing a level of human impact, encroached on the landward side by coastal development and on the ocean side by sea level rise and coastal erosion and affected by many different types of human pressures from recreation to pollution to coastal armoring (Lastra, 2012).Sandy beaches provide many ecosystem services including storage and transport of sediment, wave dissipation and associated buffering against extreme weather events, dynamic response to sea level rise breakdown of organic materials and pollutants, water filtration nutrient, mineralization and recycling, storage of water in dune aquifers and groundwater discharge through beaches maintenance of biodiversity and genetic resources, providing a nursery area for juvenile fishes, nesting sites or rookeries for turtles, shorebirds and pinnipeds, prey for birds and other terrestrial wildlife, scenic vistas and recreational opportunities and functional links between terrestrial and marine environment.(Defeoet al., 2009). The high tide line is an ecologically vibrant zone on the beach kelp and seagrasses wash up to this zone forming what is called the wrack line .As the wrack breaks down, it provides nutrients that form the base of the food chain on the beach supporting everything from tiny invertebrates to shorebirds (Dugan and Hubbard,2011)
Sandy beaches are dynamic ecosystem driven by prominent physical processes that shape the habitat for different functional and taxonomic groups. The term sandy beach can be used to describe a wide range of environments from high energy open ocean beaches to sheltered estuarine sand flats (Mclachlan,1983). Sandy beaches are in general dynamic environments occurring worldwide along ice-free coastlines and located at the transition between the land and a water body such as oceans seas or lakes. The beach sediment may be supplied by rivers or by the erosion of highlands adjacent to the coast and the sea may also contribute to the sediment supply through input of biogenic structures(animal skeletons, coral and shell fragments) (Mclachlan and Brown 2006).Sandy beaches are very productive and are exploited commercially through recreational activities. They represent an important transition zone between marine and terrestrial environments, where physical interactions between sediment and water movement determine beach morphology.
Beaches range from reflective (narrow, steep and high energy) to dissipative(wide, flat and low energy) with most being an intermediate between these extremes (schimel, 2011). The physical environment of sandy beaches is becoming intensely modified by anthropogenic activities, partly due to the advent of tourism and population growth in coastal areas. Overall these factors, are altering the ecology and morphology of coastal ecosystems and increasingly, coasts are becoming sites of conflict over resource use between human demands and ecosystem preservation. Threats to beach ecosystems arise from a range of stressors that span differing impacts, from global effects (e.g sea level rise,) to more localized ones (e.g trampling of dune vegetation (Meadow, et al., 1979). Off road vehicle (ORV) use is one of the most environmentally damaging human activities undertaken on sandy beaches and can alter the physical properties of coastlines through the compaction, rutting and displacement of the sand matrix and can decrease organic matter in soils and change the microclimate of the sand.
Macroinvetebrates are those organisms without backbone and are found on the substrata of an aquatic ecosystem They play a key role in mineralization of organic matter and play a significant role in marine benthic food chain and form an important link in energy transfer, form an important role in ecosystem processes such as nutrient cycling, pollutant metabolism dispersion and burial and secondary production (Snelgrove, 1998). Sediment parameters like grain size, food availability, organic content are factors affecting benthic community structure (Sanders, 1958; Kari, 2002).
Most sandy beach invertebrate phyla are represented either as meiofauna or macrofauna. The invertebrate macrofauna is most well studied component of sandy beaches and comprises benthic forms too large to move in the space between sand grains(McLachlan and Brown, 2006). The benthic macrofauna of sandy beachesinclude representatives of many phyla but crustaceans, molluscs and polychaetes are usually dominant making up more than 90% of species and biomass on ocean beaches(McLachlan and Brown, 1990). Their most pronounced characteristic is a high degree of mobility including the ability to burrowrapidly(McLachlan and Brown, 2006). Their habitat is defined by tides, waves and sand(Defeo and McLachlan.,2005) Other factors influencing their assemblages include erosion,accretion dynamics of the sediment, freshwater discharge, food supply, slope of the beach, Aeolian transport mechanisms and storm events(Brown and McLachlan, 2002; Mclean,2006).Excirolanaarmata occurred only in beaches with fine sands, Emerita brazillensis occurred in fine and coarse sand beaches(Rodil,et al., 2012).
