Invertebrates in restoration

Invertebrate habitat

-many have life cycles with stages that require different habitats and even ecosystems and this must be taken into account during restoration

Ex. Freshwater mussels Fig. 9.1 require suitable habitats for adults, parasitic glochidia larvae, host fish, and metamorphosed juveniles (Vaughan 2010)

-some are habitat specialist and some are more generalist, for example some have glochidia that can develop on a wide variety of fish and others only one species

-obligate mutualists often have high host specificity Ex. Reef forming corals must partner with specific dinoflagellates and fig wasps can only partner with appropriate fig species

-in some, genders require specific habitats Ex. Hine’s emerald dragonfly Fig. 9.2 or habitat resources Ex. Ground beetles that require decomposing wood Fig. 9.3

Figure 9.1 Freshwater mussels (Unionidae) have a complex life cycle, each stage of which has distinct habitat requirements

Figure 9.2 This female Hine’s emerald dragonfly has returned to a wetland to breed with males specific to wetlands after spending most of her adult life in meadows and forest clearings

Figure 9.3 A ground beetle (Nebria brevicolis) feeding on decomposing wood in an English forest

Selecting Focal (Flagship) Invertebrates

-select species rich groups that significantly overlap other groups in resource requirements Ex. Ground beetles are species rich and include species that feed at several trophic levels like the detrivore on decomposing wood, herbivores, and predators

-rare species or those threatened are often specialists with narrow geographic ranges and restoration may be part of their recovery plan Ex. Table 9.1

-some exist as community modules-set of obligate mutualists that must exist together for each to survive

Ex. In UK, large blue butterfly lays eggs only on thyme and larvae drop to ground and secrete sugar solutions that attract a species of brood rearing ants that take them into their burrow where they feed on ant larvae and pupate into adult Fig. 9.4

Table 9.1

Figure 9.4 The endangered large blue butterfly exists as part of a community module, which includes host plants from one genus, Thymus (thyme), and one species of brood-rearing ants

Habitat Restoration-Habitat Structure

Figure 9.5 A single rock in a river channel provides microhabitats that support a wide range of aquatic invertebrate species and functional groups

Figure 9.6 The functional group composition of ants changed over time in a restored uranium mine in Northern Australia. Meat ants (green) did well in early succession but as plants changed typical forest ants became as or more dominant

Habitat Restoration- Habitat Heterogeneity

Habitat heterogeneity-greater array of different types of habitat; > supports > diversity organisms

Ex. In Iowa, the highway department manages some roadsides for native prairie plants that provides invertebrate habitat Fig. 9.7

Ex. In the Jarrah (eucalyptus) Forest restoration in Western Australia, ant fauna is more diverse when a more diverse seed mix was used and was more similar to nearby reference sites Fig. 9.8

Ex. River restoration teams add heterogeneity by adding coarse woody debris and creating structures that cause high and low-flow environments Fig. 9.9

Figure 9.7 Butterfly diversity is twice as high on restored prairie roadsides like this one as on roadsides planted with only one or a few introduced species

Figure 9.8 The similarity of ant species composition in planted, seeded, and naturally recolonizing restored jarrah forests to that of reference sites

Figure 9.9 Physical habitat heterogeneity can be restored to rivers by adding coarse woody debris, creating bank structures, and installing features to create riffles and pools

Habitat Restoration- Landscape-scale stressors

-habitat fragmentation, pollution, and altered species interactions are some of landscape-scale stressors involved in invertebrate restoration

-habitat fragmentation follows tenants of island biogeography theory in regard to immigration-islands (restoration sites) closer to mainland (colonization source) have more diversity Fig. 9.10

-pollution like sewage is particularly important in aquatic ecosystems causing eutrophication Fig. 9.11

-increases of the coral-predator crown-of-thorns seastar, which may be related to overfishing (removes juvenile seastar predators) cause changes in species interactions and has affected the Great Barrier Reef ecosystem

-no-take fishing zones have fewer outbreaks Fig. 9.12

Figure 9.10 In rainforests of Queensland, Australia, older restoration sites and those closer to rainforests had a more rainforest-like beetle composition

Figure 9.11 Sewage outfall in a coral reef contributes to eutrophication

Figure 9.12 (A) Crown-of-thorns starfish preying on corals. (B) Crown-of-thorns starfish outbreaks on the Great Barrier Reef, 1992–2004, for mid-shelf reefs where most outbreaks occur

Nontarget impacts of restoration actions on invertebrates

Figure 9.13 (A) The cottony cushion scale, which feeds on plant sap, was introduced to the Galápagos Islands from Australia and affected several rare plant species. (B) Scale populations were reduced by introducing a ladybird beetle that only feeds on the scale.

Invertebrate species translocations

-9% of reintroduction programs worldwide involve reintroductions even though invertebrates constitute 77% of species on the planet

-since many endangered invertebrates are habitat specialist precise information about the species life cycle and its connections to habitat are crucial

-be sure source populations are large enough to survive losing individuals for translocation Ex. New Zealand’s Mana Island restoration involved removal of introduced mice which allowed population of wetas to dramatically increase and be used for reintroduction to other islands Fig. 9.14

-Rescues of invertebrates when habitat has been destroyed can also be used in translocations Ex. Coral obtained after ship groundings and re-attached or used to establish coral nurseries Figs. 9.15-9.16

Figure 9.14 Cook Strait weta populations on Mana Island were used as source populations for translocations to nearby islands

Figure 9.15 Diver reattaching small colonies of coral to a stable reef substrate using epoxy

Figure 9.16 This coral nursery raises corals for reef restorations in the Red Sea, Israel

Captive breeding and releases

-must determine methods of capture and transport, numbers needed for genetic diversity, food sources, housing, sanitation, control of environmental conditions, and colony maintenance

-removing many individuals from wild populations can increase the risk of that population becoming extinct and one way to reduce impact to source populations is to collect eggs and larvae from species with long-lived adults like mussels where glochidia from gills are used for captive breeding Fig. 9.17

-founder populations from near the restoration should be used so the source population and release site are well matched in terms of environmental conditions Ex. Large blue butterfly reintroductions into the United Kingdom had to take into account the migration patterns to allow adults to lay eggs on thyme flower buds Fig. 9.18

Figure 9.17 A mussel recovery specialist for the Aquatic Wildlife Conservation Center checks units for rearing juvenile mussels at the AWCC’s facility in Marion, Virginia

Figure 9.18 A large blue butterfly larva on Thymus flower buds. Restoration sites had to have flowers in bud at the same time as source sites for success

Releases-Hard or Soft?

Figure 9.19 Restorationists releasing larvae of the marsh fritillary (Euphydryas aurinia) near the River Liza in the U.K.

Figure 9.20 The regal fritillary (Speyeria idalia) was reintroduced to the Neal Smith National Wildlife Refuge using a “soft release” approach. The cage was left out for a month and contained nectar bearing violets that allowed the gravid butterflies to acclimate before being released.

Management of invertebrate habitat

Management of invertebrate habitat

Figure 9.21 The blue-winged grasshopper lays its eggs in open habitats on coastal dunes, but requires dense patches of vegetation for feeding

Monitoring invertebrates in restored ecosystems

Three common approaches and examples:

Figure 9.22 Scientists used network analysis to understand why a typical bumblebee parasitoid of ancient heathlands was much less prevalent in restored heathlands in the U.K. After 15 years, the networks were still different.