2.6 – Biodiversity in New Zealand Stream Communities
Zody Takurua 11DN
Introduction: Produce a formal report about the pattern in an ecological community. Investigate the aspects of of the Turitea and Manawatu waterway ecosystems. Compare the distribution of the invertebrates in relation to biotic (living) and abiotic (nonliving) factors. Analyse and interpret information about the Turitea and Manawatu waterway ecosystems, and a connecting environmental factor that relates to the pattern and how it may affect at least two species in the ecosystems.
TASK ONE – RECORDING DATA
Water Velocity:
Location
1 meter
2 meter
3 meter
4 meter
5 meter
6 meter
River
1.462ms-1
1.658ms-1
1.706ms-1
1.618ms-1
2.132ms-1
3.722ms-1
Stream
1.08ms-1
1.076ms-1
1.134ms-1
1.064ms-1
1.082ms-1
1.146ms-1
Average Velocity of River: 2.05ms-1
Average Velocity of Stream: 1.097ms-1
Note that we only measured six meters across the river to equal the stream's width. In actual context the river was too wide to measure the complete width with the equipment we were using. This is the reason why we only measured six meters out from the rivers closest embankment.
Stream Depth:
Location
1 meter
2 meter
3 meter
4 meter
5 meter
6 meter
River
62 cm
69 cm
75 cm
81 cm
81 cm
85 cm
Stream
59 cm
60 cm
56 cm
60 cm
48 cm
36 cm
Substrate Types:
Location
1 meter
2 meter
3 meter
4 meter
5 meter
6 meter
River
Mud / Silt
Smaller stones
Mixed Substrate
Larger Stones
Larger Stones
More rocks
Stream
Mixed substrate
Mixed Substrate
Larger Sharp stones
Mixed Substrate
Smaller stones
Mossy
Species Counts:
Location
Mayfly
Worms
Dobsonfly
Koura
Beetles
Snails
Caddisfly
River
1
8
2
0
5
9
0
Steam
10
3
2
1
0
0
8
Kite Graphs and cross sectional area of locations:
Description of Pattern:
The distribution pattern in the ecological community of the Turitea Stream is between Mayflies (Ephemeroptera) and Caddisflies (Trichoptera). The pattern of distribution relates to the fact that both theses species of invertebrate are located in the same areas across the stream. A point of interest was that the Manawatu river only had one Mayfly. As well as this no caddisfly specimens were found. They tend to be found in the same location due to the resources needed to survive.
The distribution pattern in the ecological community of the Manawatu River is related between Dobsonflies (Plecoptera) and snails (Gastropods). The pattern ecological distribution relates to the context of these two species of invertebrate co existing in the same natural bio-diverse community. This could be due to various biotic and abiotic factors. They tend to be in the same location as they share the same resources needed for their survival.
Abiotic Environment
During our investigation we observed that there were some abiotic (nonliving) features of the environment that could have affected our results. These features include Wind, Humidity, Water Temperature, Air Temperature, The amounts of dissolved oxygen in the water, Cloudiness of the water and the relative pH of the water.
Turitea Stream
Wind 0ms-1
Humidity 74%
Turbidity: 144.5 ntu
Ground Temperature: 11′
Air Temperature:16′
Water Temperature: 17′
Dissolved Oxygen: 9.5mg/L
pH: 7.1
Ammonia Present – Not visible with naked eye
Manawatu River
Humidity 80%
Turbidity: 154.5 ntu
Ground Temperature: 20′:
Air Temperature : 15′
Water Temperature: 15′
Dissolved Oxygen: mg/L
pH: 6.9
Ammonia Present – No
Biology of an Ecological community: Information about organisms found in ecosystems’
Caddisfly
The Caddisfly (Trichoptera) is an aquatic invertebrate that commonly inhabits clean, fresh water waterways and lakes. According to the ‘Photographic Guide of Freshwater Invertebrates of New Zealand’ handbook it has a sensitivity score of seven.
Lifecycle
The Caddisfly has a relatively short lived life cycle. Each stage of physical development genuinely taking around a year. The first stage of the Caddisfly life cycle begins with the female adult laying eggs in or closeby to a source freshwater. The eggs are secured in a gelatinous nursery for protection. The larvae then penetrate the skin of this nursery once their cilia (small hairs on exoskeleton) detect moisture. The larvae proceed to craft a protective shelter by doing one of two things. They either spin a net made of saliva and abdominal fluids or construct a mobile collection of small stones, sticks and debris. The larvae of caddisflies live out on average five instars (development stages) being sub-aquatic invertebrates. During the final instar, the caddisfly will form a cocoon and proceed to transform into a pupa. The pupa in this cocoon will eventually develop into a mature caddisfly. The pupa uses the mandibles (a specialised appendage that a pupa has) on it’s body, to make an incision and open the cocoon. The mature Caddisfly then swims to the surface. The newly immerged caddisfly will then spend 10-60 minutes drying its four wings before flying away. Mature Caddisflies have been recorded to live in between several weeks and several months. During this time period two caddisflies of opposite sex will mate and produce eggs. And after mating, the female Adult Caddisfly will lay her eggs thus continuing the life cycle. The caddisfly life cycle is described as complete metamorphosis. This is because the caddisfly undergoes four changes (morph means to change and meta means living being). Metamorphosis means complete change of a living being.
Ecological Niche
Caddisfly larvae have a diet regime that typically involves scavenging natural plant material. They inhabit in the bottom of clean, freshwater waterways and systems. They eat eat plants, algae and various organic matter. Subsequent to this, larger Caddisfly larvae may eat small invertebrates like Water Fleas and aquatic worms. Caddisfly larvae are also vulnerable to an extensive variety of predators. These predators include many species of fish like juvenile Galaxiids, Trout and Salmon, native amphibians such as Frogs and newts, birds like the Dipper, kingfishers and a large variety of waterfowl. As well as this they are prey for larger insects like Stoneflies.
Adaptations
Behavioural – A behavioural adaptation of the Caddisfly larvae is existent during the second instar. This is when the larvae crafts a protective casing out of mucus and abdominal fluids or by constructing a portable shelter out of debris and natural matter and materials. The reason for this behaviour is to provide protection for their soft bodies. Things like hard debris moving down the river can hurt them as well as providing camouflage from predators,this is because the case looks like the rest of the riverbed as it is made of natural materials. This makes it more difficult for predator to see the larvae and eat it. This behavioural adaptation allows the Caddisfly to survive more effectively in its environment by allowing it to grow larger, reduce injury and minimise the chance of being prey.
A secondary behavioural adaptation of the Caddisfly, is the ability for the Caddisfly pupa to move around inside its cacoon. This movement increases the water flow in the case, therefore the amount of dissolved oxygen they have access to is also increased. This behavioural adaptation helps the caddisfly larvae to survive in its ecological community more effectively. This is by allowing it to survive even when the dissolved oxygen levels in water are not at the substantial level.
Anatomical –
To the right is a drawing of a caddisfly larvae. Caddisfly larvae closely resemble the physical body of caterpillars. However one notable difference is that caterpillars have many pro-limbs (appendages on the abdominal segment) while Caddisfly larvae only have one full set. This pair of prolegs is of paramount importance to the caddisflies survival. This is because it helps them to either spin their nets made of fluid or to hold on to their mobile home protective casing. This anatomical adaptation allows the Caddisfly larvae to live more effectively in their environment by allowing the invertebrate to use its body parts to produce an item of protection necessary to survive.
Dobsonfly
The common dobsonfly (Plecoptera) is an invertebrate that is typically found in clean, freshwater waterways with relatively high levels of dissolved oxygen (faster flowing water). It has a sensitivity score of 8 in accordance to (Photographic Guide of Freshwater Invertebrates of New Zealand).
Life Cycle
The first stage of the dobsonflies life cycle is the deposition of eggs by the female adult dobsonfly. A large numbers of eggs are generally deposited in the waterway. They do this by either by dropping into the water while flying over. The female will dip her abdomen below the water's surface and deposit them in the water. These eggs will then hatch into Dobsonfly larvae. The larvae then stage through 10-30 instars (development stages). They move from one instar to the next by shedding their exoskeleton. This shedding takes somewhere between 1-3 years. During the last stage of development, Dobsonfly larvae will crawl onto land and moult their final exoskeleton. They are now classified as an adult Dobsonfly. Mature Stoneflies are short lives (1-4 weeks) and during this time they breed. After this, the female Adult Caddisfly will lay her eggs thus continuing the life cycle.
Ecological Niche
Dobsonfly larvae usually inhabit the river beds of clean, fast-flowing freshwater waterways with a relatively stony substrate base and high concentration of dissolved oxygen concentration. Dobsonfly larvae tend to be herbivorous in early instars. They eat plant material and algae. However during the later instars, Dobsonfly larvae often become omnivorous or carnivorous and typically eat smaller inhabitants of the river including smaller Caddisfly and Mayfly larvae.
Dobsonfly larvae have several major competing predators. These including bigger invertebrates such as dragonfly nymphs, larger Caddisfly larvae, fish such as Mountain Trout, Galaxiids and salmon as well as various water Beetle larvae.
Adaptations
Anatomical
The Dobsonfly larvae has several anatomical adaptations. Firstly the structure of the oral cavity and cranial segment of the larvae vary so when it is herbivorous it has suitable tools to digest and breakdown food that requires grinding and scraping. In contrast it will have suitable tools for when it is carnivorous. It will have a mouth adapted to clasping and piercing. This anatomical adaption allows dobsonfly larvae to eat and break down food more effectively. Secondly Dobsonfly larvae have protruding antennae which allow them to feel motion induced vibrations more effectively. This anatomical adaption of the dobsonfly larvae, allows it to sense and proceed after its prey.
Behavioural
Dobsonfly larvae have a behavioral adaptation of being ‘opportunistic feeders’. This means they eat what they can when it is available around them. This is relevant even though Dobsonfly larvae are herbivorous in early instars. This behavioural adaptation makes it easier for Dobsonfly larvae to survive, even if environmental factors around them don’t provide them with their preferred dietary needs.
Mayfly
Mayfly larvae (Ephemeroptera) is an invertebrate that is commonly found in shallow, cold and clean fresh waterways including streams, lakes near oceanic shores. It has a sensitivity score of 8.
Life Cycle
First of all in the life cycle, the female adult imago Mayfly deposits its eggs in the water. It does this by submerging the tip of her abdomen in the water whilst flying. She will lay several eggs per flyover. Quickly after being deposited, Mayfly nymphs hatch from their egg’s casing. The nymphs are less than 1mm and don’t have gills. It grows gills during its 15-25 instars . At the conclusion of these instars the nymph molts and intakes as much air as possible. This causes the nymph to rises to the water's surface. At the surface of the water, its wings come out and the mayfly is considered an adult,but in its subimago stage. The Mayfly is very vulnerable here. This is because it is too weak to takeoff in flight. Eventually the mayfly gains enough strength to fly away to a protected area where it molts once more and enters its imago stage. The adult Mayfly imago will only be alive for between several hours to several days. In this time the mayfly will breed. The female adult imago will then use its ovipositor to lay eggs thus continuing the mayflies life cycle.
Adaptations
Anatomical- The Mayfly nymph has the anatomical adaptation of having a protruding claw on on the end of each of the Mayfly nymphs limbs. This anatomical adaptation allows it to maneuver along the riverbed substrate. This allows it to be more mobile thus being able to eat more food.
Behavioral – The Mayfly nymph has the behavioural adaptation of elevating the three tails appendages.It does this when a predator approaches. This behavioural adaptation makes the Mayfly nymph look more intimidating and dangerous and so means that there is a reduced chance that the oncoming predator will eat them. If this ceases to work then Mayfly nymphs also possess the behavioural adaptation of folding their tails above their body. This behavioural adaptation creates the illusion of the Mayfly nymph being larger, this also reduces the risk that the predator will devour them. These behavioural adaptations allow the Mayfly nymph to have an increased chance of survival.
Gastropod
The Gastropod (Common freshwater snail) is a mollusk that is generically found in slow flowing freshwater. This water typically has high dissolved calcium carbonate levels and a neutral pH. It has a sensitivity score of 4.
Life Cycle
The primary stage of the gastropods life cycle involves the female mature Gastropod giving birth to live young. These offspring appear extremely similar to the mature Gastropod also have a shell. These offspring develop rapidly and start to breed young to reimburse the fact that they do not have a larval or pupal stage. Many female Gastropods of certain species can successfully undergo parthenogenesis. This is the fertilisation of their own eggs. Either way the mature female Gastropod then gives birth to live offspring, thus continuing the life cycle.
Ecological Niche
Gastropods generally live of the surface of the riverbed substrate in slow flowing freshwater with relatively neutral pH.
Gastropods tend to be herbivorous. This is because they generally just eat algae growing on the surface of stones and submerged sticks and branches. In saying this, some Gastropods are also opportunistic feeders, devouring dead organic matter. Gastropods pick up food by using their radula. This acts as an arm and passes the food to the mouth.Gastropods are an important part of many food chains in various freshwater ecosystems. There are two different types of predators involving the gastropods. They Are shell crushers and the shell invaders. Shell crushers are much bigger than the gastropod and use force to open the Gastropod’s shell and eat it. Shell crushers include fish such as mud minnows as well as freshwater koura. Shell invaders are smaller than shell crushers and are too weak to split the Gastropod’s shell so what they do instead is pull the Gastropod from their shell then eat them. Examples of shell invaders include smaller crayfish, giant water bugs and leeches.
Adaptations
Anatomicals – The Gastropod has several anatomical adaptations. The first anatomical adaption of gastropods is their shell. Their shells are constructed with calcium carbonate (CaCO3) that has dissolved in the water. This anatomical adaption makes it partially more difficult for the gastropods predators to eat it. This allows the Gastropod to have a higher chance of survival.
The second anatomical adaption of gastropods is having a hard plate located on the roof of their mouths. This plate acts as teeth and allows the Gastropod to press food against it to break it down. This anatomical adaptation therefore allows Gastropods to eat food of different sizes so therefore it allows Gastropods to be able to consume more types of food.
Physiological – The female adult Gastropods have the physiological adaption of parthenogenesis. This is the ability to fertilise their own eggs. This physiological adaptation allows the female adult Gastropod to produce offspring even when there is limited mates of desirable characteristics. This allows the Gastropod population to stay stable even when there are low numbers of them in a certain area. This gives them an increased chance of survival.
Venn Diagram of Species –
Maps – Manawatu river
Map – Turitea Stream ‘Massey End’
Discussion
Turitea Stream –
The reason why there is an ecological pattern of distribution between the caddisfly and Mayfly Larvae nymphs, is because they compete for the same resources to survive. Both the mayfly and caddisfly nymphs eat the same food and inhabit the same water conditions. Their food consists of scavenging natural plant material, plants, algae and various organic matter. As well as this, larger specimens may eat small invertebrates like Water Fleas and aquatic worms. Shadowing this the two invertebrates share the same place of inhabitance. They inhabit in the bottom of clean, freshwater waterways and systems.
Because of the similarities between these two interlinking factors, we find that caddisflies and mayflies inhabit the same area and eat the same food.
Manawatu River –
The reason why there is an ecological pattern of distribution between the dobsonfly larvae and gastropods is due to the predator-prey relationship between them. Where Gastropods (prey) are, there will be Dobsonfly (predator). This predator-prey relationship relates to the pattern of distribution as the predator (dobsonfly) wants to be near the prey (gastropod) making it easier to catch them and survive easier. Therefore in the Manawatu River these two invertebrates live close together due to their predator prey relationship.
Abiotic and Biotic environmental factors may affect organisms in the community and the distribution pattern. The Abiotic factor of water temperature may affect the related organisms in both the Turitea Stream community and Manawatu River community. In relation to the distribution pattern in each ecosystem, water temperature would be especially important to the distribution pattern of Dobsonfly nymphs and Gastropods appearing in the same place in the Manawatu River. This is because water temperature is very important to Dobsonflies. This is because Dobsonflies need a lot of oxygen and the temperature of the water affects the amount of oxygen dissolved in it. More specifically, by increasing the water temperature, the kinetic energy of particles in the water increases too. This means that particles move around more, thus making a larger space between particles in the water. The large spaces allow oxygen to escape more easily. Therefore when the temperature increases, the amount of oxygen in the water decreases. The opposite happens when the water temperature is decreased. This is important since Dobsonflies need lots of oxygen, raising the temperature will increase the amount of oxygen lost in the river and so therefore lower the numbers of Dobsonflies that can survive in the river. Higher or lower numbers of Dobsonfly nymphs would likely change the distribution pattern between Dobsonfly nymphs and gastropods, as if there are more Dobsonflies then there would be less gastropods as more would be eaten. Therefore the abiotic factor of water temperature likely affects the distribution pattern of Dobsonfly nymphs and Mayfly nymphs in the ecological community of the Turitea Stream.
The Abiotic factor of illumination may affect many organisms in both the Turitea Stream community and Manawatu River community. In relation to the pattern in each ecosystem, illumination would be especially important to the distribution pattern of Caddisfly larvae and Mayfly Larvae appearing in the same place in the Turitea Stream. This is because illumination affects the Biotic factor of algae growth. This is because for algae to survive it must photosynthesize and to do so it needs sunlight. Therefore the more illumination (sunlight) the algae gets, the more it can photosynthesize and therefore the larger it will grow. This works in the opposite as well, if the algae gets less illumination, it will photosynthesize less and therefore grow in less abundant supply. This Biotic factor of algae growth affects the distribution pattern of Caddisfly larvae and Mayflies appearing in the same. This is because algae is the main part of the diet of these two invertebrates, so if the amount of algae changes the numbers of these two specimens will likely change too find balance with the amount of food available. This means that if the amount of algae increases there will be more food available therefore invertebrate numbers increase. However if the amount of algae decreases then there will be more competition for the algae so therefore the invertebrate count will be less. Therefore the abiotic factor of illumination likely affects the biotic factor of algae growth which in turn affects the distribution pattern between Caddisfly and Mayfly larvae.